Gamma irradiation effect on physicochemical properties of Guazuma ulmifolia leaves and their antiproliferative activities against human cancer cell lines

Guazuma ulmifolia leaves (GUL) has a long been used in traditional medicine, including anticancer. To preserve the simplicia, many companies utilize gamma irradiation techniques. The research aimed to study the irradiation effect on GUL simplicia that preserved using gamma irradiation based on its physicochemical properties and antiproliferative activities against human cancer cell lines. GUL was irradiated at 7.5 kGy, then the irradiated sample (IRGUL) and un-irradiated sample (GUL) as a control were gradually macerated using n-hexane, ethyl acetate, and ethanol. The obtained ethyl acetate extracts from control sample (EAE-GUL) and irradiated samples (EAE-IRGUL) were then fractionated by silica gel column chromatograph using combination of n-hexane/ethyl acetate/methanol. The EAE-GUL, EAE-IRGUL, and its active fraction (fraction 4) were then evaluated their total phenolic and total flavonoid contents (TPC, TFC), thin layer chromatograph-densitometry (TLC-densitometry), LC/MS/MS, as well as in vitro bioassay against human cancer cells (THP1 leukemia, MCF7 breast cancer, and K562 erythroleukemia). The results showed that the n-hexane, ethyl acetate, and ethanol extracts of EAE-IRGUL were lower than these extracts of EAE-GUL. Analysis of TPC, TFC showed that their TPC and TFC of EAE-IRGUL decreased by 15.8% and 4.9%, respectively, compared to EAE-GUL. In vitro bioassay showed that the irradiation dose of 7.5 kGy could decrease their antiproliferative activity of ethyl acetate extracts and their fraction 4 against THP1, MCF7, and K562 cancer cells, however, the decrease did not eliminate their bioactivity. Therefore, good manufacturing practices to obtain low bioburden is important, so the irradiation dose can be kept as low as possible. In addition, increasing the active ingredient dosage may be applied with regard to the decrease in physicochemical and biological properties of GUL simplicia due to irradiation exposure. TLC-densitometry and LC/MS/MS analysis showed that some main spots on TLC and main peaks at total ion chromatogram (TIC) of F4 of EAE-IRGUL decreased, while other spots on TLC and peaks in TIC increased compared to control. More studies are needed to evaluate the effect of gamma radiation on individual compounds using chromatographic techniques and NMR as well.