Theophilus Duku Asamoah

Vulvovaginal candidiasis is a common infection that affects women of reproductive age, with a high prevalence among pregnant women. When left untreated, it can lead to pregnancy complications including miscarriage. The study evaluated the activity of the ethyl acetate (EtOAc) extract of Paullinia pinnata and its isolated compound 6α-(3’-methoxy-4’-hydroxybenzoyl)-lup-20(29)-ene-3-one against drug-resistant strains and clinical isolates of Candida albicans , Candida glabrata , Candida krusei , Candida parapsilosis and Candida tropicalis . Furthermore, the effects of the combinations of 6α-(3’-methoxy-4’-hydroxybenzoyl)-lup-20(29)-ene-3-one with voriconazole, nystatin or caspofungin on the Candida strains and isolates as well as its antibiofilm activity against the drug-resistant strains are reported in this study. The EtOAc leaves extract of P. pinnata demonstrated considerable activity against the drug-resistant Candida strains and clinical isolates with minimum inhibitory concentrations (MICs) of 31.25 to 500 µg/mL when assessed for anti- Candida activity using the microbroth dilution method. The extract was column fractionated to obtain five bulk fractions, and from the most active bulk fraction, BF4 (MIC = 3.91–31.25 µg/mL), 6α-(3’-methoxy-4’-hydroxybenzoyl)-lup-20(29)-ene-3-one was isolated. This study is the first reported biological activity of the compound. 6α-(3’-methoxy-4’-hydroxybenzoyl)-lup-20(29)-ene-3-one exhibited strong activity against the panel of drug-resistant Candida species with MIC ranging from 0.5 to 16 µg/mL (0.85–27.10 µM). This activity was within similar range to that of ketoconazole (MIC = 1–8 µg/mL) and amphotericin B (MIC = 0.5–2 µg/mL). When combined with voriconazole, nystatin or caspofungin using the checkerboard assay, 6α-(3’-methoxy-4’-hydroxybenzoyl)-lup-20(29)-ene-3-one recorded synergism of 33.33% to 83.33% with the antifungals, with majority of the synergistic interactions observed against C. albicans and C. glabrata strains and isolates. 6α-(3’-methoxy-4’-hydroxybenzoyl)-lup-20(29)-ene-3-one also demonstrated anti-biofilm activity. Its IC ₅₀ values against the formation of biofilms and preformed biofilms of the Candida species were 15.30–46.40 μg/mL (25.91–78.60 μM) and 25.40–90.84 μg/mL (43.02–153.86 μM), respectively. In conclusion, P. pinnata possesses strong anti- Candida activity and its isolated compound, 6α-(3’-methoxy-4’-hydroxybenzoyl)-lup-20(29)-ene-3-one displayed potent anti- Candida and anti-biofilm action. These findings identify 6α-(3’-methoxy-4’-hydroxybenzoyl)-lup-20(29)-ene-3-one as a promising anti- Candida compound warranting further investigation, including cytotoxicity in mammalian cells, before its therapeutic potential can be fully assessed.

The present study investigated the antifungal activity of the 70% ethanol extracts of the leaves (IGL), stem bark (IGSB) and roots (IGR) of Irvingia gabonensis against multidrug‐resistant Candida albicans and Candida glabrata strains and clinical isolates. The inhibitory activities of extracts against biofilm formation and mature biofilms were also investigated. Furthermore, the effects of the combinations of I. gabonensis extracts with amphotericin B, ketoconazole, voriconazole, nystatin and caspofungin, against the resistant Candida strains and isolates were evaluated using the checkerboard assay. Qualitative and quantitative assessments of the phytoconstituents in the plant extracts, as well as their antioxidant activities, were then analysed. IGSB displayed considerable anti‐ Candida activity with minimum inhibition concentrations (MICs) of 15.63 μg/mL–500 μg/mL, while IGR showed MICs of 125 μg/mL–1000 μg/mL. IGL demonstrated limited activity with MICs of 500 μg/mL–> 2000 μg/mL. IGSB also exerted significant antibiofilm activity against the drug‐resistant C . albicans and C . glabrata strains and isolates with SMIC ₉₀ of 31.25 μg/mL–1000 μg/mL and 125 μg/mL–2000 μg/mL against the formation of biofilms and mature biofilms, respectively. In the checkerboard assay, IGSB recorded the most synergistic interactions with the conventional antifungal drugs producing median FICI values that ranged between 0.35 to 0.61 and 0.30 to 0.68, and synergistic action that ranged between 50% to 66.67% and 55.56% to 100%, against the MDR C. albicans and C. glabrata isolates, respectively. The extracts displayed strong antioxidant activities, which correlated with their total phenol, flavonoid and tannin contents. The presence of phytochemicals such as glycosides, coumarins and triterpenoids was also detected in I. gabonensis extracts. The study findings have demonstrated that I. gabonensis , particularly its stem bark, is a potential source of bioactive compounds that could be developed into novel antifungal agents.