Dihydropyridinone alkaloid artifacts from Curcuma longa and their anti-migration activity against HepG2 cells

A new 2,3-dihydropyridin-4(1H)-one alkaloid (2), and two other known derivatives (1 and 3) were isolated from Curcuma longa. The isolated alkaloids are shown to be artifacts formed during extraction procedure. Three new (2, 5 and 7) and two known (4 and 6) methoxylated compounds were derived from 1 and 3. Structures were assigned using IR, HRESIMS analyses and 1 and 2D NMR spectroscopy. The anti-migration and anti-proliferation activities against the hepatocellular carcinoma cells, HepG2 were investigated. Compounds 3 showed remarkable anti-migration activity at 40 μM (absolute migration capability, MC_A = -7.4 x 10^-4 mm/h). The methylated derivatives 4 showed pronounced anti-migration activity (MCA = -4.9 x 10-4 mm/h) compared to its parent compound 1 (MCA = 1.49 x 10-3 mm/h) at 20 μM. The dihydropyridinone derivatives were shown to develop actin stress fibres in treated HepG2 cells which may indicate its role in cell migration inhibition. Compared to curcumins I, II and III, the obtained dihydropyridinone analogues showed lower anti-proliferative activity.