Chemical constituents from whole herbs of Azolla imbricata / 中草药

ABSTRACT

Objective: To investigate the chemical constituents from whole herbs of Azolla imbricata. Methods: The chemical constituents were separated and purified by various chromatographic techniques of silica gel, ODS, Sephadex LH-20 gel, and semi-preparative HPLC. Their structures were identified by NMR and MS spectroscopic methods. Results: Twenty compounds were isolated from A. imbricata and identified as chlorogenic acid methyl ester (1), 4-O-caffeoylquinic acid (2), 3,4-O-dicaffeoylquinic acid methyl ester (3), 3,4,5-O-tricaffeoylquinic acid methyl ester (4), (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-3-hydroxy-L-tyrosine (5), (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tyrosine (6), (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tyrosine methyl ester (7), (-)-N- [4'-hydroxy-(E)-cinnamoyl)]-L-tyrosine (8), brainicin (9), quercetin-3-O-β-D-glucoside (10), naringenin-7-O-β-D-glucoside (11), kaempferol-3-O-(6″-O-caffeoyl)-β-D-glucoside (12), caffeic acid (13), epirhododendrin (14), myzodendrone (15), trans-ferulic acid-β-D-glucoside (16), 5,7-dihydroxychromone-2-carboxylic acid (17), pinoresinol-4-O-β-D-glucoside (18), phytol (19) and trans-12-oxo-(10Z,15Z)-phytodienoic acid (20). Conclusion: Compounds 1-12, 14-18, and 20 are isolated from the genus Azolla for the first time and compound 19 is isolated from A. imbricata for the first time. Compounds 1-7, 10, 12, and 13 exhibit good antioxidant activity.