Effect of streptococcal lipids on Ehrlich ascite tumor cells.

The lipids extracted from group A hemolytic streptococci (strain Su, Blackmore and C203U) were examined for their antitumor effect against Ehrlich ascites carcinoma in mice. Total lipids were extracted from streptococcal cells according to the method of Folch et al, and separated into 9 lipid fractions by thin-layer chromatography, using various solvent systems. Three fractions were compound lipids (diphosphatidyl glycerols, monoglucosyl diglycerides and diglucosyl diglycerides), and the remaining 6 fractions were neutral lipids such as free fatty acids, glycerides, sterols and sterol esters. For biological testing, the lipid fractions suspended in physiological saline containing Tween 20 (0.02%) were incubated with Ehrlich tumor cells at 37 degrees C for 90 min, and the cell mixture was given intraperitoneally into mice thereafter. Among 9 lipid fractions, free fatty acids and monoglycerides from the streptococci examined were highly active in suppressing the depressing the development of ascites carcinoma in mice. Diphosphatidyl glycerols from two strains of streptococci (BLackmore and C203U) were also effective in suppressing the tumor growth in mice. However, the other lipid fractions had little effect on the tumor growth.