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 need to identify novel molecules for antimicrobial chemotherapy. Here, the antimicrobial activities of aqueous crude extract 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.Antibacterial and Anti-Acanthamoebic Properties of Catha Edulis (Khat) leaves of Catha edulis were purchased from a Somali shop on Edgware Road, London, UK. Approximately, 55 g of the plant material were ground and soaked in 100 mL of methanol (100 %) in a water bath at 25°C for 24 h with continuous shaking using Cole Parmer Orbital shaker at 40 g. The extract was filtered, concentrated at 40°C under reduced pressure, and methanol was dried in a freeze-dryer [8]. Finally, the extracts were re-suspended in 20 mL methanol and stored at 4°C until tested for antimicrobial activities. High performance liquid chromatography (HPLC)The crude methanolic extract were applied to a reverse phase C18 column with flow rate of 1 mL per min. Using HPLC, methanolic extracts were eluted with 0, 50 and 100 % methanol. Fraction collected from the crude methanolic extract were freeze dried. The lyophilised fractions were reconstituted in 1 mL of methanol and tested for antimicrobial activities [9]. Microbial strainsThe microbial strains used in the present study were bacteria [Escherichia coli K1 strain RS218 (O18:K1:H7), a cerebrospinal fluid isolate from a neonate with meningitis, and environmental isolates of Brevundimonas diminuta, Bacillus magaterium, Micrococcus luteus], yeast (Aspergillus varicolor, Penicillium solitum, P. brevicompactum), and the protist (Acanthamoeba castellanii, a keratitis isolate belonging to the T4 genotype). All isolates were available in the University microbial collection (stored at -80°C and available upon request)

Incidence of Severe Malaria Syndromes and Status of Immune Responses among Khat Chewer Malaria Patients in Ethiopia

“…The parasite load observed among khat users was also lower than the one among non-khat chewers. Even though anti-plasmodial activity of khat is not known yet, there are its reports on its antimicrobial activity against some human pathogens [ 39 , 40 ], and it has also resistance-modifying potential [ 41 ]. The current report was in agreement with the practice documented among some endogenous people of East Africa and Meru tribe of Kenya who use khat for treatment of malaria [ 18 – 21 ].…”

Enhanced HIV‐1 Reverse Transcriptase Inhibitory and Antibacterial Properties in Callus of Catha edulis Forsk.

“…The use of tissue culture propagated callus in traditional medicine could serve to reduce the exploitation of wild populations of khat. A few tissue culture protocols, bioactivity and secondary metabolite analysis studies have been published for khat (Elhag, ; El‐Domiaty et al, ; Elhag and Mossa, ; Al‐Hebshi et al, ; Siddiqui et al, ). However, rapid mass propagation of callus and anti‐HIV and antibacterial tests from callus and leaves of mother plants remains major bottlenecks.…”

Antimicrobial Properties of Catha edulis (Miraa) against Select Bacterial and Fungal Pathogens, an in-vitro Experimental Study

“…The varieties of C. edulis in Yemen, South Africa, Saudi Arabia, and Lebanon have been shown to have antibiotic effects against various bacteria in in-vitro studies [8][9][10][11][12]. Fatima et al [8] tested methanol, dimethyl sulfoxide (DMSO), and water extracts of Catha edulis Forsk in Saudi Arabia against Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, and Candida albicans clinical isolates.…”

“…Fatima et al [8] tested methanol, dimethyl sulfoxide (DMSO), and water extracts of Catha edulis Forsk in Saudi Arabia against Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, and Candida albicans clinical isolates. The methanol and DMSO extracts had signi cant zones of inhibition in all the bacteria tested while the aqueous extract was only active against gram positive organisms, particularly Staphylococcus aureus [8] Siddiqui [11] tested methanolic crude extracts of C. edulis purchased from a shop in London against various laboratory-stocked microbes (Escherichia coli, Bacillus magaterium, Brevundimonas diminuta, and Micrococcus luteus) using the antibiotic disc diffusion assay. The researcher established that the extracts had signi cant (breakpoint of 14 mm) antimicrobial effect against all the bacteria tested (zones of inhibition >16 mm for B. magaterium; >19mm for M. luteus) except E. coli (zone of inhibition <11 mm) [11].…”

“…The methanol and DMSO extracts had signi cant zones of inhibition in all the bacteria tested while the aqueous extract was only active against gram positive organisms, particularly Staphylococcus aureus [8] Siddiqui [11] tested methanolic crude extracts of C. edulis purchased from a shop in London against various laboratory-stocked microbes (Escherichia coli, Bacillus magaterium, Brevundimonas diminuta, and Micrococcus luteus) using the antibiotic disc diffusion assay. The researcher established that the extracts had signi cant (breakpoint of 14 mm) antimicrobial effect against all the bacteria tested (zones of inhibition >16 mm for B. magaterium; >19mm for M. luteus) except E. coli (zone of inhibition <11 mm) [11]. The variation in E. coli results in the studies by Fatima et al [8] and Siddiqui [11] imply that Catha edulis grown in different geographical areas could be having varying antimicrobial effects.…”