[Chemical constituents from leaves of Nelumbo nucifera].

To study the chemical constituents, twenty-seven compounds were isolated from the 70% ethanol extract from leaves of Nelumbo nucifera by modern chromatographic techniques. Their structures were identified as 10-octacosanol (1), beta-sitosterol (2), 1-undecanol (3), 1-eicosanol (4), daucosterol (5), 6'-hydroxy-4,4'-dimethoxychalcone (6), 3,7,8-trimethoxy-1-hydroxy-xanthone (7), rhamnetin-3-O-beta-D-glucopyranoside (8), chrysoeriol-7-O-beta-D-glucoside (9), quercetin-3-O-beta-D-glucopyranoside (10), quercetin-3-O-alpha-L-rhamnopyranosyl (11), hyperoside (12), quercetin-3-O-rutinoside (13), astragalin (14), isorhamnetin-3-O-alpha-L-rhamnopyranosyl-(1--> 6)-[alpha-D-lyxopyranosyl-(1 --> 2) -beta-D-glucopyranoside] (15), isorhamnetin-3-O-alpha-D-lyxopyranosyl-(1 --> 2) -beta-D-glucopyranoside (16), isorhamnetin-3-O-beta-D-glucopyranoside (17), isorhamnetin-3-O-alpha-L-rhamnopyranosyl-(1 --> 6)-beta-D-glucopyranoside (18), quercetin (19), kaempferol (20), dehydronuciferine (21), roemerine (22), stigmast-7-en-3-O-beta-D-glucopyranoside (23), stigmast-7-en-3beta-ol (24), and benzene-1,2-diol (25) on the basis of spectral data analysis. Compounds 1, 6, 7, 8, 24 and 25 were isolated from this plant for the first time, and compounds 15-18 were isolated from the leaves for the first time. Compounds 6, 8, 10, 11, 13 and 15 showed inhibitory activities against beta amyloid (1-42) by A-beta aggregation method with inhibition rates of (63.99 +/- 24.29)%, (79.61 +/- 4.49)%, (49.96 +/- 12.61)%, (101.19 +/- 8.19)%, (88.41+/-6.76)% and (72.48 +/- 8.97)%, respectively.