Flemingins G−O, Cytotoxic and Antioxidant Constituents of the Leaves of Flemingia grahamiana

Abstract

The known flemingins A–C (1–3) and nine new chalcones, named flemingins G–O (4–12), along with deoxyhomoflemingin (13) and emodin (14) were isolated from a leaf extract of Flemingia grahamiana. The isolated chalcones were found to have a geranyl substituent modified into a chromene ring possessing a residual chain, as shown by spectroscopic methods. The leaf extract showed an IC50 value of 5.9 μg/mL in a DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay. The chalcones flemingins A, B, C, G, and H were active in the DPPH radical scavenging assay (ED50 4.4–8.9 μM), while flemingins A and C showed cytotoxicity against MCF-7 human breast cancer cells (IC50 8.9 and 7.6 μM, respectively).