Antibacterial and Anti-Acanthamoebic Properties of Catha Edulis (Khat)

Abstract

Infectious diseases remain a significant threat to human health, contributing to more than 17 million annual deaths thus indicating an urgent to identify novel molecules for antimicrobial chemotherapy. Here, the antimicrobial activities of aqueous crude extracts of Catha edulis (khat widely used in Africa and southern parts of Arabia) were tested against a panel of microorganisms including Gram-positive bacteria (Bacillus magaterium, Micrococcus luteus), Gram-negative bacteria (Escherichia coli, Brevundimonas diminuta), yeast (Aspergillus varicoluor, Penicillum solitum, Penicillum brevicompactum) and the protist (Acanthamoeba castellanii) in vitro. At 100 μg, C. edulis extracts exhibited potent antibacterial activity against B. diminuta (19 mm ± 2.3), B. magaterium (16 mm ± 0.7) and M. luteus (22 mm ± 3.1) but not against E. coli and yeast (A. varicoluor, P. solitum, P. brevicompactum). Notably, C. edulis extracts showed amoebicidal effects (>50 % reduction in amoeba numbers of the original inoculum) as evidenced by the uptake of Trypan blue dye. The remaining sub-population of A. castellanii remained viable but cultures remained static over longer incubations. These findings show that C. edulis extract possess selective antibacterial properties. For the first time, it is shown that C. edulis extract exhibit anti-Acanthamoebic properties. Further studies are needed to identify active components and assess their clinical relevance.