Effect of steroidal glycoalkaloids of the potato on the permeability of liposome membranes

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Abstract
At pH 7.2, the potato glycoalkaloid α‐chaconine caused release of entrapped peroxidase from phosphatidylcholine liposomes containing different free sterols but was ineffective against sterol‐free liposomes. The alkaloid was able to complex with all the tested sterols in vitro although there was no close correlation between the extent of sterol binding and liposome disruption. α‐Solanine also complexed with sterols in vitro but had no effects on sterol‐containing liposomes under these conditions. Both sterol concentration and alkaloid concentration were limiting factors in the action of chaconine but did not markedly affect that of solanine. Solanine destabilized liposome membranes only at pH values of 8 and above but was less effective than chaconine. The importance of the carbohydrate moiety of glycoalkaloids was further demonstrated by the inability of β2‐chaconine to complex with sterols or disrupt liposomes.