Abstract
Chemical investigation of the South China Sea soft coral Lemnalia sp. afforded 13 structurally diverse terpenoids, including three new neolemnane sesquiterpene lineolemnenes E–G (1–3); a new aristolane-type sesquiterpenoid, 2-acetoxy-aristolane (4); four new decalin-type bicyclic diterpenes, named biofloranates A−D (5−8); a new serrulatane, named euplexaurene D (9); and a new aromadendrane-type diterpenoid cneorubin K (10), together with three known related compounds (11−13). The structures of the new compounds were elucidated by NMR spectroscopy, the Mosher’s method, and ECD analysis. Compounds 1–13 were tested in a wide panel of biological assays. Lineolemnene J (3) showed weak cytotoxicity against the CCRF-CEM cancer cell line. The isolated new diterpenes, except euplexaurene D (9), demonstrated moderate antimicrobial activity against Bacillus subtilis and Staphylococcus aureus with a MIC of 4−64 μg/mL. Compound 2 exhibited a mild inhibitory effect against influenza A H1N1 virus (IC50 = 5.9 µM).
Highlights
In the competition for food and living space for survival, marine organisms accumulate and secrete secondary metabolites that are deterrent, offensive, or even toxic to other organisms—that is, chemical defense substances [1]. Marine invertebrates, such as soft corals, grow slowly and lack physical defense capabilities, but they can survive in competitive marine environments
A geranylgeranyl-PP (GGPP, C20) has been regarded as the same biosynthetic precursor of these diterpenoids, and we further propose biosynthesis for these diterpenoids, as illustrated in Scheme 1
Germany) with a 5 mm inverse detection triple resonance (H-C/N/D) cryoprobe. 1H chemical shifts were referenced to the residual CDCl3 (7.24 ppm) and 13C chemical shifts were referenced to the CDCl3 (77.0 ppm) solvent peaks
Summary
In the competition for food and living space for survival, marine organisms accumulate and secrete secondary metabolites that are deterrent, offensive, or even toxic to other organisms—that is, chemical defense substances [1] Marine invertebrates, such as soft corals, grow slowly and lack physical defense capabilities, but they can survive in competitive marine environments. The marine soft coral genus Lemnalia has afforded structurally diverse novel terpenoids, including sesquiterpenes and diterpene glycosides, with promising biological activity [7]. China Sea. The acetone extracts were chemically investigated, resulting in the discovery of 13 structurally diverse terpenoids, including four new sesquiterpenes (1–4), six new. Cytotoxic, antimicrobial, and antiviral activity of the isolated compounds were investigated Their isolation, structure, and biological activity activity are described.
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