Susumu Kawakami, Chieko Kanagawa, Liva Harinantenaina Rakotondraibe, Masanori Inagaki, Motohiro Nishimura, Hideaki Otsuka, Toshio Seyama, Katsuyoshi Matsunami, Falitiana Marrino Rakotoarisoa, Stéphan Richard Rakotonandrasana, Alain Michel Ratsimbason
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...
2022: Chemical & Pharmaceutical Bulletin