Khat (Catha edulis) consumption causes genotoxic effects in humans

Abstract

We used the micronucleus (MN) test to determine the genetic damage caused by khat, a widely consumed psychostimulant plant, in exfoliated cells of volunteers who chewed the drug on a regular basis. In the first study in which we compared the frequency of MN in buccal and bladder mucosa cells in 20 khat consumers (10 -160 g/day) and 10 controls, a pronounced (8-fold) increase in micronucleated buccal mucosa cells was seen among khat consumers; khat consumption did not lead to a detectable elevation of micronucleated bladder mucosa cells. Among heavy khat chewers, 81% of the MN had a centromere signal indicating that khat is aneuploidogenic. To investigate the effect of simultaneous consumption of tobacco and alcoholic beverages, we compared the MN frequency in buccal cells of 25 khat consumers (20 -85 g/day) who smoked cigarettes (15-60/day) and drank alcoholic beverages (15-80 g of pure ethanol/day) with a control group (control group I) of 25 individuals matched for age, body weight, tobacco and alcohol consumption and with another control group of 25 individuals (control group II) not consuming any of the drugs. The frequency of buccal mucosa cells with MN was higher in control group I than in group II and the effect of khat, tobacco and alcohol was found to be additive. A time-kinetics study on khat-induced MN showed that the highest frequency of MN was observed during the fourth week after consumption. In light of the large body of evidence on the close association between genetic damage and cancer, these results suggest that khat consumption, especially when accompanied by alcohol and tobacco consumption, might be a potential cause of oral malignancy. © 2001 Wiley-Liss, Inc. Key words: khat; buccal mucosa; micronuclei; aneugenThe habit of khat chewing has prevailed for centuries among populations in the horn of Africa and the Arabian peninsula. The leaves of Catha edulis (commonly termed as q'at or khat) contain the natural amphetamine cathinone, which has euphoric and psychostimulant effects. 1,2 Due to its widespread consumption, the production of khat has become an important economic factor. Apart from coffee, khat is the largest cash crop in Yemen and Ethiopia. 3 It has been estimated that in Somalia and Yemen up to one-third of the family income is spent on chewing khat 2 and about 80% of the adult population of these countries are consumers of khat. In Yemen, approximately US$700 million are spent on khat, and in Somalia the annual expenditure for the khat import is about US$57 million.Toxic effects of khat in humans have been studied over the last 20 years and include multiple symptoms such as euphoria, anorexia, insomnia, gastritis, hypertension and impotence. 4 In bacteria, crude khat extract caused gene mutations and cathinone and crude khat extract induced structural chromosomal aberrations 5 and MN formation 6 in bone marrow cells of mice. However, no data on the potential genotoxic effects of khat in humans are available. It is well established that genotoxic effects lead to induction of cancer...

Khat (Catha edulis)-induced apoptosis is inhibited by antagonists of caspase-1 and -8 in human leukaemia cells

“…Despite the body of knowledge on the adverse systemic effects of khat related to neurological disorders, hypertension, myocardial infarction and development of cancer (Al-Motarreb et al, 2002 for a recent review), so far, very little is known about the biological effects of khat on cells (Carvalho, 2003). Khat consumption leads to formation of micronuclei in human buccal and bladder mucosa, suggesting a genotoxic effect of khat use (Kassie et al, 2001). In rats, a decreased serum level of free radical metabolising/ scavenging enzymes and glucose has been observed after oral administration, suggesting a deranged systemic capacity to handle oxidative radicals after khat use (Al-Qirim et al, 2002).…”

Oral cancer: Breath of death

“…4 There is evidence connecting khat chewing to genetic damage of the oral mucosa and cancer. 5 Mahantayya V. Math, Yashoda R. Kattimani, India…”

La toxicité du khat impose-t-elle une modification de la réglementation de son usage en Europe?

“…[64] confirment que cette pratique est un facteur de risque de cancer. La génotoxicité du khat est suspectée par la mise en évidence de micronoyaux dans des cellules exfoliées buccales et vésicales lors de la consommation de khat [65]. Cependant, il n'existe pas de données épidémiologiques solides liant l'usage chronique du khat et la survenue de cancer de la cavité buccale.…”