Abstract
Three triterpenoidal derivatives [Sipholenol A (
), sipholenol L (
) and sipholenone A (
)] were isolated from the Red Sea sponge
sp. The structures were determined based on spectroscopic measurements (NMR, UV, IR and MS). The isolated compounds were evaluated for their cytotoxic activity against three cancer cell lines; HepG2, Caco-2 and HT-29. Moreover, the effects of these metabolites on cell cycle progression as well as cell cycle regulating proteins were assessed. Compounds
,
and
showed moderate activity against HepG2 cells with IC
values of 17.18 ± 1.18, 24.01 ± 0.59 and 35.06 ± 1.10 μM, respectively. Compounds
and
exerted a considerable antiproliferative effect with IC
values of 4.80 ± 0.18 and 26.64 ± 0.30 μM, respectively, against Caco-2 cells. Finally,
and
exhibited antiproliferative activity against colorectal cancer cells (HT-29) with IC
values of 24.65 ± 0.80 and 4.48 ± 0.1 μM, respectively. Cell cycle analysis indicated that these compounds induced cell cycle arrest particularly in G0/G1 and S phases. Furthermore, the triterpenoids increased the expression of cyclin-B1, cyclin-D1 and cleaved caspase-3, as determined by immunofluorescence, indicating an important role of apoptosis in cell death induced by these compounds.