Studies On The Chemical Constituents And Antioxidant Activity Of The Ethylacetate Fraction Of V. Macrocephalum

Viburnum macrocephalum Fort.f.keteleeri(Carr.)Rehd.belongs to the genus Viburnum.It is the peculiar species which can be used as folk medicine and widely distributed in China.In this paper,23 compounds were separated from the aerial part of V,macrocephalum by using recrystallized and varieties of chromatographic methods.On the basis of spectroscopic analysis and physicolchemical characters,their structures were identified as following.Apigenin 7-0-[6-0-(3-hydroxy-3-methylglutaryl)]-?-D-glucopyranoside(1),apigenin 7-O-?-D-glucopyranoside(2),(S)-prunin(3),(R)-prunin(4),astragalin(5),kaempferol 3-0-(6"-O-crotonoyl)-?-D-glucopyranoside(6),kaempferol 3-0-(6"-O-acetyl)-?-D-glucopyranoside(7),afzelin(8),kaempferol 4'-O-?-L-rhamnopyranoside(9),tachioside(10),methyl 2-?-D-glucopyranosyloxy-6-hydroxybenzoate(11),benzyl?-D-glucopyranoyl-(1?6)-?-D-glucopyranoside(12),syringenin 4-0-(6-cinnamoyl)-?-D-glucopyranoside(13),erigeside ?(14),benzyl 4-?-D-glucopyranosyloxy-3-hydroxybenzoate(15),(+)-8-hydroxylinalool(16),3,7,11-trimethyl-1,6-dodecadien-3,10,11-triol(17),bridelionoside B(18),?-sitosterol(19),daucosterol(20),methyl 2-a-L-rhamnopyranosyloxyacetate(21),methyl 3-?-L-rhamnopyranosyloxyglycerate(22),methyl 4-?-L-rhamnopyranosyloxy-3-hydroxybutanoate(23).Among them,1,13,21-23 were new compounds;compounds 3,4,6,7,9,11-15,17,18 were isolated from this genus for the first time.The antioxidant activities of flavonoids 1-9 isolated from V.macrocephalum were evaluated in vitro.Among them,compounds 3 and 4 showed obvious scavenging capability against DPPH radical,with ICso value of 34.06 ?M,30.76 ?M(Trolox IC50 30.14 ?M),respectively.And components 5-9 exhibited high scavenging capability against ABTS radical,with IC50 value of 13.69 ?M,10.80 pM,12.10?M,10.08 ?M,12.54 ?M(Trolox ICso 26.35?M),respectively.