(+)-Tephrodin - A New Flavone from Tephrosia purpurea

Abstract

Tephrosia species are widely used in East African traditional medicinal practice to treat various infectious diseases. In our continued search for antiplasmodial agents from Tephrosia species found in Kenya a new flavone [(+)-Tephrodin] from the stem of T. purpurea was isolated.1 Its 1H NMR spectrum is identical with the spectrum reported for tephrodin which was isolated from T. polystachyoides.2 1 Muiva-Mutisya L., Macharia B., Heydenreich M., Koch A., Akala H.M., Derese S., Omosa L.K., Yusuf A.O., Kamau E., Yenesew, A. Phytochem. Lett., in press. 2 Vleggar R., Smalberger T.M., de Waal H.L. Tetrahedron Lett. 13 (1972) 703 However, in contrast to the levorotatory tephrodin found by Vleggar et al. our compound showed dextrorotatory behaviour ([α]D20 = +4.7°). This suggests that both compounds must be stereoisomers. To clarify the relative configuration of our compound experimental data are compared with theoretical quantum chemical calculations (DFT B3LYP 6311G**). For configurational and conformational analysis the coupling constants between H-3“ and both protons H-2“ (2.3 and 1.0 Hz, resp.) can be used: