In our continuing studies on the chemical constituents of Taiwanese octocorals, the gorgonian coral Isis hippuris and the sea pen coral Virgularia juncea, which were collected from the coast of Green Island and Peng-Hung Islands, respectively, have been the subjects of our investigations. Six compounds, including two new steroids, hippuristerones A and E (1 and 2), along with three known steroids 3β-hydroxy-5α-pregnan -20-one (3), prenga-4-ene-3,20-dione (4), prenga-1,4-diene-3,20-dione (5) and a known sesquiterpene subergorgic acid (6) were isolated from I. hippuris. Four compounds, incoulding a new sesquterpene, junceol A (7) and two known diterpenoids, sclerophytin A (8), cladiellisin (9) and a known steroid 24-methylenecholesterol (10) were isolated from V. juncea.
The structures of above isolates were determined by physical (mp and optical rotation) and extensive spectral (UV, IR, MS, HRMS, 1D and 2D NMR) analysis and by comparison with the related physical and spectral data from other known compounds. The structure, including the relative configuration of hippuristerone A (1) was further confirmed by a single-crystal X-ray analysis.Furthermore, the relative configuration of hippuristerone E (2) was supported by the chemical dynamics calculations.