INTRODUCTION:

Numerous antimicrobial molecules, such as antimicrobial peptides, proteins, and small molecular weight organic substances are present in Plants acting as host defense mechanisms^{1, 2}. Numerous compounds with broad spectrum of inhibitory activity against pathogenic Bacteria and Fungi. The antimicrobial properties of plants have been investigated by a number of studies worldwide and many of them have been used as therapeutic alternatives because of their antimicrobial properties.

There are 2600 plant species of whish more than 700 are noted for their uses as medicinal herbs. In folk medicine, medicinal herbs and plant products were used in treating a wide spectrum of infections and other diseases^3,4. Today a great number of different tea and other plant products are available in market (including cosmetics and pharmaceuticals) which contains biologically active substances. In recent years, there has been a gradual revival of interest in the use of medicinal and aromatic plants in developed as well as developing countries, because plant divided drug have been reported to be safe and without side effects⁶. This study was undertaken to investigate the antimicrobial property of methanol extract of leaf powder. In this present study 3 different plants have been chosen for the investigation of in vitro antimicrobial activity

MATERIALS AND METHODS:

Plant material:

Mimosa pudica, Psidium guajava and Ipomoea aquatica forsk were procured in bulk from a medicinal plants farm and the leaves were identified for the strain and the species by a botanist^5,7. The three types of leaves were separately washed to remove dirt. After washing leaves were shade and dried, followed by hot air oven drying at 40o C for 7 to 8 hours. Powder was made from dried leaves and stored in air tight containers for further analysis. Nutrient and anti nutrient composition anti oxidant activity and anti microbial analysis (0-6 months) were done in the leaf powder and other natural food products were also used. Mimosa pudica 20 %, Psidium guajava leaves 10%, Ipomoea aquatica forsk 10% were taken for the study. The ancient medicine system of India Its primary application was for adult onset diabetes (type II). A condition for which it continues to be recommended today in India. Mimosa pudica extract has been found effective in managing diabetes and mint leaf powder can decrease fasting and post prandial blood sugar and serum cholesterol. These three plants are been used in poly herbal formations like Siddha medicine looking into the severity of the beneficial effects of these herbal plants in managing diabetes and present study was planned. Leaf extract powder has been found effective in managing diabetes^8-15.

Extraction of plant Powder:

10 grams of leaf powder was accurately weighed and taken 100ml of methanol was added to it. Thoroughly mixed and allowed to stand for 5 hours before filtering with what man filter paper no.1. From this different concentrations are prepared.

Test microorganisms:

4 Gram-negativ bacterial strains and 2 fugal strains were used in the study, these were four namely, Shigella sonnei, Pseudomonas aeruginosa, Salmonella typhi, Escherichia Coli and fungi are Aspergillus niger, Candida albicans.

Antimicrobial Assay:

Antimicrobial activity was evaluated by the Disc diffusion method on nutrient agar medium (NAM) for bacteria and potato dextrose agar medium (PDA) for fungi. The Nutrient Agar Medium was prepared by dissolving Beef extract- 0.3%,Yeast extract- 0.3%,Peptone-0.5%Nacl- 0.5%,Agar medium-1.0gram, Distilled water- 1000ml and maintained PH 7.0. The Potato Dextrose Agar Medium was prepared by dissolving Potato starch-4.0grams, Dextrose- 20.0grams,

Agar-15.0grams in 1000ml water and pH maintained at 5.4.

The sterile medium (20ml) was uniformly smeared in Petri dishes by using sterile cotton swabs with test pure cultures of bacteria Escherichia Coli, Pseudomonas aeruginosa, Salmonella typhi, Shigella sonnei and fungi Aspergillus niger, Candida albicans. The discs (5mm in diameter) were impregnated with 1mg/ml, 0.1mg/ml, and 0.01mg/ml leaf powder extract followed by air drying and were placed on seeded agar plates. A disc loaded without leaf compound was regarded as control. For each treatment two replicates were prepared. The plates were incubated for bacteria at 370c for 24 hours and for fungi 28^0cfor 48hours.After incubation the resulting zone of inhibition was measured.

RESULT AND DISCUSSION:

The results of the antimicrobial test by using leaf powder extract are presented in Table 1.The extract showed inhibition of bacterial growth. The zones of inhibition for bacteria i.e., Escherichia Coli is 15±3 mm for 1.0mg/ml; 7±3 for 0.5mg/ml; 4±3 for 0.1mg/ml, Pseudomonas is 13±2mm for 1.0mg/ml; 6±2mm for 0.5mg/ml; 3±2 mm for 0.1mg/ml, Salmonella typhi 14±1mm for 1.0mg/ml; 6±1mm for 0.5mg/ml; 3±1mm for 0.1mg/ml, Shigella sonnei 13±1mm for 1.0mg/ml; 7±1mm for 0.5mg/ml; 3±1mm for 0.1mg/ml.

The zones of inhibition for fungus Aspergillus niger 14±1mm for 1.0mg/ml; 8±1mm for 0.5mg/ml; 5±1mm for 0.1mg/ml, Candida 12±mm for 1.0mg/ml; 6±2mm for 0.5mg/ml; 3±1mm for 0.1mg/ml. bacterial and anti fungal activity was observed in this study. The results showed that essential oil of leaf extract exhibited the highest antibacterial activity against E.Coli with 15±3mm zone of inhibition followed by Salmonella typhi (14±1) and shigella sonnei, Pseudomonas (13±2) were exhibiting similar anti bacterial activity for 1mg/ml concentration. And leaf powder extract having more anti fungal activity on Aspergillus niger (14±1) than Candida (12±1) for 1mg/mlconcentration.

Table 1

Name of the organism	Conc. of the sample in mg/ml	Diameter of the inhibitory zone in mm
Escherichia Coli	1.0mg/ml	15±3
	0.5mg/ml	7±3
	0.1mg/ml	4±3
Pseudomonas aeruginosa	1.0mg/ml	13±2
	0.5mg/ml	6±2
	0.1mg/ml	3±2
Salmonella typhi	1.0mg/ml	14±1
	0.5mg/ml	6±1
	0.1mg/ml	3±1
Shigella sonnei	1.0mg/ml	13±1
	0.5mg/ml	7±1
	0.1mg/ml	3±1
Aspergillus niger	1.0mg/ml	14±1
	0.5mg/ml	8±1
	0.1mg/ml	5±1
Candida	1.0mg/ml	12±1
	0.5mg/ml	6±2
	0.1mg/ml	3±1

In summary, this study confirms that leaf extract posse’s in-vitro antimicrobial activity. This obviously justifies the use of above leaf powder in traditional medicine.

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Received on 17.09.2011 Accepted on 25.10.2011

Asian J. Pharm. Res. 1(4): Oct. - Dec. 2011; Page 108-110