Fig. 3

Proposed effects of radioprotectant agents in the cell cycle. This figure presents an overview of the cell cycle and includes the proposed effects of the radioprotectant agents discussed in this review. Resveratrol was one of the most widely studied in this area, having effects on cyclin expression and thus cell cycle progression. It also was shown to induce p53 [30,31,32, 37]. Additionally, amifostine was shown in one study to induce expression of p53 and inhibit its degradation. Melatonin was shown to inhibit progression to the G0 phase in endothelial cells. Carvacrol had an inhibitory effect on cellular apoptosis. Vitamin E, kukoamine, and acteoside inhibited pro-apoptotic proteins Bax and Bak. Acteoside shown to inhibit expression of caspase 3, and thus decrease apoptosis. Similarly, atorvastatin was shown to decrease expression of caspase 3. Isofraxidin both inhibited cytochrome C and caspases, specifically caspase 3, leading to a reduction in apoptosis. Most authors proposed that the studied radioprotectants may act as free radical scavengers or inducers of natural antioxidants (see Table 1)