Three new biphenyls, 4,7,8-trimethoxy-2,3-methylenedioxydibenzofuran （1）, 7-hydroxy-4,8- dimethoxy-2,3-methylenedioxydibenzofuran （2）, and 3＇,5-dimethoxy-3,4-methylenedioxybiphenyl （3）, along with eighteen known compounds （4-21） were isolated from the aerial part of Ribes takare D. Don. Their structures were elucidated on the basis of spectroscopic data. Compound I and compound 2 showed mild α-glucosidase inhibitory activity.
Eight new 9,10-anthraquinones(1-8)including three acetonide derivatives of 3-hydroxy-2-hydroxymethyl-9,10-anthraquinones(68)were isolated from an ethanol extract of the roots of Knoxia valeriamoides.On the basis of chemical transformation reactions of the co-occurring 14 and 15 combined with HPLC-DAD-ESI-MS analysis of the extracts,the previously and newly isolated 2-methoxymethy-and 2-ethoxymethyl-9,10-anthraquinones(4,5,and 9-13),as well as the 3-hydroxy-2-hydroxymethyl-9,10-anthraquinone acetonide derivatives(68),were shown to be solvolytic artifacts.In the in vitro assays,compound 4 was active to protect hepatocyte(WB-F344)damage.
Three new sesquiterpene glycosides,named codonopsesquilosides A C(1 3),were isolated from an aqueous extract of the dried roots of Codonopsis pilosula.Their structures including absolute configurations were determined by spectroscopic and chemical methods.These glycosides are categorized as C_(15) carotenoid(1),gymnomitrane(2),and eudesmane(3)types of sesquiterpenoids,respectively.Compound 1 is the first diglycoside of C_(15) carotenoids to be reported.Compound 2 represents the second reported example of gymnomitrane-type sesquiterpenoids from higher plants.The absolute configurations were supported by comparison of the experimental circular dichroism(CD)spectra with the calculated electronic CD(ECD)spectra of 13,their aglycones,and model compounds based on quantummechanical time-dependent density functional theory.The influences of the glycosyls on the calculated ECD spectra of the glycosidic sesquiterpenoids,as well as some nomenclature and descriptive problems with gymnomitrane-type sesquiterpenoids are discussed.
Yueping JiangYufeng LiuQinglan GuoChengbo XuChenggen ZhuJiangong Shi
