Identification, quantification, and bioactivity of Vitex negundo phenolic acids as efficacious anti-candidal and antibiofilm agents targeting Candida albicans

Abstract

Phenolic acids derived from the leaf of Vitex negundo have been widely recognized for their natural antifungal properties. This study evaluates the bioactive potential of these phenolic acids against Candida albicans, a significant fungal pathogen responsible for various infections in humans. The total phenolic content (TPC) of the plant extract was quantified using the Folin-Ciocalteu reagent and expressed in terms of gallic acid equivalent (GAE), with a TPC of 90.1 ± 3.36 mg GAE/g dry weight extract. The antioxidant activity, measured through the DPPH radical scavenging assay, demonstrated a substantial inhibition rate of 60.776 ± 2.32 % at 1 mg/mL concentration. LCMS analysis identified 18 phenolic acids, with p-coumaric acid showing the highest concentration at 34.3575 µg/ml. In-silico screening highlighted chlorogenic acid, caffeic acid, coumaric acid, and 2,4-dihydroxybenzoic acid having the top four compounds with antifungal potential, which was further validated through in-vitro assays. Caffeic acid emerged as the most potent anti-candidal agent (among these 4 shortlisted compounds) with an MIC of 64 ± 2.31 µg/ml, exhibiting both fungistatic and fungicidal effects. The FE-SEM analysis confirmed the complete eradication of C. albicans biofilm and significant membrane damage post-treatment with caffeic acid. These findings underscore the dual mechanisms of action, i.e., antioxidant and anti-candidal potential of V. negundo phenolic extracts, presenting them as promising candidates for developing natural anti-candidal therapeutics. Future research should explore the molecular interactions and potential synergistic effects with other antimicrobial agents to enhance efficacy and mitigate drug resistance development.