Evaluation of the toxicity potential of acute and sub-acute exposure to the aqueous root extract of Aristolochia ringens Vahl. (Aristolochiaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Aristolochia ringens Vahl. (Aristolochiaceae) is used traditionally in Nigeria for managing a number of ailments including gastrointestinal disturbances, rheumatoid arthritis, pile, insomnia, oedema, and snake bite venom. Some studies in our laboratory have demonstrated a scientific justification for some of such uses. This study aims at investigating the toxicological actions of the aqueous root extract of Aristolochia ringens (AR). MATERIALS AND METHODS: Brine shrimp lethality assay was carried out using 10, 100 and 1000 µg/ml of the extract. Oral and intraperitoneal acute toxicity tests were carried out using mice. The effect of sub-acute (30 days) repeated oral exposure to the extract at 10, 50 and 250 mg/kg in rats was also evaluated via weekly assessments of body weights and general observations as well as end of exposure haematological, biochemical and histological examinations of blood and tissue samples of treated rats. Phytochemical analyses to determine the presence of aristolochic acid I in the extract was also carried out using high performance liquid chromatography (HPLC). RESULTS: The aqueous root extract of A. ringens showed potential for biological activity and cytotoxicity with an LC50 of 175 µg/ml in brine shrimps. AR was found to be relatively safe on acute oral exposure with LD50 estimated to be greater than 10 g/kg, while its LD50 on intraperitoneal administration was 407.38 mg/kg. Upon 30 days sub-chronic exposure, AR induced significant weight loss in female rats, enlargement of male rats' stomach, oxidative stress in male and female rats' kidney and liver tissues and disruption of leukocytes level in female rats. It also showed evidence of kidney and liver injuries inducible by oxidative damage and the potential to cause male sterility. HPLC revealed the presence of 0.003 mg/1 g of aristolochic acid in AR. CONCLUSION: These results show that AR contains detectible aristolochic acid I and has potential to induce toxic responses. Caution must therefore be exercised in its medicinal application especially when required for a prolonged use.

Toxicological evaluation of the aqueous whole plant extract of Aerva lanata (l.) Juss. ex Schult (Amaranthaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Aerva lanata (L.) of the family Amaranthaceae is a Nigerian medicinal plant used traditionally for the management of lithiasis, headache, renal disorder, haematemesis, bronchitis, nasal bleeding, cough, scorpion stings, fractures and spermatorrhoea. Studies that show the pharmacological basis for some of such uses have been reported. There is, however, no scientific report on its toxicity profile to the best of our knowledge. AIM OF THE STUDY: This study was therefore aimed at investigating the toxicity profile of the aqueous extract of Aerva lanata. MATERIALS AND METHODS: Acute toxicity tests for the extract administered orally at 1-30g/kg and intraperitoneally at 0.1-2g/kg were carried out in albino mice; while a sub-chronic toxicity test was done by daily oral administration of the extract at 40-1000mg/kg to albino rats for 90 days. Anthropometric, biochemical and haematological parameters' assessments as well as vital organs histological examinations were performed in the sub-chronic toxicity study. RESULTS: The LD50 of the extract for oral and intraperitoneal acute toxicity tests were 22.62g/kg and 0.432g/kg respectively. The extract produced apparent changes in body weights of both male and female rats and significantly (p < 0.05) increased the weights of lungs, brain and pancreas of female rats while reducing the weight of testes in male rats. Haematological parameters were also altered with total leukocytes significantly (p < 0.05) increased and platelets significantly (p < 0.05) reduced in female rats; while neutrophils significantly (p < 0.05) increased in male rats. The extract (40-1000mg/kg) produced significant (p < 0.05) reduction of serum alanine transaminase concentration in both male and female rats. Aspartate transaminases and albumin were also significantly (p < 0.05) reduced in both male (at 1000mg/kg) and female (at 200mg/kg) rats. Alkaline phosphatase was also significantly (p < 0.05) reduced in female rats at 200mg/kg of the extract. Substantial alterations of creatinine, urea and uric acid were also observed. Triglyceride and cholesterol concentrations were significantly increased in male rats but decreased in female rats. At 1000mg/kg, the extract significantly elevated catalase and superoxide dismutase levels with no effect on malondialdehyde levels. It also reduced sperm count and motility of male rats. Mild to moderate cellular changes in the brain, kidney, liver, lungs, spleen and testes of treated rats were observed on histological examinations. Significant changes in biochemical and haematological parameters were also noted in treated animals when compared to control animals 30 days after cessation of treatment. CONCLUSION: The overall findings of this study suggest that the aqueous extract of A. lanata is relatively safe on acute oral exposure, moderately toxic on acute intraperitoneal administration and is relatively safe with antioxidant actions on prolonged exposure. It however shows potentials for toxic effects such as cellular damage to organs, dyslipidaemia and reduction in male reproductive capacity. Caution must therefore be applied in its use on a long term basis.

Antinociceptive and anti-inflammatory activities of ethanolic extract of Alafia barteri

This study analyzes the antinociceptive and anti-inflammatory properties of ethanolic leaf extract of Alafia barteri Oliv., Apocynaceae, based on its medicinal use in the treatment of toothaches, inflammation and fevers. The antinociceptive effect was assessed in mice using acetic acid-induced writhing, tail clip, tail immersion and formalin assays. Anti-inflammatory activity was evaluated on carrageenan-induced paw oedema in rats, and xylene-induced ear oedema in mice. In acetic acid-induced writhing test, the extract at different doses (50, 100 and 200 mg/kg, p.o.) significantly (p < 0.05) and dose-dependently reduced pain by 35.04, 56.49 and 84.25%, respectively. The extract also significantly inhibited both the early and late phases of formalin-induced nociception in mice. In the tail immersion test, the extract caused a significant inhibition of pain (34.43% inhibition, after 90 min) at a dose of 200 mg/kg, while the effect of the extract in the tail clip test was only significant at the 100 mg/kg dose. A. barteri caused a significant inhibition of paw oedema development in the carrageenan and xylene-induced oedema tests. There was no mortality recorded following treatment with the extract (5 g/kg, p.o.). The results support the traditional use of A. barteri in the treatment of various diseases associated with pain and inflammation.

Effects of Telfairia occidentalis (fluted pumpkin; Cucurbitaceae) in mouse models of convulsion, muscle relaxation, and depression.

Telfairia occidentalis (Cucurbitaceae) is a leafy vegetable used in soup and folk medicine in southern Nigeria. Ethnobotanical survey revealed that preparations of the plant are used in the treatment of central nervous system-related disorders including convulsion. This study was conducted to investigate the effect of the hydroethanolic leaf extract of T. occidentalis in mouse models of convulsion, muscle relaxation, and depression. The strychnine and isoniazid convulsion, traction and climbing muscle relaxation, and forced swim and tail suspension depression tests were used in this study. The extract was administered orally (p.o.) at dose range of 25-800 mg/kg while distilled water (10 mL/kg p.o.) served as negative control. Diazepam (5 mg/kg p.o.) was used as positive control in the convulsion and muscle relaxation models while imipramine (64 mg/kg p.o.) served the same purpose in the depression tests. T. occidentalis significantly increased the onset (P<.001) and reduced the duration of convulsion (P<.05, .01) in the strychnine test and increased the time to death (P<.05, .01, .001) in the isoniazid model. The extract insignificantly increased the reaction time in the traction test while it significantly increased the time in the climbing test (P<.001). In the forced swim and tail suspension models, T. occidentalis significantly (P<.001) and dose-dependently increased the duration of immobility. The results obtained in this study suggest that the hydroethanolic leaf extract of T. occidentalis possesses anticonvulsant and muscle relaxant properties, thus justifying its folkloric use.

Analgesic and anti-inflammatory activities of the aqueous stem and leaf extract of Asystasia gangetica (Linn) T. Anderson.

BACKGROUND: Asystasia gangetica (Linn) T. Anderson [family Acanthaceae] is used commonly in the sub-tropics and tropics for the management of inflammatory and algesic conditions. OBJECTIVE: The study was done to evaluate the analgesic and inflammatory activity of the aqueous stem and leaf extract of Asystasia gangetica. METHODS: The analgesic effect of the aqueous stem and leaf extract of Asystasia gangetica (25, 50, 100 and 200 mg/kg) was evaluated in rats and mice using the acetic acid induced writhing, cold water tail flick and hot plate models. Its anti-inflammatory effect was evaluated using carrageenan induced rat paw oedema and xylene induced mouse ear oedema models. RESULTS: The aqueous stem and leaf extract of Asystasia gangetica (25-200 mg/kg) significantly (p < 0.05) reduced the number of writhes in the acetic acid induced writhing test. At 100 mg/kg, it produced an increase in pain threshold comparable to that produced by morphine (10 mg/kg) in the tail flick test and peak analgesia at 200 mg/kg in the hot plate test. The extract (25-200 mg/kg) also produced significant (p < 0.05) inhibition of oedema comparable to indomethacin (10 mg/kg) in the carrageenan induced paw oedema model. The extract (200 mg/kg) produced a significant inhibitory effect (p < 0.05) comparable to that produced by 1 mg/kg dexamethasone in the xylene induced mouse ear oedema model. Preliminary phytochemical screening showed that the extract contains alkaloids, tannins, cardiac glycosides and flavonoids. It did not produce mortality or any visible sign of lethality 24 hours after single oral administration of 10 g/kg. CONCLUSION: The results show that the aqueous stem and feaf extract of Asystasia gangetica possesses analgesic and antiinflammatory activities.