Nowadays, many of antioxidants on the market, but most of the antioxidant is heat sensitive which their antioxidant capacity is decreased during processing. So, a heat stable antioxidant is important to ensure their effectiveness for neutralize the free radical in the human body. The aim of this study is to determine a presence of heat stable antioxidant activity of Plecranthus amboinicus leaves. Dried-powdered leaves was soaked water and heated at 95 °C for 0, 30, 60, 90 and 120 minutes, respectively. Water extracts were freeze dried to obtain the powdered water extracts. The remaining of leave’s biomass was sequential extracted with ethanol and ethyl acetate to obtain ethanol and ethyl acetate extract. The antioxidant activity and total phenolic content of the extracts were determined by 2,2-diphenyl-1-picrylhydrazyl and Follin Ciocalteau assay, respectively. The results were shown that the ethanol extract had the highest (p ≤ 0. 05) antioxidant activity compared to the water and ethyl acetate extract. The ethanol extract had also the highest phenolic content (77.99 ± 0.52 GAE µg/0.5 mg extract). It can be concluded that the leaves of P.amboinicus might contained a heat stable antioxidant substance which contributed by phenolic substances.
