Studies on the Chemical Constituents of Stem Bark of Millettia leucantha: Isolation of New Chalcones with Cytotoxic, Anti-herpes Simplex Virus and Anti-inflammatory Activities

Four new chalcone derivatives (1, 4, 7, 10) were isolated from the stem bark of Millettia leucantha KURZ (Leguminosae) along with two known ones (2, 6) and five known flavones (3, 5, 8, 9, 11). Structure elucidation and unambiguous assignment of the isolates were achieved with the aid of 1D and 2D NMR extensive studies. Correlation of 10 to 4 was successfully done by reduction with Et3SiH/CF3CO2H. Moderate cytotoxic activity was observed in chalcones (1, 10), whereas dihydrochalcones (4, 6) showed moderate anti-Herpes Simplex Virus (HSV) activity. Interestingly, flavone 8 showed significant anti-inflammatory effects inhibiting both cyclooxygenase (COX)-1 and -2.