Antimicrobial and Antioxidant Activities of Extracts and Compounds From Trifolium Baccarinii With Their Mechanisms of Antibacterial Action

Abstract The treatment of infectious diseases with antimicrobial agents continues to present problems in modern-day medicine with many studies showing significant increase in the incidence of bacterial resistance to several antibiotics. The screening of plant extracts and natural compounds for antimicrobial activity has demonstrated that higher plants represent a potential source of new anti-infective agents. The aim of this study was to evaluate the antimicrobial and antioxidant activities of extracts and compounds from the whole plant Trifolium baccarinii Chiov. with their mechanisms of antibacterial action. Biochanin A (1), formononetin (2), luteolin (3), luteolin-4'-O-β-D-glucopyranoside (4), 4,7,2'-trihydroxy-4'-methoxyisoflavanol (5), sissotrin (6), 1-méthyl-β-D-glucopyranoside (7), ononin (8), D-mannitol (9) and 3-O-β-D-glucuronopyranosylsoyasapogenol B (10) were isolated from T. baccarinii. The MeOH, EtOAc and n-BuOH extracts as well as compounds 1–6 from T. baccarinii displayed the most antimicrobial and antioxidant activities. The MeOH extract and compound 5 exhibited antibacterial activity through bacteriolytic effect and reduction of the antioxidant defenses in the bacterial cells. Interestingly, none of the tested samples showed cytotoxic activity against normal cells; highlighting their good selectivity toward pathogenic bacteria and yeasts. Hence, they are promising lead candidates with antibacterial potential against methicillin resistant S. aureus (MRSA).