Gamma irradiation is an effective technique can be used to reduce contaminants in herbal products. Peperomia pellucida (L.) Kunth belongs to piperaceae family has activity as antioxidant and ACE inhibitor. The aimed of this research were to determine the effects of gamma irradiation on microbiological, phytochemical content, antioxidant and  ACE inhibition activity. Samples were irradiated at various doses of  0, 2.5, 5, 7.5 and 10 kGy.Microbiological was determined as total aerobic plate count (TAPC) and total yeast and mold (TYC), Total phenolic content (TPC), total flavonoid content (TFC), antioxidant and ACE inhibition activity were investigated by various in vitro colorimetric methods.  Irradiation dose of 10 kGy reduced TAPC and TYC. Irradiation dose of 10 kGy slightly increased TPC, antioxidant, and ACE inhibition activity (p<0.05) but reduced TFC significantly (p<0,05) and caused degradation of flavonoids in this plant. Correlation analysis showed that phenolic compounds have a role as antioxidant and ACE inhibitor.

Keywords: ACE inhibitor, Antioxidant,  gamma irradiation, microbiological,  Peperomia pellucida (L.) Kunth, phytochemical content