Effect of Daily Chewing Soft Buds and Leaves of Catha edulis (Khat) on the Antioxidant Defense System and Oxidative Stress Markers in Blood


Catha edulis (Khat) is one of the major economic, social and health problems in Yemen. This paper aimed to study the effect of Khat on the oxidative status of Khat chewers by measuring the levels of enzymatic and non-enzymatic antioxidant as well as lipid peroxidation. The results exhibited significant reduction in erythrocytes superoxide dismutase (SOD, EC:, and catalase (CAT, EC: in Khat chewers, in addition to elevation of serum glutathione-S-transferase (GST, EC: Furthermore, non-enzymatic antioxidants glutathione (GSH) and vitamin C were significantly reduced (p <  0.001; p <  0.015), whereas malondialdehyde (MDA) was significantly elevated (p <  0.001). The depletion of GSH and vitamin C along with MDA elevation in Khat chewers compared with control reflects the obvious oxidative status, a result of enormous reactive oxygen species (ROS) formation, leading to membrane damage. ROS possibly induced by active components of Khat or by pesticides added to the Khat tree. In addition, the reduction of SOD and CAT is indicative to cellular proteins damage which occurred by ROS. As well, the elevation of GST may due to a leakage of cellular GST to blood stream; this implies that GST active site was not affected. This study concludes that daily chewing Khat for long period certainly induce ROS production, leading to oxidative toxicity. Both enzymatic and non-enzymatic antioxidants are involved in the protection against this toxicity. People who habitually chew Khat for long term will be susceptible to the oxidative toxicity; therefore, they recommended giving up of Khat chewing.

This is a preview of subscription content, access via your institution.


  1. 1

    Chance, B.; Sies, H.; Boveris, A.: Hydroperoxide metabolism in mammalian organs. Physiol. Rev. 59(3), 527–605 (1979)

    Google Scholar 

  2. 2

    Young, I.S.; Woodside, J.V.: Antioxidants in health and disease. J. Clin. Pathol. 54, 176–186 (2001)

    Article  Google Scholar 

  3. 3

    Valko, M.; Leibfritz, D.; Moncol, J.; Cronin, M.; Mazur, T.; Telser, M.: Free radicals and antioxidants in normal physiological functions and human disease. Int. J. Biochem. Cell Biol. 39, 44–84 (2007)

    Article  Google Scholar 

  4. 4

    Yu, B.P.: Cellular defenses from damage from reactive oxygen species. Physiol. Rev. 74, 139–162 (1994)

    Google Scholar 

  5. 5

    Reiter, R.J.: Oxidative processes and antioxidative defense mechanism. FASEB J. 9, 526–533 (1995)

    Google Scholar 

  6. 6

    Abdollahi, M.; Ranjbar, A.; Shadnia, S.; Nikfar, S.; Rezaie, A.: Pesticides and oxidative stress: a review. Med. Sci. Monit. 10, RA141–RA147 (2004)

    Google Scholar 

  7. 7

    Dhaifalah, I.; Santavy, J.: Khat habit and health effect. A natural amphetamine. Biomed. Pap. Med. Fac. Univ. Palacky Olomouc Czech Repub. 148, 11–15 (2004)

    Article  Google Scholar 

  8. 8

    Wagner, G.C.; Preston, K.; Ricaurte, G.A.; Schuster, C.R.; Seiden, L.S.: Neurochemical similarities between d, l-cathinone and d-amphetamine. Drug Alcohol Depend. 9, 279–284 (1982)

    Article  Google Scholar 

  9. 9

    Halbach, H.: Medical aspects of the chewing of Khat leaves. Bull. World Health Organ. 47, 21–29 (1972)

    Google Scholar 

  10. 10

    Kalix, P.: Review; the pharmacology of Khat. Gen. Pharmacol. 15, 179–187 (1984)

    Article  Google Scholar 

  11. 11

    Colzato, L.S.; Ruiz, M.; van den Wildenberg, W.; Hommel, B.: Khat use is associated with impaired working memory and cognitive flexibility. PLoS One (2011). doi:10.1371/journal.pone.0020602

  12. 12

    El Hadrani, A.M.; Al Hoot, M.A.: An Association between Khat and Diabetes. Egypt. J. Surg. 19(1), 16–19 (2000)

    Google Scholar 

  13. 13

    Ranjbar, A.; Pasalar, P.; Abdollahi, M.: Induction of oxidative stress and acetylcholinesterase inhibition in organophosphate pesticide manufacturing workers. Hum. Exp. Toxicol. 21, 179–182 (2002)

    Article  Google Scholar 

  14. 14

    WHO: Regional Office for the Eastern Mediterranean Country Cooperation. Country Cooperation Strategy for WHO and the Republic of Yemen (2007)

  15. 15

    Kalix, P.; Geisshusler, S.; Brenneisen, R.; Koelbing, U.; Fisch, H.U.: Cathinone, a phenylpropylamine alkaloid from Khat leaves that has amphetamine effects in humans. NIDA Res. Monogr. 105, 289–290 (1990)

    Google Scholar 

  16. 16

    Al-Qirim, T.M.; Shahwan, M.; Zaidi, K.R.; Uddin, Q.; Banu, N.: Effect of Khat, its constituents and restraint stress on free radical metabolism of rats. J. Ethnopharmacol. 83(3), 245–250 (2002)

    Article  Google Scholar 

  17. 17

    Lukandu, O.M.; Costea, D.E.; Neppelberg, E.; Johannessen, A.C.; Vintermyr, O.K.: Khat (Catha edulis) induces reactive oxygen species and apoptosis in normal human oral keratinocytes and fibroblasts. Toxicol. Sci. 103(2), 311–324 (2008)

    Article  Google Scholar 

  18. 18

    Al-Akwa, A.A.; Shaher, M.; Al-Akwa, S.; Aleryani, S.L.: Free radicals are present in human serum of Catha edulis Forsk (Khat) abusers. J. Ethnopharmacol. 125(3), 471–473 (2009)

    Article  Google Scholar 

  19. 19

    Aleryani, S.L.; Aleryani, R.A.; Al-Akwa, A.A.: Khat a drug of abuse: roles of free radicals and antioxidants. Drug Test Anal. 3(9), 548–551 (2011)

    Article  Google Scholar 

  20. 20

    Winterbourn, C.C.; Hawkins, R.E.; Brian, M.; Carrell, R.W.: The estimation of red cell superoxide dismutase activity. J. Lab. Clin. Med. 85(2), 337–341 (1975)

    Google Scholar 

  21. 21

    Aebi, H.: Catalase in vitro. Methods Enzymol. 105, 121–126 (1984)

    Article  Google Scholar 

  22. 22

    Habig, W.H.; Pabst, M.J.; Jakoby, W.B.: Glutathione-S-transferases: the first enzymatic step in mercapturic acid formation. J. Biol. Chem. 249, 7130–7139 (1974)

    Google Scholar 

  23. 23

    Lowry, O.H.; Rosenbrough, N.J.; Far, A.L.; Randel, R.J.: Protein measurement with Folin-phenol reagent. J. Biol. Chem. 193, 265–275 (1951)

    Google Scholar 

  24. 24

    Ellman, G.L.: Tissue sulfhydryl groups. Arch. Biochem. Biophys. 82, 70–77 (1959)

    Article  Google Scholar 

  25. 25

    Ohkawa, H.; Ohishi, N.; Yagi, K.: Assay for lipid peroxides in animal tissues by TBA reaction. Anal. Biochem. 95, 351–358 (1979)

    Article  Google Scholar 

  26. 26

    Omaye, S.T.; Turnbull, J.D.; Sauberlich, H.E.: Selected methods for the determination of ascorbic acid in animal cells, tissues, and fluids. Methods Enzymol. 62, 3–11 (1979)

    Article  Google Scholar 

  27. 27

    Buege, J.A.; Aust, S.D.: The thiobarbituric acid assay. Methods Enzymol. 52, 306–307 (1978)

    Google Scholar 

  28. 28

    Wayner, D.D.M.; Burton, G.W.; Ingold, K.U.; Barclay, L.R.C.; Locke, S.J.: The relative contributions of vitamin E, urate, ascorbate and proteins to the total peroxyl radical-trapping antioxidant activity of human blood plasma. Biochim. Biophys. Acta 924, 408–419 (1987)

    Article  Google Scholar 

  29. 29

    Woodford, F.P.; Whitehead, T.P.: Is measuring serum antioxidant capacity clinically useful?. Ann. Clin. Biochem. 35, 48–56 (1998)

    Article  Google Scholar 

  30. 30

    Al-Hashem, F.H.; Bin-Jaliah, I.; Dallak, M.A.; Nwoye, L.O.; Al-Khateeb, M.; Sakr, H.F.; Eid, R.A.; Al-Gelban, K.S.; Al-Amri, H.S.; Adly, M.A.: Khat (Catha edulis) extract increases oxidative stress parameters and impairs renal and hepatic functions in rats. Bahrain Med. Bull. 33(1), 1–9 (2011)

    Google Scholar 

  31. 31

    Alhifi, M.: Oxidative stress in chick embryo brain, liver and heart treated with mixture of dimethoate and methidathion. Sci. Technol. Vis. 6, 32 (2010)

    Google Scholar 

  32. 32

    Pejić, S.; Todorović, A.; Stojiljković, V.; Cvetković, D.; Lucić, N.; Radojicić, R.M.; Saicić, Z.S.; Pajović, S.B.: Superoxide dismutase and lipid hydroperoxides in blood and endometrial tissue of patients with benign, hyperplastic and malignant endometrium. Anais da Academia Brasileira de Ciencias 80, 515–522 (2008)

    Google Scholar 

  33. 33

    MacMillan-Crow, L.A.; Thompson, J.A.: Tyrosine modifications and inactivation of active site manganese superoxide dismutase mutant (Y34F) by peroxynitrite. Arch. Biochem. Biophys. 366, 82–88 (1999)

    Article  Google Scholar 

  34. 34

    Alvarez, B.; Demicheli, V.; Duran, R.; Trujillo, M.; Cervenansky, C.; Freeman, B.A.; Radi, R.: Inactivation of human Cu, Zn superoxide dismutase by peroxynitrite and formation of histidinyl radical. Free Radic. Biol. Med. 37, 813–822 (2004)

    Article  Google Scholar 

  35. 35

    Lardinois, O.M.: Reactions of bovine liver catalase with superoxide radicals and hydrogen peroxide. Free Radic. Res. 22, 251–274 (1995)

    Article  Google Scholar 

  36. 36

    Raijmakers, M.T.M.; Steegers, E.A.P.; Peters, W.H.M.: Glutathione-S-transferases and thiol concentrations in embryonic and early fetal tissues. Hum. Reprod. 16, 2445–2450 (2001)

    Google Scholar 

  37. 37

    Lei, X.G.: In vivo antioxidant role of glutathione peroxidase: evidence from knockout mice. Methods Enzymol. 347, 213–225 (2002)

    Article  Google Scholar 

  38. 38

    Fang, Y.; Yang, S.; Wu, G.: Free radicals, antioxidants and nutrition. Nutrition 18, 872–879 (2002)

    Article  Google Scholar 

  39. 39

    Frei, B.; England, C.; Ames, B.N.: Ascorbate is an outstanding antioxidant in human blood plasma. Proc. Natl. Acad. Sci. USA 86, 6377–6381 (1989)

    Article  Google Scholar 

  40. 40

    Baynes, J.W.: Reactive oxygen in the aetiology and complications of diabetes. In: Ioannides, C.; Flatt, P.R. (eds.) Drug, Diet and Disease: Mechanistic Approach to Diabetes, vol. 2, pp. 203–231. Ellis Horwood Limited, Hertfordshire (1995)

  41. 41

    Al-Zubairi, A.; Al-Habori, M.; Al-Geiry, A.: Effect of Catha edulis (Khat) chewing on plasma lipid peroxidation. J. Ethnopharmacol. 87(1), 3–9 (2003)

    Article  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Khalid Mohammed Naji.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Naji, K.M., Al-Maqtari, M.A., Al-Asbahi, A.A. et al. Effect of Daily Chewing Soft Buds and Leaves of Catha edulis (Khat) on the Antioxidant Defense System and Oxidative Stress Markers in Blood. Arab J Sci Eng 40, 1–6 (2015). https://doi.org/10.1007/s13369-014-1492-x

Download citation


  • Khat chewing
  • Antioxidant
  • Oxidative stress
  • Catha edulis
  • Antioxidant enzymes