Antibacterial Activity Of Plant Extracts Research Articles

In vitro antibacterial and antibiotic-potentiation activities of five edible plant extracts and mode of action against several MDR Gram-negative phenotypes

Abstract Background: Bacterial infections involving the multidrug resistant (MDR) strains are among the top leading causes of death throughout the world. Healthcare system across the globe has been suffering from an extra-ordinary burden in terms of looking for the new and more potent antimicrobial compounds. The aim of the present study was to determine the antibacterial activity of some Cameroonian edible plants (Garcinia lucida bark, Phoenix dactylifera pericarps, Theobroma cacao pod, Solanum macrocarpon leaves and Termitomyces titanicus whole plant) and their antibiotics-potentiation effects against some MDR Gram-negative bacteria phenotypes expressing efflux pumps (Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa and Providencia stuartii strains). Methods: The antibacterial activities of plant extract alone and in combination with usual antibiotics were carried out using the micro-dilution method. The effects of the most active plant extract (Garcinia lucida bark) on H+-ATPase-mediated proton pumps and on bacterial growth kinetic were performed using experimental protocols, while qualitative reference methods were used to highligh the major groups of secondary metabolites present in the extracts. Results: Qualitative phytochemical screening of plant extracts indicated that all analysed secondary metabolites were present in Theobroma cacao and Termitomyces titanicus while one (saponins) of them was absent in Garcinia lucida and Solanum macrocarpon. Only three of them (polyphenols, flavonoids and saponins) were detected in Phoenix dactylifera. Antibacterial essays showed that G. lucida was the most active plant as it inhibited the growth of all studied bacteria with strong activity (MIC<100 µg/mL) against E. coli ATCC8739, significant activity (100≤MIC≤512 µg/mL) against 80% of bacteria and moderate activity (512<MIC≤2048 µg/mL) against E. coli AG100A and E. aerogenes (EA289 and CM64). It was followed by T. cacao and S. macrocarpon extracts which exhibited an antibacterial potential against 95% and 80% of bacterial strains, respectively. These three extracts exhibited a bactericidal effect on a few bacteria. Extracts from T. titanicus and P. dactylifera were less active as they moderately (512<MIC≤2048 µg/mL) inhibited the growth of 35% and 10% of bacteria. All extracts selectively potentiated the activities of all antibiotics with improvement activity factors (IAF) ranging from 2 to 256. G. lucida, T. cacao and S. macrocarpon potentiated the activities of 100%, 89% and 67% of antibiotics respectively against more than 70%, suggesting that they contain bioactive compounds which could be considered as efflux pumps inhibitors. Whereas T. titanicus and P. dactylifera improved the activities of almost 40% and 20% of antibiotics, respectively. This increase of activities also characterizes synergistic effects between antibiotics and these bioactive compounds. G. lucida extract at all tested concentrations, strongly inhibited the growth of bacterial strain E. coli ATCC8739 and exhibited an inhibitory effect on this bacterial H+-ATPase-mediated proton pumps increasing the pH of the medium. Conclusion: The overall results indicated that food plants among which G. lucida, T. cacao and S. macrocarpon could have a benefit interest in combatting resistant types of bacteria. Keywords: Food plants; infectious diseases; MDR bacteria; efflux pumps; antibiotics; secondary metabolites.

Antibacterial Activity of Extracts of Solanum xanthocarpum, Aegle marmelos and Capparis spinose Against Antibioticresistant Staphylococcus cohnii

Background: The antibacterial activity of plant extracts and phytochemicals analysis was evaluated with antibiotic susceptible and resistant micro-organisms. In addition, of the possible coefficient effects when associated with antibiotics were studied. Extracts from the following plants Solanum xanthocarpum, Aegle marmelos and Capparis spinose were utilized. Materials and Methods: Collected clinical samples were inoculated in different media and the plates were incubated at 37°C for 48 hr. After incubation to identified Colony Morphology, Microscopic Observation and biochemical characterization and molecular identification of the Selected Bacterial isolate as Staphylococcus cohnii. Extracts from the following plants were Solanum xanthocarpum, Aegle marmelos and Capparis spinose were utilized. Antimicrobial Susceptibility Assay and Minimal inhibitory concentration tests performed. Results: Ethanol, methanol and chloroform extracts of Solanum xanthocarpum, Aegle marmelos and Capparis spinose gave the maximum zones of inhibition of 20 mm, 9 mm in ethanol, 25 mm to17 mm in methanol and 24 mm to 12mm in chloroform extract and MIC values of 1.03 to 0.51 mg/ml, 1.00 to 0.06 mg/ml and 1.03 to 0.60 mg/ml respectively, against Staphylococcus cohnii. Methanol extracts of Solanum xanthocarpum gave the maximum zones of inhibition of 25 mm followed by ethanol 20 mm and 24 mm chloroform extracts. The highest MIC values 0.06 mg/ml in methanol extract respectively and 0.51mg/ml in ethanol and 0.60mg/ml in chloroform extract against Staphylococcus cohnii. The result indicated that all extracts exhibited antibacterial activity against Staphylococcus cohnii. Conclusion: The methanol extract showed greater activity than ethanol and chloroform extracts. Among various extracts, only the methanol extract show potential agents against bacterial Staphylococcus cohnii strain greater than standard Vancomycin test control. Thus, the extract of Solanum xanthocarpum could be used to treat microbial wound infection. Solanum xanthocarpum have the potential to be developed as antibacterial agents, especially against Staphylococcus cohnii strain.

ANTIBACTERIAL, ANTIOXIDANT ACTIVITIES AND ASSOCIATION AMONG PLANT GROWTH RELATED TRAITS OF LEPIDIUM DRABA

The Lepidium draba or white tope also known as hoary cress belongs to family Brassicaceae, has been known as one of the perennial herbs which grow normally from seeds and also produced horizontal long creeping roots. It normally grows as a weed plant in farm fields. The present study was conducted to find out the antibacterial and antioxidant activities along with the plant traits of Lepidium draba. The shoot, root and inflorescence extracts were taken through using ethanol, water and n-hexan as extraction solvents. It was found from our studies that the plant extracts were heaving alkaloids, saponins, flavonoids, coumarins, anthocyans, quinons, steroids, sterols and terpenoids as potential phenolic compounds. The bacterial strains including Escherichia coli, Klebsiella pneumonia and Staphylococcus aureus were cultured to access the antibacterial activities of plant extracts. The higher antibacterial activity was reported from n-hexan extract which indicate that the n-hexan extract may be used for extracting phytochemicals to be used as potential antibacterial biomedicines. The water extract showed higher antioxidant activities as compared with ethanol and n-hexan extracts which indicated that the use of water extract may be as a useful antioxidant under stress conditions, may also have anticancer activities. The lower coefficient of variation was recorded for all of the studied traits which indicated the consistency of results and reliability of selecting plants from various locations. There was significant and positive correlation among plant height with inflorescence weight, leaf area and leaf length, the inflorescence weight showed positive correlation with plant height, lea length and leaf area. There was higher contribution of plant height while leaf area contributed lower and negatively towards fresh plant weight. We have concluded from our study that the Lepidium draba plant extract showed antibacterial and antioxidant activities through using ethanol, water and n-hexan as extraction solvents. The significant correlation and regression associations indicated that the plants can tolerate harsh environmental conditions.

Antibacterial activity of plant extracts against Xanthomon asaxonopodis Pv. Punicae causing Bacterial blight of Pomegranate (Punica granatum L.)

Pomegranate ( Punicagranatum L.) is the important fruit crop cultivated throughout the world. It is famous for its refreshing fruits. The crop is affected by ‘bacterial blight’ caused by Xanthomonasaxonopodispv. punicae , which is responsible for the failure of crop. It results in the dropping of leaves as well as fruits. It is very hard to manage the disease with chemicals as well as antibiotics and farmers suffer from heavy economic losses. In the present study, aqueous, ethyl alcoholandacetone extracts of ten medicinally useful plants were used against Xanthomonasaxonopodispv. punicaein vitro . The plant extracts showed antibacterial activity and caused inhibition of growth of Xanthomonasaxonopodispv. Punicae . Among them, Menthaspicata, MurrayaKoeninngi, Allium sativum and Tridaxprocumbens caused maximum inhibition of the test bacterium.

Antibacterial activity of plant extracts against Listeria monocytogenes isolated from ready-to-eat salads

Abstract Ready-to-eat salads are becoming more and more popular. However, due to their ingredients, they represent a suitable growth environment for different microbes. In the prevention of foodborne diseases, hygienic food preparation and appropriate storage conditions are very important. During this study, ten different ready-to-eat salads were analysed for the presence of Listeria monocytogenes. Five different selective agar mediums were used for the enumeration and isolation of Listeria monocytogenes. The isolated bacterial strains were subjected to morphological and biochemical confirmation tests. The antibacterial effects of five different freshly squeezed vegetable juices (carrots, celery, beets, horseradish, and onions) and of five essential oils (dill, thyme, oregano, lemongrass, and sage) were determined against Listeria monocytogenes, Listeria innocua, and L. monocytogenes strains isolated from ready-to-eat salads. Based on the results obtained from fresh vegetable juices, carrot juice exerted the highest antibacterial effect, while the others showed no or slight inhibitory effect (horseradish, beets, onions) against Listeria species. Among the essential oils, thyme, lemongrass, and oregano showed the strongest antibacterial effect against the studied Listeria species.

Antibacterial effects of plant extracts with hurdle technology against Vibrio cholerae.

Vibrio cholerae is an etiological cause of cholera implicated in several pandemics. Antibacterial activity of plant extracts has been established. However, these extracts exhibit activity at a concentration that may alter organoleptic attributes of water and food, hence limiting their application. In this light, there is need to device ways of reducing plant extracts' effective levels in order to widen their application. Thus, this study was conducted to improve activities of plant ethanolic extracts through combination with other generally recognized as safe antimicrobials. Combination of plant extracts with sodium acetate (NaOAc) 0.4% at pH 7.0 reduced minimum inhibitory concentrations (MICs) of clove, lemon eucalyptus, rosemary and sage from 0.2 to 0.025%. At pH 6.4, combinations were more effective reducing MICs of clove, lemon eucalyptus, rosemary and sage from 0.2 to 0.0125% with NaOAc at 0.2%. At pH 7.0, the combination resulted in additive effect. Nevertheless, at pH 6.4, synergic effect was established. No interactive effect was observed with combinations involving glycine. Combination of plant extracts with NaOAc at mildly acidic pH creates a hurdle effect that may have potential application to control the growth of V. cholerae.

Antibacterial and Synergistic Effects of Herbal Extracts in Combination with Amikacin and Imipenem Against Multidrug-Resistant Isolates of Acinetobacter

Acinetobacter species are defined as multidrug-resistant pathogens and the development of resistance against antimicrobials is a major problem in the treatment of infections caused by them. This study aimed to evaluate the antibacterial activity of aqueous and methanol extracts of Salvia chorassanica and Artemisia khorassanica on multidrug-resistant Acinetobacter isolates and also examining the interaction of the methanol extract of the plants with the combination of amikacin and imipenem. First, the presence of adeI and adeB genes in bacterial isolates was investigated. The aqueous and methanol extracts of the leaves of the plants were prepared by ‏Maceration method. Minimum Inhibition Concentration (MIC) values were determined to evaluate the antibacterial activities of plant extracts and antibiotics. Combined effects of the antibiotics with plant extracts were performed using the checkerboard method. The accumulation assay was used to examine the inhibitory effects of plant extracts on the bacterial efflux pump. MIC results indicated that the methanol extracts were effective against Acinetobacter species. FICI values indicated that the combination of antibiotics with methanol plant extracts improves bacterial sensitivity to antibiotics. The extracts also exhibited efflux pump inhibitory activities. Consequently, combination of the plant extracts with antibiotics could enhance the antibiotic susceptibility of resistant pathogens.

Exploration of Antibacterial Compounds from the Commiphora myrrha Through GC-MS and Their Evaluation Against the Bacteria Isolated from Corvus splendens

The Corvus splendens (Indian house crow) normally fed on the garbage therefore, they have many pathogenic bacteria, which can infect the human and cause severe infection in human irrespective to the gender, age and region. The bacteria samples were isolated from the faeces, blood lever, and intestines of the crows in Luria-Bertani (LB) agar plates. The culture plates were incubated at 37°C until the colonies were appeared. The colonies were identified morphologically and through molecular marker using 16S-rDNA. The Commiphora myrrha plant extract was used to determine the antibacterial activities against the pathogenic bacteria isolated from crows. The plant was crushed with 70% methanol and filtered. The filtrates were dried and dissolved in 100% methanol. Antibacterial activities of plant extracts were determined against the pathogenic bacteria isolated from crows. The results showed that the plant extracts were very effective against the pathogenic bacteria and showed 100% antibacterial activities. The plants extracts were analyzed for the characterization of different antimicrobial compound through gas chromatography mass spectrometry (GC-MS). The undecane, tetrasiloxane, hexadecanoic acid, heptasiloxane, benzocyclohepten and many other compounds. The antibacterial activities of the plant extracts were might be because of their compound which had been reported previously as well as an antimicrobial compound.

Antibacterial activity of plant extracts in different solvents against pathogenic bacteria: An in vitro experiment

Objective: To assess the antibacterial activity of 5 selected plants against 4 pathogenic bacteria. Methods: Three solvents with different polarities were used to extract antimicrobial agents from the plants via maceration technique. The agar-disc diffusion technique was adopted to primarily screen antibacterial activities. Broth-dilution assay was employed to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Results: Among all extracts, the ethanol extract of Piper betle Linn showed highest antibacterial activity against Gram-positive and the negative bacteria. MIC and MBC of the ethanol extract of Piper betle Linn against Salmonella typhimurium were the same (1 562.50 mg/L); while it showed the highest MIC and MBC against Pseudomonas aeruginosa of 6 250 mg/L and 12 500 mg/L, respectively. Conclusions: Salmonella typhimurium is the most susceptible bacteria while Pseudomonas aeruginosa is the most resistant bacteria towards the ethanol extract of Piper betle Linn. Piper betle possesses compounds with potential antibacterial activity and might be useful as an alternative to control infectious diseases.

Evaluation and phytochemical screening and antibacterial activity of Ficus dalhousiae Miq

The aim of the present study was to isolate the Extract from the leaves of Ficus dalhousiae Miq and subse-quently evaluate their antibacterial and antifungal activity. The crude various extracts of the plant n-Hexane, Chloroform, Ethyl acetate, Methanol extract was obtained by using continuous soxhlation tech-nique using soxhlet apparatus. The antibacterial activity of plant extract were carried using cup plate method against three bacterial species Staphylococcus aures, Bacillus subtilis, Escherichia coli using agar diffusion method. those are compared with standard reference drug Ciprofloxacin. This study confirmed that bark extracts have more active constituents compare to leaf extracts. by pharmacological evaluation of Ficus dalhousea Miq. Various extracts, most of them are capable of showing moderate antibacterial activity.

Atividade Antibacteriana dos Extratos Etanolícos do Caule e da Folha de Qualea parviflora Mart. (Pau-terra)

A resistência aos antimicrobianos por micro-organismos patogênicos é consequência, principalmente, do uso irracional de antibióticos e constitui uma ameaça para o controle das doenças infecciosas. Estudos das atividades antibacterianas de extratos de plantas podem fornecer alternativas para o tratamento antimicrobiano e, por isso têm despertado interesse pela investigação para o potencial da flora brasileira. Objetivou-se analisar a possível atividade antibacteriana da espécie Qualea parviflora Mart. (Pau-terra). Os ensaios foram realizados por difusão em discos previamente sensibilizados com extratos obtidos por maceração do caule e folhas nas concentrações de 50 e 100% (etanol 99,5ºGL como extrator). Realizaram-se testes para cepas Gram-positivas (Staphylococcus aureus e Streptococcus pyogenes) e Gram-negativas (Escherichia coli). Os discos sensibilizados foram dispostos nas placas de cultivo e essas incubadas a 37 ºC/24 horas. Os halos de inibição foram analisados por leitura visual. Os extratos concentrados (100%) da casca e folha apresentaram inibição contra Gram-positivas e Gram-negativas, sendo o obtido da folha mais eficaz. Na concentração de 50%, a inibição somente foi observada com o macerado das folhas. Os extratos da maceração das folhas apresentaram maior inibição contra Gram-negativos. A ação inibitória registrada para os extratos da Q. parviflora Mart. pode estar relacionada a sua composição fitoquímica, pois apresenta vários metabolitos secundários com atividade antimicrobiana. Porém, são necessários estudos complementares para comprovação da presença dos compostos secundários capazes de atuar na inibição de micro-organismos, além de testes como a microdiluição em caldo para auxiliar na confirmação da ação inibitória dos compostos presentes na Q. parviflora Mart.Palavras-chave: Antibiótico. Cerrado. Extratos Vegetais.AbstractAntimicrobial resistance to pathogens is mainly due to the irrational use of antibiotics and constitutes a threat to the control of infectious diseases. Studies of the antibacterial activities of plant extracts can provide alternatives for the antimicrobial treatment and, therefore, has aroused interest by the investigation for the potential of the Brazilian flora. It was aimed to analyze the possible antibacterial activity of the species Qualea parviflora Mart. The tests were carried out by diffusion in disks previously sensitized with extracts obtained by stem maceration and leaves at concentrations of 50 and 100% (99.5 °GL ethanol as extractor). Tests were performed for Gram-positive strains (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Escherichia coli). The sensitized discs were placed in the culture plates and incubated at 37 °C / 24 hours. Inhibition halos were analyzed by visual reading. Concentrated (100%) extracts of bark and leaf showed inhibition against Gram-positive and Gram-negative, being the most effective leaf extract. At 50% concentration the inhibition was only observed with leaf maceration. Extracts from leaf maceration showed greater inhibition against Gram negative. The inhibitory action recorded for the extracts of Q. parviflora Mart. may be related to its phytochemical composition, since it presents several secondary metabolites with antimicrobial activity. However, further studies are necessary to prove the presence of secondary compounds capable to act in inhibition of microorganisms, as well as testing broth microdilution to assist in confirming the inhibitory action of the compounds present in Q. parviflora Mart. Keywords: Antibiotic. Cerrado. Plant Extracts. AbstractAntimicrobial resistance to pathogens is mainly due to the irrational use of antibiotics and constitutes a threat to the control of infectious diseases. Studies of the antibacterial activities of plant extracts can provide alternatives for the antimicrobial treatment and, therefore, has aroused interest by the investigation for the potential of the Brazilian flora. It was aimed to analyze the possible antibacterial activity of the species Qualea parviflora Mart. The tests were carried out by diffusion in disks previously sensitized with extracts obtained by stem maceration and leaves at concentrations of 50 and 100% (99.5 °GL ethanol as extractor). Tests were performed for Gram-positive strains (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Escherichia coli). The sensitized discs were placed in the culture plates and incubated at 37 °C / 24 hours. Inhibition halos were analyzed by visual reading. Concentrated (100%) extracts of bark and leaf showed inhibition against Gram-positive and Gram-negative, being the most effective leaf extract. At 50% concentration the inhibition was only observed with leaf maceration. Extracts from leaf maceration showed greater inhibition against Gram negative. The inhibitory action recorded for the extracts of Q. parviflora Mart. may be related to its phytochemical composition, since it presents several secondary metabolites with antimicrobial activity. However, further studies are necessary to prove the presence of secondary compounds capable to act in inhibition of microorganisms, as well as testing broth microdilution to assist in confirming the inhibitory action of the compounds present in Q. parviflora Mart. Keywords: Antibiotic. Cerrado. Plant Extracts.

In Vitro Anti-Helicobacter pylori Activity of Berberine and Barberry Extracts: A Preliminary Report

The berberine accumulation in Berberis vulgaris and antibacterial activity of plant extracts against Helicobacter pylori were examined. The antibacterial activities of berberine, the main alkaloid ...

Determination of In Vitro Antimicrobial Activity of Five Sri Lankan Medicinal Plants against Selected Human Pathogenic Bacteria.

Introduction Antibiotic resistance is one of the greatest threats of the 21st century. Scientists search for potential antimicrobial sources that can cope with antibiotic resistance. Plants used in traditional medicine can be identified as potential candidates for the synthesis of novel drug compounds to act against antibiotic-resistant bacteria. Objective To determine the potential antimicrobial effects of ethanol, aqueous, and hexane extracts of five Sri Lankan medicinal plants against four human pathogens. Methods Asparagus falcatus (tubers), Asteracantha longifolia (whole plant), Vetiveria zizanioides (roots), Epaltes divaricata (whole plant), and Coriandrum sativum (seeds) were used in the study. Plant extracts were screened against four clinically important Gram-positive and Gram-negative bacterial strains, Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), and Klebsiella pneumoniae (ATCC 700603). Antibacterial activity of plant extracts were monitored using the agar disc diffusion method. Eight concentrations of each positive plant extract were used to determine the minimum inhibitory concentration (MIC) by 5-fold dilution of plant extracts yielding a serial dilution of the original extract. Results Ethanol, aqueous, and hexane extracts of E. divaricata gave the maximum zones of inhibition of 16.3 mm, 7.4 mm, and 13.7 mm and MIC values of 0.48 mg/ml, 1.2 mg/ml, and 1.6 mg/ml, respectively, against S. aureus. Ethanol and hexane extracts of V. zizanioides gave the maximum zones of inhibition of 12.1 mm and 11.4 mm and MIC values 2.4 mg/ml and 0.003 mg/ml, respectively, against S. aureus. None of the other plants were effective against any microorganism used for the study. Conclusions It can be concluded that E. divaricata and V. zizanioides crude ethanol, aqueous, and hexane extracts exhibited significant in vitro antibacterial activity against S. aureus, and the active compounds isolated from them can be potential sources for the synthesis of antibacterial drugs.

Presumptive Relationship between Oxidoreduction Potential and Both Antibacterial and Antioxidant Activities of Herbs and Spices: Oxidoreduction Potential as a Companion Tool for Measuring the Antioxidant Activity

Antibacterial and antioxidant activities form an essential component of the bioactive properties of plant products. The antibacterial and the antioxidant properties of three types of aqueous extracts of four herbs and spices were evaluated. While the total phenolic content, DPPH radical scavenging activity and oxidoreduction potential methods were used for the antioxidant properties determination, the inhibition diameters of extracts toward the growth of Staphylococcus warneri, Bacillus cereus, Enterobacter cloacae and Proteus vulgaris were evaluated. Although the phenolic content did not correlate with the antibacterial activity of plant extracts, it linearly correlated (R2 = 0.827) with DPPH scavenging activity of the studied plants following the order: sumac > ginger > rosemary > cinnamon. The oxidoreduction potential values linearly correlated with both the phenolic content (R2 ≈ 0.88) and DPPH scavenging activity values (R2 ≈ 0.96). The oxidoreduction potential could be proposed as a useful companion tool combined with other techniques when determining the antioxidant activity of plant extracts and food products is considered.

CHEMICAL CONSTITUENTS AND ANTIBACTERIAL ACTIVITY OF Prosopisfarcta (Fabacea) FRUIT FROM IRAQ-KURDISTAN REGION

The chemical constituents of di chloro methane and hexane extracts of Prosopis Farcta (Fabacea family)were studied by gas chromatography, mass spectrometry. Their relative concentrations were determined and both extracts contained 8 expected compounds. There were 7 compounds found in hexane extract which are: 1- methyl pyrrole (8.08%), alpha-ethyl aspartate (9.96%), spiropentane  propyl (13.75%), ethyl oleate (43.43%), 1-iodo-n-Nonyliodide (7.6%), Borane-diethyl (decyloxy) (9.34%), Sulfurous acid, 2-ethyl hexyl ester (7.84%). While one compound was found in dichloromethane extract namely: 3-O-methyl-d-glucose (100%) was recorded as the principle constituents. The antibacterial activities of dichloromethane and hexane extracts were measured against three pathogenic bacteria, which are Staphylococcus aureus, Escherichia coli and Streptococcus Pneumonia using diffusion method. Significant dissimilarities in the antibacterial activity of plant extracts were noticed depending on the type of bacterial strain and the concentration of plant extracts.

In vitro Antibacterial Effect of Medicinal Plants Against Multidrug Resistant Gram Negative Bacteria

Objectives: The aim of this work was to determine the antibacterial activity of methanol extract of herbal plants against the Multidrug resistant (MDR) Gram negative bacteria isolated from clinical samples.
 Methods: Gram negative bacteria isolated from various clinical samples were processed for antibiotic susceptibility test by modified Kirby-Bauer disc diffusion method and MDR bacteria were selected. Methanol extracts of six different medicinal plants Acorus calamus (bojho), Ocimum sanctum (tulsi), Azadirachta indica (neem), Cinnamomum tamala (tejpatta), Aloe vera and Zanthoxylum alatum (timur), were tested for antibacterial activity against the selected MDR bacteria by agar well diffusion method.
 Results: From clinical samples, 8 different MDR Gram negative bacteria isolated were Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter spp., Proteus mirabilis, Proteus vulgaris, Acinetobacter spp. and Pseudomonas spp. with E. coli dominated the number. Out of six medicinal plants extracts, Z. alatum, C. tamala and Ocimum sanctum were found to be effective with zones of inhibition ranging from 9-13 mm. The medicinal plants with antibacterial activity can be an alternative source of medicine against MDR Gram negative bacteria.
 Conclusion: Several herbal plants extracts exhibit antibacterial activity against MDR Gram negative bacteria. Antibacterial activity of plant extracts can vary with type of plant and extraction methods. Thus, for optimal benefit of plant extract, an appropriate extraction method and use of purified product is essential.

Evaluation of Antibacterial Activity of Plant Extracts of Euphorbia thymifolia Against Human Pathogenic Bacteria

The present study was aimed at assessing the antimicrobial potential of various extracts of Euphorbia thymifolia against human pathogenic strains of Salmonella typhimurium and Shigella boydii. The antibacterial activity was determined by agar disc diffusion and broth microdilution techniques. The results showed that the growth of the organisms were inhibited by both acetone and hexane extracts of Euphorbia thymifolia. The acetone extracts showed significantly higher zones of inhibition. The minimum inhibitory concentration of the leaf and stem extracts were 0.078, 0.156, 0.312mg/ml. The phytochemical analysis was carried out for the different parts of the plant. The qualitative analysis showed that alkaloids, phenols and flavonoids were present in both acetone and hexane extracts. The result of the present study indicate that Euphorbia thymifolia has many medicinal values and can be widely studied to extract natural compounds which are beneficial to human beings.

Antibacterial activity of Lamiaceae plant extracts in clinical isolates of multidrug-resistant bacteria.

The antibacterial activity of plant extracts of the Lamiaceae family was evaluated against clinical isolates of multi-resistant Gram-negative bacteria by broth microdilution technique. Promising results were obtained considering that all extracts were active for at least two bacterial species with MIC ranging from 0.5 to 2.0 mg/mL.

In vitro Antibacterial Activity and Phytochemical Analysis of Nicotiana tabacum L. Extracted in Different Organic Solvents.

Background:Controlling infectious disease using medicinal plants is the oldest healthcare known to mankind. Regardless of the enormous advances observed in modern medicine, medicinal plants are still playing vital roles. However, only a small proportion of medicinal plants are examined for bioactive compounds which may vary in different factors. This study aimed to evaluate phytochemical constituent and antimicrobial activities of Nicotiana tabacum L. extracted by different solvents against three set of bacteria.Methods: Nicotiana tabacum L. was collected from the Western Ethiopia and extracted in seven organic solvents. An in-vitro anti-bacterial activity of plant extracts was carried out by agar well diffusion assay against microbial type culture collection of human pathogens, clinical bacterial isolates, and biofilm forming bacteria. Gas Chromatographic and Mass Spectroscopic (GC-MS) analysis was used to determine the phytochemical constituents.Results:Antimicrobial activities of plant extract vary by extraction solvents; and ethyl acetate based extracts showed better antimicrobial activities. Of the experimental organisms, biofilm forming uropathogens were the most sensitive while clinical isolates were quite resistant. Analysis of the active ethyl acetate extract by GC-MS evinced a mixture of five volatile compounds; and Pyridine, 3-(1-methyl-2-pyrrolidinyl)-, (S) was the major compound detected. The overall results of the present study revealed that N. tabacum L extract has high antimicrobial activities against biofilm forming uropathogens.Conclusion:High antimicrobial activity was observed in ethyl acetate extract of N. tabacum against the biofilm forming bacteria whereas the clinically isolated bacteria were the most resistant group. The antibacterial property demonstrated could be due to Pyridine, 3-(1-methyl-2-pyrrolidinyl)-(S) with a broad spectrum of activity.

Antibacterial activity of plant extract and zinc nanoparticles obtained from Syzigium aromaticum L.

Nanotechnology deals with the use of nanoparticles in various remarkable fields of present time with vast medicinal, agricultural and industrial applications. Biological approaches using microorganisms and plants or plant extracts for metal nanoparticles, have been suggested as valuable alternatives to chemical methods. In present study Syzigium aromaticum L. extracts in water and ethanol were used for the green synthesis of zinc oxide nanoparticles. After being treated with zinc sulphate solution, the color of all the extracts of plant changed indicating the formation of zinc nanoparticles and their color change was also monitored by using Ultraviolet-Visible spectroscopy. Particle size analyzer showed 44.4 nm for water extract nanoparticles and 103nm for ethanolic NPs. Antibacterial activity of these nanoparticles was evaluated against four bacterial strains, namely Klebsiella pneumonia, Pseudomonas aureginosa, Escherichia coli and Acetobactor bauminii. The zinc oxide nanoparticles of S. aromaticum developed by ethanolic extract did not show the significant antibacterial activity against any bacterial strain. The zinc nanoparticles of S. aromaticum developed by water extract showed maximum inhibition zone against K. pneumonia as 1.43mm, P. aureginosa is 1.00mm, E. coli as 2.14mm and against A. bauminii as 2.30mm as compared to 1.15mm, 1.86mm, 1.76mm and 1.53mm respectively by plant extract. Keywords: Antimicrobial activity; Green nanotechnology; Microwave assisted extraction (MAE); Plant extract; Ultraviolet-visible spectroscopy (UV-Vis); Zinc nanoparticles http://dx.doi.org/10.19045/bspab.2017.600115