Carbohydrate Modifications of Neoandrographolide for Improved Reactive Oxygen Species-Mediated Apoptosis through Mitochondrial Pathway in Colon Cancer

Modifications at the carbohydrate moiety of neoandrographolide, isolated from the medicinal plant Andrographis paniculata , result in more potent and less toxic derivatives, namely, 4',6'-benzylidene neoandrographolide ( 2b ) and 4'6'- p -methoxybenzylidene neoandrographolide ( 2c ). These showed improved cytotoxicity against SW-620, PC-3, and A549 cancer cell lines. Nuclear morphology studies were conducted on compound 2b by 4',6-diamidino-2-phenylidole staining and detection of intracellular reactive oxygen species (ROS) accumulation. It showed an increase in the generation of cellular and mitochondrial ROS level. The probable relation of B-cell lymphoma-2 (Bcl-2, an apoptosis inhibitor) to B-cell lymphoma-2-associated X protein (Bax, an apoptosis promoter) ratio with caspase-3 (apoptosis coordination enzyme) in the colon cancer cell line SW-620 was investigated, and it was discovered that upon 2b treatment, the expression of caspase-3 Bax increased remarkably. However, in 2b- treated cells, the expression of Bcl-2 was downregulated as compared to untreated cells.