Pharmaceutical Communication Biosci. Biotech. Res. Comm. 10(1): 44-50 (2017) Evaluation of antimicrobial and synergistic effects of selected medicinal plants of Hail area with antibiotics Abdel Moneim E. Sulieman, Sherif M. Shaarawy, Ahmed A. Alghamdi, Vajid N. Veettil*, Mohanad Abdelgadir and Nasir A. Ibrahim Department of Biology, Faculty of Science, University of Hail, Hail, Kingdom of Saudi Arabia ABSTRACT In this study, the antibacterial activity of selected medicinal plants and their synergistic effect with antibiotics were investigated. Different antibiotic resistant bacterial species were employed including: Escherichia coli (E. coli), Kleb- siella pneumoniae (K. pneumonia), Acinetobacter baumannii (A.baumannii), Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus) and Salmonella spp. The results indicated that methanol extracts of most of the tested plants inhibited growth of the tested bacteria, however, the highest inhibition was by Senna followed by Har- mal, saffower and Guaada, where the inhibition zone diameter was 8 mm, 4 mm, 3 mm, 2 mm and 2 mm, respec- tively. The synergism between plants extract and antibiotics resulted in inhibition of the tested organisms; generally, the synergism with Harmal extract was more effective in inhibition of antibiotic-resistant bacteria, followed by Senna and fnally Saffower. The outcomes additionally demonstrated that methanolic concentrate of the plant has more inhibitory impact than that of the water extract. Further investigation of the plants extract to seclude and recognize the dynamic fxings is prescribed. KEY WORDS: ANTIBIOTIC-RESISTANT BACTERIA, INHIBITION ZONE, SAFFLOWER, METHANOL. 44 ARTICLE INFORMATION: *Corresponding Author: vajidnv@gmail.com Received 12 th Jan, 2017 Accepted after revision 22 nd March, 2017 BBRC Print ISSN: 0974-6455 Online ISSN: 2321-4007 CODEN: USA BBRCBA Thomson Reuters ISI ESC and Crossref Indexed Journal NAAS Journal Score 2017: 4.31 Cosmos IF : 4.006 © A Society of Science and Nature Publication, 2017. All rights reserved. Online Contents Available at: http//www.bbrc.in/ INTRODUCTION Plants as a source of medicinal compounds have kept on assuming to play a dominant role in the maintenance of human health since ancient times. As indicated by the World Health Organization plant extracts or their dynamic constituents are utilized as people prescription in customary treatments of 80% of the total population. More than half of all modern clinical drugs are of regu- lar item source (Kirbag et al., 2009). Medicinal plants possess immunomodulatory and antioxidant properties, prompting to antibacterial activities. They are known to have adaptable immunomodulatory activity by stimulating both non-particular and particular immu- nity (Pandey and Chowdhry, 2006). In the most recent couple of years, various reviews have been directed in