Effect of ester groups on the haemolytic action of sapogenins—II: Esterification with bifunctional acids

Abstract

The cause for the enhancement of haemolysing capacity of sapogenin esters was investigated. For this purpose the haemolysis induced by sapogenins esterified with an acid bearing an extra polar group (i.e. OH or COOH) was compared with that of the corresponding simple esters. It was shown that the presence of a free OH or COOH group in the acid part of the ester inhibits haemolysis. This inhibition may be overcome by acetylation or methylation of the OH or COOH group respectively. It appears that it is not the introduction of an ester group which enhances haemolysis but the removal of the polar group. Sapogenins bearing two polar groups, the esterification of one of them, no matter which, enhances haemolysis, whereas the blocking of the second group reduces this effect. It was further shown that neither the presence of an OH group nor that of any oxygen function at position 3 in the sapogenin is essential for haemolysis.