The burden of the COVID-19 pandemic in Peru has led to people seeking alternative treatments as preventives and treatment options such as medicinal plants. This study aimed to assess factors associated with the use of medicinal plants as preventive or treatment of respiratory symptom related to COVID-19 during the pandemic in Cusco, Peru.
A web-based cross-sectional study was conducted on general public (20- to 70-year-old) from August 31 to September 20, 2020. Data were collected using a structured questionnaire via Google Forms, it consisted of an 11-item questionnaire that was developed and validated by expert judgment using Aiken’s V (Aiken’s V > 0.9). Both descriptive statistics and bivariate followed by multivariable logistic regression analyses were conducted to assess factors associated with the use of medicinal plants for COVID-19 prevention and respiratory symptom treatment during the pandemic. Prevalence ratios (PR) with 95% Confidence Interval (CI), and a P-value of 0.05 was used to determine statistical significance.
A total of 1,747 respondents participated in the study, 80.2% reported that they used medicinal plants as preventives, while 71% reported that they used them to treat respiratory symptoms. At least, 24% of respondents used medicinal plants when presenting with two or more respiratory symptoms, while at least 11% used plants for malaise. For treatment or prevention, the multivariate analysis showed that most respondents used eucalyptus (p < 0.001 for both), ginger (p < 0.022 for both), spiked pepper (p < 0.003 for both), garlic (p = 0.023 for prevention), and chamomile (p = 0.011 for treatment). The respondents with COVID-19 (p < 0.001), at older ages (p = 0.046), and with a family member or friend who had COVID-19 (p < 0.001) used more plants for prevention. However, the respondents with technical or higher education used less plants for treatment (p < 0.001).
Citation: Villena-Tejada M, Vera-Ferchau I, Cardona-Rivero A, Zamalloa-Cornejo R, Quispe-Florez M, Frisancho-Triveño Z, et al. (2021) Use of medicinal plants for COVID-19 prevention and respiratory symptom treatment during the pandemic in Cusco, Peru: A cross-sectional survey. PLoS ONE 16(9): e0257165. https://doi.org/10.1371/journal.pone.0257165
Editor: Mohd Adnan, University of Hail, SAUDI ARABIA
Received: May 12, 2021; Accepted: August 24, 2021; Published: September 22, 2021
Copyright: © 2021 Villena-Tejada et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: Anonymized data set supporting the findings of this study is stored at the Dryad data repository (https://datadryad.org/stash/share/Yke7zt5MuVeD7aE8ie5G_jrbYPE8ZaRCLH58FuYI9QI).
Funding: The authors would like to thank the Universidad Nacional de San Antonio Abad del Cusco (UNSAAC) grant R-446-2020-UNSAAC. The funder provided support in the form of expenses related to the data collection from the survey, commercial license for the statistical software, translation and publication fees. The funder did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the Author Contributions section.
Competing interests: The authors declare that they have no conflict of interests. JAY is currently employed by the commercial company Teoma Global, but there is no conflict of interest related to any of the medicinal plants or commercial products. This does not alter our adherence to PLOS ONE policies on sharing data and materials.
COVID-19 was declared a pandemic by the World Health Organization (WHO) on March 11, 2020 because of its rapid transmission and infection rates worldwide [1, 2]. This disease is characterized by a progressive and severe pneumonia, and the most common symptoms are fever, dyspnea, dry cough, fatigue, headache, anosmia, and ageusia [2–4]. However, recent evidence indicates that multiple neurological complications, besides anosmia, could present in COVID-19 patients . Some of those neurological complications include headache, myalgia, dizziness, encephalitis, stroke, epileptic seizures and Guillain-Barre syndrome . As of May 11, 2021, more than 159 million global confirmed cases and more than 3 million deaths have been reported . The first confirmed case in Peru was reported on March 8, 2020 , and the number of cases rapidly increased despite the measures established by the Peruvian government [8, 9]. In less than four months, Peru ranked second among Latin American countries, following Brazil, for the highest number of COVID-19 cases and deaths [10, 11]. Physical isolation was the main preventive measure implemented worldwide to avoid the contagion [8, 12, 13], which caused multiple lifestyle changes in people. Many people have experienced the death of family and friends [14–17], which has resulted in anxiety and mental distress [18–21]. The widespread disinformation [7, 22], fake news  and anti-vaccine comments [23, 24] have caused an increase in self-medication , use of medicinal plants, and other alternative treatments . Many have urged that the general state of disinformation be addressed by governmental institutions [7, 27, 28]. Multiple publications have illustrated the fragmented healthcare system in Peru, which has not been the most effective during the COVID-19 pandemic resulting in a high number of physicians’ deaths , limited public policies , and detrimental effects in the mental status of the population [21, 27]. Furthermore, Peru has reported discrepancies in the official reports of COVID-19 deaths nationwide , poor execution of SARS-CoV-2 testing and reporting , and an increase number of COVID-19 cases in children and adolescents [8, 16].
The current pandemic generates fear in the population who seek solutions to prevent or alleviate the symptoms of the disease since they feel the only resource available to the is to self-help, self-care and self-medicate . Therefore, it has been reported that some people resource to self-medication  and others to the use of medicinal plants  as potential but unproven methods to ameliorate and/or prevent symptoms related to COVID-19. The Ministry of Health in Peru published the symptomatic pharmacological treatment options for COVID-19 to control the pandemic . These options included the clinical use of hydroxychloroquine and ivermectin for mild cases of COVID-19 and hydroxychloroquine plus azithromycin and/or chloroquine phosphate plus ivermectin for moderate and severe cases of COVID-19 [7, 34, 35]. However, this recommendation led to self-medication reports in Peru [7, 25], which also gets accompanied with the use of medicinal plants. This practice has become increasingly common in Peru as panic spread in the general population, who anxiously wait for positive news about the prevention, treatment and vaccination . It has been reported that medicinal plants and bioactive compounds that previously exhibited antiviral activity against SARS-CoV-1 and MERS-CoV, could also exhibit potential efficacy against SARS-CoV-2 [36, 37]. This potential activity has been proposed to be due to their activity on the ACE-2 receptor, 3CLpro and other SARS-CoV-2 viral protein targets . Another approach has been centered around the computational approaches to search for potential inhibitory compounds against the active binding pockets of SARS-CoV-2 target proteins . It has been also reported that mesenchymal stem cells (MSCs) and their exosomes (MSCs-Exo) can significantly lower the risk of lung injuries related to alveolar inflammation and related pathological conditions, such as the one observed in COVID-19 patients .
The idiosyncrasy of the population has also focused on the use of medicinal plants, natural products or preparations, with antiviral and anti-inflammatory properties to strengthen the immune system or treat respiratory diseases . Countries, such as China, India, Bolivia, Morocco, Nepal, Peru and Brazil, are using traditional medicine against COVID-19 [40–49]. There are approximately 50,000 plant species with medicinal uses, and the WHO has estimated that 80% of the population of developing countries use traditional medicine as their main source of medicines . In Europe, the clinical use of medicinal plants is approved under the directive 24/2004 for the treatment of colds ; these treatments are accessible and available. In Latin America, the Regional Office of WHO for the Americas (AMOR/PAHO) indicates that 71% and 40% of the population of Chile and Colombia, respectively, use traditional medicine [52, 53]. In Peru, a megadiverse country, the use of medicinal plants for the treatment of various conditions, such as malaise and gastrointestinal and respiratory diseases, dates from the Inca period [41, 53–56], and currently approximately 1,400 species are used for medicinal purposes in both native and urban communities [41, 53]. It comes as no surprise that traditional medicine is currently being used by the Peruvian population in the context of the COVID-19 pandemic. Thus, the objective of this study was to assess factors associated with the use of medicinal plants as an adjuvant for the treatment or prevention of respiratory symptoms during the COVID-19 pandemic in Cusco, Peru.
Materials and methods
The survey was approved by the San Antonio Abad del Cusco National University ethics committee (#007-2020-CBI-UNSAAC). Written consent was obtained from the participants before starting the survey. The participants remained anonymous and had the option to finish the survey at any time, and their information was kept confidential. All the survey participants were well-versed on the study intentions and were required to consent before the enrollment. The participants were not involved in any of the planning, execution and reporting stages of the study.
We conducted an online cross-sectional multicenter survey, which was initially evaluated by 10 expert judges using Aiken’s V . After including the experts’ observations, a pilot study was performed (from August 16 to 24, 2020) with 336 respondents in in five districts of Cusco, Peru. The pilot data was used to calculate the minimal sample size necessary for the actual study. It was determined that a minimum sample size of 1,530 was necessary to achieve a minimum percentage difference of 2.5% (49.0% versus 51.5%), a statistical power of 80%, and a confidence level of 95%. The sample size was calculated using power analysis .
The actual survey consisted of an online questionnaire that was sent via WhatsApp, Messenger, and Facebook. The shared questionnaire was made anonymous ensuring data confidentiality and reliability. The survey was performed from August 31 to September 20, 2020 after approximately 9 months of lockdown and social distancing measures in Peru due to the COVID-19 outbreak. At the beginning of the survey (August 31) the number of COVID-19 confirmed cases was 652,037 and 28,944 deaths , while at the end of the survey (September 20) the confirmed cases increased to 772,896 and the deaths increased to 31,474 . We surveyed general public who were adults of both genders aged 20 to 70 years in five districts of Cusco, Peru with high-risk COVID-19 transmission according to the Epidemiological Alert AE-017-2020 . The five districts were Cusco, San Jerónimo, San Sebastián, Santiago, and Wanchaq. Participants were recruited by the research team of the Universidad Nacional de San Antonio Abad del Cusco. There were no exclusions because we implemented that it was mandatory to reply all the answers. Therefore, we only obtained complete and high-quality answers, which was verified by a data quality check.
Outcomes and covariates
The survey (S1 Annex) included 11 questions, 5 were demographic questions, 2 were related to the use of medicinal plants as preventive or treatment of respiratory symptoms related to COVID-19, 2 were related to the diagnosis of COVID-19 in themselves and the close environment (family and friends), and the last 2 questions related to the medicinal plants were used and to what respiratory symptom(s) they were used for. The demographic questions included sex, age, education level, occupation or professional activity and the district of residence in Cusco.
The respondents were asked to indicate if during the COVID-19 lockdown they used medicinal plants to prevent or treat respiratory symptoms related to COVID-19. Then, the respondents were asked if they were diagnosed with COVID-19, and if any family member or friend was diagnosed with COVID-19. The respondents were asked to select from a list of 17 selected medicinal plants the ones they have used to prevent or treat COVID-19 related respiratory symptoms. The selection of the medicinal plants was based on ethnopharmacological reports of the ones used for respiratory problems in Peru [62–68]. Finally, the respondents were asked to select the symptom(s) why they consumed any of the medicinal plants indicated on the previous question. The symptoms included cough, sore throat, fever, headache or malaise. Loss of taste or smell, nausea/vomiting and diarrhea were not included. The selected symptoms relate to the most common COVID-19 symptoms reported by the Center of Disease Control and Prevention (CDC) .
Data analysis was done in STATA version 14 (Stata Corp) with a significance level set at p<0.05. Descriptive analysis of categorical (demographic) variables was performed to show the frequency and percentage of each response. The results were summarized in unidimensional tables to identify the medicinal plants that are most used by the respondents. Chi-square test was performed in the bivariate analysis to determine the association between the studied variables. Generalized linear models were used in the multivariate analysis using the Poisson family, the log-link function, and the models for variances of robust models and the district of residence as a cluster, thereby obtaining the prevalence ratios (PR). The 95% confidence intervals (CI) and p-value < 0.05 were considered as the limit of statistical significance.
Sociodemographic characteristics of the respondents
A total of 1,747 respondents participated in this study. The majority of the study participants were female [59.1% (1,033)], the median age was 31 years (interquartile range: 24–41 years), 29.7% (518) were university and high school students, 59.2% (1,035) had higher education, and 33.3% (582) lived in the district of Cusco. Concerning to the COVID-19 questions and use of medicinal plants, 12.2% (214) had COVID-19, 65.9% (1,151) had a family member or friend with COVID-19, 80.2% (1,401) used medicinal plants to prevent respiratory symptoms, and 71.0% (1,241) used medicinal plants to treat respiratory symptoms (Table 1).
Use of medicinal plants as preventive or treatment for respiratory symptoms
As shown on Table 2, the use of medicinal plants for the prevention of respiratory symptoms was associated with gender (p < 0.001), age (p < 0.001), occupation (p < 0.001), education (p < 0.001), and whether a family member or friend had COVID-19 (p < 0.001). However, no association was observed with the district of residence (p = 0.702) and if the respondent had COVID-19 (p = 0.632). In the case of the use of medicinal plants for the treatment of respiratory symptoms, the bivariate analysis showed that it was associated with gender (p = 0.013), age (p < 0.001), occupation (p < 0.001), education (p < 0.001), district of residence (p = 0.005), whether the respondent had COVID-19 (p < 0.001), and whether a family member or friend had COVID-19 (p < 0.001).
Medicinal plants used and respiratory symptoms associated with their use as treatment options
As shown on Table 3, the respondents reported the use of medicinal plants from a preselected list for the treatment of COVID-19 related respiratory symptoms. The most frequently used medicinal plant was eucalyptus (Eucalyptus globulus Labill.) followed by ginger (Zingiber officinale Roscoe), garlic (Allium sativum L.), matico (Piper aduncum L.), chamomile (Matricaria recutita L.) and coca (Erythroxylum coca Lam.). It was observed that all the medicinal plants were used for 2 or more respiratory symptoms. The bivariate statistics showed that the use of medicinal plants was associated with the occurrence of two or more symptoms (24–51%), followed by malaise (11–41%). In addition, there was a difference in consumption according to the type of symptom (p < 0.041) for all medicinal plants except panty (Cosmos peucedanifolius Wedd.) (p = 0.076).
Multivariate analysis of the factors associated to the use of medicinal plants
In the multivariate analysis (Table 4) of the use of medicinal plants for the treatment or prevention of respiratory symptoms during the COVID-19 pandemic found a positive association with the use of eucalyptus (Eucalyptus globulus Labill.) for treatment (PR: 1.26, 95% CI: 1.16–1.37, p < 0.001) and prevention (PR: 1.24, 95% CI: 1.15–1.35, p < 0.001). Followed by the use of matico (Piper aduncum L.) for treatment (PR: 1.20, 95% CI: 1.07–1.34, p = 0.011) and prevention (PR: 1.12, 95% CI: 1.06–1.19, p < 0.001). In addition, there is also a positive association between the use of ginger for treatment (PR: 1.13, 95% CI: 1.03–1.25, p = 0.011) and prevention (PR: 1.08, 95% CI: 1.01–1.16, p = 0.021), the use of garlic (Allium sativum L.) for prevention only (PR: 1.06, 95% CI: 1.01–1.11, p = 0.023), and the use of chamomile (Matricaria recutita L.) for treatment only (PR: 1.12, 95% CI: 1.03–1.23, p = 0.011).
There was also a negative association between the use of wira wira (Ganaphalium viravira Molina) for treatment (PR: 0.9, 95% CI: 0.82–0.98, p = 0.016) and prevention (PR: 0.89, 95% CI: 0.85–0.93, p < 0.001) and the use of panty for treatment only (PR: 0.87, 95% CI: 0.78–0.97, p = 0.009). Therefore, eucalyptus (Eucalyptus globulus Labill.), matico (Piper aduncum L.), ginger (Zingiber officinale Roscoe), and chamomile (Matricaria recutita L.) were the most used for the treatment of respiratory symptoms, whereas panty (Cosmos peucedanifolius Wedd.) and wira wira (Ganaphalium viravira Molina) were the least used. As for prevention, eucalyptus (Eucalyptus globulus Labill.), matico (Piper aduncum L.), ginger (Zingiber officinale Roscoe), and garlic (Allium sativum L.) were the most used, whereas wira wira (Ganaphalium viravira Molina) was the least used.
Regarding the adjustment of demographic variables and the use of medicinal plants for the treatment or prevention of respiratory symptoms, it is important to mention that there was a positive association between age and prevention (PR: 1.00, 95% CI: 1.00–1.01, p = 0.046). Precisely, older respondents used more medicinal plants for prevention. There was also a positive association between the respondents diagnosed with COVID-19 and the use of medicinal plants for treatment (PR: 1.22, 95% CI: 1.11–1.34, p < 0.001); precisely, those with COVID-19 used more medicinal plants for prevention. There was also a positive association between the respondents with a family member or friend diagnosed with COVID-19 and the use of medicinal plants for treatment (PR: 1.11, 95% CI: 1.06–1.17, p < 0.001) and prevention (PR: 1.08, 95% CI: 1.04–1.13, p < 0.001), but the respondents used fewer plants for treatment if they had a technical or higher education (PR: 0.89, 95% CI: 0.83–0.95, p < 0.001).
Regarding the prevention of COVID-19 respiratory symptoms, this study showed that 80.2% of the population of Cusco, Peru, used medicinal plants for this purpose. Comparatively, a study conducted in a population of the state of Querétaro in Mexico showed that the main conditions treated with medicinal plants were asthma (18.42%), bronchitis (2.6%), flu (5.2%), congestion in the respiratory tract (10.5%), sore throat (21%), throat infection (15.7%), pneumonia (5.2%), sinusitis (10.55%), cough (55.2%), and tuberculosis (2.6%) . Additionally, there are populations in many regions of the world that are using medicinal plants for the prevention of COVID-19, because these plants are more readily available than Western medicine. In this regard, a study performed in the Moroccan population has mentioned medicinal plants similar to those reported in this study, such as eucalyptus, garlic, onion, ginger, thyme, turmeric, and rosemary .
Regarding the use of medicinal plants for the treatment of COVID-19 respiratory symptoms, 29.0% of the respondents did not use any plant, whereas 71.0% did. One of the most relevant clinical manifestations of COVID-19 is the great damage on the respiratory tract, causing respiratory distress that can lead to death, and for this reason, effective and non-invasive treatments are required . This includes the use of medicinal plants, which were revalued during this pandemic to manage the COVID-19 symptoms, because plants are a source of plant metabolites with antiviral activity . In this context, a study carried out in Bolivia evaluated eucalyptus, wira wira, and chamomile for their antibacterial, anti-inflammatory, and fungicidal properties . Alternatively, it has been reported that diet supplementation with probiotics and nutraceuticals play a fundamental role in the treatment of respiratory symptoms, because many products produce an immune response to respiratory viruses in addition to their regulatory activity for the inflammation caused by COVID-19 . The therapeutic use of medicinal plants has increased in many Latin American countries over time . Our study reported that 80% of the respondents used medicinal plants when they or their family member or friend had COVID-19, which correlates to previous reports .
As for the socio-educational factors associated with the use of medicinal plants for the prevention of respiratory symptoms, our study reported that female respondents (83.1%) used them. This correlates to previous studies where women are more versed in the properties of medicinal plants  and that they typically use medicinal plants to take care of the health of their family members [78, 79]. Therefore, probably in most populations, women are those who transmit the traditional domestic knowledge from generation to generation . Sighal obtained different results in a study performed in 2005 on the role of gender in the use and management of medicinal plants in indigenous communities of India, as it was found that both females and males had the knowledge and appreciation of their use . The study of Biniam et al. found a greater tendency for women to use medicinal plants than men . This relevant role of women is not only in medicinal plants but also in food safety practices . This factor is relevant in the current context of the COVID-19 pandemic, and it is relevant to focus on females as an important element for the prevention and rational treatment of patients with COVID-19.
Regarding the significant association between the use of medicinal plants with primary and secondary education, this is explained by the fact that those with professional training are more likely to use a scientifically validated treatment, abandoning the use of medicinal plants. It has been reported that elder and low education people could be at higher risk of disease complications because they prefer the use of medicinal plants over the adherence to pharmacological treatment . This could potentially be riskier for patients with COVID-19.
For the treatment of COVID-19 respiratory symptoms, 24 to 51% of respondents in our study used medicinal plants when there were more than two symptoms and 11 to 41% when they presented malaise. There are studies describing the ethnomedicinal use during the COVID-19 pandemic of different communities and cultures around the world, especially in Asian countries, such as India, China, Japan, and Pakistan and some parts of Africa . COVID-19 symptoms develop with inflammation and hemotoxicity, which could suggest that blood-purifying plants with anti-inflammatory, antioxidant, and antiviral properties could be considered as candidates for the treatment of COVID-19 . There are also herbal remedies, such as those made from Uncaria tomentosa or cat’s claw, a climbing vine that grows in the Peruvian jungle, which is used to stimulate the immune system . The most used plants in our study included eucalyptus (Eucalyptus globulus Labill.), garlic (Allium sativum L.), lemon balm (Melissa officinalis L.), and geranium (Geranium sibiricum L.). It has been reported that eucalyptus (Eucalyptus globulus Labill.) is an effective antiviral agent against SARS-CoV-2 for its eucalyptol content, which was assessed in molecular docking studies . Moreover, it has been reported that jensenone, a compound obtained from the essential oil of eucalyptus exhibits antiviral effect against the main protein of SARS-CoV-2 . Additionally, garlic (Allium sativum L.) exhibited an inhibitory effect on SARS-CoV-2 replication; thus, it is a promising agent against COVID-19 . A similar effect was found for palillo, a curcumin extracted from turmeric , as determined by molecular docking studies . A meta-analysis study performed on medicinal plants suggested that plants, such as turmeric, can be used as a prophylaxis against SARS-CoV-2 according to docking studies that suggest its use; therefore, more trials should be carried out . Another study was performed on natural molecules from plants with antiviral properties such as rosemary and cinnamon, reporting that they present low toxicity, and abundant active ingredients that can be used against viral infections . There are also other studies on medicinal plants, such as ginger (Zingiber officinale Roscoe), whose rhizome has been used to alleviate fever and other COVID-19 symptoms in Africa . The essential oil of eucalyptus (Eucalyptus globulus Labill.) has been reported to enhance the innate cell-mediated immune response and can be used in infectious diseases as an immunoregulatory agent . An analysis of the essential oil detected 11 bioactive compounds such as 1.8 cineole (85.8%), α-pinene (7.2%) and β- myrcene (1.5%) . Other compounds identified in the oil were β-pinene, limonene, α-phelandrene, γ-terpinene, linalol, pinocarveol, terpinen-4-ol and α-terpineol, that exhibited antimicrobial effects .
In the case of ginger (Zingiber officinale Roscoe), a randomized controlled study was performed to assess its effects on respiratory manifestations in patients with acute respiratory syndrome due to COVID-19 . The experimental group was administered the standard treatment for COVID-19 according to the protocol of the Iranian Ministry of Health along with ginger tablets (Vomigone®) in a dose of 1000 mg, 3 times a day, for a period of seven days . An improvement in clinical symptoms was evidenced within 7 days of treatment including fever, dry cough, fatigue and other symptoms such as thrombocytopenia, lymphocytopenia and C-reactive protein . The consumption of ginger has been attributed to have properties against pneumonia and pulmonary fibrosis, and in the latter case it reduces oxidative stress and the inflammatory response in animal models that were chemically induced with pulmonary fibrosis .
Garlic (Allium sativum L.) is consumed around the world as a condiment and is an important part of traditional Chinese and Indian medicine since its active principles are organosulfides, saponins and polysaccharides . Its immunomodulatory activity is mainly due to the polysaccharides as they regulate the homeostasis of the immune system, maintain the immune response and the expression and proliferation of cytokine genes . The bioactive compounds present in garlic have potential effects on respiratory tract infections, intra-alveolar edema, pulmonary fibrosis, sepsis, and acute lung injury . Its active principles: allicin, s-allyl cysteine (SAC), alliin and diallyl thiosulfonate (allicin) showed antiviral, antifibrotic, antioxidant, anti-inflammatory and immunomodulatory properties . Asmachilca (Aristeguietia gayana (Wedd.)) is used for its expectorant effect and in asthma cases . However, caution needs to be applied because it contains 1,2-dehydropyrrolizidine alkaloid esters , which have been reported to potentially cause hepatotoxicity, pneumotoxicity, genotoxicity and carcinogenicity . It is important to mention that certain medicinal plants reported as potential complementarity treatments for COVID-19 can contain compounds that could be harmful . For instance, Echinacea purpurea can increase the release of IL-1, IL-10 and TNF-α by macrophages [98, 99]. Thus, causing hypercytokinaemia or the increase of proinflammatory cytokines that can cause complication in COVID-19 patients [37, 100]. Another example is Chinchona sp. because it contains quinine, which has a mode of action similar to chloroquine . Quinine has been reported to have a dual effect related to immune response, it acts as immunostimulator when it effectively intensifies the production of IFN-α . However, it can also inhibit the release of TNF-α causing an immunosuppressant effect . This dual effect should caution healthy people to constantly consume Chinchona sp. as a COVID-19 preventive because of the potential harmful effect it can cause .
Peru is one of the countries that have a wide pantry of medicinal plants that are one of the main alternatives in health care to prevent and treat various diseases. In different countries, there is also a worldwide wealth of knowledge, theories, and practices on the use of plants as natural medicines for the treatment of diseases. Medicinal plants have been used since prehistoric times–a tradition that has been passed down from generation to generation. Traditionally, medicinal plants are consumed as the fresh form (i.e. ginger) or dry leaves, both in infusions with hot water. The World Health Organization (WHO) considers the Natural and Traditional Medicine, which includes treatment with medicinal plants, as the most natural, safe, effective, and affordable medicine . The use of medicinal plants for respiratory conditions has also been reported in various parts of the world from China , India , Saudi Arabia  to Mexico  and Ecuador . However, it needs to be acknowledged that the ethnopharmacological use of medicinal plants for prevention or treatment of respiratory symptoms related to COVID-19 still needs to be evaluated in clinical settings in order to have solid evidence of their effectiveness and to isolate compounds with potential pharmacological use. Another important factor to evaluate in more detail is the effect that the COVID-19 pandemic in the dynamics of the community as well as the SARS-CoV-2 prevalence and fate in environmental matrices, which could help policy maker to develop mitigation strategies [26, 106, 107].
The limitations of this study included the fact that the results cannot be extrapolated to the entire Peruvian population. The objective of this study was to determine the association between the use of medicinal plants and the treatment or prevention of respiratory symptoms in the population of the five districts of Cusco, one of the most important cities in Peru. However, this study is the first to investigate this association in this population; therefore, this could become a basis for other studies that could cover a larger population from all over the country.
Another limitation was the selection bias cause by not having performed random sampling to obtain the responses. Because of the nature of the study (cross-sectional study design) we could not determine definitive cause and effect associations. Similarly, the responders performed a self-reported assessment in an online data collection platform, which could lead to under or over-reporting and the data collector has not ability to verify or validate. Another limitation was that we did not assess frequency of consumption of medicinal plants, nor the amount of plant consumed.
The current study reported an association between the use of 17 medicinal plants and the treatment or prevention of the respiratory symptoms related to COVID-19, and the most used plants were eucalyptus, ginger, spiked pepper, chamomile, and garlic. Moreover, it was determined that the study population used a greater number of plants for disease prevention when the respondent was older and if they or a friend or family member had contracted COVID-19. It was also observed that respondents with technical or higher education used less plants for treatment. The potential use of medicinal plants for respiratory conditions is acknowledged but more research is necessary to have solid evidence of their effectiveness and to isolate compounds with potential pharmacological use. Further studies are warranted to determine proper doses, forms of preparation and potential combination of these medicinal plants.
S1 Annex. Survey to assess the use of medicinal plants in the prevention and treatment of respiratory symptoms during the COVID-19 pandemic.
- 1. Juscamayta-López E, Tarazona D, Valdivia F, Rojas N, Carhuaricra D, Maturrano L, et al. Phylogenomics reveals multiple introductions and early spread of SARS-CoV-2 into Peru. bioRxiv. 2020:2020.09.14.296814.
- 2. González-Bustamante B. Evolution and early government responses to COVID-19 in South America. World Development. 2021;137:105180. pmid:32921879
- 3. Yang W, Cao Q, Qin L, Wang X, Cheng Z, Pan A, et al. Clinical characteristics and imaging manifestations of the 2019 novel coronavirus disease (COVID-19): A multi-center study in Wenzhou city, Zhejiang, China. Journal of Infection. 2020;80(4):388–93. pmid:32112884
- 4. Gavriatopoulou M, Korompoki E, Fotiou D, Ntanasis-Stathopoulos I, Psaltopoulou T, Kastritis E, et al. Organ-specific manifestations of COVID-19 infection. Clinical and Experimental Medicine. 2020;20(4):493–506. pmid:32720223
- 5. Kumar D, Jahan S, Khan A, Siddiqui AJ, Redhu NS, Wahajuddin, et al. Neurological Manifestation of SARS-CoV-2 Induced Inflammation and Possible Therapeutic Strategies Against COVID-19. Molecular Neurobiology. 2021;58(7):3417–34. pmid:33715108
- 6. Dong E, Du H, Gardner L. An interactive web-based dashboard to track COVID-19 in real time. The Lancet Infectious diseases. 2020;20(5):533–4. pmid:32087114
- 7. Rojas Román B, Moscoso S, Chung SA, Limpias Terceros B, Álvarez-Risco A, Yáñez JA. Tratamiento de la COVID-19 en Perú y Bolivia y los riesgos de la automedicación. Revista Cubana de Farmacia. 2020;53(2):1–20.
- 8. Yáñez JA, Alvarez-Risco A, Delgado-Zegarra J. Covid-19 in Peru: from supervised walks for children to the first case of Kawasaki-like syndrome. BMJ (Clinical research ed. 2020;369:m2418. pmid:32571770
- 9. Alvarez-Risco A, Mejia CR, Delgado-Zegarra J, Del-Aguila-Arcentales S, Arce-Esquivel AA, Valladares-Garrido MJ, et al. The Peru Approach against the COVID-19 Infodemic: Insights and Strategies. The American Journal of Tropical Medicine and Hygiene. 2020;103(2):583–6. pmid:32500853
- 10. Ibanez A, Kosik KS. COVID-19 in older people with cognitive impairment in Latin America. The Lancet Neurology. 2020;19(9):719–21. pmid:32822627
- 11. Munayco C, Chowell G, Tariq A, Undurraga EA, Mizumoto K. Risk of death by age and gender from CoVID-19 in Peru, March-May, 2020. Aging. 2020;12(14):13869–81. pmid:32692724
- 12. Salathé M, Althaus C. L., Neher R., Stringhini S., Hodcroft E., Fellay J., et al. COVID-19 epidemic in Switzerland: on the importance of testing, contact tracing and isolation. Swiss medical weekly. 2020;150:1112. pmid:32191813
- 13. MacIntyre CR. Case isolation, contact tracing, and physical distancing are pillars of COVID-19 pandemic control, not optional choices. The Lancet Infectious Diseases. 2020;20(10):1105–6. pmid:32559453
- 14. Gonzales-Tamayo L, Arevalo-Oropeza M, Yanez JA. COVID-19 Physician Deaths in Peru: A Result of An Underfunded and Fragmented Healthcare System. 2020.
- 15. VanderWeele TJ. Challenges Estimating Total Lives Lost in COVID-19 Decisions: Consideration of Mortality Related to Unemployment, Social Isolation, and Depression. JAMA. 2020;324(5):445–6. pmid:32639547
- 16. Yáñez JA, Alvarez-Risco A, Delgado-Zegarra J. Rapid Response: Clearing the path for COVID-19 in Peru? The decision of supervised walks for children and adolescents: The British Medical Journal; 2020 [Available from: https://www.bmj.com/content/369/bmj.m1918/rr-9.
- 17. Yáñez JA, Alvarez-Risco A, Delgado-Zegarra J. Rapid Response: Does Peru really have that high number of COVID-19 confirmed cases? The deception of combining RT-PCR and rapid test results: The British Medical Journal; 2020 [Available from: https://www.bmj.com/content/369/bmj.m2518/rr-4.
- 18. Zhang SX, Chen J, Afshar Jahanshahi A, Alvarez-Risco A, Dai H, Li J, et al. Succumbing to the COVID-19 Pandemic—Healthcare Workers Not Satisfied and Intend to Leave Their Jobs. International journal of mental health and addiction. 2021; Online ahead of print:1–10.
- 19. Chen X, Zhang SX, Jahanshahi AA, Alvarez-Risco A, Dai H, Li J, et al. Belief in a COVID-19 conspiracy theory as a predictor of mental health and well-being of health care workers in Ecuador: Cross-sectional survey study. JMIR Public Health Surveill. 2020;6(3):e20737. pmid:32658859
- 20. Yañez JA, Afshar Jahanshahi A., Alvarez-Risco A., Li J., Zhang S. X. Anxiety, Distress, and Turnover Intention of Healthcare Workers in Peru by Their Distance to the Epicenter during the COVID-19 Crisis. The American Journal of Tropical Medicine and Hygiene. 2020;103(4):1614–20. pmid:32815512
- 21. Yan J, Kim S, Zhang SX, Foo M-D, Alvarez-Risco A, Del-Aguila-Arcentales S, et al. Hospitality workers’ COVID-19 risk perception and depression: A contingent model based on transactional theory of stress model. International Journal of Hospitality Management. 2021;95:102935.
- 22. Bernard R, Bowsher G, Sullivan R, Gibson-Fall F. Disinformation and Epidemics: Anticipating the Next Phase of Biowarfare. Health security. 2020;19(1):3–12. pmid:33090030
- 23. Stolle LB, Nalamasu R, Pergolizzi JV, Varrassi G, Magnusson P, LeQuang J, et al. Fact vs Fallacy: The Anti-Vaccine Discussion Reloaded. Advances in therapy. 2020;37(11):4481–90. pmid:32965654
- 24. Burki T. The online anti-vaccine movement in the age of COVID-19. The Lancet Digital Health. 2020;2(10):e504–e5. pmid:32984795
- 25. Quispe-Cañari JF, Fidel-Rosales E, Manrique D, Mascaro-Zan J, Huamán-Castillón KM, Chamorro-Espinoza SE, et al. Self-medication practices during the COVID-19 pandemic among the adult population in Peru: a cross-sectional survey. Saudi Pharmaceutical Journal. 2021;29(1):1–11. pmid:33519270
- 26. Yáñez JA, Chung SA, Román BR, Hernández-Yépez PJ, Garcia-Solorzano FO, Del-Aguila-Arcentales S, et al. Chapter 14—Prescription, over-the-counter (OTC), herbal, and other treatments and preventive uses for COVID-19. In: Hadi Dehghani M, Karri RR, Roy S, editors. Environmental and Health Management of Novel Coronavirus Disease (COVID-19): Academic Press; 2021. p. 379–416.
- 27. Alvarez-Risco A, Del-Aguila-Arcentales S, Y??ez JA. Telemedicine in Peru as a Result of the COVID-19 Pandemic: Perspective from a Country with Limited Internet Access. The American Journal of Tropical Medicine and Hygiene. 2021;105(1):6–11.
- 28. Pomeranz JL, Schwid AR. Governmental actions to address COVID-19 misinformation. Journal of public health policy. 2021;42(2):201–10. pmid:33510401
- 29. Gonzales-Tamayo L, Arevalo-Oropeza M, Yáñez JA. COVID-19 physician deaths in Peru: A result of an underfunded and fragmented healthcare system. Available at SSRN: https://ssrncom/abstract=3676849. 2020.
- 30. Mejia CR, Ticona D, Rodriguez-Alarcon JF, Campos-Urbina AM, Garayar-Peceros H, Catay-Medina JB, et al. Percepción de las medidas de salud pública en Perú para frenar el avance de la COVID-19. Revista Cubana de Investigaciones Biomédicas. 2021;40.
- 31. Yáñez JA, Chung SA, Inga-Berrospi F, Mejia CR. Demographic and Geographic COVID-19 Death Risk Factors in Peru. A Nationwide Analysis. EClinicalMedicine. 2020(Available at SSRN: https://ssrn.com/abstract=3648543).
- 32. Matias T, Dominski FH, Marks DF. Human needs in COVID-19 isolation. Journal of health psychology. 2020;25(7):871–82. pmid:32375564
- 33. Lim XY, Teh BP, Tan TYC. Medicinal Plants in COVID-19: Potential and Limitations. Frontiers in pharmacology. 2021;12:611408. pmid:33841143
- 34. MINSA. Resolución Ministerial N° 270-2020-MINSA—Prevención, Diagnóstico y Tratamiento de personas afectadas por COVID-19. Ministerio de Salud del Perú; 2020.
- 35. Siddiqui AJ, Jahan S, Ashraf SA, Alreshidi M, Ashraf MS, Patel M, et al. Current status and strategic possibilities on potential use of combinational drug therapy against COVID-19 caused by SARS-CoV-2. Journal of Biomolecular Structure and Dynamics. 2020:1–14. pmid:32752944
- 36. Siddiqui AJ, Danciu C, Ashraf SA, Moin A, Singh R, Alreshidi M, et al. Plants-Derived Biomolecules as Potent Antiviral Phytomedicines: New Insights on Ethnobotanical Evidences against Coronaviruses. Plants. 2020;9(9):1244. pmid:32967179
- 37. Nugraha RV, Ridwansyah H, Ghozali M, Khairani AF, Atik N. Traditional Herbal Medicine Candidates as Complementary Treatments for COVID-19: A Review of Their Mechanisms, Pros and Cons. Evidence-Based Complementary and Alternative Medicine. 2020;2020:2560645. pmid:33101440
- 38. Surti M, Patel M, Adnan M, Moin A, Ashraf SA, Siddiqui AJ, et al. Ilimaquinone (marine sponge metabolite) as a novel inhibitor of SARS-CoV-2 key target proteins in comparison with suggested COVID-19 drugs: designing, docking and molecular dynamics simulation study. RSC Advances. 2020;10(62):37707–20.
- 39. Alzahrani FA, Saadeldin IM, Ahmad A, Kumar D, Azhar EI, Siddiqui AJ, et al. The Potential Use of Mesenchymal Stem Cells and Their Derived Exosomes as Immunomodulatory Agents for COVID-19 Patients. Stem Cells International. 2020;2020:8835986. pmid:33014070
- 40. Maldonado C, Paniagua-Zambrana N, Bussmann RW, Zenteno-Ruiz FS, Fuentes AF. La importancia de las plantas medicinales, su taxonomía y la búsqueda de la cura a la enfermedad que causa el coronavirus (COVID-19). Ecología en Bolivia. 2020;55(1):1–5.
- 41. Moncada-Mapelli E, Salazar-Granara A. Medicina tradicional y COVID-19, oportunidad para la revaloración de las Plantas Medicinales Peruanas. Revista Del Cuerpo Médico Del HNAAA. 2020;13(1):103–4.
- 42. Khadka D, Dhamala MK, Li F, Aryal PC, Magar PR, Bhatta S, et al. The use of medicinal plants to prevent COVID-19 in Nepal. Journal of ethnobiology and ethnomedicine. 2021;17(1):26. pmid:33832492
- 43. Khan SA, Al-Balushi K. Combating COVID-19: The role of drug repurposing and medicinal plants. Journal of infection and public health. 2021;14(4):495–503. pmid:33743371
- 44. Ahmad S, Zahiruddin S, Parveen B, Basist P, Parveen A, Gaurav , et al. Indian Medicinal Plants and Formulations and Their Potential Against COVID-19-Preclinical and Clinical Research. Frontiers in pharmacology. 2020;11:578970. pmid:33737875
- 45. Chaachouay N, Douira A, Zidane L. COVID-19, prevention and treatment with herbal medicine in the herbal markets of Salé Prefecture, North-Western Morocco. European journal of integrative medicine. 2021;42:101285. pmid:33520016
- 46. Fu R, Li J, Yu H, Zhang Y, Xu Z, Martin C. The Yin and Yang of traditional Chinese and Western medicine. Med Res Rev. 2021. pmid:33599314
- 47. Remali J, Aizat WM. A Review on Plant Bioactive Compounds and Their Modes of Action Against Coronavirus Infection. Frontiers in pharmacology. 2020;11:589044. pmid:33519449
- 48. Mirzaie A, Halaji M, Dehkordi FS, Ranjbar R, Noorbazargan H. A narrative literature review on traditional medicine options for treatment of corona virus disease 2019 (COVID-19). Complementary therapies in clinical practice. 2020;40:101214. pmid:32891290
- 49. Grigore A, Cord D, Tanase C, Albulescu R. Herbal medicine, a reliable support in COVID therapy. Journal of immunoassay & immunochemistry. 2020;41(6):976–99. pmid:33356860
- 50. WHO. WHO global report on traditional and complementary medicine 2019. World Health Organization; 2019.
- 51. Amending, as regards traditional herbal medicinal products, Directive 2001/83/EC on the Community code relating to medicinal products for human use, (2004).
- 52. Ordinola Ramírez CM, Barrena Gurbillón MÁ, Rascón J, Corroto F, Barrena Ordinola CM, Cucho Hidalgo MNA, et al. Uso de plantas medicinales para el síndrome febril por los pobladores del Asentamiento Humano Pedro Castro Alva del distrito de Chachapoyas (Chachapoyas—Perú). Arnaldoa. 2019;26:1033–46.
- 53. Bussmann RW, Sharon D. Plantas medicinales de los Andes y la Amazonía—La flora mágica y medicinal del Norte del Perú. 2018. 2018;15:293.
- 54. Elferink J. The Inca healer: Empirical medical knowledge and magic in pre-Columbian Peru. Revista de Indias. 2015;75:323–50.
- 55. Enciso J, Amiel J, Miranda V, Mayanga A, Tapia S, Fabian F. Ethnomedicinal use, phytochemistry and biological activity of the Andean plant Buddleja incana Ruiz & Pav. (Scrophulariaceae). 2020. 2020;20:14.
- 56. Olagorta M, Regil B, Lázaro ML, Díez MA. Afecciones digestivas: tratamiento fitoterápico. Farmacia Profesional. 2017;31(3):30–6.
- 57. Aiken LR. Three Coefficients for Analyzing the Reliability and Validity of Ratings. Educational and Psychological Measurement. 1985;45(1):131–42.
- 58. Walker VM, Davies NM, Windmeijer F, Burgess S, Martin RM. Power calculator for instrumental variable analysis in pharmacoepidemiology. International journal of epidemiology. 2017;46(5):1627–32. pmid:28575313
- 59. MINSA. Minsa: Casos confirmados por coronavirus Covid-19 ascienden a 652 037 en el Perú (Comunicado N°225): Ministerio de Salud del Perú (MINSA); 2020 [Available from: https://www.gob.pe/institucion/minsa/noticias/297141-minsa-casos-confirmados-por-coronavirus-covid-19-ascienden-a-652-037-en-el-peru-comunicado-n-225.
- 60. MINSA. Minsa: Casos confirmados por coronavirus Covid-19 ascienden a 772 896 en el Perú (Comunicado N°247): Ministerio de Salud del Perú (MINSA); 2020 [Available from: https://www.gob.pe/institucion/minsa/noticias/303420-minsa-casos-confirmados-por-coronavirus-covid-19-ascienden-a-772-896-en-el-peru-comunicado-n-247.
- 61. MINSA. Alerta Epidemiológica AE-017-2020—Alerta Epidemiológica ante desplazamiento fuera del domicilio de niños, niñas y adolescentes menores de 14 años y transmisión de COVID-19 en el Perú: Ministerio de Salud—Centro Nacional de Epidemiología, Prevención y Control de Enfermedades; 2020 [Available from: https://cdn.www.gob.pe/uploads/document/file/716882/alerta-epidemiologica-ae-017-2020.pdf.
- 62. de la Cruz MG, Malpartida SB, Santiago HB, Jullian V, Bourdy G. Hot and cold: medicinal plant uses in Quechua speaking communities in the high Andes (Callejón de Huaylas, Ancash, Perú). Journal of ethnopharmacology. 2014;155(2):1093–117. pmid:24995836
- 63. Oblitas G, Hernández-Córdova G, Chiclla A, Antich-Barrientos M, Ccorihuamán-Cusitito L, Romaní F. [Use of medicinal plants among people attending two reference hospitals in Cuzco, Peru]. Rev Peru Med Exp Salud Publica. 2013;30(1):64–8. pmid:23612815
- 64. Monigatti M, Bussmann RW, Weckerle CS. Medicinal plant use in two Andean communities located at different altitudes in the Bolívar Province, Peru. Journal of ethnopharmacology. 2013;145(2):450–64. pmid:23159468
- 65. Rehecho S, Uriarte-Pueyo I, Calvo J, Vivas LA, Calvo MI. Ethnopharmacological survey of medicinal plants in Nor-Yauyos, a part of the Landscape Reserve Nor-Yauyos-Cochas, Peru. Journal of ethnopharmacology. 2011;133(1):75–85. pmid:20837126
- 66. Bussmann RW, Glenn A, Meyer K, Kuhlman A, Townesmith A. Herbal mixtures in traditional medicine in Northern Peru. Journal of ethnobiology and ethnomedicine. 2010;6:10. pmid:20226092
- 67. Bussmann RW, Sharon D. Traditional medicinal plant use in Northern Peru: tracking two thousand years of healing culture. Journal of ethnobiology and ethnomedicine. 2006;2:47. pmid:17090303
- 68. Jenks AA, Kim SC. Medicinal plant complexes of Salvia subgenus Calosphace: an ethnobotanical study of new world sages. Journal of ethnopharmacology. 2013;146(1):214–24. pmid:23291572
- 69. CDC. Coronavirus Disease 2019 Symptoms: Center for Disease Control and Prevention; 2020 [Available from: https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html.
- 70. Juárez-Pérez JC, Cabrera-Luna JA. Plantas para afecciones respiratorias comercializadas en tres mercados de la ciudad de Santiago de Querétaro. Polibotánica. 2019:167–78.
- 71. EL ALAMI A, FATTAH A, CHAIT A. Medicinal plants used for the prevention purposes during the Covid-19 pandemic in Morocco. 2020. 2020;2(1).
- 72. Oladele JO, Ajayi EI, Oyeleke OM, Oladele OT, Olowookere BD, Adeniyi BM, et al. A systematic review on COVID-19 pandemic with special emphasis on curative potentials of Nigeria based medicinal plants. Heliyon. 2020;6(9):e04897. pmid:32929412
- 73. Bhuiyan FR, Howlader S, Raihan T, Hasan M. Plants Metabolites: Possibility of Natural Therapeutics Against the COVID-19 Pandemic. Frontiers in Medicine. 2020;7(444). pmid:32850918
- 74. Infusino F, Marazzato M, Mancone M, Fedele F, Mastroianni CM, Severino P, et al. Diet Supplementation, Probiotics, and Nutraceuticals in SARS-CoV-2 Infection: A Scoping Review. Nutrients. 2020;12(6):1718.
- 75. Soria N. Las Plantas Medicinales y su aplicación en la Salud Pública. Revista de salud publica del Paraguay. 2018;8:7–8.
- 76. Mostacero-León J, López E, Cruz-Castillo L, Gil-Rivero A, Calderón A, Charcape Ravelo J. "Cold plants" and "Hot plants" potential resources in the prevention and / or treatment of COVID-19. Manglar. 2020;13:209–20.
- 77. Alberti-Manzanares P. Los aportes de las mujeres rurales al conocimiento de plantas medicinales en México: Análisis de género. Agricultura, sociedad y desarrollo. 2006;3:139–53.
- 78. Vázquez Medina B, Martínez Corona B, Aliphat Fernández MM, Aguilar Contreras A. Uso y conocimiento de plantas medicinales por hombres y mujeres en dos localidades indígenas en Coyomeapan, Puebla, México. Interciencia. 2011;36(7):493–9.
- 79. Rosete Blandariz S, Sáenz Véliz RS, Jiménez González A, Pin Figueroa FE. Criterios que inciden en la identificación y uso de las plantas de interés para el turismo en Jipijapa, Manabí, Ecuador. Revista Cubana de Ciencias Forestales. 2020;8:54–74.
- 80. de las Mercedes Rodríguez L. De enfermedades y remedios: la transmisión oral del uso doméstico de plantas con fines medicinales en Campeche, México. Apuntes: Revista de Estudios sobre Patrimonio Cultural—Journal of Cultural Heritage Studies. 2012;25:62–71.
- 81. Singhal R. Medicinal Plants and Primary Health Care: The Role of Gender. Journal of Health Management. 2005;7(2):277–93.
- 82. Paulos B, Fenta TG, Bisrat D, Asres K. Health seeking behavior and use of medicinal plants among the Hamer ethnic group, South Omo zone, southwestern Ethiopia. Journal of ethnobiology and ethnomedicine. 2016;12(1):44. pmid:27716305
- 83. Belahsen R, Naciri K, El Ibrahimi A. Food security and women’s roles in Moroccan Berber (Amazigh) society today. Maternal & Child Nutrition. 2017;13(S3):e12562. pmid:29359441
- 84. Martins RR, Duarte Farias A, Russel Martins R, Gouveia Oliveira A. Influence of the use of medicinal plants in medication adherence in elderly people. Int J Clin Pract. 2016;70(3):254–60. pmid:26799730
- 85. Jahan I, Onay A. Potentials of plant-based substance to inhabit and probable cure for the COVID-19. Turk J Biol. 2020;44(3):228–41. pmid:32595359
- 86. Abdullahi Temitope J, Christiana Eleojo A, Ismail Abiodun A, Abdulwakeel Ayokunnun A, Saheed S. Phytotherapeutic Evidence Against Coronaviruses and Prospects for COVID-19. Pharmacognosy Journal. 2020;12(6).
- 87. Mirzaie A, Halaji M, Dehkordi FS, Ranjbar R, Noorbazargan H. A narrative literature review on traditional medicine options for treatment of corona virus disease 2019 (COVID-19). Complementary therapies in clinical practice. 2020;40:101214. pmid:32891290
- 88. Mohan S, Elhassan Taha MM, Makeen HA, Alhazmi HA, Al Bratty M, Sultana S, et al. Bioactive Natural Antivirals: An Updated Review of the Available Plants and Isolated Molecules. Molecules. 2020;25(21). pmid:33105694
- 89. Vroh BTA. Diversity of plants used in traditional medicine against the main symptoms of COVID-19 in sub-Saharan Africa: review of the literature. 2020. 2020;20:14.
- 90. Panyod S, Ho C-T, Sheen L-Y. Dietary therapy and herbal medicine for COVID-19 prevention: A review and perspective. Journal of Traditional and Complementary Medicine. 2020;10(4):420–7. pmid:32691006
- 91. Damjanović Vratnica B, Djakov T, Sukovic D, Damjanovic J. Antimicrobial Effect of Essential Oil Isolated from Eucalyptus globulus Labill. from Montenegro. Czech Journal of Food Sciences. 2011;29:277–84.
- 92. Safa O, Hassaniazad M, Farashahinejad M, Davoodian P, Dadvand H, Hassanipour S, et al. Effects of Ginger on clinical manifestations and paraclinical features of patients with Severe Acute Respiratory Syndrome due to COVID-19: A structured summary of a study protocol for a randomized controlled trial. Trials. 2020;21(1):841. pmid:33036662
- 93. Thota SM, Balan V, Sivaramakrishnan V. Natural products as home-based prophylactic and symptom management agents in the setting of COVID-19. Phytotherapy Research. 2020;34(12):3148–67. pmid:32881214
- 94. Alhazmi HA, Najmi A, Javed SA, Sultana S, Al Bratty M, Makeen HA, et al. Medicinal Plants and Isolated Molecules Demonstrating Immunomodulation Activity as Potential Alternative Therapies for Viral Diseases Including COVID-19. Front Immunol. 2021;12(1721). pmid:34054806
- 95. Ganoza FJ. Asmachilca: Vernacular name of Eupatorium triplinerve Vahl, Aristeguietia discolor R.M. King & H. Rob., Aristeguietia gayana Wedd, Baccharis sp. (Asteraceae), Peru. Ethnobotany Research and Applications. 2020;19(0):1–19.
- 96. Colegate SM, Boppré M, Monzón J, Betz JM. Pro-toxic dehydropyrrolizidine alkaloids in the traditional Andean herbal medicine “asmachilca”. Journal of ethnopharmacology. 2015;172:179–94. pmid:26087231
- 97. Edgar JA, Molyneux RJ, Colegate SM. Pyrrolizidine Alkaloids: Potential Role in the Etiology of Cancers, Pulmonary Hypertension, Congenital Anomalies, and Liver Disease. Chemical research in toxicology. 2015;28(1):4–20. pmid:25483859
- 98. Burger RA, Torres AR, Warren RP, Caldwell VD, Hughes BG. Echinacea-induced cytokine production by human macrophages. International journal of immunopharmacology. 1997;19(7):371–9. pmid:9568541
- 99. Prompetchara E, Ketloy C, Palaga T. Immune responses in COVID-19 and potential vaccines: Lessons learned from SARS and MERS epidemic. Asian Pacific journal of allergy and immunology. 2020;38(1):1–9. pmid:32105090
- 100. Huang C, Wang Y, Li X, Ren L, Zhao J, Hu Y, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. The Lancet. 2020;395(10223):497–506.
- 101. Abolghasemi E, Moosa-Kazemi SH, Davoudi M, Reisi A, Satvat MT. Comparative study of chloroquine and quinine on malaria rodents and their effects on the mouse testis. Asian Pac J Trop Biomed. 2012;2(4):311–4. pmid:23569921
- 102. World Health Organization. Programme on Traditional M. Estrategía de la OMS sobre medicina tradicional 2002–2005. Ginebra: Organización Mundial de la Salud; 2002.
- 103. Alyami HS, Orabi MAA, Aldhabbah FM, Alturki HN, Aburas WI, Alfayez AI, et al. Knowledge about COVID-19 and beliefs about and use of herbal products during the COVID-19 pandemic: A cross-sectional study in Saudi Arabia. Saudi Pharmaceutical Journal. 2020;28(11):1326–32. pmid:32904846
- 104. Sotero-García AI, Gheno-Heredia YA, Martínez-Campos ÁR, Arteaga-Reyes TT. Plantas medicinales usadas para las afecciones respiratorias en Loma Alta, Nevado de Toluca, México. Acta botánica mexicana. 2016:51–68.
- 105. Fernández E, Espinel-Jara V, Gordillo-Alarcón S, Castillo-Andrade R, Ziarovska J, Zepeda-del-Valle J-M, et al. ESTUDIO ETNOBOTÁNICO DE PLANTAS MEDICINALES UTILIZADAS EN TRES CANTONES DE LA PROVINCIA IMBABURA, ECUADOR ETHNOBOTANICAL STUDY OF MEDICINAL PLANTS USED IN THREE DISTRICTS OF IMBABURA PROVINCE, ECUADOR. Agrociencia. 2019;53:797–810.
- 106. Kumar S, Singh R, Kumari N, Karmakar S, Behera M, Siddiqui AJ, et al. Current understanding of the influence of environmental factors on SARS-CoV-2 transmission, persistence, and infectivity. Environmental Science and Pollution Research. 2021;28(6):6267–88. pmid:33387315
- 107. Dehghani MH, Karri RR, Roy S. Environmental and Health Management of Novel Coronavirus Disease (COVID-19): Elsevier Science; 2021.