Studies On Liposoluble Constituents Of Corn Silk

Corn silk (stigma maydis), as a traditional Chinese herbal drug, has usuallybeen used for treating diabetes and hypertension. Modern pharmacological studieshave confirmed that corn silk possessed antioxidant, anticancer, hypoglycemic,antibacterial, improve immunity activities and so on. This study has done someresearch on the chemical composition of corn silk and related activities in order toclarify the chemical composition of corn silk and promote the development andutilization of resources.Firstly, this study compared the chemical composition and antioxidant activityof different polar fractions (ethanol extract, petroleum ether, ethyl acetate, n-butanol,water) of corn silk to clear the active site. The petroleum ether fraction of corn silkhad the highest total sterols contents, and the ethyl acetate fraction of corn silk hadthe highest total flavonoids, total phenolic contents, but also showed the highestantioxidant activities (DPPH radical scavenging activity, nhibitory effect on lipidperoxidation induced by Fe2+/ascorbic acid, ferric reducing/antioxidant poweractivity) by the study.Secondly, a variety of separation and purification methods (normal phase silicagel column chromatography, gel column chromatography, preparative TLC, etc.)were used for the separation and purification of petroleum ether, ethyl acetate andn-butanol fractions of corn silk. And the compounds isolated were identified by1H-NMR, etc. Seventeen compounds were isolated, fourteen of which wereidentified as friedelin (1), stearic acid (2), β-sitosterol (3), stigmasterol (4), ergosterolperoxide (5), stigmasta–5–en–3β,7–diol (6), stigmasta–5,22–diene–3β,7–diol (7), stigmasta–4–en–3β,6β–diol (8), stigmasta–4,22–diene–3β,6β–diol (9), luteolin (12), pseudolario acid (13), stigmasterol–3–O–β–D–glucoside(14), sitosterol–3–O–β–D–glucoside (15),3’,5–dihydroxy–4’–methoxyflavon–7–rhaminosylglucosid (17), and ergosterol peroxide (5) was firstlyisolated from corn silk.Thirdly, this study compared the contents of total sterols, total phenolic andflavonoids and individual flavonoids (luteolin, apigenin, formononetin), antioxidantand anticancer activities of six corn silk varieties (Denghai6702, Delinong988,Tunyu808, Zhongdan909, Liangyu208, Jingke968) to analyze the influence of varieties on corn silk. Results showed that Zhongdan909had the highest totalphenolic contents with the highest DPPH radical scavenging activity and inhibitoryactivity against human breast cancer cells MCF7, while Tunyu808had the highesttotal flavonoids contents with the highest reducing power activity.