Physicochemical Analysis of the Aqueous Extracts of Six Nigerian Medicinal Plants

ABSTRACT

Purpose: Extracts of Picralima nitida seeds; Detarium microcarpum stem bark; Aframomum melagueta seeds; Terminalia catappa leaves; Acacia nilotica pods; and Morinda lucida stem bark; are under consideration for development into suitable dosage forms for treating diabetes mellitus; sickle cell anemia and malaria. This study aimed at evaluating the extracts for features that would influence decisions on them in the course of the project. Methods: Physicochemical determinations; including proximate analysis; were done by sensory examination; and gravimetric and electrochemical techniques. Thin layer chromatography was carried out with normal silica plates using various solvent systems. Metallic content analyses were carried out by atomic absorption spectroscopy. Results: The extracts were dry but hygroscopic; with a loss on drying range of 0.26 - 12.00w/w. The pH of the 5 - 10solutions ranged 5 - 7. No harsh sensory effects; such as lacrimation; were detected in any of the extracts. Total ash ranged from 3.79 - 20.68w/w; while acid insoluble ash values were below detection. The extracts yielded reproducible chromatograms on normal silica plates developed with various solvent systems. Copper; present at 0.16 - 0.58 mg/100g; was the lowest occurring microelement while calcium content was highest; at 41 - 216 mg/100g. The level of lead; a heavy metal; was 0.05 - 0.22 mg/100g. Conclusion: The results confirm that the extracts require no special handling; possess characteristics that would allow their possible development into solid dosage forms; and that their lead contents complied with official limits