Abstract

EVALUATION OF THE ANTIMICROBIAL EFFECTS OF SYZYGIUM AROMTICUM (CLOVE) AND GARCINIA KOLA (BITTER KOLA) EXTRACTS SINGLY AND IN COMBINATION, ON SOME BACTERIA

Ugwu C. C.*, Ezeonu I. M., Mbah-Omeje K., Agu C. G. and Onuorah S. C.

ABSTRACT

Aqueous and organic(or ethanolic and methanolic) extracts of Syzygium aromaticum (clove) and Garcinia kola (bitter kola) were evaluated for their antimicrobial effects against Staphylococcus aureus, Bacillus cereus (NRRL-B-14727) and Pseudomonas aeruginosa using agar well and disc diffusion methods. The ethanolic extract had more inhibitory effect than the aqueous and methanolic extract. The inhibition zone diameters (IZD) for the ethanolic extract of clove ranged between 10 and 35 mm while that of bitter kola ranged between 10 and 20mm. For the aqueous extract, the IZD ranged between 10 and 18 mm for clove and 8 and 18 mm for bitter kola. The IZD for the methanolic extract ranged between 9 and 16mm and 8 and 18mm for Garcinia kola. The combination of these plant extracts produced greater zones of inhibition than the aqueous and methanol extracts used separately. The MIC varied between 3.125 and 6.25 mg/ml as well as 3.125 and 50.0mg/ml for aqueous, ethanolic and methanolic extracts respectively. S. aureus was found to show the greatest sensitivity, while P. aeruginosa showed the least sensitivity of all the isolates. Phytochemical analyses of the extracts revealed the presence of alkaloids, tannins, saponins, flavonoids and essential oils. This study shows that extracts of these plants possess antimicrobial properties which could be used as alternative to conventional antibiotics.

Keywords: Syzygium aromaticum, Garcinia kola, Synergy, Antimicrobial activity, MIC.