Screening Of Antimicrobial Activity Research Articles

Screening for antimicrobial and antioxidant activities of quinazolinone based isoxazole and isoxazoline derivatives, synthesis and In silico studies.

Two novel series of quinazolinone based isoxazole and isoxazoline hybrid compounds were synthesized from 6-aminoquinazolinone as a key precursor. The title compounds were achieved in synthetic routes via propargylation and allylation reactions of the precursor followed by cyclization with various chloroximes. The new compounds 4a-g and 6a-g were screened for their antimicrobial activity against two Gram-positive bacteria, two Gram-negative bacteria and two fungi by employing Ampicillin and Itraconazole as standard reference. Among all, the 4-bromosubstituted analogues in isoxazole series 4d and in isoxazoline series 6d demonstrated potent activity against all bacterial and fungal strains compared to Ampicillin as well as Itraconazole. The MIC of these compounds were determined as 0.012μM. The antioxidant investigation revealed that compounds 4f and 6f with dimethyl substitution, exhibited significant activity. Their respective IC50 values were 1.28 ± 0.33, 1.39 ± 0.38µM and 1.07 ± 0.24, 1.10 ± 0.26µM, when compared to Ascorbic acid. The compounds 4g and 6g with dichloro substitution, exhibited promising results with IC50 values were 2.72 ± 0.34µM and 2.78 ± 0.41µM for 4g, and 2.24 ± 0.93µM and 2.45 ± 0.53µM for 6g, respectively. Their antimicrobial and antioxidant activities were authenticated by the molecular docking study against crystal structure of DNA gyrase and NADPH oxidase. The predicted ADME properties of these molecules progressed favourable drug-likeness properties.

Design, Synthesis, and Screening for Anticancer and Antimicrobial Activities of New Dihydropyridine‐Anchored Pyrazole and 1,2,3‐Triazole Hybrids

AbstractTwo new libraries of diethyl and dimethyl dihydropyridines‐based pyrazole and 1,2,3‐triazole hybrids (7a–g and 7h–n) were synthesized via a series of reactions involving click chemistry, pyrazole synthesis, and multicomponent reaction. All the new compounds were screened for their in vitro anticancer activity and antimicrobial activities. The 4‐chloro substituted analogue (7i) in dimethyl ester series showed an excellent activity against all three, namely, human breast adenocarcinoma (MCF‐7), human cervical cancer (HeLa), and human breast cancer triple‐positive (BT‐474) cell lines with IC50 values of 0.119 ± 0.58 µM, 0.135 ± 0.13 µM, and 0.163 ± 0.31 µM, respectively compared to abemaciclib. Molecular docking studies performed on the best active compound 7i against crystal structure of CDK6 revealed its best binding score and interactions. Additionally, these libraries were screened for their antimicrobial activities and determined their MIC. Compounds with ─Cl (7b), ─OMe (7d), ─Me (7a) substitution, and without substitution (7e) significantly showed better MIC values in comparison to ampicillin and nystatin.

Phytochemical screening and evaluation of antiradical and antimicrobial activities of Annona senegalensis and Detarium microcarpum leaves used in Benin to treat urinary infections

The challenge of resistance to synthetic antimicrobials necessitates new alternative solutions. Medicinal plants are rich in active compounds with various medicinal properties that can be used in treatment of urinary infections. This work aims to highlight the value of Annona senegalensis and Detarium microcarpum by evaluating phytochemical and antimicrobial potentials of their leaf extracts. Qualitative and quantitative analyses were carried out using color and precipitation reactions and spectrophotometric assays. The antiradical activity was evaluated using the DPPH test, and the antimicrobial activity was assessed by the agar diffusion method. Phytochemical screening showed that both plants contain anthraquinones, catechic tannins, coumarins, flavonoids, reducing compounds, sterols and terpenes. Hydroethanolic extract of Detarium microcarpum and A. senegalensis showed IC50 inhibition percentages of 0.20 mg/mL and 0.22 mg/mL respectively. Regarding antimicrobial activity, the hydroethanolic leaf extracts of D. microcarpum and A. senegalensis were found to be bactericidal and fungicidal against the tested bacteria and molds. This extract showed more pronounced antimicrobial activity than amoxicillin and ciprofloxacin, which are synthetic antimicrobials. Diversity of secondary metabolites and notable antimicrobial activity of D. microcarpum and A. senegalensis may justify their use in traditional medicine for treating urinary infections in Benin.

Antimicrobial Activity of Commercial Essential Oils Available in the Market of Kathmandu

Given the increasing global apprehension surrounding antibiotic resistance, there has been growing interest in exploring natural compounds, specifically essential oils, as potential substitutes for combating microbial pathogens. This research work aimed to evaluate the antimicrobial activity exhibited by commercial essential oils and by diluting them with the carrier oils at equal concentration. The screening of antimicrobial activity was conducted using the agar well diffusion method with eight essential oils. Using the broth dilution method, the antibacterial activity of eight commonly used essential oils: lavender, tea tree, eucalyptus, peppermint, thyme, citrus, rosemary, and cinnamon were assessed. Both Gram-positive and Gram-negative species were selected for antimicrobial activity. The minimum inhibitory concentration (MIC) was determined by the broth dilution method. Following MIC determination, a sub-culture was performed on nutrient agar plates to ascertain the minimum bactericidal concentration (MBC). All the antibiotics used in the study demonstrated sensitivity when subjected to the antibiotic susceptibility test. Thyme, cinnamon and peppermint strongly inhibited the growth of S. epidermidis 46 mm, 30mm, and 34 mm respectively. Findings revealed distinct variations in the MIC values among the different essential oils and bacteria tested. Thyme and tea tree oils exhibited the broadest antibacterial spectrum, inhibiting both Gram-positive and Gram-negative bacteria at relatively low concentrations. Thyme (15.625 μl/ml) and tea tree (31.25 μl/ml) oil demonstrated promising activity against Gram-positive pathogen, while tea tree oil (15.625 μl/ml) displayed better efficacy against Gram-negative bacteria. A significant outcome was observed when the essential oils were diluted with carrier oils, indicating promising results in terms of antibacterial activity. These findings highlight the potential of essential oils, particularly thyme and tea tree oils, as effective natural antimicrobial agents.

Synthesis of Nodupetide Analogue: Substitution of β- to α-hydroxy Acid

Nodupetide, a cyclodepsipeptide with the potential as an antimicrobial agent, was isolated from the fermentation of the fungi Nodulisporium sp strain IFB-A163. It possessed antibacterial activity against Pseudomonas aeruginosa and revealed an insecticidal activity. In our effort to synthesized nodupeptide, the preparation of the (3S,4S)-3-hydroxy-4-methylhexanoic acid (HMHA) as one of the nodupetide residue was found to be challenging, where it is not commercially available and the synthetic trial of the HMHA was not successful. This led us to synthesize nodupetide derivative by replacing HMHA with its a-hydroxy acid to give the analogue [(2S,3S)-Hmp]2-nodupetide. A combination of solid- and solution-phase peptide synthesis was applied in the synthesis nodupetide analogue. Esterification on the resin for synthesis [(2S,3S)-Hmp]2-nodupetide was achieved by placing the reaction at the last stage of the linear peptide synthesis and obtained in overall yield of 4.3 %. We also conducted antimicrobial activity screening for [(2S,3S)-Hmp]2-nodupetide and its linear precursor, showing inactive activity. The alter of hydrophobicity on the nodupetide analogue has very important role in the difference of bioactivity compared to their parent compound. HIGHLIGHTS The synthesized analogue compound has not been reported previously we studied the synthesis strategy of cyclodepsipeptide. We studied the change of beta hydroxy carboxylic acid residue to alpha hydroxy carboxylic acid, which has a very significant effect on biological activity. GRAPHICAL ABSTRACT

LC-MS and GC-MS Analyses on Green Algae Penicillus Capitatus: Cytotoxic, Antimicrobial and Anticholinesterase Activity Screening Enhanced by Molecular Docking & Dynamics and ADME Studies.

In this comprehensive screening study, the chemical composition, and cytotoxic, antimicrobial, and anticholinergic activities of the green algae Penicillus capitatus, collected from Antalya-Türkiye, were determined as in vitro and in silico. GC-MS analysis of the hexane extract revealed a high content of fatty acids, with hexadecanoic acid constituting half of the total fatty acid content. LC-HRMS analysis of the DCM:MeOH extract identified ascorbic acid as the most abundant compound, followed by (-)-epigallocatechin and salicylic acid. The DCM:MeOH extract exhibited potent cytotoxicity against MDA-MB-231 and MCF7 breast cancer cell lines, outperforming doxorubicin with lower IC50 values and a higher selectivity index. Additionally, the extract demonstrated significant antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans, along with selective inhibition of acetylcholinesterase (hAChE) over butyrylcholinesterase (hBChE). Molecular docking and dynamics studies revealed that apigenin-7-O-glucoside and epigallocatechin form stable interactions with estrogen receptor alpha (ERα) and hAChE, suggesting their potential as inhibitors. In silico ADME studies indicated favorable pharmacokinetic profiles for the detected compounds, supporting their potential as drug candidates. The promising cytotoxic activity of the P. capitatus extracts, coupled with significant antimicrobial properties and selective hAChE inhibition, highlights their therapeutic potential for breast cancer treatment, infection management, and neurodegenerative disease intervention.

Comparative genomics and phenotypic assessment of lactic acid bacteria isolated from artisanal cheese as potential starter cultures

Novel starter cultures are coveted by the dairy industry for enhancing the sensory, quality, and safety attributes of fermented dairy products. In this study, artisanal cheeses were investigated as a source of novel starter cultures. Lactic acid bacteria (LAB) were isolated from the cheese and underwent an antimicrobial activity screening. Six potential antimicrobial producers were selected for whole genome sequencing and were confirmed to be new LAB strains belonging to the genera Lacticaseibacillus, Lactococcus, Leuconostoc, and Enterococcus. Genes associated with carbohydrate utilization, proteolytic enzyme production, and exopolysaccharide synthesis were identified. Additionally, in silico analysis revealed safety-related traits including absence of antibiotic resistance genes, intact prophage regions, and biogenic amine production genes. Genome-guided phenotypic confirmation of important identified traits was completed, which included utilization of multiple carbohydrates, hydrolysis of casein, coagulation of milk, and susceptibility to antibiotic. Among these LAB strains, Lactococcus lactis OSY-92 contained and expressed the necessary genes for a dairy starter culture. The strain displayed anti-Gram-positive antimicrobial activity, a strong preference for lactose and galactose, limited casein hydrolysis, and ability to coagulate milk in 7.5 h. When all these findings were considered, L. lactis OSY-92 qualified as a potential novel and safe starter culture for dairy fermentations.

Insight into Romanian Wild-Grown Heracleum sphondylium: Development of a New Phytocarrier Based on Silver Nanoparticles with Antioxidant, Antimicrobial and Cytotoxicity Potential.

Background: Heracleum sphondylium, a medicinal plant used in Romanian ethnopharmacology, has been proven to have remarkable biological activity. The escalating concerns surrounding antimicrobial resistance led to a special attention being paid to new efficient antimicrobial agents based on medicinal plants and nanotechnology. We report the preparation of a novel, simple phytocarrier that harnesses the bioactive properties of H. sphondylium and silver nanoparticles (HS-Ag system). Methods: H. sphondylium's low metabolic profile was determined through gas chromatography-mass spectrometry and electrospray ionization-quadrupole time-of-flight-mass spectrometry. The morphostructural properties of the innovative phytocarrier were analyzed by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, dynamic light scattering, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The antioxidant activity was evaluated using total phenolic content, ferric reducing antioxidant power, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) in vitro assays. The antimicrobial activity screening against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli was conducted using the agar well diffusion method. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay estimated the in vitro potential cytotoxicity on normal human dermal fibroblasts (NHDF) and cervical cancer (HeLa) cells. Results: A total of 88 biomolecules were detected, such as terpenoids, flavonoids, phenolic acids, coumarins, phenylpropanoids, iridoids, amino acids, phytosterols, fatty acids. The HS-Ag phytocarrier heightened efficacy in suppressing the growth of all tested bacterial strains compared to H. sphondylium and exhibited a significant inhibition of HeLa cell viability. Conclusions: The new HS-Ag phytocarrier system holds promise for a wide range of medical applications. The data confirm the capacity to augment the pertinent theoretical understanding in the innovative field of antimicrobial agents.

Phytochemical Screening and Evaluation of Antimicrobial Activity of Desmostachya bipinnata Roots

This study was conducted for preliminary phytochemical study of different extracts and to study antimicrobial effects of methanolic extract of Desmostachya bipinnata roots. Desmostachya bipinnata Stapf is an official drug of ayurvedic pharmacopoeia, belongs to the family of Poaceae/Gramineae. Phytochemical screening was done to identify the main groups of chemical constituents present in different extract of Desmostachya bipinnata by their colour reactions with different reagents. Four extracts viz: Petroleum, chloroform, ethyl acetate and methanolic, were subjected for carbohydrates, flavonoids, glycosides, alkaloids, saponins, proteins and amino acids using a test procedure. Preliminary antimicrobial test of D. bipinnata extract was carried out by well diffusion method. The extract was subjected for antimicrobial screening using reference standard, Gentamicin (10µg). The antimicrobial screening of the plant extract revealed the antimicrobial activity against Staphylococcus aureus (Gram positive microorganism) and Escherichia coli (Gram negative microorganism).

Preliminary Screening of Phytochemicals and Antibacterial Activity of Medicinal Plant Ber (<i>Ziziphus mauritiana</i> Lamark)

The most important genus in the Rhamnaceae family is Ber (Ziziphus mauritiana Lamk). Phytochemicals present in Ziziphus have antioxidant as well as antimicrobial properties. The present study aimed to detect various phytochemicals and evaluate the antibacterial activity in the Z. mauritiana leaf extracts. Leaves from 14 cultivars/germplasm/varieties of Z. mauritiana were used to explore the presence of various phytoconstituents such as alkaloids, flavonoids, cardiac glycosides, phenols, saponins, protein, steroids, tannins, lignins, and reducing sugar. These phytoconstituents have antioxidant, antibacterial, and hepatoprotective activities. The preliminary antimicrobial activity screening of Ziziphus leaf extract against bacterial strains-Bacillus subtilis (Gram-positive), Staphylococcus aureus (Gram-positive), Salmonella abony (Gram-negative), E. coli DH5α (Gram-negative) were performed by using well diffusion method. The results of various phytochemicals like alkaloids, phenolics, flavonoids, tannins, carbohydrates, proteins, lipids, and amino acids were reported in all selected commercial varieties/cultivars/ germplasm. On the other hand, saponins were found completely absent in methanolic solvents of all varieties/cultivars. The aqueous and methanolic solvent leaf extract were tested for antibacterial activity at different concentrations (25mg/ml, 50mg/ml, and 100mg/ml) against the bacterial strains of B. subtilis, S. aureus, S. abony, and E. coli DH5α, respectively. This study showed that the phytochemicals extracted from Z. mauritiana leaves have potential antimicrobial activities.

Synthesis of phenyl esters 2-oxo-2H-1-benzopyran-3-carboxylic acids as promising antimicrobial agents

Corresponding chloroanhydrides were synthesized by the interaction of coumarin-3-carboxylic and 6-methoxycoumarin-3-carboxylic acids with an excess of thionyl chloride under heating. Due to the quantitative yields and the formation of volatile products within the reaction, chloroanhydrides were used without additional purification in acylation of substituted phenols for the synthesis of phenyl esters of 2-oxo-2H-1-benzopyran-3-carboxylic acids. The reaction was carried out by heating in anhydrous dioxane environment in the presence of pyridine as a catalyst. The structure of the obtained esters was proven using instrumental methods of analysis. The antimicrobial and antifungal activity of the synthesized compounds was studied in vitro by the method of two-fold serial dilutions in liquid and solid nutrient environments. Antimicrobial activity screening showed that the synthesized esters have a moderate activity against gram-negative microorganisms and C. albicans. It was found that the 4-methyl-2-chlorophenyl ester of coumarin-3-carboxylic acid had the greatest bacteriostatic activity against Ps. aeruginosa and Pr. vulgaris, 2-chlorophenyl ester of coumarin-3-carboxylic acid against Ps. aeruginosa and E. coli, coumarin-3-carboxylic acid 4-hydroxyphenyl ester against Pr. vulgaris, and coumarin-3-carboxylic acid 2-isopropyl-5-methylphenyl ester against E. coli at a concentration of 31.25 g/ml. 2-Chlorophenyl ester also showed a bactericidal effect against E. coli. The synthesized compounds also have an antifungal effect against the C. albicans. strain used in the experiment. Thus, 4-methyl-2-chlorophenyl ester, 4-fluorophenyl ester, 4-hydroxyphenyl ester, 2,3-dihydroxyphenyl ester, 2-isopropyl-5-methylphenyl ester of coumarin-3-carboxylic acid are active at a concentration of 31.25 g/ml.

Phytochemical Screening and Evaluation of Antimicrobial Activity of Azadirachta Indica (Neem)

Phytochemical Screening and Evaluation of Antimicrobial Activity of Azadirachta Indica (Neem)

Qualitative investigation and screening of antimicrobial activity of stem extract in Clerodendrum infortunatum plant

Clerodendrum infortunatum is known as hill glory bower and a plant which is widely distributed throughout the whole world. Up to now, many species of C. infortunatum have been described in various indigenous systems of medicine that are used in preparation of folklore medicines for the treatment of various life-threatening diseases, and much of this plant have been very well studied for their chemical constituents and biological activities. It also is used in Unani, Ayurveda, and siddha system of medicine for many years. From Clerodendrum infortunatum many compounds, including mono-turpentine and its derivatives, sesquiterpene, diterpenoids, tri-terpentine, flavonoid, quercetin, acacetin, gallic acid, sterol and flavonoid glycoside, phenylethanoid glycoside, steroids and steroid glycosides, cyclohexylethanoids, anthraqunine, cyanogenic glycolsides, and others have been isolated and identified. In the present study, Chloroform, pet. ether, and water stem extract of Clerodendrum infortunatum obtained by Soxhlet extraction was screened to detect the presence or absence of several bioactive compounds which are reported to cure different diseases. Anti-microbial analysis of stem extract was carried out against lactobacillus, E.coli and staphylococcus aureus organisms by agar well diffusion method. It was observed that the zone was recorded against this organism. The results indicate that the chloroform, pet.ether and water extracts of C. infortunatum are having anti- microbial efficiency in controlling the microorganisms. So, Clerodendrum infortunatum is the plant which are beneficial on human health.

Qualitative Investigation and Screening of Antimicrobial Activity of Stem Extract of Clerodendrum Infortunatum Plant

Qualitative Investigation and Screening of Antimicrobial Activity of Stem Extract of Clerodendrum Infortunatum Plant

Screening of Anti-inflammatory and Antimicrobial activity on Flower Extracts of Morinda coreia Buch Ham.

Objectives: Morinda coreia has rich active components which has been used in folk medicine for the treatment of several diseases. Their active substance content may vary according to plant genetics, parts used,as well as to climatic factors, quality of the ground in which the plants were grown, the time of harvesting, and the extraction methods. Basically the flowers can heal the common cold, improve memory, aid relaxation due to presence of volatile oil. Flowers could be used as a new approach for the development of nutraceutical products or functional foods. The flower part of this plant are not documented. To develop and apply it, we report Pharmacological effects such as anti-inflammatory, antimicrobial activity. Methods: The extracts were prepared by cold maceration process with aqueous and organic solvents such as ethanol and ethyl acetate. The anti-inflammatory activity were evaluated using carrageenan-induced paw edema method and the antimicrobial activity by agar well diffusion method. Results: The maximum zone of inhibition for Bacillus subtilis was found to be more susceptible toward the ethanolic extract (14mm) at the maximum conc. of 300µl followed by ethyl acetate (10mm) and aqueous extract (12mm). Similarly for Klebsiella pneumonia maximum inhibitory zone (13mm) followed Pseudomonas auroginosa (13mm), Staphylococcus aureus (12mm), Candida albicans was moderate sensitive towards ethanolic extract (11mm) Conclusion: The ethanolic extract of Morinda coreia flower possessed high anti-inflammatory, antimicrobial activity than ethyl acetate and aqueous extracts on comparing with standards.

A very promising antibiofilm activity against Candida albicans from an in vitro screening for antimicrobial, antibiofilm and antiproliferative activity of new synthesized 4-cinnamamido- and 2-phenoxyacedamido-1H-pyrazol-5-yl)benzamides

Several new synthesized 4-cinnamamido- and 2-phenoxyacedamido-(1H-pyrazol-5-yl)benzamides were obtained by two multi step different synthetic routes in order to maximize their yield. The new derivatives were screened to determine the antiproliferative, antimicrobial and antibiofilm activity. The biological results showed how, respect to the antiproliferative and antimicrobial activities, the compounds have a low to missing activity. Different are the results obtained concerning the antibiofilm activity, especially towards Candida albicans. Most of the synthesized compounds showed a good percentage inhibition of biofilm formation ranging from 60 to 73% with a Biofilm Inhibition Concentration 50% (BIC50) from 0.13 to 0.01 µM. Among the synthesized compounds the ethyl 5-(4-(2-(4-chlorophenoxy)acetamido)benzamido)-1-methyl-1H-pyrazole-4-carboxylate (27c) resulted the most active molecule with a BIC50 of 0.01 µM. According to the results obtained, such compound could be considered a lead subject of further studies to obtain novel and more effective antibiofilm agents against C. albicans.

Methods for screening and evaluation of antimicrobial activity: A review of protocols, advantages, and limitations.

Infectious diseases pose a formidable global challenge, compounded by the emergence of antimicrobial resistance. Consequently, researchers are actively exploring novel antimicrobial compounds as potential solutions. This endeavor underscores the pivotal role of methods employed for screening and evaluating antimicrobial activity-a critical step in discovery and characterization of antimicrobial agents. While traditional techniques such as well-diffusion, disk-diffusion, and broth-dilution are commonly utilized in antimicrobial assays, they may encounter limitations concerning reproducibility and speed. Additionally, a diverse array of antimicrobial assays including cross-streaking, poisoned-food, co-culture, time-kill kinetics, resazurin assay, bioautography, etc., are routinely employed in antimicrobial evaluations. Advanced techniques such as flow-cytometry, impedance analysis, and bioluminescent technique may offer rapid and sensitive results, providing deeper insights into the impact of antimicrobials on cellular integrity. However, their higher cost and limited accessibility in certain laboratory settings may present challenges. This article provides a comprehensive overview of assays designed to characterize antimicrobial activity, elucidating their underlying principles, protocols, advantages, and limitations. The primary objective is to enhance understanding of the methodologies designed for evaluating antimicrobial agents in our relentless battle against infectious diseases. By selecting the appropriate antimicrobial testing method, researchers can discern suitable conditions and streamline the identification of effective antimicrobial agents.

Antimicrobial metabolites from pig nasal microbiota

The mammal microbiome is considered an attractive source of bioactive compounds, including antibiotics. In this work, we studied cultivable microorganisms from the nasal microbiota of the Hungarian domestic pig (Sus domesticus). Taxonomy positions of the 20 isolated strains (18 bacteria, 1 yeast, 1 fungus) were determined by phylogenetic analysis, morphological study and a substrate utilization assay. The strains were subjected to antibiotic susceptibility testing and antimicrobial activity screening. Pseudomonas aeruginosa strain SM-11 was found to produce 4 known antibacterial molecules (pyocyanine, pyochelin, pyoluteorin, monorhamnolipid). Production of pyocyanine was induced by cocultivation with test microorganisms Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922. The results suggest that the mammal microbiota might serve as a valuable source of antimicrobial-producing strains, including those of rare taxa. Cocultivation techniques are promising approach to explore antimicrobials from silent biosynthetic gene clusters.

Phyto-extract-mediated Synthesis of Silver Nanoparticles using Blumea lacera Leaf Extract and Antimicrobial Activity Screening

Phyto-extract-mediated Synthesis of Silver Nanoparticles using Blumea lacera Leaf Extract and Antimicrobial Activity Screening

Screening of Antimicrobial Activity of Murraya koenigii Leaf Extracts Against Pathogenic Bacterial Strains Staphylococcus aureus and Escherichia coli Isolated from Contaminated Water

Aim: Murraya koenigii is a widely used plant both as a potential medicinal agent and also for common cooking purposes. Aim of this present study was to determine the antimicrobial activity of Murraya koenigii leaf extracts on Staphylococcus aureus and Escherichia coli. 
 Study Design: Screening and isolation of pathogenic bacterial strains from contaminated water. Preparation of Murraya koenigii leaf extracts using petroleum ether, acetone and ethyl acetate by using serial extraction method with Soxhlet apparatus.
 Place and Duration of Study: Department of microbiology, Agro biotec research centre Ltd, Poovanthuruthu, Kottayam, Kerala, India, between 2014 January to 2014 May.
 Methodology: Staphylococcus aureus and Escherichia coli were the bacterial strains used in this study. Morphological and biochemical analysis of microorganisms were conducted to identify the strains. Leaf extracts (petroleum ether, acetone and ethyl acetate) of Murraya koenigii were screened using MHA disc diffusion methods.
 Results: Various concentration of plant extracts were used to check its activity against isolated pathogens. Acetone extract of curry leaves exhibit maximum zone of inhibition against Staphylococcus aureus and petroleum ether extracts shown maximum inhibition against Escherichia coli.