Our previous study showed that
quercetin enhances the anticancer effect of
trichostatin A (
TSA) in xenograft mice given
quercetin intraperitoneally (10 mg/kg, 3 times/week). Herein, we investigate whether
quercetin administered orally exerts such an effect and prevents the cytotoxic side effects of
TSA. We found that
quercetin given orally (20 and 100 mg/kg, 3 times/week) failed to enhance the antitumor effect of
TSA although it increased the total
quercetin concentration more than
quercetin administered intraperitoneally in the plasma. The compound
quercetin-3-glucuronide (Q3G) increased the most. However,
quercetin administered intraperitoneally increased the total
quercetin level in
tumor tissues more than oral
quercetin. Oral and intraperitoneal administration of
quercetin similarly decreased lymphocyte DNA damage and plasma lipid peroxidation level induced by
TSA. Furthermore, we found that the enhancing effect of Q3G on the antitumor effect of
TSA and the incorporation of Q3G was less than that of
quercetin in A549 cells. However, we found that A549 cells possessed the ability to convert Q3G to
quercetin. In conclusion, different from
quercetin administered intraperitoneally,
quercetin administered orally failed to enhance the antitumor effect of
TSA because of its metabolic conversion. However, it prevented
TSA-induced DNA damage and lipid peroxidation.