Seven new minor
triterpene glycosides, cucumariosides A2 (1), A7 (2), A9 (3),
A10 (4), A11 (5), A13 (6) and A14 (7) have been isolated from the Far Eastern sea cucumber Eupentacta fraudatrix. Structures of the
glycosides were elucidated by 2D NMR spectroscopy and MS.
Glycosides 1-7 belong to the group of cucumariosides A, having linear tetrasaccharide
carbohydrate moieties without any
sulfate group and possessing 3-O-methyl-D-xylose as a terminal
monosaccharide unit.
Glycosides 1, 2, 5-7 differ from each other in side chain structures in aglycone moieties, while
cucumarioside A10 (4) has a 23,24,25,26,27-pentanorlanostane aglycone with 18(16)-lactone.
Cucumarioside A9 (3), having an uncommon 18-hydroxy group, is the second representative of the unique metabolically active
glycosides that are regarded as intermediates of
glycoside biosynthesis in sea cucumbers. Cytotoxic activities of
glycosides 1-7 and
cucumarioside A8 (8) against mouse spleen lymphocytes and the cells of the ascite form of mouse Ehrlich
carcinoma, along with hemolytic activity against mouse erythrocytes and antifungal activity were studied. Cucumariosides A2 (1), A8 (8) and A13 (6) demonstrated high hemolytic activities.
Glycosides 1, 4 and 6 showed moderate cytotoxic activity. Only
cucumarioside A8 (8), having an 18-oxymethylene group and a 24(25)-double bond, was very active in all the tests.