Anti‐tumor Effect of Chemically Synthesized Sulfolipids Based on Sea Urchin's Natural Sulfonoquinovosylmonoacylglycerols

We recently reported that 3′‐sulfonoquinovosyl‐1′‐monoacylglycerol (designatedA‐5) extracted from sea urchin intestine was effective in suppressing the growth of solid tumors. Although the major fatty acid component of A‐5 was a saturated C(16) acid, there were five other fatty acids, 14:0, 18:0, 14:1, 16:1, and 18:1, which constitute minor components of A‐5. Therefore, it remains unclear as to which of these six fatty acid components of A‐5 has the anti‐tumor effect. In this study, we synthesized sulfolipids each containing only one of these six fatty acids and tested their cytotoxicity against tumor cells and in vivo anti‐tumor effects on nude‐mice bearing solid tumors of human lung adenocarcinoma cell line A‐549. The IC(50) values of all products against tumor cells were more than 10(‐5)M, suggesting weak cytotoxic activity compared with other chemotherapeutic compounds for cancer. On the other hand, in vivo anti‐tumor assay showed that sulfoquinovosyl‐monoacylglycerols (SQMG) composed of 14:1 and 18:1 (designated SQMG(14:1) and SQMG(18:1), respectively) were significantly effective in suppressing the growth of solid tumors. Our data suggested that these two SQMGs had a substantial anti‐tumor effect in vivo, and they are of interest as candidate drugs for anti‐cancer treatment.