Holostane

Recently, some examples of holothurins having uncommon non-holostane aglycones have appeared in the literature. These glycosides have been isolated from seven species of sea cucumbers belonging to the order Dendrochirota. All are sulfated compounds, the majority monosulfated at the glucose or xylose units. 

Fig. (18). Structures of non-holostane glycosides isolated from the sea cucumbers Eupentacta jraudatrtx and Pentamera calcigera...

Koreoside A (20) isolated from Cucumaria koraiensis is one of the two examples of non-holostane glycosides with three sulfate groups in the oligosaccharide chain, Fig. (20). 

C-NMR data for non-holostane triterpenoid aglycones in intact glycosides are shown in Table 2. 

DS-penaustrosides A (79) and B (80) revealed cytotoxic activities against murine lymphoma L1210 and human epidermoid carcinoma KB cell lines [IC5o=0.12 (L1210) and 0.62 (KB) p.g/ml for 79 2.1 (L1210) and 4.6 (KB) ig/ml for 80] [69]. Unfortunately, the authors did not show the data on activities of relative holostane derivatives in the same experimental conditions. 

Some examples of sulfated holothurins with uncommon non-holostane aglycones have been isolated from eight species of sea cucumbers belonging to the order Dendrochirotida. Glycosides 62a-62e, Fig. (30) contain aglycones with a 18(16)-lactone [69, 70, 97, 98]. 

Recently, frondoside A2-8 (65), a new saponin with a non-holostane aglycone containing a A double bond, a hydroxyl group at C-20 and an acetoxy group at C-22 was isolated from the sea cucumber Cucumaria frondosa. Fig. (33) [62]. 

Another general observation is that the holothurins are structurally more homogeneous than the saponins of sea stars. On the carbon skeleton of holostane there are only about 20 side chains and some 30 osidic parts, whereas more than 150 side chains and more than 50 osidic parts have been found in asterosaponins and related derivatives. 

Some rare holuthurins not having the carbon skeleton of holostane are displayed in Figure 26.27. 

Kalinin, V.I., Kahnovsku, A.I., Stonik, V.A., Dmitrenok, P.S., and Elldn, Y.N. (1989) Structure of psolusoside B, a non-holostane triterpene glycoside from the holothurian genus Psolus. Khim. Prir. Soedin., 361-368. 

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