Six New Diterpene Glycosides from the Soft Coral Lemnaliabournei.

Xia Yan,Yutong Shi,Te Li,Bin Wu,Shan He,Xiaojun Yan,Han Ouyang

doi:10.3390/md19060339

Abstract

A chemical study on the extracts of soft coral Lemnalia bournei resulted in the isolation and identification of six new bicyclic diterpene glycosides including three new lemnaboursides E–G (1–3), and three new lemnadiolboursides A–C (4–6), along with three known lemnaboursides (7–9). Their structures were elucidated by detailed spectroscopic analysis, ECD analysis, chemical methods, and comparison with the literature data. Lemnadiolboursides A–C (4–6) contained a lemnal-1(10)-ene-7,12-diol moiety compared with the lemnaboursides. All these compounds were evaluated for antibacterial activity; cell growth inhibition of A549, Hela, HepG2, and CCRF-CEM cancer cell lines; and inhibition of LPS-induced NO production in RAW264.7 macrophages. The results indicated that compounds 1, 2, and 4–6 exhibited antibacterial activity against Staphylococcus aureus and Bacillus subtilis (MIC 4–16 μg/mL); compounds 1–9 displayed low cytotoxicity on the CCRF-CEM cell lines (IC50 10.44–27.40 µM); and compounds 1, 2, and 5 showed weak inhibition against LPS-induced NO production (IC50 21.56–28.06 μM).

Highlights

Soft corals of the genus Lemnalia (Coelenterata, Octocorallia, Alcyonacea, and Nephtheidae) consist of more than 30 species, which are widely distributed in the South China Sea, Taiwan, and off the coast of Australia and
The spectral data of 1 were similar to those of diterpene glycosides isolated from the soft coral Lemnalia bournei (Tables 1 and 2) with the differences reflecting the mono-acetylate position of the sugar residue [9]
The theoretical electronic circular dichroism (ECD) spectra of the isolated compounds were calculated with the Gaussian09 program package based on the relative configurations determined by their 1D-NOE spectra (Gaussian Inc., Wallingford, CT, USA)