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The study investigated the influence of Annona muricata extracts on the action of selected antibiotics against biofilm-forming MRSA. The various parts of the plant were processed into powder and extracted with ethanol or hot water and then screened for the presence of phytochemicals. The modulatory effect of the Annona muricata extract was also tested on some antibiotics against Methicillin-resistant Staphylococcus aureus (MRSA). The findings from this study revealed that the various parts of the Annona muricata extract (ethanolic and aqueous) contained different proportions of secondary metabolites. Varied antimicrobial activities were observed when the extract of the A. muricata was exposed to MRSA strain at a concentration of 100 mg/mL. The stem recorded the highest (17.00 and 18.00 mm) inhibitory activity against MRSA for both the aqueous and the ethanolic extract, respectively, and this was not different from the control, tetracycline. Again, the results on the modulatory action indicated that out of the 10 extracts of A. muricata, 4 of them antagonized the activity of ampicillin against the tested MRSA by a factor of 0.5 folds and the rest potentiated the drug within 1–4 folds, respectively. On the other hand, the various test extracts significantly potentiated the efficacy of streptomycin and tetracycline against the MRSA by a range of 1–32 folds with the aqueous root extract recording the highest synergistic effect and ethanol seed extract with the least effect. The findings of this study support the antibacterial activities of the A. muricata plant parts.

Vulvovaginal candidiasis (VVC) is the second most common vaginal infection that affects women of reproductive age. Its increased occurrence and associated treatment cost coupled to the rise in resistance of the causative pathogen to current antifungal therapies has necessitated the need for the discovery and development of novel effective antifungal agents for the treatment of the disease. We report in this study the anti-Candida albicans activity of Solanum torvum 70% ethanol fruit extract (STF), fractions and some isolated compounds against four (4) fluconazole-resistant strains of C. albicans. We further report on the effect of the isolated compounds on the antifungal activity of fluconazole and voriconazole in the resistant isolates as well as their inhibitory effect on C. albicans biofilm formation. STF was fractionated using n-hexane, chloroform (CHCl3) and ethyl acetate (EtOAc) to obtain four respective major fractions, which were then evaluated for anti-C. albicans activity using the microbroth dilution method. The whole extract and fractions recorded MICs that ranged from 0.25 to 16.00 mg/mL. From the most active fraction, STF- CHCl3 (MIC = 0.25–1.00 mg/mL), four (4) known compounds were isolated as Betulinic acid, 3-oxo-friedelan-20α-oic acid, Sitosterol-3-β-D-glucopyranoside and Oleanolic acid. The compounds demonstrated considerably higher antifungal activity (0.016 to 0.512 mg/mL) than the extract and fractions and caused a concentration-dependent anti-biofilm formation activity. They also increased the sensitivity of the C. albicans isolates to fluconazole. This is the first report of 3-oxo-friedelan-20α-oic acid in the plant as well as the first report of betulinic acid, sitosterol-3-β-D-glucopyranoside and oleanolic acid from the fruits of S. torvum. The present study has demonstrated the anti-C. albicans activity of the constituents of S. torvum ethanol fruit extract and also shown that the constituents possess anti-biofilm formation and resistance modulatory activities against fluconazole-resistant clinical C. albicans isolates.

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