title: Eudesmane and megastigmane glucosides from Laggera alata.
abstract: Four eudesmane glucosides, alatosides A-D (1-4), and one megastigmane glucoside, alatoside E (5), were isolated from the BuOH fraction of Laggera alata along with six known compounds. Structures of the new compounds were elucidated by a combination of chemical and spectroscopic methods. Alatosides A-E were characterized as: 1alpha-O-(beta-D-glucopyranosyloxyl)-7-epi-eudesma-11-en-2beta,4alpha-diol (1), 2beta-O-(beta-D-glucopyranosyloxyl)-eudesma-4alpha-hydroxyl-11(13)-en-12-oic-acid (2), 5beta-O-(beta-D-glucopyranosyloxyl)-eudesma-4(15),11(13)-dien-12-oic-acid (3), 5alpha-O-(beta-D-glucopyranosyloxyl)-eudesma-3,11(13)-dien-12-oic acid (4) and 3beta-O-(beta-D-glucopyranosyloxyl)-megastigma-9-one (5), respectively. Based on the chemical characteristics of eudesmane derivatives isolated from the Laggera genus, it was suggested that there are probably two different biogenetic pathways for these secondary metabolites in this genus.
authors.affiliation: Department of Traditional Chinese Medicine and Natural Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310031, China.
authors.forename: Qunxiong
authors.initials: Q
authors.lastname: Zheng
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Xu
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Sun
authors.forename: Wei
authors.initials: W
authors.lastname: Yao
authors.forename: Handong
authors.initials: H
authors.lastname: Sun
authors.forename: Christopher H K
authors.initials: CH
authors.lastname: Cheng
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D019659:Asteraceae / Q000737:chemistry*; D003512:Cyclohexanones / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry* / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D045792:Norisoprenoids / Q000737:chemistry*; D045787:Sesquiterpenes, Eudesmane / Q000737:chemistry*
chemical_list: D003512:Cyclohexanones; D005960:Glucosides; D045792:Norisoprenoids; D045787:Sesquiterpenes, Eudesmane; C413264:megastigmane; C015872:eudesmane