1. Omphalines A-E: ent-Rosane-Type Diterpenoids from the Madagascar Endemic Plant, Omphalea oppositifolia.
- Author
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Kawakami S, Kanagawa C, Rakotondraibe LH, Inagaki M, Nishimura M, Otsuka H, Seyama T, Matsunami K, Rakotoarisoa FM, Rakotonandrasana SR, and Ratsimbason AM
- Subjects
- Madagascar, Circular Dichroism, Euphorbiaceae, Diterpenes, Diterpenes, Kaurane
- Abstract
From the less polar fraction of the MeOH extract of the leaves and twigs of Omphalea oppositifolia, five new ent-rosane-type diterpenoids, named omphalines A-E (1-5), were isolated together with one known compound, 7-keto-ent-kaurane-16β,17-diol (6), by a combination of various kinds of chromatography. The structure of omphaline A (1) was elucidated to be 19-nor-ent-rosane-4,15-diene-2β,6α-diol-3-one. Omphalines B (2), C (3), D (4), and E (5) possessed two double bonds at 5- and 15-positions, and hydroxy functional groups at 3β-, 2α,3α-, 2α,3β-, and 2α,19-positions, respectively. The absolute configuration of 1 was determined by the comparison of the experimental electronic circular dichroism (ECD) spectrum and calculated ECD spectra.
- Published
- 2022
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