Antibacterial and antioxidant activities of myricetin-3-O-rhamnoside and ethyl acetate from Prosopis africana leaves (Mimosaceae).

TRACK 4: GLOBAL HEALTH/ONE HEALTH
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Antibacterial and antioxidant activities of myricetin-3-O-rhamnoside and ethyl acetate from Prosopis africana leaves (Mimosaceae).
Yanda1,2* L., Tatsimo2 S.J.N., Tamokou3J.D., Kengne3 I.C., Meli Lannang2 A., Sewald4 N.
1Department of Chemistry, Faculty of Sciences, University of Maroua, Maroua Cameroon ; 2 Natural Product and Environmental Chemistry group (NAPEC), Department of Chemistry, Higher Teachers’ Training College, University of Maroua, Box 55 Maroua, Cameroon; 3 Department of Biology, Faculty of Science, University of Dschang, Dschang, Cameroon; 4 Department of Chemistry, Organic and Bioorganic Chemistry, Bielefeld University, Bielefeld, Germany. *Correspondence to : lambertyanda@yahoo.com

Background: Resistance of microbes for most widely used antibiotics remains a global burden. Internationally, there is a growing concern over antimicrobial resistance (AMR) which is currently estimated to account for more than 700,000 deaths per year worldwide. If no appropriate measures are taken to halt its progress, AMR will cost approximately 10 million lives and about US$100 trillion per year by 2050. Among the severe cases of antibiotic resistant, are include S. aureus, Enterococcus faecalis, P. aeruginosa, Escherichia coli and K. pneumonia. However, due to the increasing prevalence of antimicrobial resistance it is necessary to develop new drugs for the treatment of bacterial infections. In this study, we report the antioxidant and antibacterial activities of ethyl acetate extract (EtOAc) and myricetin-3-O-rhamnoside from P. africana leaves. Methodology: Myricetin-3-O-rhamnoside was isolated from ethyl acetate extract (EtOAc) of P. africana leaves by column chromatography. Colorimetric assay was performed to assess the minimal inhibitory concentrations (MICs) of extracts and myricetin-3-O-rhamnoside against a panel of Gram negative and Gram-positive bacteria. Furthermore, the mechanism of antibacterial action was performed against E. coli and E. faecalis using lysis, salt tolerance assays and antioxidant enzyme activities. Results: The EtOAc extract and myricetin-3-O-rhamnoside exhibited interesting antioxidant (EC50 = 5.67 – 77.56 µg/mL; GEAC = 36.58 – 89.28 µg/mL) and antibacterial (MIC = 8 – 64 µg/mL) activities against Gram negative and Gram positive bacteria. The EtOAc extract and myricetin-3-O-rhamnoside from P. africana exhibited antibacterial activity through bacteriolytic effects and reduction of the antioxidant defenses in the bacterial cells. Conclusion: The biological activities of ethyl acetate extract and myricetin-3-O-rhamnoside justify the traditional uses of P. africana leaves for the treatment of diseases related to bacterial infections.

Keywords: antioxydant, antibacterial, Prosopis africana, Mimisaceae, myricetin 3-rhamnoside