Quality assessment of South African herbal medicines by means of HPLC fingerprinting.

An estimated 70% of South Africans regularly use traditional plant medicines. Incorporation of these medicines within the formal health care system, which is the stated intention of the Health Ministry, requires the establishment of standards for quality control. Except in the case of a handful of South African plant species, such standards are lacking. Of central importance with respect to quality control is correct identification of the species concerned, whether in the fresh, dried or powdered state. In cases where botanical identification is impossible, high performance liquid chromatography (HPLC) with diode array detection (DAD), offers an alternative qualitative profile and is being increasingly used for the authentication of crude drugs or their extracts. As a contribution to establishing quality standards for South African plant species used as traditional medicines, HPLC-DAD "fingerprints" of 60 commonly-used species have been generated in our laboratory. One of these species is presented here, together with UV spectra of individual components represented by major peaks in the HPLC profiles.

Anticonvulsant activity of aqueous extract of Leonotis leonurus.

Water extract of Leonotis leonurus was tested for anticonvulsant activity against seizures produced in mice by pentylenetetrazole, picrotoxin, bicuculline and N-methyl-DL-aspartic acid (intraperitoneal injections). L. leonurus extract in the doses of 200 and 400 mg/kg respectively protected 37.5% and 50% of animals used and significantly (p < 0.05; Student's t-test) delayed pentylenetetrazole (90 mg/kg)-induced tonic seizures. Similarly, the same doses of L. leonurus extract significantly (p < 0.05; Student's t-test) delayed the onset of tonic seizures produced by picrotoxin (8 mg/kg) and N-methyl-DL-aspartic acid (400 mg/kg). However, all the doses of aqueous extract of L leonurus used did not alter the seizures induced by bicuculline (20 mg/kg) to any significant extent. The data suggest that the extract of L. leonurus has anticonvulsant activity and may probably be acting through non-specific mechanisms, since it affects both gabaergic and glutaminergic systems. High performance liquid chromatography (HPLC) and phytochemical tests carried out respectively show a spectrum profile, characteristic of L. leonurus and the presence of alkaloids, saponins and tannins in the extract.