Antibacterial and Anti-Biofilm Activity of Flavonoids and Triterpenes Isolated from The Extracts of Ficus Sansibarica Warb. Subsp. Sansibarica (Moraceae) Extracts

Background: Ficus species are used in African traditional medicine in the treatment of a wide variety of ailments and diseases such as convulsive disorder, wound healing, gonorrhea, tuberculosis, diabetes, diarrhoeal infections, dysentery, malaria and HIV. The aim of this study was to isolate the phytochemical constituents in the plant and test them for their antibacterial activity.Materials and methods: The fruits, leaves and stem bark were extracted with organic solvents and the compounds in the extracts separated and purified by column chromatography before being identified by NMR spectroscopy and by comparison of the NMR data against values reported in the literature. The antibacterial activity of the pure compounds and extracts were tested using the disk diffusion method.Results: Three triterpenes and three flavonoids: lupeol acetate (1); cycloart-23-ene-3,25-diol (2); β-sitosterol (3); 5,7,4'-trihydroxyflavan-3-ol (4); epicatechin (5); and isovitexin (6) were isolated in this study. Antimicrobial activity was observed at 8 mg mL-1 for Staphylococcus aureus ATCC 29213 with four of the six isolated compounds, with no activity being observed at 1 – 4 mg mL-1 against Escherichia coli ATCC 25922, E. coli ATCC 35218 and S. aureus ATCC 43300. Epicatechin (5) was found to decrease adhesion of E. coli ATCC 25922 and S. aureus ATCC 29213. Decreased adhesion of S. aureus ATCC 29213 was also observed with 5,7,4'-trihydroxyflavan-3-ol (4) and isovitexin (6).Conclusions: The results of this study provide baseline information on F. sansibarica’s potential validity in the treatment of infections associated with Gram-positive microorganisms.Key words: Moraceae, Ficus sansibarica, antimicrobial, anti-adhesion properties, flavonoids, triterpenoids

Green Synthesis of Silver Nanoparticles from Diospyros villosa Extracts and Evaluation of Antioxidant, Antimicrobial and Anti-Quorum Sensing Potential.

The biosynthesis of silver nanoparticles (AgNPs) from Diospyros villosa leaves and stem bark extracts is described. The stem bark AgNPs of D. villosa synthesized at 80 °C (S80) showed good scavenging activity with a lower IC50 value of 8.75 µg·mL-1 compared to ascorbic acid (9.58 µg·mL-1). The total phenol content of the S80 AgNPs was measured and found to be 10.22 ± 0.14 mg.g-1 gallic acid equivalence (GAE). Bacterial growth inhibition (% GI) and violacein inhibition (% VI) of 10.08% and 58.83%, respectively, was observed against C.subtsugae CV017 with leaf AgNPs synthesized at 80 °C (L80) at 80 μg·mL-1. Stem bark AgNPs synthesized at room temperature (SRT) also indicated % GI of 13.83% and % VI of 65.97% against C. subtsugae CV017 at 160 μg·mL-1. Leaf AgNPs of D. villosa synthesized at room temperature (LRT), showed % GI of 29.07% and % VI of 56.53%, respectively, against C. violaceum ATCC 12472 at 320 μg·mL-1. The L80 and SRT at 160 μg·mL-1 and LRT at 320 μg·mL-1 may be considered as potential QS inhibitors following their activity against C. subtsugae CV017 and C. violaceum ATCC 12472, respectively. Therefore, D. villosa represents a potential source of antioxidants as well as an anti-quorum sensing therapeutic candidate for the control of Gram-negative bacterial infections

Organic acids as potential growth promoters in the South African abalone Haliotis midae

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Additional file 1: of Faecal colonization of E. coli and Klebsiella spp. producing extended-spectrum beta-lactamases and plasmid-mediated AmpC in Mozambican university students

Table S1. Resistance genes identified and sensitivity results of E. coli and Klebsiella spp. (DOCX 38 kb

Multi-scale energy exchanges between an elasto-plastic oscillator and a light nonsmooth system with external pre-stress

International audienceVibratory energy exchanges between twocoupled oscillators is studied: the main elasto-plasticoscillator is coupled to a nonlinear energy sink(NES)with nonsmooth potential. Both oscillators are underpre-stressing terms. Two different methods are implementedfor tracing system behaviours: (i) the timeevent-driven technique which builds exact solutions ofgoverning equations of the system phase by phase and(ii) the multi-scale method which traces system behavioursat different scales of time. It detects invariant ofthe system at fast timescale and equilibrium/singularpoints at slow timescales. The pre-stressing terms producea more complex shape for the invariant, whiledetected dynamics at slow timescale let us have controlat the behaviour of the system during its quasi-steadystateregime(s) which leads to have analytical designtools for tuning parameters of nonlinear energy sink according to design purposes (passive control and/orenergy harvesting)