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Three undescribed isoflavones, derriscandenon A, B, and C, together with seven known isoflavones were isolated and structurally characterized during a study of the chemical constituents in the leaves of Derris scandens (Roxb.) Benth (Leguminosae, Fabaceae) collected in Bangladesh. The inhibitory activity of the compounds against activation of Epstein-Barr virus antigen (EBV-EA) by 12-O-tetradecanoylphorbo-13-acetate (TPA) was measured to identify possible chemopreventive agents. Mild inhibitory effects (IC 50 278-290 mol ratio/32 pmol TPA) against EBV-EA induction compared with curcumin (IC 50 341 mol ratio/32 pmol TPA) were observed for four known compounds (lupalbigenin, isopalbigenin, glyurallin, and isangustone A). Next, we focused on antitumor effects and investigated cell viability, cell proliferation, and mitochondria membrane potential by using an MTT assay, a live cell monitoring system, and fluorescence staining. Of the seven isoflavones tested for cell viability, a dose-dependent decrease in cell viability was observed for four isoflavones (derriscandenon B and C, derrubone, and glyurallin) in KB cells and two compounds (derriscandenon B and isochandaisone) in NALM6-MSH+ cells. In addition, the proliferation of KB cells was significantly inhibited by these four compounds at a concentration of 5 μM. The mitochondria membrane potentials of KB cells treated with derriscandenon C, derrubone, and glyurallin at the IC 50 concentration were decreased by about 55%, whereas undescribed compound derriscandenon B had no effect. Our results show that some of the compounds isolated from D. scandens may be suitable as seed compounds for cancer prevention and therapy., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

As part of the phytochemical studies of the plant genus Glycosmis, the constituents of the plant Glycosmis arborea were investigated. Three new carbazole alkaloids named glybomines A (1), B (2), and C (3), along with known monomeric alkaloids belonging to the carbazole, quinazoline, furoquinoline, quinolone, and acridone classes, were isolated from stems of the plant collected at Mymensing in Dhaka, Bangladesh. Glybomine A (1) is the first example of a 2,5-oxygenated carbazole alkaloid from natural sources. As a primary screening test for anti-tumor promoters, nine alkaloids isolated from this plant have been tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) induction by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). All alkaloids tested showed inhibitory activity.