Persicaria minor (Huds.) from the family Polygonaceae is a common medicinal plant found in South East Asia. In Malaysia the plant is locally know as kesum. The kesum leaves are often consumed as ulam (raw medicinal plants consumed with daily meals) for preventive health care. In the Malaysian Traditional Medicine System, the decoction of kesum leave is recommended for digestive disorders and stomach pain. In a previous study (Vimala et al. 1999), preliminary screening of various Malaysian medicinal plants showed that kesum leaf possessed high antioxidant activity (>90%). Thus kesum is a potential and interesting plant for antioxidant evaluation. In this study, to obtain the antioxidant profile of kesum, the leaf aqueous extract was subjected to 3 antioxidant pathways representing Lipid Peroxidation Inhibition, Superoxide Scavenging and DPPH Free Radical Scavenging. The leaf extract was also subjected to Total Phenolic Content (TPC) and HPLC evaluation. The kesum leaf aqueous extract was further subjected to cytotoxicity evaluation using WRL-68 human liver and Vero monkey kidney cell lines. The extract was also subjected to microbial load count and heavy metal analysis. The results of the present study showed that kesum leaf aqueous extract possessed high antioxidant activity which was exhibited as >70% inhibitory activity in all 3 antioxidant assays. Kesum leaf also showed high Total Phenolic Content (2800.6 mg/100g GAE). The HPLC analysis showed the presence of flavanoids, phenolics and oxalic acid in kesum leaf. The leaf extract was found to be free from cytotoxicity (IC50 >300 µg/ml) in WRL-68 human liver and Vero monkey kidney cells. Microbial contamination and heavy metals were not detected. Thus kesum is a potential antioxidant plant for cultivation and exploitation as food additive. Oxalic acid is a powerful oxidizing agent that binds calcium to aid the digestive system. The scientific findings of this study support the traditional claims of kesum leaf as a medicinal plant for preventive health care and digestive disorders. Thus the kesum leaf is recommended as an antioxidant food additive for preventive health care.

Keyword: Persicaria minor, kesum, antioxidant, oxalic acid, polyphenolics, preventive health care

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