By Ermias Dagne, Emeritus Professor of Chemistry, Addis Ababa University, Ethiopia.

Catha eduils Forsk.

Family: Celastraceae

Catha edulis is a shrub or tree 1-25 m high, that is widely distributed in the eastern part of Africa from Ethiopia, Kenya, Uganda, Tanzania, Malawi, Mozambique, Madagascar to South Africa and beyond the Red Sea into Yemen and parts of Saudi Arabia.

This Plant is known by several names, the common ones being: Chat (Amharic). Jaat. Qaad, Qaat (Somali). Gat, Khat, Qat (Arabic), Miraa, Mlonge (Swahili). Bushman’s tea (South Africa) etc. In most scientific papers the plant is referred to by its Arabic name “Khat’.

Khat is cultivated on small farms and in home gardens at altitudes ranging from 1100 to 2100 m. The custom of chewing fresh leaves of Khat is widespread in much of East Africa and Arabian Peninsula because of the stimulating and euphoric effects, which are similar to coffee though Khat may be slightly stronger. Thus in terms of its effects, its social value to societies that regularly use it, and also its economic significance, Khat may be considered as a rival of coffee, as was pointed out several years ago by Amare Getahun and Krikorian (1973). Since only fresh leaves are active, this habit was almost unknown outside the regions where the plant grows. Recently, however, Khat has made its appearance in the immigrant quarters of the United States and several European countries.

Thanks to the numerous scientific and other studies conducted by research groups in many parts of the world much is now known about the chemistry and pharmacology of this plant.

Although the study of the chemistry of Khat was a topic of research in many chemical laboratories since 1875, the first major breakthrough in chemical research on Khat came about in 1975 when the simple compound cathinone or alpha amino propiophenone was found to be the most important active chemical constituent of the fresh plant. Cathinone dodged chemists for several years because early researches were done on dried Khat materials, in which the concentration of the active principle is very low. This is also why khat users prefer fresh material to the dried one. It is important to note that when the plant dries the active principle cathinone is converted gradually to the less active compound known as cathine.

Pharmacological studies by Kalix et al. revealed the close similarity between cathinone the well known man-made stimulant amphetamine, leading to the conclusion cathinone may be considered as a ‘natural amphetamine’. This simplified matters a great because much that was already known about effects of amphetamine on the human body was extrapolated to cathinone. The reasons for the physical and mental effects observed when chew Khat thus became more evident.

The World Health Organization has classified Khat cathinone as a “Substance of Abuse” but not narcotic. However, some European countries prohibit import Khat, although international law on whether khat should be legal or not is still highly ambiguous.

The effects of long-term use of Khat on humans are becoming more evident from scientific studies conducted in laboratories and field studies. Islam (1994) have found evidence from animal studies that use of Khat during pregnancy results malformation of the fetus and to its reduced weight, Brenneisen et al. (1990) showed Khat increased blood pressure, due to the presence of cathinone in blood plasma, while a study conducted in Yemen (Al-Motarreb et al. 2002) showed the increased blood pressure and heart rate may lead to myocardia infraction. Significant association between Khan chewing habit and development of hemorrhoid was shown by Al-Hadrani (2000), who found that nearly 60% of chronic Khat chewers developed the disease.

Casual and chronic Khat chewers should be aware of the fact that Khat may interact with certain drugs. Attef et al. (1997) showed that Khat reduced the absorption of the antibiotics amoxicillin and ampicillin from the gastrointestinal tract. This is similar to the effect of milk on tetracycline absorption where the calcium present in milk binds with the drug and reduces its bioavailability. In the case of Khat it is suspected that the effect is due to the binding of tannins with these antibiotics.

A study by Mesfin Belew et al. (2000) conducted in the Jimma area of Ethiopia showed prevalence of Khat chewing to be 31.7 %, where Muslims more than Christians, males more than females, those between the ages of 15 to 34 years more than other age groups, were habitual users.

Khartab and Amer (1995), using aviation workers as Subjects, determined that Khat chewing has adverse effect on perceptual visual memory and decision speed. This means Khat chewing habit may not compatible with safe driving. A more serious conclusion is that of Kalix (1988) who argued, long term use leads to Khat intoxication and psychic dependence.

Since Khat is freely used and traded in several African countries and Yemen and also exported some extent to other parts of the world, there is now worldwide concern about the short and long term consequences of chewing it. More attention should therefore be given to Khat research so that policies countries on Khat use and abuse and information disseminated to the public are based on facts the grave

Khat chewers should pay attention to the grave consequences of their habit so that they reduce we usage or abandon it altogether before it is too late is that it is not worth putting at risk one’s health for momentary pleasures and stimulation

References

Al-Hadrani, AM, Khat induced hemorrhoidal disease in Yemen Saudi Medical Journal, 21, 475-7 (2000)

Al-Motarreb, A. et al., Khat Pharmacological and medical aspects and its social use in Yemen Phytotherapy Research, 16, 403-413 (2002)

Amare Getahun and Krikorian. AD Chat Coffee’s rival from Harrar, Ethiopia Economic Botany, 27, 353-389 (1973)

Attef, O.A. et al., Effect of Khat chewing on the bioavailability of ampicillin and amoxicillin. Journal of Antimicrobial Chemotherapy, 39, 523-525 (1997).

Mesfin Belew et al., The magnitude of Khat use and its association with health, nutrition and socio-economic status Ethiopian Medical Journal, 38, 11-26 (2000)

Islam, M.W. et al. Evaluation of teratogenic potential of Khat (Catha eduils Forsk.) in rats. Drug and Chemical Toxicology, 17, 51-68 (1994).

Kalix, P., Khat a plant with amphetamine effects. Journal of Substance Abuse Treatment, 5, 163-9 (1988).

Khatab, N.Y. and Amer, G., Undetected neuro psychophysiological sequelae of Khat chewing in standard aviation medical examination Aviation Space, & Environmental Medicine, C6,739-44 (1995)