Protective Effects Of Amygdalin On Glutamine Deprivation Induced Apoptosis Of Hepatocarcinoma HepG2Cells Through Antioxidation

As a naturally occurring substance, amygdalin has been suggested to beefficacious in treatment of diseases especially in treatment of cancer. But, thebiological effects of amygdalin as an antioxidant are poorly studied. In the presentstudy, we demonstrated first time by means of biological experiments that amygdalinhad antioxidantion effects. Our study showed that the generation of hydroxyl freeradicals and the accumulation of ROS in glutamine deprived HepG2cells wereincreased, which could lead to an apoptosis of the cells.0.5mg/ml amygdalin reducedthe generation of hydroxyl free radicals and the accumulation of ROS in the glutaminedeprived HepG2cells. The antioxidation effects of amygdalin could protect the cellsfrom apoptosis elicited by the glutamine deprivation.The present study showed that glutamine deprivation resulted in apoptoticalterations of HepG2cells including a decrease in viability of the cells measured byMTT assay, an increase in the ratio of apoptotic cells to the total population of thecells measured by the flow cytometry with Annexin V-FITC/PI double staining, andan increased in the ratio of mRNA of Bax/Bcl-2. The apoptosis in the glutaminedeprived HepG2cells measured by the methods mentioned above was alleviated bytreating the cells with0.5mg/ml amygdalin.The present study further showed that0.5mg/mL amygdalin inhibited thegeneration of hydroxyl free radicals and the accumulation of ROS in the glutaminedeprived HepG2cells observed with a DCFH-DA probe, under a florescencemicroscope and by flow cytometry and increased the expressions of mRNA andprotein of SOD1and CAT as well as their activities in the cells.Amygdalin is composed of two molecules of glucose, one molecule ofbenzaldehyde and one molecule of hydrocyanic acid. The molecules of benzaldhydecan be further broken down to generate molecules of benzoic acid. Our results showedthat benzoic acid, but not amygdalin and benzaldehyde,could inhibit the generation ofhydroxyl free radicals in an in vitro system。We hypothesize that broken downproduct of amygdalin-benzoic acid-might contribute also to the antioxidation effectsof0.5mg/ml amygdalin on the glutamine deprived HepG2cells in addition to its promotion of expressions and activities of SOD1and CAT, which remains to befurther studied.