Evaluation of Antibacterial Activities of Clove Bud Oil and Extract on Bacterial Isolates from Dental Caries
Authors: Chinelo Agu, Mellisa , Omebere Tasie Floretta 
Published: September 2024

Dental caries remains one of the most prevalent oral health issues worldwide, primarily caused by bacterial activity w ithin the oral cavity. This study investigates the antibacterial activities of clove oil bud against bacteria associated with dental caries. The clove buds were collected, identified, and processed for ethanol extraction of bioactive compounds. Also, 30 samples of dental caries were obtained using swab sticks and cultured on nutrient agar, MacConkey agar, and Mannitol salt agar, then incubated for 24 hours and identified using biochemical tests and molecular analysis. Qualitative and quantitative phytochemical analysis confirmed the presence of alkaloids (5.033%), saponins (3.50%), flavonoids (0.407%), phenols (0.4545%), tannins (5.227%), and glycosides (2.1285%) in the ethanol extract, while the clove oil contained saponins (8.70%) and a small amount of glycosides (0.0375%). The extracted compounds underwent Gas Chromatography-Mass Spectrometry (GC-MS) analysis, which identified key constituents such as eugenol, Caryophyllene oxide, and 9,12-Octadecadienoic acid. The characterization of the clove oil revealed a density of 0.86 g/cm³, viscosity of 113.59 mm²/s, refractive index of ≥36% Brix, saponification value of 39.19 mg KOH, iodine value of 21.488 g/ml, peroxide value of 13.4 mEq/kg, and a free fatty acid content of 1.37%. Biochemical tests on the bacterial isolates from dental caries samples identified several species, including Actinomyces spp., Streptococcus spp., Lactococcus spp., Lacticaseibacillus paracasei, Staphylococcus aureus strain CIB, Bifidobacterium spp., Veillonella spp., and Bacillus subtilis. Antimicrobial activity assay shows that clove oil exhibited significant inhibition of microbial growth at higher concentrations: B.subtilis had inhibition zones of 12 mm at 100 mg/ml, 6 mm at 50 mg/ml, and 2 mm at 25 mg/ml. Similarly, Lacticaseibacillus agile 1365 showed inhibition zones of 14 mm at 100 mg/ml, 8 mm at 50 mg/ml, and 3 mm at 25 mg/ml. S.aureus strain B3A22 had inhibition zones of 10 mm at 100 mg/ml and 6 mm at 50 mg/ml. In contrast, L. paracasei showed minimal inhibition, indicating lower susceptibility to clove oil. On the other hand, the result also illustrates that clove extract was more effective at lower concentrations compared to clove oil. B.subtilis had inhibition zones of 14 mm at 100 mg/ml, 8 mm at 50 mg/ml, and 5 mm at 25 mg/ml. L.paracasei demonstrated inhibition zones of 16 mm at 100 mg/ml, 11 mm at 50 mg/ml, and 8 mm at 25 mg/ml. S.aureus strain B3A22 had inhibition zones of 10 mm at 100 mg/ml and 6 mm at 50 mg/ml. The Minimum Inhibitory Concentration (MIC) of clove oil was found to be 25 mg/ml for B.subtilis, 100 mg/ml for L.paracasei, 25 mg/ml for L.agile 1365, and 25 mg/ml for both S.aureus strain CIB and strain B3A22 respectively. In comparison, clove extract demonstrated lower MIC values: 12.5 mg/ml for B.subtilis, 12.5 mg/ml for L.paracasei, 12.5 mg/ml for L.agile 1365, 25 mg/ml for S.aureus strain CIB, and 25 mg/ml for S.aureus strain B3A22. The Minimum Bactericidal Concentration (MBC) of clove oil was 50 mg/ml for B.subtilis, for L.paracasei, 25 mg/ml for L.agile 1365, 50 mg/ml for S.aureus strain CIB, and 100 mg/ml for S.aureus strain B3A22. In contrast, clove extract showed an MBC of 25 mg/ml for B.subtilis, 50 mg/ml for L.paracasei, 25 mg/ml for L.agile 1365, 50 mg/ml for S.aureus strain CIB, and 25 mg/ml for S.aureus strain B3A22. These results underscore the significant antibacterial activity of clove extract, particularly due to its higher potency at lower concentrations compared to clove oil, supporting its potential use in developing alternative treatments for dental caries.