Fig 1.
Representative plots of the evolution of the fluorescence (left panels), growth–as OD600- (center panels) and fluorescence intensity corrected for growth (fluorescence/OD600) (right panels) of E. coli strain Top 10 transformed with plasmid pSB1A3—BBa_T9002 after treatment with ethanol 50% (v/v) extracts of Warburgia ugandensis Sprague (Code P20), Leonotis nepetifolia L. (Code P9), Acacia gerrardii Benth. (Code P22) and Elaeodendron buchananii Loes (Code P21) applied at 0.5 and 1.0 mg/mL (as per legend in the top-left panel).
The E. coli quorum sensing response was induced by the addition of (3OC6HSL) to a final concentration of 0.5 nM. OD600 and fluorescence intensity were measured every six minutes with the appropriate parameters (fluorescence λex = 485 nm, fluorescence λem = 520 nm, integration time = 40 μs, number of flashes = 10, gain = 100, measurement mode = top). Data are mean values ± SD (n = 3).
Fig 2.
Summarized bioactivity of the 25 screened plant extracts about growth (OD600) and quorum sensing (FL/OD600) response of the E. coli strain Top 10 transformed with plasmid pSB1A3—BBa_T9002 after treatment with ethanol 50% (v/v) extracts at concentrations of: 1.0 mg/mL (a) and (b), and 0.5 mg/mL (c) and (d) relative to the untreated control, as recorded during the last 294 min of incubation at 37°C. Key: Code P1 (Oxalis corniculata L.), Code P2 (Urtica dioica L.), Code P3 (Erlangea marginata S. Moore), Code P5 (Rubia cordifolia L.), Code P6 (Spilanthes mauritiana DC.), Code P7 (Orthosiphon hildebrandtii Vatke), Code P8 (Dichrocephala integrifolia Kuntze), Code P9 (Leonotis nepetifolia (L) R. Br.), Code P10 (Rhoicissus tridentata (L.f) Wild & Drumm), Code P11 (Toddalia asiatica (L.) Lam), Code P12 (Asparagus africanus Lam.), Code P13 (Balanites orbicularis Sprague), Code P14 (Clerodendrum myricoides (Hochst) R.Br. & Vatke), Code P15 (Caesalpinia decapetala (Roth) Alston), Code P16 (Solanum renschii Vatke), Code P17 (Croton macrostachyus Hochst. ex Delile), Code P18 (Erythrina abyssinica Lam.), Code P19 (Rhus natalensis Bernh. Ex Krauss), Code P20 (Warburgia ugandensis Sprague), Code P21 (Elaeodendron buchananii Loes), Code P22 (Acacia gerrardii Benth.), Code P23 (Carissa edulis Vahl), Code P24 (Cassia didymobotrya Fresen, Code P25 (Acacia nilotica (L.) Delile.) and Code P26 (Bischofia javanica Blume). Data are mean values ± SD. Statistical test: Kruskal-Wallis test (n = 3, *p<0.01, **p<0.05, ***p<0.001).
Fig 3.
Summarized bioactivity of the Elaeodendron buchananii (a) and (b) and Acacia gerrardii (c) and (d) extracts about growth (OD600) and quorum sensing (FL/OD600) response of the E. coli strain Top 10 transformed with plasmid pSB1A3—BBa_T9002 after treatment with various solvents extracts at concentrations of: 1 mg/mL (a) and (c), and 0.5 mg/mL (b) and (d) relative to the untreated control, as recorded during the last 294 min of incubation at 37°C. Data are mean values ± SD. Statistical test: One way ANOVA test (n = 3, *p<0.01, **p<0.05, ***p<0.001 & ****p<0.0001).
Fig 4.
Summarized bioactivity of the Elaeodendron buchananii (a) and (b) and Acacia gerrardii (c) and (d) extracts about growth (OD600) and quorum sensing (FL/OD600) response of the E. coli pBCA9145_jtk2828::sfGFP after treatment with various solvents extracts at concentrations of: 1 mg/mL (a) and (c), and 0.5 mg/mL (b) and (d) relative to the untreated control, as recorded during the last 294 min of incubation at 37°C. Data are mean values ± SD. Statistical test: One way ANOVA test (n = 3, *p<0.01, **p<0.05, & ***p<0.001).
Fig 5.
Summarized bioactivity of various concentrations of methanol extracts of E. buchananii about growth (OD600) (a) and quorum sensing (fluorescence/OD600) (b) response of the E. coli Top10. Data are mean values ± SD. Statistical test: One way ANOVA test (n = 3, *p<0.01, **p<0.05, and ***p<0.001).
Fig 6.
Antibiofilm activity of methanol extracts of E. buchananii and A. gerrardii against E.coli Top 10.
One way ANOVA test (n = 3, *p<0.01, and **p<0.05).
Fig 7.
Cytotoxicity of 50% ethanol extracts of E. buchananii and A. gerrardii against MDCK-C7 cells (n = 3, * p < 0.05, *** p < 0.001; Friedman test and *** p < 0.001).