Pharmacognostic Study of the Leaves of Piliostigma thonningii Schum (Ceasalpiniaceae)

The existence of huge species and varieties of plants that bear resemblance in their macro-morphological features but differs in micro-morphology and phytochemical constituents has led to misidentification and replacement of one species/variety of plant for another. Hence, the need for standard documentation of the macro and micro morphological features, unshared and unique characters and phytochemical compositions of individual plant drug cannot be over emphasized. This research studied the pharmacognostic profile of Piliostigma thonningii Schum leaf using pharmacognostic tools for crude drug standardization such as macromorphological / organoleptic evaluation, qualitative and quantitative microscopy, analytical evaluation (physicochemical constants) and phytochemical screening. The results of the microscopical evaluation of Piliostigma thonningii leaf showed that it has actinocytic stomata on the upper epidermis, uniseriate trichomes and schizo-lysigenous cavities on the lower epidermis, reticulate and spiral xylem vessels and rosette shape calcium oxalate crystals. While the analytical standard of the powdered drug revealed 9 moisture content, 4.1 total inorganic ash, 2.2 water soluble ash, 0.85 acid insoluble ash, 4.8 sulphated ash, 13 alcohol extractive, 11.5 water extractive and 4.61% n-hexane extractive. The phytochemical screening revealed the presence of saponins, alkaloids, tannins, flavonoids, steroids, glycosides and terpenoids. The overall results of this research can serve as reference standard for proper identification of Piliostigma thonningii plant.