Thymoquinone, a component of the Middle East spicy seed Nigella sativa, decreases oxidative DNA damage in a rat model of mammary cancer (693.21)

Abstract

Tamoxifen (TAM) is used widely for treatment and prevention of breast cancer. However, TAM has been reported to have a negative effect on the antioxidant glutathione (GSH) levels and 8‐hydroxydeoxyguanosine (8‐OHdG), a fingerprint of free radial attack on DNA. Thymoquinone (TQ), the main active ingredient of Nigella sativa, is used in the Middle East for treatment of several diseases like cancer. The aim of my research was to investigate the role of TQ in improving 8‐OHdG and GSH compared with TAM in female Sprague Dawley rats treated with DMBA, a drug used to induce mammary carcinoma in experimental rodents. Five groups of 10 rats (Controls, DMBA, TAM, TQ, and TAM+TQ) were treated for 10 weeks after injection of DMBA. 8‐OHdG in blood samples was significantly higher in the TAM group compared with the controls (P=0.008), the DMBA group (P=0.041), and the TQ group (P <0.001). TQ significantly decreased 8‐OHdG by itself compared with DMBA (P=0.039) and TAM (P=0.001), but did not significantly reduce the effect of TAM in the TAM+TQ group. On the other hand, GSH did not differ among treatments. Body weight gain over 12 weeks was significantly different among the groups (P<0.001). The TAM and TAM+TQ groups had the lowest weight gain compared with the other groups. This is the first study to show that TQ protects against oxidative DNA damage. I conclude that TQ could be a better anticancer drug than TAM because it decreased 8‐OHdG and protected growth.