Antipyretic and antinociceptive properties of Mentha longifolia Huds. (Lamiaceae) leaf aqueous extract in rats and mice.

The antipyretic and antinociceptive properties of Mentha longifolia Huds. (Lamiaceae) leaf aqueous extract were investigated using lipopolysaccharide (LPS)-induced pyrexia in rats, and acetic acid and hot plate analgesia tests in mice. Pentoxifylline, paracetamol and morphine were used as standard drugs for comparison. M. longifolia leaf aqueous extract and pentoxifylline (37.5-150 mg/kg i.p.) significantly (P < 0.05-0.02) reduced the LPS (50 g/kg i.m.)-elicited pyrexia. Pentoxifylline (50 mg/kg i.p.) also significantly (P < 0.01) reduced LPS (50 g/kg i.m.)-induced pyrexia. M. longifolia leaf aqueous extract (6.25-100 mg/kg i.p.) and paracetamol (500 mg/kg i.p.) profoundly inhibited the writhes produced by 3% acetic acid. Furthermore, the plant extract (25-400 mg/kg i.p.) and morphine (10 mg/kg i.p.) significantly (P < 0.001) delayed the hot plate reaction time in mice. The LD(50) values for oral and intraperitoneal administration of the plant extract were > 3200 mg/kg and 1730 mg/kg, respectively. Phytochemical analysis revealed the presence of flavonoids, saponins, tannins, reducing sugars, cardiac glycosides and triterpene steroids in the leaves of M. longifolia. These data indicate that M. longifolia leaf aqueous extract has antipyretic and antinociceptive properties. Furthermore, the relatively high LD(50) values obtained for oral and intraperitoneal administration of the plant extract demonstrate that the plant extract is non-toxic to mice.

Acute and chronic toxicity of the aqueous extract of Artemisia afra in rodents.

Artemisia afra (Jacq. Ex. Willd), "African Wormwood" is widely used traditionally in South Africa with no literature evidence substantiating its safety. The aim of this study was to investigate the safety of the aqueous extract of Artemisia afra by determining its pharmaco-toxicological effects after acute and chronic administration in mice and rats, respectively. The aqueous extract mimicked the traditional decoction dosage form of Artemisia afra. In mice, single intraperitoneal injections of Artemisia afra-extract (1.5-5.5g/kg) induced a regular dose-dependent increase in the death rate and incidence of general behaviour adverse effects, while with single oral doses (2-24g/kg) the increases in incidence of general behaviour adverse effects and mortality rate were dose-independent. The LD(50s) after acute intraperitoneal and oral doses were 2.45 and 8.96g/kg, respectively. Rats given oral doses of Artemisia afra-extract (0.1 or 1g/kg/day) survived the 3 months of dosing (i.e. LD(50) much higher than 1g/kg), experienced no significant changes in general behaviour and haematological and biochemical parameters, except for transient decrease in AST activity. No significant changes were observed in organ weights, and histopathological results showed normal profile suggesting no morphological alterations. Collectively, the results indicate that Artemisia afra-extract is non-toxic when given acutely, has low chronic toxicity potential and, in high doses, may have a hepatoprotective effect.