Phytochemical Composition, Antioxidant Activity and Antimicrobial Properties of the Methanolic Extract and Solvent Fractions of Ritchiea Longipedicellata
Abstract
Antimicrobial resistance continues to pose a serious threat to global health, driving the search for new bioactive compounds from natural plant sources. Ritchiea longipedicellata (Capparaceae), traditionally used in West Africa to treat infectious diseases, remains poorly characterized in medicinal chemistry. This study investigated the phytochemical content, antioxidant activity, and antimicrobial properties of hexane and chloroform fractions from a methanolic extract of R. longipedicellata's aerial parts, collected from the Forestry Research Institute of Nigeria (FRIN), Ibadan. Aerial parts were air-dried, pulverized, macerated in methanol, and sequentially partitioned with hexane and chloroform. Qualitative screening confirmed alkaloids, flavonoids, tannins, phenolics, saponins, terpenoids, steroids, diterpenoids, and cardiac glycosides in both fractions. Quantitative analysis showed the hexane fraction had higher phenolic (189.98 ± 0.28 mg GAE/g) and flavonoid (32.41 ± 0.42 mg QE/g) content than the chloroform fraction. DPPH assays showed good antioxidant activity for the crude extract, hexane, and chloroform fractions (81.06%, 84.20%, and 77.98% inhibition at 500 μg/mL) versus 96.40% for ascorbic acid, with dose-dependent effects. Antibacterial and antifungal MIC values across the tested extracts and organisms ranged from 1.5625 mg/mL to >50 mg/mL, with the chloroform fraction consistently the most active, achieving MICs of 1.5625 mg/mL against both Staphylococcus aureus and Escherichia coli. MBC/MFC values (3.125–50 mg/mL) confirmed bactericidal or fungicidal activity at higher concentrations for several extract–organism combinations, though extract MICs remained substantially higher than that of ciprofloxacin. Candida albicans and Trichophyton rubrum were also susceptible to the chloroform fraction, with MICs of 12.5 mg/mL and 3.125 mg/mL, respectively.