An emulsion of sulfoquinovosylacylglycerol with long-chain alkanes increases its permeability to tumor cells

The alpha-anomer form of sulfoquinovosyl-onoacylglycerol with a saturated C18 fatty acid (alpha-SQMG-C-18:0) is a natural sulfolipid that is a clinically promising antitumor agent. It forms vesicles, micelles or an emulsion in water, depending on several physicochemcal conditions. The type of aggregate formed appears to strongly influence the bioactivity level. Thus, we investigated the nature of the aggregates in relation to their bioactivi ties. The structure of the alpha-SQMG-C-18:0 assembly was greatly affected by the type of additive used in the preparation. Emulsification with ethanol and n-decane might be more effective at inhibiting tumor cell growth than the micelle or vesicle preparations. alpha-SQMG-C-18:0 formed an "emulsion-like-aggregate" in ethanol containing an n-decane concentration in the range of 1.03-103 mM. These ethanol/n-alkane/alpha-SQMG-C-18:0 aggregates inhibited cell growth in a dose-dependent manner, under optimum conditions (i.e., ethanol containing 103 mm of n-decane or n-dodecane dispersed in phosphate-buffered saline or culture medium). Based on these data, we discuss the relationship between the molecular action of and antitumor activity by alpha-SQMG-C-18:0.