Abstract
This study was undertaken to investigate the phytochemical and antibacterial activities of Vernonia amygdalina leaf extract against clinical isolates obtained from the University of Benin Teaching Hospital, using agar well diffusion method. Phytochemicals present in Vernonia amygdalin included flavonoids, cardiac glycosides, reducing sugar, terpenoids and saponins. Ethanolic extract acted against with inhibition zones ranging from 7.0±0.0mm at 25mg/ml to 14.5±2.5mm at 200mg/ml against E. coli ; 6.5±0.5mm at 100mg/ml to 9.0±2.0mm at 200mg/ml against S. aureus ; 11.0±1.0mm at 50mg/ml to 16.5±5.0mm at 200mg/ml; 7.5±1.5mm at 25mg/ml to 11.5±0.5mm at 200mg/ml. Inhibition zones in aqueous extract ranged from 8.0±2.0mm at 25mg/ml to 12.5±1.5 at 200mg/ml against P. aeruginosa ; 9.0±1.0mm at 50mg/ml to 15.0±1.5mm at 200mg/ml against S aureus . The minimum inhibitory concentration of ethanolic extract ranged from 25mg/ml in S. aureus , P . aeruginosa , B. subtilis and K. pneumoniae to 50mg/ml in E. coli. Minimum bactericidal concentration of the ethanol extract was 50mg/ml in P. aeruginosa and K. pneumonia and 100mg/ml for E. coli , S. aureus and B. subtilis . MBC of 200mg/ml was observed for B. subtilis , S. aureus and P. aeruginosa in the aqueous fraction of the plant. The most antibiotic resistant bacterial strain was S. aureus (80%) while the least resistant was P. aeruginosa (10%). The most resistant bacterial strain was S. aureus (80%) while the least resistant was P. aeruginosa (10%). The most effective antibiotics were perfloxacin, ciprofloxacin, septrin and choramphenicol. Vernonia amygdalina extract was found to be more potent than conventional antibiotics. Keywords: Antimicrobial, Phytochemical, Antibiotics, Susceptibility, Resistance
Highlights
The World Health Organization (WHO) estimates that approximately 80% of the world’s inhabitants rely on traditional or herbal medicines for their primary health care and plants have long formed the basis of sophisticated traditional medicine systems and purportedly provide excellent leads for new drug developments (Sofowora, 1993; Pravi, 2006; Akinjogunla et al, 2009)
The increasing problems of multidrug resistant (MDR) bacteria is of great concern to both the clinicians and pharmaceutical industries and this has made it significant to search for newer drugs that are highly effective, affordable, acceptable and available (Martino et al, 2002; Akinjogunla et al, 2011)
Vernonia amygdalina is a valuable medicinal plant that is widespread in West Africa, it is known as bitter leaf due to its characteristic bitter taste and flavour, and can be used as an active anticancer, antibacterial, antimalarial and antiparastic agent
Summary
Plant Materials: Vernonia amygdalina leaves purchased from a local market. The leaves were air dried, ground using a blender. Test for Glycosides: A 25ml of dilute H2SO4 was added to 5ml of plant extract in a 100 ml flask. It was boiled (15 min), cooled and neutralized with 10% NaOH. Test for steroids: One gram of the test substance (plant extracts) was dissolved in a few drops of acetic acid It was gently warmed and cooled under the tap water and a drop of concentrated sulphuric acid was added along the sides of the test tube. One milliliter (1 ml) of nutrient broth was added and a loopful of the test organism previously diluted to 0.5 McFarland turbidity standard was introduced to the tubes.
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