Wheat bran lipophilic compounds with in vitro anticancer effects

Wheat bran has been widely recognised as a cancer preventive agent, although the mechanism of the protection is not yet fully understood. Some reports suggested that, for the protection, lipophilic phytochemicals from the bran were more important than the physiological function of bran fibre. Wheat bran lipophilic extracts were scrutinised using bioactivity-guided fractionation (HPLC) against the growth of human prostate adenocarcinoma (PC3) cells. The fractions containing unsaturated free fatty acid, phytosteroids and alkylresorcinols exerted high cytotoxic activity. Detailed research of the alkylresorcinol fraction isolated seven pure compounds, four of them with strong inhibitory properties against the growth of PC3 cells, including 5-heptadecylresorcinol (IC₅₀ = 22.5 μg/ml), 5-(16-heneicosenyl)resorcinol (trans) (IC₅₀ = 13.7 μg/ml), 5-(14-nonadecenyl)resorcinol (trans) (IC₅₀ = 42.2 μg/ml) and 5-(2-oxotricosanyl)resorcinol (IC₅₀ = 10.9 μg/ml). The alkylresorcinols in wheat bran were quantified using a Single Ion Monitoring (SIM) method developed on LC-MS. The active alkylresorcinols were found to be minor components in wheat bran, however, they exerted higher cytotoxic effects on cancer cells than the positive control chlorambucil (IC₅₀ = 58.7 μg/ml). This research suggested that alkylresorcinols are important for the cancer preventive activity of wheat bran. Other lipophilic compounds such as some free unsaturated fatty acids and phytosteroids may also contribute to the anticancer activity.