P Muthumani, P DEVI, R MEERA, B KAMESWARI, B ESWARAPRIYA
amikacin, and fungicidal concentration, minimum bactericidal, minimum inhibitory concentration, mirabilis jalapa
P Muthumani, P DEVI, R MEERA, B KAMESWARI, B ESWARAPRIYA. In Vitro Antimicrobial Activity Of Various Extracts of Mirabilis jalapa Leaves. The Internet Journal of Microbiology. 2008 Volume 7 Number 2.
The leaves of the plant
To a bacterium, the human body is a collection of environmental niches that provide the warmth, moisture, and food necessary for organism to grow. The bacteria have acquired genetic traits that enable them to enter the environment, remain in a niche, gain access to food sources, and escape clearance by host immune and non immune protective responses. Unfortunately, many of the mechanisms that bacteria use to maintain their niche and the by-products of bacterial growth are incompatible with the system of the human host. Many of these genetic traits are virulence factors, which enhance the ability of a bacterium to cause disease. Although most bacteria cause disease by directly destroying tissue, some release toxins, which are then disseminated by the blood to cause system-wide pathogenesis. Not all bacteria cause disease, but some always cause disease once infection occurs. The symptoms of a disease are determined by the function of the tissue affected, although systematic responses, produced by toxins and immune responses may also occur. The serious of the symptoms depends on the importance of the organ affected and the extent of the damage caused by the infection. The inoculums size is a major factor in determining whether disease occurs. However, this can vary from a relatively small inoculums (e.g. fewer than 200
material and methods
Preparation of extracts
The shade dried and powdered leaves were extracted successively with petroleum ether, benzene, chloroform, ethanol , methanol by soxhlet extractor and water extract by cold maceration.
Preliminary phytochemical investigation 5,6,7,8
The qualitative chemical test of various extracts of
Micro organisms used
Gram - positive bacteria :
Gram - negative bacteria :
Antimicrobial activity testing of disc- diffusion assay9,10,11
Various extracts were dissolved in the same solvent to a final concentration of 30mg/ml and sterilized .Antimicrobial tests were then carried out by disc-diffusion method. The density of the bacterial suspension was standardized by using Mac Farland standard method. The discs were impregnated with 10µl of the extracts (300/disc) at the concentration of 30mg/ml and placed on the inoculated agar. Negative controls were prepared using the same solvents employed to dissolve the plant extracts. Ciprofloxacin 10µg/disc and Amphotericin B 100 units/disc were used as positive reference standards. The inoculated plates were incubated at 37 0C bacteria and 25 0C for fungi (Monica Cheesbrough, 1985).
Micro dilution assay12,13
The minimal inhibition concentration values were also studied for the microorganisms in disc-diffusion assay. The inoculums prepared from 12-hour broth cultures and suspensions were adjusted to 0.5 Mc Farland standard turbidity. The
Disc diffusion assay
The antimicrobial activity of
Minimum inhibitory concentration (Table 2 )
Minimum Bactericidal and Fungicidal Concentration (Table 2)
The bactericidal and fungicidal maximum concentration of
Results and discussion
Result reveal that various extracts of