Biologically Active Glycosides from Asteroidea, XII. Steroid Oligoglycosides from the Starfish Asterina pectinifera Müller et Troschel, 1 Structures of Two New Sapogenins and Two New Oligoglycoside Sulfates: Pectinioside A and Pectinioside B

The four steroid sapogenins 1, 2, 3 , and 4 were obtained as solvolysis products of the enzymatic hydrolysis of a crude oligoglycoside fraction prepared from the aqueous extract of the starfish Asterina pectinifera Müller et Troschel (Asterinidae). Two novel steroid oligoglycoside sulfates, 5 and 6 , were also obtained from the same crude glycoside fraction. On the basis of chemical and spectroscopic evidence, the structures of these sapogenins were determined as (3β,5α,6α)‐3,6‐dihydroxypregn‐9(11)‐en‐20‐one (asterone) ( 1 ), (3β,5α,6α,20 S )‐3,6,20‐trihydroxycholest‐9(11)‐en‐23‐one (20 S ‐thornasterol A) 1,3) ( 2 ), (3β,5α,6α,20 R , 22 R ,23 S ,24 S )‐22,23‐epoxy‐3,6,20‐trihydroxy‐24‐methylcholest‐9(11)‐ene (aglycone of regularoside A) 4) ( 3 ), and (3β,5α,6α,20 S ,24ξ)‐24‐ethyl‐3,6,20‐trihydroxycholest‐9(11)‐en‐23‐one ( 4 ). The oligoglycosides were characterized as the 6‐ O ‐β‐ D ‐fucopyranosyl‐(1→2)‐β‐ D ‐glucopyranosyl‐(1→4)‐[β‐ D ‐quinovopyranosyl‐(1→2)]‐β‐ D ‐quinovopyranosyl‐(1→3)‐β‐ D ‐quinovopyranoside 5 of the 3‐ O ‐sodium sulfate of 2 and the 6‐ O ‐β‐ D ‐galactopyranosyl‐(1→4)‐[β‐ D ‐fucopyranosyl‐(1→2)]‐β‐ D ‐glucopyranosyl‐(1→4)‐[β‐ D ‐quinovopyranosyl‐(1→2)]‐β‐ D ‐xylopyranosyl‐(1→3)‐β‐ D ‐quinovopyranoside 6 of the 3‐ O ‐sod um sulfate of 3 . Compound 3 has not yet been isolated as aglycone, and compound 4 is a novel natural product. Moreover, the sugar moieties of compounds 5 and 6 are unique oligosaccharides. Negative FAB‐mass and PRFT‐ 13 C‐NMR spectra were useful in providing information on the molecular masses and the structures of these complex oligoglycoside sulfates.