Exploring hydrophilic 2,2-di(indol-3-yl)ethanamine derivatives against Leishmania infantum

Alessia Centanni; Aurora Diotallevi; Gloria Buffi; Diego Olivieri; Nuno Santarém; Antti Lehtinen; Jari Yli-Kauhaluoma; Anabela Cordeiro-da-Silva; Paula Kiuru; Simone Lucarini; Luca Galluzzi

doi:10.1371/journal.pone.0301901

Peer Review History

Original SubmissionJanuary 16, 2024
8 Feb 2024 Decision Letter - Nisha Singh, Editor PONE-D-24-01889Exploring hydrophilic 2,2-di(indol-3-yl)ethanamine derivatives against Leishmania infantumPLOS ONE Dear Dr. Lucarini, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Mar 24 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. 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Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Partly Reviewer #3: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes Reviewer #3: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes Reviewer #3: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes Reviewer #3: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: This is an interesting original work that describing Exploring hydrophilic 2,2-di(indol-3-yl)ethanamine derivatives against Leishmania infantum. Following the review of the manuscript, I have no recommendations, except one: Explain how to euthanize the mice. Reviewer #2: Dear authors, I congratulate you on your effort in creating the manuscript. However, the drug under study needs to show better protection results, and the use of a high dose of PEG is also not recommended. I am sorry, but I need to reject the manuscript. Reviewer #3: The manuscript (PONE-D-24-01889) entitled ‘Exploring hydrophilic 2,2-di(indol-3-yl)ethanamine derivatives against Leishmania Infantum’ by prof. Simone Lucarini, Paula Kiuru and coworkers describes the design and synthesis of a new library of hydrophilic bisindole substituted analogues based on the structure of the antileishmanial compound namely URB1483, previously developed by them, which failed on the in vivo evaluation probably due to its low water solubility as the authors mentioned. In addition, the authors provide the biological evaluation of the synthesized compounds concerning against Leishmania infantum promastigotes and simultaneously for their toxicity on human macrophage-like THP-1 cells. The most active compounds 2c and 1h with IC50= 2.7 μM and IC50= 4.1 μM showed comparable activity with the oral drug miltefosine (IC50= 3.6 μM) and also comparable selectivity index only in case of 1h. The toxicity profile of the 1h was slightly better than miltefosine. On the other hand the most active compound compound 2c was more toxic than miltefosine but seems to be promising for further chemical modifications in order to achieve an improved toxicity outcome. The manuscript overall is well written and the compounds are well characterized but some corrections are needed. These are the following: a) I don’t fully understand the rationale related with the design of the synthesized series of compounds 2 and 3. More specifically, among the synthesized compounds included in the first series of compounds (free amine bis-indoles), 1a, 1b, 1c, 1f and 1h were found to be active against L. infantum promastigotes in the low micromolar range, with IC50s between 12.9 – 4.1μM. Among them 1a have no substitution at the aromatic ring of the NH-Indole moieties, 1b, 1c and 1f are substituted at position 6 of the NH-Indole moieties with a fluorine, chlorine or a methylester respectively and finally 1h bearing a methyl group at the indole nitrogen atoms. Since none of them bearing a 6-bromo substitution at the indole moieties and also taking into consideration that the most active was 1h with no substitution at position 6, in my opinion the authors should provide a more detailed discussion in the manuscript explaining the rationale followed for the design and synthesis of compound series 2 and 3 and mainly should explain why they proceeded only with modifications on the structure of 1d (bearing bromine atoms at 6 position of the indoles). b) In the general procedure A used for the synthesis of bisindoles 1 the authors described that the reaction performed under microwave irradiation. Since it would be very useful for the readership of PLOS ONE, they should provide more details about the reaction condition such as the microwave power (watts) used in all the reactions performed under microwaves. Overall, the manuscript merits publication in PLOS ONE as long as minor revision takes place according to the above suggestions. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: No Reviewer #3: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. 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Revision 1
13 Feb 2024 Author Response Reviewer #1 Comments: This is an interesting original work that describing Exploring hydrophilic 2,2-di(indol-3-yl)ethanamine derivatives against Leishmania infantum. Following the review of the manuscript, I have no recommendations, except one: Explain how to euthanize the mice. A: We thank the reviewer 1 for its supportive comments on our work. The animals were euthanised with an overdose of isoflurane followed by cervical dislocation as reported at page 4, lines 116-117 of the paper. Reviewer #2 Comments: Dear authors, I congratulate you on your effort in creating the manuscript. However, the drug under study needs to show better protection results, and the use of a high dose of PEG is also not recommended. I am sorry, but I need to reject the manuscript. A: Due to the low water solubility of URB1483, 60% of PEG 400 as cosolvent was utilized to obtain a stable and injectable formulation in rats. PEG 400 is one of the most utilized cosolvent for developing formulations since it is both biocompatible and water soluble (see ref. 22-24 of the manuscript) and its concentration generally ranges from 20 to 70% in commercial injection products (Int J Pharm. 2007, 341, 1), although higher values can be also tested (Int J Pharm. 2007, 341, 1). Since in our formulation up to 60% of PEG 400 is present, the dosage is perfectly in line with literature data. In addition, as written in the text, the aim of this research work was to find a more water-soluble analogue of URB1483, which failed the in vivo test. Indeed, we found two new hydrophilic antileishmanial agent, 1h and 2c, which could also represent promising lead compounds for the generation of new innovative and more potent anti-infective agents. Reviewer #3 Comments: The manuscript (PONE-D-24-01889) entitled ‘Exploring hydrophilic 2,2-di(indol-3-yl)ethanamine derivatives against Leishmania Infantum’ by prof. Simone Lucarini, Paula Kiuru and coworkers describes the design and synthesis of a new library of hydrophilic bisindole substituted analogues based on the structure of the antileishmanial compound namely URB1483, previously developed by them, which failed on the in vivo evaluation probably due to its low water solubility as the authors mentioned. In addition, the authors provide the biological evaluation of the synthesized compounds concerning against Leishmania infantum promastigotes and simultaneously for their toxicity on human macrophage-like THP-1 cells. The most active compounds 2c and 1h with IC50= 2.7 μM and IC50= 4.1 μM showed comparable activity with the oral drug miltefosine (IC50= 3.6 μM) and also comparable selectivity index only in case of 1h. The toxicity profile of the 1h was slightly better than miltefosine. On the other hand the most active compound compound 2c was more toxic than miltefosine but seems to be promising for further chemical modifications in order to achieve an improved toxicity outcome. The manuscript overall is well written and the compounds are well characterized but some corrections are needed. Overall, the manuscript merits publication in PLOS ONE as long as minor revision takes place according to the following suggestions: a) I don’t fully understand the rationale related with the design of the synthesized series of compounds 2 and 3. More specifically, among the synthesized compounds included in the first series of compounds (free amine bis-indoles), 1a, 1b, 1c, 1f and 1h were found to be active against L. infantum promastigotes in the low micromolar range, with IC50s between 12.9 – 4.1μM. Among them 1a have no substitution at the aromatic ring of the NH-Indole moieties, 1b, 1c and 1f are substituted at position 6 of the NH-Indole moieties with a fluorine, chlorine or a methylester respectively and finally 1h bearing a methyl group at the indole nitrogen atoms. Since none of them bearing a 6-bromo substitution at the indole moieties and also taking into consideration that the most active was 1h with no substitution at position 6, in my opinion the authors should provide a more detailed discussion in the manuscript explaining the rationale followed for the design and synthesis of compound series 2 and 3 and mainly should explain why they proceeded only with modifications on the structure of 1d (bearing bromine atoms at 6 position of the indoles). A: We thank the referee for constructive comments that allow us to improve our manuscript quality. As correctly noticed, the 6-Br bisindole 1d did not show preliminary promising results as 1a-c, 1f or 1h. However, we designed the compounds library before biological test results considering the known biological activity of the privileged scaffold 1d. Indeed, classes 2 and 3 were synthetized from 1d, which is a marine bisindole alkaloid isolated from the californian tunicate Didemnum candidum and the new caledonian sponge Orina spp. Furthermore, these 6-Br bisindole derivatives could be easily functionalized by classical cross coupling reactions (e.g., Mizoroki-Heck reaction, Stille reaction, Suzuki-Miyaura reaction), therefore representing a class of useful starting materials that would easily allow the obtainment of new drug candidates. These considerations have been added in the text at page 12, lines 380-384, together with the opportune references 30 and 31. b) In the general procedure A used for the synthesis of bisindoles 1 the authors described that the reaction performed under microwave irradiation. Since it would be very useful for the readership of PLOS ONE, they should provide more details about the reaction condition such as the microwave power (watts) used in all the reactions performed under microwaves. A: Thanks for the suggestion. Microwave syntheses were performed using the set temperature mode, which foresees to keep the temperature constant and the instrument automatically and consequently adjusting the power. Depending on the chosen temperature (i.e. 120°C or 80°C), the microwave power varied from 30 to 75 W. As required by the reviewer, this information has been added. Attachments Attachment Submitted filename: Response to Reviewers.pdf https://doi.org/10.1371/journal.pone.0301901.r002
25 Mar 2024 Decision Letter - Nisha Singh, Editor Exploring hydrophilic 2,2-di(indol-3-yl)ethanamine derivatives against Leishmania infantum PONE-D-24-01889R1 Dear Dr. Lucarini, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Nisha Singh, Ph.D. Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: All comments have been addressed Reviewer #3: (No Response) ******** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #3: (No Response) ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #3: (No Response) ****** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #3: (No Response) ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #3: (No Response) ****** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: (No Response) Reviewer #3: (No Response) ****** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #3: No ******** https://doi.org/10.1371/journal.pone.0301901.r003
Formally Accepted
4 Jun 2024 Acceptance Letter - Nisha Singh, Editor PONE-D-24-01889R1 PLOS ONE Dear Dr. Lucarini, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Nisha Singh Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0301901.r004

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