Phytoche, antimicrobial and antioxidant evaluation of the stem bark of Thomandersia hensii (Acanthaceae).

Abstract

The methanolic extract of the stem bark of Thomandersia hensii (Acanthaceae), was screened for its phytochemical constituents, in vitro antioxidant and antimicrobial activities using standard procedures. The results revealed the presence of alkaloids, polyphenols, sugars and steroids. T. hensii extract showed significant 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity (IC50 = 0.1343±0.0262 µg/ml), and polyphenol content (118.08±0.95 mg/g of extract). Chromatographic separation of the extract led to the isolation of four compounds among which two were identified to bergenin and sitosterol 3-O-AŸ-D-glucopyranoside. In vitro antimicrobial activities of the extract and identified compounds showed growth inhibition of Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus saprophyticus, Shigella flexneri, Salmonella typhimurium and Candida albicans. Also, bergenin exhibited antibacterial activity against an amoxicilline resistant P. aeruginosa strain. This study showed that T. hensii extract is rich in phenolic compounds, contains bergenin and sitosterol 3-O- AŸ -D-glucopyranoside, and possess antioxidant and antimicrobial activities.