Abstract
Combination therapy comprising natural polyphenols and anticancer drugs has been used to decrease the adverse effects and increase the effectiveness and antioxidant activities of the drugs. The antioxidant and anticancer effects of quercetin (Q), a nutritive polyphenol, have been observed both in vitro and in vivo. Likewise, the anticancer activity of sulfamethoxazole (S) has been demonstrated in vitro and in vivo. This study aimed to investigate the in vitro and in vivo anticancer effects of Q alone and in combination with S. The in vitro effects of S, Q, and S + Q on HCT-116, HepG2, MCF-7, and PC3 cell lines were examined. Additionally, the in vivo effects of these drugs were evaluated using Ehrlich ascites carcinoma (EAC) tumor-bearing mice. The in vitro data revealed the potent anticancer activity of S + Q through the induction of apoptosis and cell cycle arrest. The EAC-inoculated mice treated with S + Q presented with elevated SOD, GSH, CAT, and TAC levels and decreased malondialdehyde levels compared with the untreated EAC group, thus revealing the antioxidant and protective actions of S + Q against EAC cell invasion. Furthermore, the downregulation of NFkB and upregulation of the caspase3 gene in the EAC-inoculated mice treated with the S + Q indicated the induction of the apoptotic pathway and decrease in both cell proliferation and metastasis. In conclusion, the combination of S and Q might exert anticancer effects by inducing apoptosis and exhibiting selective toxicity against the cancer cells and thereby protecting the vital organs.