Cyanidin and Malvidin from Oryza sativa cv. Heugjinjubyeo Mediate Cytotoxicity against Human Monocytic Leukemia Cells by Arrest of G2/M Phase and Induction of Apoptosis

Oryza sativa cv. Heugjinjubyeo (Gramineae), anthocyanin-pigmented rice, having dark purple grains, is known broadly as enriched rice with an improved taste. Two bioactive compounds were isolated from the 0.5% HCl−ethyl alcohol soluble fraction of the aleurone layer of O. sativa cv. Heugjinjubyeo through an activity-monitored fractionation and isolation method. From spectral analysis, the cytotoxic components were the anthocyanidins cyanidin (1) and malvidin (2). The 50% growth inhibitory concentrations (IC50) of cyanidin and malvidin on U937, human monocytic leukemia cells, were 60 and 40 μg/mL, respectively. These compounds showed cytotoxicity through the arrest of the G2/M phase of cell cycle and induction of apoptosis. Keywords: Oryza sativa cv. Heugjinjubyeo; Gramineae; anthocyanidin; cyanidin; malvidin; cytotoxicity; phytonutrients; human monocytic leukemia cells; cell cycle arrest; apoptosis