Pharmacopoeial standardization of three Nigerian Khaya Species for antisickling properties
The study examined the macro and micro morphology of Khayasenegalensis(K.S)A.Juss (Welw), Khayagrandifoliola(K.G)C.DcandKhayaivorensis(K.I)A.Chevof the family Meliaceae, identified any morphological differences in the three species, evaluated some pharmacognostic parameters for pharmacopoeial standardization of the three plants and compared their anti-sickling activities. This was with a view to providing information on the different species of Khaya and their anti-sickling potential. The leaves and the stem bark of K. senegalensisA.Juss (Welw), K. grandifoliolaC.Dc, and K. ivorensisA.Chev were collected, authenticated, processed and extracted separately using three different solvents:absolute ethanol, water and petroleum spirit. The extracts were concentrated in vacuo, freeze dried and evaluated separately for their anti-sickling inhibitory and reversal, using sodium meta-bisulphite as reducing agent, p-hydroxy benzoic acid and vanillic acid as positive controls for reversal and inhibitory activities respectively while 5% v/v Tween 80 was the negative control. The extract with the highest anti- sickling properties was subjected to thin layer chromatographic (TLC) finger printing. Comprehensive anatomical examinations, of various sections of the leaf, stem, root and stem bark were carried out using standard methods. Photomicrographs of the slides were made. Proximate analysis was carried out for the three species using simple analytical procedures, moisture content, ash values, crude fibre, total crude proteinas well as elemental analysis. The macroscopic and microscopic study of the three species revealed that there were diagnostic features in the leaf, stem, roots and bark that can be used for distinguishing among the threeKhayaspecies. The result of the proximate and elemental analysis showed that the leaves and stem bark contained necessary rich nutrients and essential minerals. The anti-sickling study of inhibitory and reversal activities showed that both leaf and stem bark of Khayaspecies studied possessed ability to inhibit the sickling of red blood cells with KI stem bark giving highest inhibitory values of 80.71% and 71.06% for hot ethanolicSoxhlet and cold ethanolicextractions respectively while its leaf gave highest reversal activities of 74.97% and 69.97% for hot ethanolicSoxhlet and cold ethanolic extractions respectively. The inhibitory and reversal of sickled red blood cells was at higher percentages than the standard drug vanillic acid of 58.20% and para-hydroxyl benzoic acid of 46.27% . The activities are dose dependent with highest activities at 4mg/ml. The activity of the petroleum spirit extracts was very low. The study concluded that the Khaya species can be developed for herbal drugs in the managementof sickle cell disease since they possessed antisickling activities.