1
Mahanine, a naturally occurring
carbazole alkaloid in some Asian vegetables, has been shown to exhibit antimutagenicity, antimicrobial activity, cytotoxicity, and other
biological properties. 2 In the present study, we investigated the effect of
mahanine on the activation of the apoptotic pathway in human
leukemia U937 cells. Various end points were used to screen for apoptosis: Morphological changes in cells, the relative numbers of viable and apoptotic cells; translocation of membrane bound
phosphatidylserine and
DNA analysis. 3 We found that
mahanine-induced apoptosis in U937 cells involved activation of
caspases, including
caspase-3, release of
cytochrome c into cytosol, loss of mitochondrial membrane permeability, and decreased levels of cellular
ATP. 4 Pretreatment of cells with
cyclosporine A, prior to/concomitant with exposure to
mahanine, effectively prevented the deleterious effects of the
alkaloid on cellular integrity and viability. 5 As mitochondrial permeability is known to be important in the regulation of
cytochrome c release, our observations indicate that mitochondria are the principal target of
mahanine. More specifically, we propose that
mahanine causes the mitochondrial membranes to lose their permeability, resulting in
caspase-3 activation and apoptosis.