Meroterpenoids from Marine Sponge Hyrtios sp. and Their Anticancer Activity against Human Colorectal Cancer Cells

Two new meroterpenoids, hyrtamide A (1) and hyrfarnediol A (2), along with two known ones, 3-farnesyl-4-hydroxybenzoic acid methyl ester (3) and dictyoceratin C (4), were isolated from a South China Sea sponge Hyrtios sp. Their structures were elucidated by NMR and MS data. Compounds 2-4 exhibited weak cytotoxicity against human colorectal cancer cells (HCT-116), showing IC₅₀ values of 41.6, 45.0, and 37.3 μM, respectively. Furthermore, compounds 3 and 4 significantly suppressed the invasion of HCT-116 cells while also downregulating the expression of vascular endothelial growth factor receptor 1 (VEGFR-1) and vimentin proteins, which are key markers associated with angiogenesis and epithelial-mesenchymal transition (EMT). Our findings suggest that compounds 3 and 4 may exert their anti-invasive effects on tumor cells by inhibiting the expression of VEGFR-1 and impeding the process of EMT.