Triterpenoid 6α-(3'-methoxy-4'-hydroxybenzoyl)-lup-20(29)-ene-3-one exhibits potent broad-spectrum anti-Candida activity and synergism.
Background
Vulvovaginal candidiasis (VVC) is a prevalent fungal infection, particularly concerning for women of reproductive age and pregnant individuals, where untreated cases can lead to severe complications, including miscarriage. The increasing incidence of drug-resistant Candida strains, especially C. albicans and non-albicans species like C. glabrata and C. krusei, poses a significant challenge to effective treatment. Current antifungal therapies often face limitations due to resistance development and side effects, necessitating the discovery of novel compounds with broad-spectrum activity and improved efficacy, particularly those that can enhance existing treatments.
Study Design
Researchers evaluated the anti-Candida activity of the ethyl acetate (EtOAc) extract from Paullinia pinnata leaves and its isolated triterpenoid, 6α-(3'-methoxy-4'-hydroxybenzoyl)-lup-20(29)-ene-3-one, against a panel of drug-resistant Candida albicans, C. glabrata, C. krusei, C. parapsilosis, and C. tropicalis strains and clinical isolates. Anti-Candida activity was assessed using the microbroth dilution method to determine minimum inhibitory concentrations (MICs). The study also investigated the effects of combining 6α-(3'-methoxy-4'-hydroxybenzoyl)-lup-20(29)-ene-3-one with voriconazole, nystatin, or caspofungin using a checkerboard assay to identify synergistic interactions. Additionally, its antibiofilm activity against drug-resistant strains was evaluated.
Results
The EtOAc extract of P. pinnata demonstrated considerable anti-Candida activity, with MICs ranging from 31.25 to 500 µg/mL against drug-resistant Candida strains and clinical isolates. Column fractionation yielded five bulk fractions, with BF4 being the most active (MIC = 3.91-31.25 µg/mL), from which 6α-(3'-methoxy-4'-hydroxybenzoyl)-lup-20(29)-ene-3-one was isolated. This compound exhibited strong activity against the panel of drug-resistant Candida species, with MICs ranging from 0.5 to 16 µg/mL (0.85-27.10 µM).
Key Findings
- The Paullinia pinnata EtOAc extract showed anti-Candida activity with MICs of 31.25-500 µg/mL.
- Isolated triterpenoid 6α-(3'-methoxy-4'-hydroxybenzoyl)-lup-20(29)-ene-3-one exhibited strong activity (MIC 0.5-16 µg/mL).
- The triterpenoid's activity was comparable to ketoconazole (MIC 1-8 µg/mL) and amphotericin B (MIC 0.5-2 µg/mL).
- Synergism with voriconazole, nystatin, or caspofungin was observed in 33.33% to 83.33% of combinations.
- Synergistic interactions were most frequent against C. albicans and C. glabrata strains.
Why It Matters
This study identifies 6α-(3'-methoxy-4'-hydroxybenzoyl)-lup-20(29)-ene-3-one as a promising natural compound with potent broad-spectrum antifungal activity against drug-resistant Candida species. Its ability to synergize with conventional antifungals like voriconazole, nystatin, and caspofungin suggests a potential strategy to overcome antifungal resistance and reduce the required doses of existing drugs. This could lead to improved treatment outcomes, fewer side effects, and enhanced efficacy, particularly for vulnerable populations such as pregnant women where current options are limited. Further research into its mechanism of action and in vivo efficacy could pave the way for novel therapeutic protocols against persistent and resistant fungal infections.
candida
antifungal
drug-resistance
triterpenoid
paullinia-pinnata
vulvovaginal-candidiasis