Four new isoflavones from Derris scandens and their in vitro antiproliferative effects

Four new compounds (derriscandenon D (1), E (2), F (3), G (4)) and six known isoflavones (warangalone (5), millewanin E (6), rhynedlin A (7), 6,8-diprenylgenistein (8), isolupalbigenin (9), isoscandinone (10)) were isolated from the acetone extract of the branches of Derris scandens. These compounds were assayed for cell viability using the human lung carcinoma cell line A549, colorectal carcinoma cell line Colo205, epidermoid carcinoma cell line KB, the human acute lymphoblastic leukaemia cell line NALM-6, and human dermal fibroblasts. Compounds 2 and 3 significantly decreased the viability of KB cells, with IC₅₀ values of 2.7 and 12.9 µM, respectively. In addition, compounds 2 and 3 reduced the mitochondrial membrane potential in KB cells. Compounds 2 and 3 strongly down-regulated the cell viability of cell lines KB and NALM-6, achieving IC₅₀ values of 2.7 and 0.9 µM, respectively, compared with the positive control staurosporine at 1.25 and 0.01 µM, respectively.