Antibacterial Activity Of The Crude Extract Of Chinese Green Tea (Camellia Sinensis) On Listeria Monocytogenes
T Mbata, L Debiao, A Saikia
antibacterial activity, chinese green tea, listeria monocytogenes
T Mbata, L Debiao, A Saikia. Antibacterial Activity Of The Crude Extract Of Chinese Green Tea (Camellia Sinensis) On Listeria Monocytogenes. The Internet Journal of Microbiology. 2005 Volume 2 Number 2.
The antibacterial activity of the methanol and aqueous extract of C
Green tea is a non-fermented tea. The tea is an infusion of flavorful leaves that has been consumed for centuries as a beverage and is valued for its medicinal properties. The phytochemical screening of tea revealed the presence of alkaloids, saponins, tannins, catechin and polyphenols [1,2]. Toda
Recent reports however indicate the tea's antibacterial and bactericidal properties on various bacterial strains isolated from patients with infected root canal . Subsequently, several studies on the antimicrobial properties of Japanese tea have been reported [3,5,6]. The antibacterial activity of Turkish tea against
Prompted by these report, the study is therefore aimed at investigating the antibacterial activity of Chinese green tea on
Materials and Methods
The air-dried leaves of Chinese green tea (
The aqueous extractions of the water-soluble ingredients were carried out using the method as described by Asuzu . 15g of each of the grounded leaves were extracted by successive soaking for 2 days using 35ml of distilled water in a 250ml sterile conical flask. The extracts were filtered using Whatman filter paper No 1. The filtrates were concentrated in vacuum at 60°C and stored in universal bottles and refrigerated at 4°C prior to use.
The methanol extractions of the active ingredient of the leaves were carried out using the method as described by Harbone . 25g of the grinded leaves were soxhlet extracted using 250ml of 95% methanol. The extraction lasted for six hours. The volatile oil obtained was concentrated by evaporation using water bath at 100°C.
The strain used in this work was
Antibacterial susceptibility testing
The antibacterial tests of the leave extracts were tested on the test bacteria using the agar-gel diffusion inhibition test and paper disk diffusion inhibition test. In the agar-gel diffusion inhibition test as described by Opara and Anasa , 0.2ml of a 24h broth culture (106cfu/ml) of the bacteria was aseptically introduced and evenly spread using bent sterile glass rod on the surface of gelled sterile Mueller-Hinton agar plates. Three wells of about 6.0mm diameter were aseptically punched on agar-plate using a sterile cork borer allowing at least 30mm between adjacent wells and between peripheral wells and the edge of the petri dish. Fixed volumes (0.1ml) of the leave extract were then introduced into the wells in the plates. A control well was in the centre with 0.01ml of the extracting solvent. The plates incubated at 37°C for 24h for the test bacteria. The plates were duplicated in all the experiments.
In the paper disc diffusion test, sterile paper discs were soaked in the leave extract for 2h. 0.2ml of a 24h broth culture (106cfu/ml) of the bacteria specie was spread on the surface of gelled sterile Mueller-Hinton agar plates. The paper discs containing the extracts were placed at different areas on the surface of each plate. The plates were incubated at 37°C for 24h. Antibacterial activity of the extract against the test bacteria was indicated by growth –free “zone of inhibition” near the respective disc.
Minimum inhibitory concentration
The agar diffusion method described by Ver-poorte  was used. The extracts were incorporated into Mueller-Hinton broth at concentration ranging from 0.01-10mg/ml. A control tube containing the growth medium and the bacteria was set-up. The mixtures were incubated at appropriate temperature of 37°C for 24h. The minimum inhibitory concentration (MIC) of the extracts were regarded as the lowest concentration of the extract that did not permit and turbidity or growth of the test organism.
The methanol extract of the leave of
Table 2 showed the antibacterial susceptibility of the aqueous extract of the leave of
The result of the study showed that the leave extract of
Although both the methanol and water extract of the leave of
The two methods used to test the antibacterial activity of the leave extract proved to be good, but the paper disc diffusion method tend to show wider zones of inhibition than the agar-gel diffusion methods.
From the result obtained in Table 3, it showed that at low doses of 0.26mg/ml and 0.68mg/ml the crude extract of the methanol or probably the water extract would inhibit the effect of the aetiologic agent causing these diseases (listeriosis). This gives credence to its ethnopharmacological use as a remedy to treat infections and diseases caused by the organism.