Spectrophotmetric evaluation of rotenone extraction from leaves and seeds of mature Tephrosia vogelii plant

Abstract

The percentage yield of rotenone extracted from Tephrosia vogelii leaves and seeds was investigated.  Ten samples of well ground leaves and seeds were each subjected to extraction in soxhlet extraction system using trichloromethane, ethanol and methanol solvents for 24 h at room temperature. The maximum absorption wavelength of rotenone was determined using Ultra violet-visible spectrophotometer.  Different solvent extracts were quantified using high performance liquid chromatography instruments fitted with Ultra Violet detector and their yield expressed as percentage rotenone. Trichloromethane recorded the highest rotenone yield from both leaves (8.3 and seeds 2.7%) compared to the other two solvents. Ethanol was second with 5.9% in leaves and 1.9% in seeds while methanol had 4.8% in leaves and 1.6% in seeds. In general, the leaves extracts were found to have a higher rotenone percentage yield by an average factor of 3 compared to seeds. Rotenone can be commercially extracted from T. Vogelii using ethanol that is locally available to complement natural pyrethrum insecticide industry. Key words:  Rotenone, Tephrosia vogelii, solvents, seeds, leaves.