In vitro anti-Neisseria gonorrhoeae activity of Albizia gummifera and Croton macrostachyus

Mesfin Tefera, Aberra Geyid, Asfaw Debella
Palabras Claves / Key words: 
Antimicrobial resistance, Medicinal plants, Natural products, Neisseria gonorrhoeae
Introduction: Neisseria gonorrhoeae is a sexually transmitted bacterial pathogen for which there is an increasing antimicrobial resistance concern. Frequency of isolation of multi drug resistant strains is increasing rendering a potential 'Super bug' status for N. gonorrhoeae. Material & methods: Agar dilution method was used to evaluate in vitro anti N. gonorrhoeae activity of crude and solvent fractions of Albizia gummifera and Croton macrostachyus plants widely used in the Ethiopian folk medicine for the treatment of gonorrhea or syphilis. Crude hydro-alcoholic (20-80 %) extracts of both plants were effective against the test organisms and their minimum inhibitory concentrations (MICs) were between 250-500 μg/mL. Sequential solvent-solvent extraction method was then used to partition crude extracts of each plants into chloroform, n-butanol and aqueous fractions and their anti N. gonorrhoeae activity was determined. Result & Discussion: Chloroform and n-butanol fractions were identified to be more active ones in C. macrostachyus with MIC values between 125-250 μg/mL. The most active fraction in A. gummifera was identified to be the n- butanol fraction, which also had MIC values between 125-250 μg/mL. Aqueous fraction of A. gummifera exhibited activity at MIC values of 500-1000 μg/mL. However, aqueous fraction of C. macrostachyus had no growth inhibition effect when tested at 125-1000 μg/mL gradient of concentrations. Chemical screening indicated the presence of secondary metabolites mainly saponins (in A. gummifera), alkaloids, phenols, sterols/terpens and glycosides in both plants. Conclusion: This implies presence of bio active compounds and the need for further activity-guided fractionation and purification of the most active fraction(s) to localize and identify active constituents from the complex matrix by excluding ubiquitous and non active components. Our results also substantiate the ethno-botanical use of these medicinal plants for the treatment of gonococcal infections