Evaluation of the chemical, nutritional, antimicrobial and antioxidant-vitamin profiles of Piliostigma thonningii leaves (Nigerian species)

In this study, the antioxidant-vitamin, phytochemical, mineral and proximate compositions as well as the antimicrobial sensitivity of Piliostigma thonningii leaves were evaluated. The dry leaf powder was found to contain alkaloids, saponins, flavonoids and tannins as phytochenicals in amounts between 0.2 to 2.1 g/100 g. The proximate analysis showed that they are rich in carbohydrate (72.17%). Other food nutrients include crude protein (10.09%), dietary fibre (23.05%), ash (9.13%), moisture (5.57%) and low amount of crude fat (2.81%). Ca, Mg, K, Na, Fe, Zn, Pb, Mn and Cu were the detectable mineral elements in the P. thoningii leaves. Ca and Pb had the highest (1740 mg/100 g) and lowest (0.4 mg/100 g) values, respectively. The plant leaves were also found to contain vitamin C (17.80 mg/100 g), vitamin E (3.29 mg/100 g) and beta carotene (12.5 mg/100 g). The results of the antimicrobial screening of the aqueous and ethanolic extracts of the leaves against eight human pathogenic microbes, five bacteria and three fungi showed that at 25 mg mL -1 concentration, both extracts exhibited potency range of 30.43 to 45.28% relative to a reference antibiotic (tetracycline). The ethanolic extract showed higher antimicrobial activities at all concentrations as compared to the aqueous extract. Results from the study have shown that Piliostigma thonningii leaves are a good source of some minerals, antioxidant-vitamins and efficient source of energy (energy value = 404.05 kcal/100 g). © 2012 Academic Journals Inc.