Calamusins J-K: new anti-angiogenic sesquiterpenes from Sarcophyton glaucum

Abstract

Chemical investigation of the organic extract of the marine soft coral Sarcophyton glaucum from Red Sea, Egypt, afforded two new hydroazulenes; calamusin J (1) and its hydroperoxide derivative calamusin K (2) in addition to eight known compounds. Structure of compounds 1-2 were confirmed by intensive NMR and mass spectrometry studies. The coral extract and the obtained compounds were examined against a set of diverse microorganisms. The in vitro anti-cancer properties were assessed against colon (Caco-2) and breast (MCF-7) cell lines together with their exerted cytotoxicity on the immortalized normal epithelium (hTERT-RPE1) cell type. The anti-angiogenic power was also highlighted through suppressing MCF-7 cell migration and the significant inactivation of VEGFR2 enzyme. Compounds 1,2 are the most potent angiogenic inhibitors (represented by 1.2- and 1.4-fold enzyme inactivation, respectively) relative to sorafenib. The polyhydroxy sterol; 5α-3β,6α,11-trihydroxy-24-methyl-9,11-seco-5a-cholest-7-en-9-one (S4) inhibited effectively the growth of Caco-2 and MCF-7 with GI₅₀ of 0.62 and 2.3 µM, respectively.

Keywords:

• Sarcophyton sp
• Calamusins J-K
• diverse metabolites
• anti-cancer
• anti-migratory
• anti-angiogenic

Acknowledgements

The authors are grateful to Prof. Laatsch, Institute of Organic and biomolecular chemistry, Goettingen for unlimited lab facilities. Dr. John for the NMR spectra, Dr. H. Frauendorf for the mass spectra. The partial financial support of this work by a short Post-doc fellowship to M. Shaaban by DAAD is gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.