The effect of gamma irradiation on cytotoxic activity of the flesh of Mahkota Dewa (Phaleria macrocarpa (Scheff) Boerl) Fruits

Gamma irradiation had been used by herbs medicine industries for preservation of medicinal plants, but the effect of irradiation on their bioactivities has not been observed. The purpose of this research was to obtain the optimum radiation dose for the preservation of mahkota dewa flesh fruits without damaging their cytotoxic activities. To evaluate the effect of irradiation, dried samples of flesh fruit of mahkota dewa were irradiated at various doses of 0; 5; 7.5; 10; 15 and 20 kGy. Microbial contamination was tested using Indonesian National Standard method, which indicated that all microbes were killed at the dose of 5 kGy. Each sample was macerated with ethanol, and the extracts obtained were then fractionated with column chromatography, from which 8 fractions were obtained. Cytotoxicity test of the fractions against leukemia L1210 cells, showed that the Fr.3 was the most cytotoxic. To determine optimal irradiation dose to inhibit and to kill bacteria and yeast/mold in the mahkota dewa flesh fruit samples without decreasing cytotoxic activity, a thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) analysis of the Fr.3 were done. The results showed that the doses of ≥ 5 kGy inhibited the growth and killed all the bacteria, yeast and mold without decreasing significantly the cytotoxic activity of ethanol extract against leukemia L1210 cell. The significant decrease of cytotoxic against leukemia L1210 of ethanol extract were occurred after ≥ 10 kGy irradiation of the samples. At the dose of 10 kGy, the cytotoxicity decreased even though it was not exceeded the limit of the fraction was declared inactive. Analysis of thin layer chromatogram profiles showed that the Fr.3 contained at least 10 components. Irradiation until the dose of 20 kGy decreased the major peak intensity. with the increasing of irradiation doses. It was concluded that the dose of 5 kGy to 10 kGy were the optimum dose for the preservation of flesh fruit of mahkota dewa without damaging their cytotoxic activities. (author)