DPPH‐Scavenging and Antimicrobial Activities of Asteraceae Medicinal Plants on Uropathogenic Bacteria
Trinh Phan-Canh, Thao Le-Thi-Thanh, Hoang-Tran-Viet Ha, TuAnh Nguyen
Abstract
Asteraceae species were widely applied in traditional medicines in Asian countries as sources of natural antioxidants and antimicrobial agents. This study aimed to evaluate DPPH‐scavenging capacities and antimicrobial activities of nine Asteraceae species collected from Southern Vietnam. Antioxidant and antimicrobial activities were determined by standard protocols. Essential oils from Ageratum conyzoides, Helianthus annuus, and Artemisia vulgaris indicated significant inhibitory effects on Staphylococcus aureus and Candida spp. Crude extracts and fractions from Taraxacum officinale, Chrysanthemum morifolium , A. conyzoides, and Tagetes erecta showed inhibitory ability on at least one testing bacterial strains including S. aureus , Escherichia coli , Klebsiella pneumoniae , and Pseudomonas aeruginosa . In a study on clinical isolates, ethyl acetate fraction from A. conyzoides flower displayed the most potent effect on uropathogenic E. coli and K. pneumoniae with MIC at 1.25–10 mg/ml and 5–12.5 mg/ml, respectively. DPPH‐scavenging assay indicated that T. erecta extract had the lowest IC 50 (17.280 μ g/ml) and is 2.4 times higher than vitamin C (7.321 μ g/ml). This study revealed that A. conyzoides has good potential against uropathogenic E. coli and K. pneumoniae, and therefore could be applied for prophylactic treatment of urinary infection.