From the leaves of Pertya glabrescens SCH. BIP. (Compositae) a new germacranolide, 3-epipertilide (III), C
15H
16O
4, [α]
17D+52°and a new glycoside (VIII), C
12H
22O
6, [α]
24D-36.5°were isolated in addition to pertic acid (Ib), 3α-hydroxypertic acid (IIb), benzoic acid, p-coumaric acid and methyl caffeate. On the basis of chemical and physicochemical evidence, III was determined to be stereoisomeric to pertilide (VI) at C-3, namely [1 (10) Z, 4E]-(3S, 7R, 8S)-germacra-1 (10), 4, 11 (13)-triene-12, 8; 14, 3-diolide, and VIII, to be the β-D-glucopyranoside of (Z)-3-hexen-1-ol (leaf alcohol). The conformation of III was assigned from the examination of its derivatives IV, Va and Vb in nuclear Overhouser effect and circular dichroism. A new bitter principle, glucohaageanolide (X), C
21H
30O
8·H
2O, mp 155-165°C (dec.), [α]
20D+51.2°was isolated from the leaves of P. scandens (THUNB.) SCH. BIP. On hydrolysis X gave D-glucose and a known sesquiterpene haageanolide (XI). In order to make clear the exact structure of X including its absolute streorchemistry, an X-ray structure analysis of X monohydrate was undertaken, resulting in determination of X to be [1 (10) E, 4E]-(6S, 7S, 9S)-9-β-D-glucopyranosyloxygermacra-1 (10), 4, 11 (13)-trien-12, 6-olide.
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