Aphelasteroside F, a new Asterosaponin from the Far Eastern Starfish Aphelasterias japonica.

A new asterosaponin aphelasteroside F (1) was isolated from the ethanolic extract of the Far Eastern starfish Aphelasterias japonica along with the previously known ophidianoside F (2). The structure of 1 was elucidated by extensive use of NMR and ESI-MS techniques, and chemical transformations. Compound 1 contains a new type of asterosaponin carbohydrate chain linked to C-6 of the steroid aglycone aphelaketotriol. Compounds 1 and 2 at non-toxic concentrations slightly inhibited cell proliferation and colony formation of the cancer melanoma cell lines SK-Mel-28, SK-Mel-5, and RPMI-7951.