Physicochemical Analysis of the Aqueous Extracts of Six Nigerian Medicinal Plants

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

The efficacy of Sphaeranthus senegalensis Vaill extract against diarrhoea in rats.

The aqueous extract of Sphaeranthus senegalensis (Asteraceae) was investigated for anti-diarrhoeal activity in rats. Its effect on castor oil-induced diarrhoea and fluid accumulation and on gastrointestinal (charcoal meal) test was evaluated. Results showed that pre-treatment for 30 min with the extract at 50, 100 and 200 mg/kg, p.o. causes a dose-dependent protection against castor oil-induced diarrhoea and intraluminal fluid accumulation and inhibited gastrointestinal transit motility. These results suggest that the plant contain active constituents that may be useful against diarrhoea.

Effect of the aqueous extract of African mistletoe, Tapinanthus sessilifolius (P. Beauv) van Tiegh leaf on gastrointestinal muscle activity.

Effects of the aqueous extract of T. sessilifolius on the gastrointestinal muscle were investigated on smooth muscle preparations isolated from rabbit jejunum, guinea pig ileum and on gastrointestinal transit in mice. Elemental analysis of the extract was also carried out. The aqueous extract of T. sessilifolius evoked a concentration dependent contraction of the rabbit jejunum and guinea pig ileum. The contractions evoked by the extract were not attenuated either by atropine or mepyramine, but they were completely blocked by verapamil. The elemental analysis revealed the presence of Mg, Zn, Fe, Cu, and very high concentration of Ca. The intraperitoneal LD50 in mice was found to be 1500 mg/kg. The aqueous extract of T. sessilifoliius possesses active components that may be mediating the observed biological activity through calcium mobilization.