In vitro antibacterial and radical scavenging activities of Malaysian table salad
Six types of table salad (ulam) namely Mentha arvensis (mint), Lactuca sativa var capitata (cabbage lettuce), Psophocarpus tetragonolobus (winged bean), Pluchea indica Less. (beluntas), Premna cordifolia (bebuas) and Limnocharis flava L. buchenau (yellow velvetleaf) were investigated for their antimicrobial and radical scavenging activities. In addition, total phenolic content (TPC) test was also carried out for the six plants. All the plants were extracted successively with dichloromethane (DCM) and ethanol (EtOH). The results showed that the DCM and EtOH extracts of L. flava displayed good antimicrobial activity against Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes. The EtOH extract of this plant was the only one that showed inhibition against Candida albicans. P. tetragonolobus had the highest scavenging activity in both extracts, while the ethanolic extract of P. indica showed the highest phenolic contents (56.287 μg/mg). The total phenolic contents of the extracts ranged from 56.287 to 46.461 μg/mg gallic acid equivalents (GAE/g dry extract). The results showed that some table salads (ulam) possess antimicrobial and antioxidant activities and therefore, could be used as a natural preservative ingredient in food and/or pharmaceutical industries.
Key words: Table salad, antimicrobial, antioxidant, disc diffusion, total phenolic content.