Antityrosinase and antioxidant activities of essential oils of edible Thai plants

This work was undertaken to explore antityrosinase and antioxidant activities of twenty essential oils of edible Thai plants. Antityrosinase activity against mushroom tyrosinase was examined by means of the dopachrome method using L-dopa as an enzymatic substrate. The essential oil of Cymbopogon citratus had the highest level of antityrosinase activity, followed by that of Ocimum canum with enzymatic inhibition of 69 +/- 4 and 66 +/- 3%. GC-MS revealed that geranial and neral were the two most abundant components of their chemical compositions. Antioxidant activity was gauged by the free radical scavenging activity test and ferric reducing/antioxidant power assay. The essential oil of Ocimum sanctum had the highest level of antioxidant activity, followed by the essential oil of Ocimum gratissimum. These results led to the conclusions that the essential oils of edible Thai plants exhibit important biological activities and are a promising choice as natural active ingredients because of their antityrosinase and antioxidant activities.