Current Bioactive Compounds Send Orders for Reprints to reprints@benthamscience.net 360 Current Bioactive Compounds 2019, 15, 360-366 RESEARCH ARTICLE Isolation and Identification of Certain Phenolic Compounds from Salix mucronata Leaf Extracts and Evaluation Them as Antimicrobial Agents Mortada M. El-Sayed a , Maher M. Abdel-Aziz b , Salah Abo-Sedra c , Heba R. Mohamed a and Ezzat E.-S. Abdel-Lateef a* a Medicinal Chemistry Department, Theodor Bilharz Research Institute, Giza, Egypt; b Department of Chemistry, Faculty of Science, Ain-Shams University, Cairo, Egypt; c Microbiology Department, National Research Center, Giza, Egypt A R T I C L E H I S T O R Y Received: November 05, 2017 Revised: July 07, 2018 Accepted: August 15, 2018 DOI: 10.2174/1573407214666180829124509 Abstract: Background: In recent years, plant extracts are considered as an important source of many drug formulations for treatment of human beings from infection diseases. The objective of this study was to evaluate the antimicrobial activity of Salix mucronata leaves extracts and isolate their bioactive phytochemicals. Methods: The dry powder of Salix mucronata was extracted with different aqueous methanol concentra- tions. The 85% methanolic extract was further fractionated using different organic solvents. The antimi- crobial activity of different extracts and fractions was evaluated. The most bioactive fractions were submitted for chromatographic isolation and structure elucidation of their phytochemicals using chro- matographic and spectroscopic methods. Results: The ethyl acetate and the butanolic fractions derived from 85% MeOH extract gave a high antimicrobial activity with inhibition zones ranging between 10 mm and 26 mm and minimum inhibi- tory concentration (MIC) value of 8 mg/mL. While the butanolic fraction showed zones of inhibition ranging between 10 mm and 25 mm with MIC 8 mg/mL. Six compounds were isolated from ethyl ace- tate fraction and their structures were elucidated as; apigenin (1), quercetin (2), quercetrin (3), rhamna- zin -3-O-β-D-glucopyranoside (4), Chrysoeriol-7-O-β-D-glucuronoid- 6ʺ -methyl ester (5), and tremu- loidin (6). Also, five compounds were isolated from the butanolic fraction and their structures were elucidated as; kaempferol (7), luteolin (8), luteolin-3ʹ - methoxy-4ʹ - O-β-D- glucopyranoside (9), isorhamnetin -3-O-β -D-glucopyranoside (10) and salicin (11). Conclusion: The results of the present study showed that the ethyl acetate and the butanolic fractions contain high flavonoids and salicinoids compounds which may attribute to their potential as antimicro- bial agents. Keywords: Antimicrobial properties, chromatography, flavonoids, phenolic compounds, salicinoids, Salix mucronata. 1. INTRODUCTION Infectious diseases due to pathogenic microorganisms represented the main cause of morbidity and mortality espe- cially in developing countries [1]. The microbial infections are increasing time by time and they are becoming harmful to public health [2]. Though antibiotics provide the basis for treatment of bacterial infections, emerging bacterial resis- tance against commonly used antibiotics is a global concern [3, 4]. On the other hand, most of the antibiotics possess toxic side effects which compel the scientific community to search for new drugs from natural sources with novel mode of action, urgently needed in medical and pharmaceutical sectors [5, 6]. Medicinal plants are rich with different kinds of phytochemicals including terpenoids, alkaloids, tannins, *Address correspondence to this author at the Department of Medicinal Chemistry, Theodor Bilharz Research Institute, P.O. Box: 30, Giza, Egypt; Tel: +2-01003924963; Fax: +2-0235408125; E-mail: ezzat@yahoo.com flavonoids and phenolic acid which possess antimicrobial activities against pathogenic microbes [7, 8]. Salix mucronata belongs to Salix genus (family Sali- caceae) which comprises more than 450 species. S. mucro- nata (S. subserrata) is widely distributed in Africa from South Africa to the Nile lands in the north especially in Egypt [9]. This species has been characterized by their me- dicinal values including anti-inflammatory, analgesic and antioxidative potentials and had been used in traditional medicine to relief various pains, fever and rheumatic disor- ders [10, 11]. Such actions could be attributed to their chemical composition such as salicylates, terpenoids, pheno- lic acids and flavonoids [10, 12, 13]. The current study was carried out to evaluate the antimicrobial activity of the dif- ferent extracts of S. mucronata leaves against five patho- genic microbes as well as chromatographic isolation and structure elucidation of the chemical composition of the most active fractions. 1875-6646/19 $58.00+.00 © 2019 Bentham Science Publishers Bentham Science Publishers Personal Use Only