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

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.