Chalcone derivatives from the fern Cyclosorus parasiticus and their anti-proliferative activity

Three new chalcone derivatives, named parasiticins A–C (1–3), were isolated from the leaves of Cyclosorus parasiticus, together with four known chalcones, 5,7-dihydroxy-4-phenyl-8-(3-phenyl-trans-acryloyl)-3,4-dihydro-1-benzopyran-2-one (4), 2′-hydroxy-4′,6′-dimethoxychalcone (5), 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (6), 2′,4′-dihydroxy-6′-methoxy-3′-methylchalcone (7). The chemical structures of the new isolated compounds were elucidated unambiguously by spectroscopic data analysis. The cytotoxic activities of compounds 1–7 were evaluated against six human cancer cell lines in vitro. Compounds 3 and 6 exhibited substantial cytotoxicity against all six cell lines, especially toward HepG2 with the IC50 values of 1.60 and 2.82 μM, respectively. Furthermore, we demonstrated that compounds 3 and 6 could induce apoptosis in the HepG2 cell line, which may contribute significantly to their cytotoxicity.