| Summary: | Seven sulfated triterpene glycosides, psolusosides B (<b>1</b>), E (<b>2</b>), F (<b>3</b>), G (<b>4</b>), H (<b>5</b>), H<sub>1</sub> (<b>6</b>), and I (<b>7</b>), along with earlier known psolusoside A and colochiroside D have been isolated from the sea cucumber <i>Psolus fabricii</i> collected in the Sea of Okhotsk. Herein, the structure of psolusoside B (<b>1</b>), elucidated by us in 1989 as a monosulfated tetraoside, has been revised with application of modern NMR and particularly MS data and proved to be a disulfated tetraoside. The structures of other glycosides were elucidated by 2D NMR spectroscopy and HR-ESI mass-spectrometry. Psolusosides E (<b>2</b>), F (<b>3</b>), and G (<b>4</b>) contain holostane aglycones identical to each other and differ in their sugar compositions and the quantity and position of sulfate groups in linear tetrasaccharide carbohydrate moieties. Psolusosides H (<b>5</b>) and H<sub>1</sub> (<b>6</b>) are characterized by an unusual sulfated trisaccharide carbohydrate moiety with the glucose as the second sugar unit. Psolusoside I (<b>7</b>) has an unprecedented branched tetrasaccharide disulfated carbohydrate moiety with the xylose unit in the second position of the chain. The cytotoxic activities of the compounds <b>2</b>−<b>7</b> against several mouse cell lines—ascite form of Ehrlich carcinoma, neuroblastoma Neuro 2A, normal epithelial JB-6 cells, and erythrocytes—were quite different, at that hemolytic effects of the tested compounds were higher than their cytotoxicity against other cells, especially against the ascites of Ehrlich carcinoma. Interestingly, psolusoside G (<b>4</b>) was not cytotoxic against normal JB-6 cells but demonstrated high activity against Neuro 2A cells. The cytotoxic activity against human colorectal adenocarcinoma HT-29 cells and the influence on the colony formation and growth of HT-29 cells of compounds <b>1</b>−<b>3</b>, <b>5</b>−<b>7</b> and psolusoside A was checked. The highest inhibitory activities were demonstrated by psolusosides E (<b>2</b>) and F (<b>3</b>).
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