Khat (Catha edulis Forsk) - And now there are three.

For centuries, a large number of people living in the southwestern part of the Arabian Peninsula and eastern Africa have chewed the fresh leaves and twigs of the plant Catha edulis Forsk, more commonly known as khat, for its psychostimulatory effect. The main active compound in khat is cathinone, whose synthetic derivatives form a part of the new psychoactive substances list. This review summaries the prevalence of khat use, its harvesting and consumption, the biosynthetic pathway in khat, the mechanism of action, the results from animal and human studies, and its dependence potential. It is unlikely that khat use will be prohibited in countries where it is traditionally consumed and socially acceptable unlike in other countries of the world where both the importation and the consumption of khat and cathinone is banned. Khat users being mainly Muslims prohibited from using alcohol or other drugs probably represent the largest global number of mono-drug users of an amphetamine-like stimulant. Thus, khat use represents a unique situation and a neglected area of research in Africa.

Proconvulsant effect of khat (Catha edulis) in Sprague dawley rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Catha edulis (khat) is a plant whose fresh young leaves are used by an estimated five million people in eastern Africa and the Arabian Peninsula as a drug of recreation. The fresh leaves and shoots are rich in cathinone, a psychostimulant with effects similar to those of amphetamines. Psychostimulants produce a dose-related excitation of the central nervous system which can lead to seizures and convulsions. However there are no reports on studies of the effect of this herb on brain excitability and seizures. This knowledge is useful for doctors who may prescribe drugs whose side effects include lowering seizure threshold because there could be additive proconvulsant effect among khat users. AIM OF THE STUDY: to determined whether khat lowers pentylenetetrazole (PTZ) seizure threshold. METHODOLOGY: Male Sprague dawley rats were given fresh aqueous khat extract, old aqueous khat extract (3 g/kg bw), methylphenidate or saline and the timed intravenous (PTZ) seizure threshold test was used to study its effect on seizure threshold. RESULTS: Fresh khat (3 g/kg) and methylphenidate (4 mg/kg) lowered PTZ seizure threshold. CONCLUSION: Khat lowers seizure threshold.

In vitro study of the effects of khat (Catha edulis Forsk) extract on isolated mouse interstitial cells.

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml, 6 mg/ml, 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml, 0.6 mg/ml and 6 mg/ml) significantly stimulated (P<0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r=0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations, may enhance testosterone production with accompanying effects on reproductive functions in male mice.