A spectroscopic technique for evaluating sterol-aponin interactions and implications for management of Ptychodiscus...

A double-beam quadruple-cell spectrophotometric technique is described that can be used to evaluate the interaction between sterols and HPLC fractions from Nannochloris sp. which are cytolytic (aponin) toward the red tide organism. The interaction with ergosterol but not beta-sitosterol is consistent with complex formation and also with the reduction of cytolytic activity of aponin in the presence of ergosterol, as previously noted. Implications for the mechanism of aponin cytolytic activity are considered.