## 4 Discussion  
Polyphenols, found in nuts, fruits, vegetables, grains, spices, tea, coffee, and wine, are known for their powerful antioxidant properties [17]. Epidemiological studies on the anticancer effects of natural polyphenols have yielded mixed results due to the difficulty of measuring dietary intake of these compounds [18]. This observation suggests that even more research, such as the current study, is needed to evaluate the therapeutic utility and safety of polyphenolic compounds. CHSP is more effective in inhibiting ovarian cancer cell proliferation than paeonol [19] or extracts of strawberry, Korean raspberry, and mulberry [20]. The lower cell viabilities demonstrate that CHSP has high potential for the prevention and therapy of ovarian cancer. Cell viability with 40 \(\upmu\)g/mL of CHSP on IOSE364 was much larger than that of OVCAR-3 and A2780/CP70 cells, indicating that the inhibitory effects of CHSP on normal ovarian cells were less than that on the ovarian cancer cells. Therefore, CHSP selectively inhibits cancer cells while having significantly weaker inhibitory effects on normal ovarian cells. Next, we assessed whether CHSP treatment in ovarian cancer cells resulted in cellular apoptosis. CHSP was shown to promote apoptosis in OVCAR-3 cells. There was also no significant apoptosis induction in IOSE364 by CHSP, further confirming the selective inhibitory effects of CHSP on ovarian cancer cells compared with normal ovarian cells. Apoptosis is a form of programmed cell death [21]. The intrinsic (mitochondria-mediated) and extrinsic (receptor-mediated) pathways are two major apoptotic pathways. The up-regulation in pro-apoptotic proteins by CHSP are related to the mitochondrial apoptosis pathway [22; 23]. Therefore, mitochondrial apoptosis pathway is likely to be the main reason for CHSP-induced apoptosis. However, some studies in breast cancer patients found that daily intake of natural polyphenols may stimulate cancer growth due to the interaction between the polyphenolic compound and endogenous steroid hormones [24]. Our previous work reported that polyphenols, prodelphinidins [25], theaflavin-3'-gallate [26] and galangin [27], induced apoptosis in ovarian cancer cells through the activation of p53 protein. To determine whether p53 is involved in CHSP-induced apoptosis of ovarian cancer cells, the expression of p53 protein was detected by Western blot. Consistent with previous results from other purified polyphenols, after CHSP treatment, p53 protein in OVACAR-3 cells was also up-regulated. This result indicates that p53 plays an important role in the apoptosis of ovarian cancer cells induced by polyphenols and CHSP can induce apoptosis through the p53-dependent pathway. VEGF plays an important role in ovarian cell proliferation and angiogenesis [28; 29]. To assess the effect of CHSP on proteins affecting cell proliferation, levels of VEGF were examined. Numerous studies have shown that HIF-1\(\alpha\) is a primary regulator of VEGF production [30; 31; 32]. Thus, we first examined the influence of CHSP treatment on HIF-1\(\alpha\) expression. To confirm that HIF-1\(\alpha\) expression is not only regulated by CHSP treatment but also plays a role in the inhibition of VEGF secretion by CHSP, OVCAR-3 cells were transfected with the VEGF-promoter reporter, together with HIF-1\(\alpha\) plasmids. The higher the expression of HIF-1\(\alpha\), the higher the increase in the expression of the VEGF reporter. These results demonstrated that CHSP inhibits VEGF production through a HIF-1\(\alpha\)-dependent pathway. This finding is consistent with our previous report that gallic acid, an important polyphenol found in Chinese hickory, inhibits the secretion of VEGF from ovarian cancer cells through the HIF-1\(\alpha\) pathway [33]. Several phytochemicals, which contain polyphenols, have shown promising results for cancer therapeutics due to their inhibition of VEGF production in ovarian cancer cells [34]. However, all polyphenols have varying effects on cancer cell growth [35].