Insight into the apoptosis-inducing action of alpha-bisabolol towards malignant tumor cells: involvement of lipid rafts and Bid

In a precedent report we showed that α-bisabolol, a sesquiterpene present widely in the plant kingdom, exerts a rapid and efficient apoptosis-inducing action selectively towards human and murine malignant glioblastoma cell lines through mitochondrial damage. The present study extends these data demonstrating the apoptosis-inducing action of α-bisabolol towards highly malignant human pancreatic carcinoma cell lines without affecting human fibroblast viability. The present study further shows the preferential incorporation of α-bisabolol to transformed cells through lipid rafts on plasma membranes and, thereafter, direct interaction between α-bisabolol and Bid protein, one of pro-apoptotic Bcl-2 family proteins, analyzed either by Surface Plasmon Resonance method or by intrinsic fluorescence measurement. Notions that lipid rafts are rich in plasma membranes of transformed cells and that Bid, richly present in lipid rafts, is deeply involved in lipid transport make highly credible the hypothesis that the molecular mechanism of α-bisabolol action may include its capacity to interact with Bid protein.