Antimicrobial, antioxidant and anticancer activities of Thai local vegetables.

Abstract

Thai local vegetables (20 species) were screened for their antimicrobial and antioxidant activities. Methanolic extracts of Cassia siamea, Garcinia cowa,Limnophila aromatica and Polygonum odoratum exhibited strong antioxidant and antibacterial activities. The sensitive bacteria to these extracts were Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus. Among all plant extracts, the extract of P. odoratum had the highest phenolic content and antioxidant activity with EC50 value of 315.35 mg extract/mg DPPH (2,2-diphenyl-1-picrylhydrazyl). These plant extracts were also tested for cytotoxicity against human oral epidermal carcinoma (KB), breast adenocarcinoma (MCF-7) and small cell lung carcinoma (NCI-H187). P. odoratum extract was moderately active against MCF-7 (IC50 value of 6.01 mg/ml). Major types of active compounds in P. odoratum extract were identified by HPLC method. Flavonoids found in this plant were rutin, catechin, quercetin, kaempferol and isorhamnetin. Among these compounds, rutin was found in the highest amount (3.77% w/w dry extract). Key words: Polygonum odoratum, Cassia siamea, Garcinia cowa, Limnophila aromatica, phenolic compounds, flavonoids.