Isolation and Identification of Novel Flavonoids from the Bract of Zea mays L

Zen mays(maize), a member of the Poaceae, is the most economically important crop in China, about 24 million hectares of Zea mays has been cultivated each year in China, there is about 600 kg of the bract of Zea mays per hectare, and thus the resources of the bract of Zen mays is extremely rich. Although there are some pharmacological activity researches about radical scavenging activity against hydroxyl radical and superoxide anion radical, reducing blood lipid and inhibiting arteriosclerosis, the studies on phytochemical constituents of the bract of Zea mays have not been reported. In order to utilize the resources of the bract of Zea mays, we investigated the chemical constituents of the bract of Zea mays. The air-dried bract of Zea mays was extracted with 95% ethanol at room temperature, the extract was subjected to Diaion AB-8 column chromatography eluatec with ethanol-H2O, and the eluate was further chromatographed on silica gel and Sephadex LH-20 columns repeatedly to yield 4 flavonoid compounds. Their structures were identified as tricin(1), tricin 5-O-beta-D-glucopyranoside(2), tricin 7-O-beta-D-glucopyranoside(3), tricin 7-O[beta-D-apifuranosyl(1 -> 2)]-beta-D-glucopyranoside(4) by spectral analysis(UV, IR, MS and ID, 2D NMR), respectively. Among them, compound 4 is a new flavonoid compound, compounds 1, 2 and 3 are firstly isolated from this plant.