Hyrtiosins F and G, two new scalarane sesterterpenes from the South China sea sponge Hyrtios erecta .

Two new scalarane sesterterpenes, hyrtiosins F and G ( 1 and 2 ), along with two known related compounds, hyrtiosin D and sesterstatin 6 ( 3 and 4 ), were isolated from the Hainan marine sponge Hyrtios erecta. The structures of new compounds 1 and 2 were determined by detailed analysis of 1D and 2D NMR spectra and by comparison of the spectroscopic data with those reported in the literatures.