Sesquiterpenoids from the Rhizomes of Homalomenaocculta

ABSTRACT: Naturally occurring oplopanane sesquiterpenoids are rarely reported. A phytochemical investigation on the rhizomes of Homalomena occulta (Lours) has resulted in the discovery of six oplopanane sesquiterpenoids (1–6), including four new (1–4) and one 3,5-seco-oplopanane (6), together with three previously reported sesquiterpenoids (7−9). In addition three new oplopananes (2a–4a) were also obtained by chemical transformation. All structures of these sesquiterpenoids were established based on the comprehensive spectroscopic analyses, including NMR, MS, and IR, and comparing with the literatures. GRAPHICAL ABSTRACT: [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13659-016-0104-8) contains supplementary material, which is available to authorized users.