Abstract
Antibiotic resistance is the major growing threat facing the pharmacological treatment of bacterial infections. Therefore, bioprospecting the medicinal plants could provide potential sources for antimicrobial agents. Mimusops, the biggest and widely distributed plant genus of family Sapotaceae, is used in traditional medicines due to its promising pharmacological activities. This study was conducted to elucidate the antimicrobial effect of three unexplored Mimusops spp. (M. kummel, M. laurifolia and M. zeyheri). Furthermore, the mechanisms underlying such antibacterial activity were studied. The Mimusops leaf extracts revealed significant antibacterial activities against the five tested bacterial strains with a maximum inhibition zone diameter of 22.0 mm against B. subtilis compared with standard antibiotic ciprofloxacin. The minimal inhibitory and bactericidal concentration values against tested Gram-positive and Gram-negative bacterial strains ranged from 3.15-12.5 µg/ml. However, weak antifungal effect was recorded against Candida albicans with MIC value ˃25 µg/ml. The 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay showed that M. caffra was the best antioxidant (IC50=14.75±0.028 µg/ml), while M. laurifolia was the least one (IC50=34.22±0.014 µg/ml). The phenolics in plant leaves extracts were identified and quantified by high performance liquid chromatography (HPLC) which revealed the presence of seven phenolic acids and four flavonoids. The abundant phenolic compounds were rutin (5.216±0.067 mg/g dried wt.) and gallic acid (0.296±0.068 mg/g) followed by myricetin (0.317±0.091 mg/g) then kaempferol (0.113±0.049 mg/g) as flavonoids. The antibacterial mechanism of M. laurifolia extract, as a representative species, induces ultrastructural changes in the model bacterium Staphylococcus aureus with cell wall and plasma membrane lysis as revealed by transmission electron microscopy. Overall, Mimusops species (M. laurifolia, M. kummel and M. zeyheri) are promising natural alternative sources for antimicrobial agents.
Highlights
The progressive increase in antibiotic resistance is the major threat facing the pharmacological treatment of bacterial infections [1]
There are a growing interest in developing novel antimicrobial agents from different sources like plant extracts, essential oils and pure secondary metabolites to cope with microbial resistance [6, 7, 28]
The four studied species have antibacterial activity against both Gram positive and negative strains, this is in line with previous studies which reported that the M. elengi extracts had antibacterial activity against P. aeruginosa, Salmonella typhi, Vibrio cholera, Streptococcus pneumonia, E. coli, B. subtilis, S. enterica, and S. mutans [14, 15]
Summary
The progressive increase in antibiotic resistance is the major threat facing the pharmacological treatment of bacterial infections [1]. There is a great demand to search for new cost effective drugs, especially those having natural origins [4] In this regard, utilization of plant-derived nutraceuticals as antimicrobial agents has attracted much attention [5]. The family Sapotaceae is flowering plants categorized into five tribes, taxonomically it is belonging to order Ericales, the family contain 53 genera and about 1250 species. It is characterized by their wide range of chemical constituents like polyphenols, flavonoids, and saponins, which have antibacterial, antifungal, antioxidant and antiinflammatory activities [11]. Bioprospecting in the genus Mimusops could provide potential sources for antimicrobial agents as an approach to face the growing antibiotic resistance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
