Formamido-Diterpenes from the South China Sea Sponge Acanthella cavernosa

Abstract

Seven new formamido-diterpenes, cavernenes A–D (1–4), kalihinenes E and F (5–6), and kalihipyran C (7), together with five known compounds (8–12), were isolated from the South China Sea sponge Acanthella cavernosa. Structures were established using IR, HRESIMS, 1D and 2D NMR, and single X-ray diffraction techniques. The isolated compounds were assessed for their cytotoxicity against a small panel of human cancer cell lines (HCT-116, A549, HeLa, QGY-7701, and MDA-MB-231) with IC50 values in the range of 6–18 μM. In addition, compound 9 showed weak antifungal activity against Trichophyton rubrum and Microsporum gypseum with MIC values of 8 and 32 μg/mL, respectively, compound 10 displayed weak antifungal activity against fungi Candida albicans, Cryptococcus neoformans, T. rubrum, and M. gypseum with MIC values of 8, 8, 4, and 8 μg/mL, respectively.

Biological Activity of Recently Discovered Halogenated Marine Natural Products

“…The South China Sea sponge Acanthella cavernosa has afforded the new cavernenes A–D ( 376 – 379 ), kalihinenes E ( 380 ) and F ( 381 ), and kalihipyran C ( 382 ) ( Figure 74 ), in addition to several known analogues [ 142 ]. These metabolites were screened against several human cancer cell lines ( Table 13 ).…”

“… Structures of cavernenes A–D ( 376 – 379 ), kalihinenes E ( 380 ) and F ( 381 ) and kalipyran C ( 382 ) from the sponge Acantella cavernosa [ 142 ]. …”

Marine Isonitriles and Their Related Compounds

“…Another variation of the cis -decalin tetrahydrofuran-substituted kalihinenes is kalihinene F ( Ken12 ), which was isolated in 2012 by Xu et al and bears a trisubstituted Δ 9 -double bond similar to Δ 9 kalihinol Y ( Kol10 ) [ 113 ].…”

Syntheses and biological studies of marine terpenoids derived from inorganic cyanide

“…The cavernene natural products, 49–52 , as well as additions to the kalihinol and kalihinene families, 53–58 , were reported through isolation efforts from Acanthella cavernosa (Figure 4A). xxiii,xxiv,xxv Notably, kalihinols M-T ( 59–66 ) were obtained from the South China Sea in a bioassay guided fraction effort targeted at biofouling. These compounds show a range of anti-biofouling activity, including several compounds in the submicromolar range.…”