Investigation of the polar steroids from an Antarctic Starfish of the family Echinasteridae: isolation of twenty seven polyhydroxysteroids and steroidal oligoglycosides, structures and biological activities

Abstract

An investigation of the extracts from a starfish collected in the Antarctic Sea, Echinasteridae family, has led to the isolation of thirteen glycosides of polyhydroxysteroids (1–13), fourteen polyhydroxysteroids (14–27), which are the subject of this report, and seven asterosaponins (penta-and hexa-saccharides), described in a previous paper. Glycosides 1–13 are composed of the same 3β,4β,6α,8,15β,26-hexahydroxysteroidal aglycone with small variations in the side chains, and a carbohydrate portion made up of one or two monosaccharide units attached at C-26, except 11, which has a steroidal aglycone with a 24,28-dihydroxylated side chain and the monosaccharide unit attached at C-24. The structures of the polyhydroxysteroids (14–27) have the hydroxyl groups typically disposed on one side of the steroid nucleus, i.e. 3β,4β,6β (or α),8,15α (or β) and 16β and the majority of them possess a 26-hydroxyl function. A selection of fifteen compounds were tested against human non-small-cell lung carcinoma cells and found to be moderately cytotoxic.