Effect on decoction on antioxidant activity in stem of Plectranthus amboinicus

There are a lots of antioxidant food are thermo-labile. The effect of the decoction of Plectranthus amboinicus (P. amboinicus) stems which were rarely utilized by people had been study in this research with three difference solvents (ethanol, ethyl acetate, and water) extraction respectively. The decoction time were divided into 0, 30, 60, 90 and 120 minutes. The powdered water extracts were obtained by freeze dried of the filtrate of decoction. The remaining biomass were further extract by ethyl acetate followed by ethanol. The antioxidant activity of P.amboinicus stems was determined by DPPH (1, 1-dipheny1-2-picrylhydrazine) scavenging assay. The total phenolic content of the P.amboinicus stems were expressed as gallic acid equivalents using acid standard curve of gallic acid (R2=0.9834). The qualitative analysis of thin layer chromatography (TLC) and DPPH autobiography were used to support the quantitative analysis as the evidence. The percentage of scavenging activity showed the ethyl acetate extracted of P.amboinicus has the highest antioxidant activity with the lowest (IC50) value 32.58 ± 0.014 at 120 minutes decoction. There are no significant difference (P<0.05) between the decoction of time and the antioxidant activity. Therefore, the decoction are not deteriorate the antioxidant activity of P.amboinicus stems. The TLC-DPPH autobiography were showed similar pattern within the three difference solvents.