Pharmacognostic and toxicological evaluation of the leaves of Piper guineense Schum. and Thonn (Piperaceae)

The leaves of Piper guineense Schum. and Thonn (Piperaceae) are used in ethnomedicine for the management/treatment of various diseases. The objective of this study was to establish the pharmacognostic and toxicological profiles of P. guineense to help practitioners in making choices, and to assist scientists involved in the research of the Piper genus. The fresh leaves were examined for their macroscopic and microscopic properties. Numerical (quantitative analysis) and phytochemical evaluations were carried out using standard methods. Acute toxicity profile of the plant, including LD 50 was investigated using mice while sub-acute toxicity to determine effects of the plant leaf extract on some major organs was investigated for 30 days in rats. The macroscopic, microscopic and numerical features observed in the leaves of P. guineense could aid in sample identification. Glycosides, alkaloids and phenolics were among the secondary plant metabolites present. Oral doses ≤ 8000 mg/kg did not lead to death of the animals. Sub-acute toxicological evaluations at the doses of 250 and 500 mg/kg showed mild congestion in all the target organs, except spleen, where at 500 mg/kg, in addition to mild stromal oedema, there was mild follicular activation and moderate hyperplasia of sinus histiocytes. These results could aid researchers and practitioners in the investigations and consumption of the leaves of P. guineense. Its overall safety profile needs to be further evaluated and care should be taken on prolonged usage.  Key words: Piper guineense, Piperaceae, pharmacognostic standardization, toxicological.