The Journal of Phytopharmacology, 2018;7(5):425-430 DOI:10.31254/phyto.2018.7504

Research Article

Resistance modulation studies of vernolide from Vernonia colorata (Drake) on ciprofloxacin, amoxicillin, tetracycline and erythromycin

Joseph Kwasi Adu¹ , Kwaku Twum¹ , Abena Brobbey² , Cedric Amengor² , Yaw Duah³

Joseph Kwasi Adu,Kwaku Twum,Abena Brobbey,Cedric Amengor,Yaw Duah

1. Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi. Ghana.
2. Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi. Ghana
3. Department of Pharmaceutics, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi. Ghana.

*Author to whom correspondence should be addressed.

Received: 11th August, 2018 / Accepted: 17th September, 2018

Abstract

Resistance modulatory activities of natural products on traditional antibiotics have gained scientific interest in recent years. This is aimed at maximizing antimicrobial potency with major strides in curbing microbial resistance and leading to potential drug discovery. The antimicrobial activity of vernolide, a compound isolated from Vernonia colorata was investigated following its forklore use as antibiotic. The compound Vernolide was isolated from the leaves of Vernonia colorata and the identity was confirmed by appearance, melting point, 1H and 13C NMR as well as UV-Vis and IR spectroscopy. The antimicrobial activity of the isolate was evaluated with MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide) assay using micro broth dilution and 96 well microtiter plates against standardized bacteria suspensions of selected inoculum. Vernolide showed activity against Escherichia coli, Staphylococcus aureus and Enterococcus faecalis with minimum inhibitory concentrations (MICs) of 0.3, 0.3 and 0.4 mg/ml respectively. The MIC of the selected antibiotics, namely on ciprofloxacin, amoxicillin, tetracycline and erythromycin were subsequently determined as a range between 0.1µg/ml to 16 µg/ml. Modulation studies between vernolide and the selected antibiotics showed that all antibiotics were able to prevent growth of the microorganisms at a concentration of 0.2 mg/mL vernolide and varying concentrations of the standard antibiotics in the range of 4.00 µg/ml to 0.0005 µg/ml which are far well below their observed MICs. Vernolide has therefore been shown to possess strong resistance modulatory activity on ciprofloxacin, amoxicillin, tetracycline and erythromycin against Escherichia coli, Staphylococcus aureus and Enterococcus faecalis.