We recently reported that colored potato extracts and an anthocyanin rich fraction suppressed lymph-node carcinoma of the prostate (LNCaP) and prostate cancer-3 (PC-3) prostate cancer cell proliferation and induced apoptosis via caspase-dependent and caspase-independent pathways. Chlorogenic acid, caffeic acid, gallic acid, catechin, malvidin, and glycoalkaloids (alpha-chaconine and solanine) have now been identified as the major bioactive components of potato, and their effects on LNCaP and PC-3 cell proliferation and apoptosis have been investigated. alpha-chaconine (5 microg/ml) and gallic acid (15 microg/ml) exhibited potent antiproliferative properties and increased cyclin-dependent kinase inhibitor p27 levels in both cell lines. Both alpha-chaconine and gallic acid induced poly [adenosine diphosphate (ADP)] ribose polymerase cleavage and caspase-dependent apoptosis in LNCaP cells; however, caspase-independent apoptosis through nuclear translocation of endonuclease G was observed in both LNCaP and PC-3 cells. alpha-chaconine and gallic acid activated c-Jun N-terminal protein kinase (JNK), and this response played a major role in induction of caspase-dependent apoptosis in LNCaP cells; whereas modulation of JNK and mitogen-activated protein kinase did not affect alpha-chaconine- and gallic acid-induced caspase-independent apoptosis. These results suggest that apoptosis induced by whole potato extracts in prostate cancer cell lines may be in part due to alpha-chaconine and gallic acid.