Antibacterial Activity Of Plant Extracts Research Articles

The methodology of determining antibacterial activity of plant extracts with disk-diffusion method in vitro

During the process of developing herbal drugs with antimicrobial action, one of the most important phases is testing of antimicrobial activity in vitro. The disk-diffusion method is performed in Petri dish, on solid feeding surface. The disks with definite concentrations of antibiotics, pure substances or plant extracts are placed on the top of feeding plates previously inoculated with pure bacterial culture. Growth of the bacterial culture depends on its susceptibility to a tested substance; if the substance has antibacterial effect, a clear zone free of bacteria will form around the disk. Minimal inhibitory concentration (MIC) of the tested substance is determined by extrapolation of the regression line: concentration of the tested substance/radius or surface of area where growth of bacteria was inhibited. This method of testing microbial susceptibility to antibiotics, pure substances or plant extracts is highly sensitive and specific.

Antibacterial Activity of Plant Extracts Against Oral Bacteria

Antibacterial Activity of Plant Extracts Against Oral Bacteria

Evaluation of diffusion and dilution methods to determine the antibacterial activity of plant extracts

The aim of this study was to evaluate diffusion and dilution methods for determining the antibacterial activity of plant extracts and their mixtures. Several methods for measurement of the minimal inhibitory concentration (MIC) of a plant extract are available, but there is no standard procedure as there is for antibiotics. We tested different plant extracts, their mixtures and phenolic acids on selected gram-positive ( Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes) and gram-negative bacteria ( Escherichia coli O157:H7, Salmonella Infantis, Campylobacter jejuni, Campylobacter coli) with the disk diffusion, agar dilution, broth microdilution and macrodilution methods. The disk diffusion method was appropriate only as a preliminary screening test prior to quantitative MIC determination with dilution methods. A comparison of the results for MIC obtained by agar dilution and broth microdilution was possible only for gram-positive bacteria, and indicated the latter as the most accurate way of assessing the antimicrobial effect. The microdilution method with TTC (2,3,5-triphenyl tetrazolium chloride) or INT (2-p-iodophenyl-3-p-nitrophenyl-5-phenyl tetrazolium chloride) to indicate the viability of aerobic bacteria was found to be the best alternative approach, while only ATP determination was appropriate for microaerophilic Campylobacter spp. Using survival curves the kinetics of bacterial inactivation on plant extract exposure was followed for 24 h and in this way the MIC values determined by the microdilution method were confirmed as the concentrations of extracts that inhibited bacterial growth. We suggest evaluation of the antibacterial activity of plant extracts using the broth microdilution method as a fast screening method for MIC determination and the macrodilution method at selected MIC values to confirm bacterial inactivation. Campylobacter spp. showed a similar sensitivity to plant extracts as the tested gram-positive bacteria, but S. Infantis and E. coli O157:H7 were more resistant.

Anti-Helicobacter pylori activity of plant extracts traditionally used for the treatment of gastrointestinal disorders

The antibacterial activity of plant extracts obtained from Bixa orellana L., Chamomilla recutita L., Ilex paraguariensis A. St.-Hil., Malva sylvestris L., Plantago major L. and Rheum rhaponticum L. has been evaluated against two reference strains and eleven clinical isolates of Helicobacter pylori. All the plant species chosen are used in popular Brazilian cuisine and folk medicine in the treatment of gastrointestinal disorders. Initial screening was made by the disk diffusion test and then minimum inhibitory concentration was determined by the agar dilution method. The results presented in this work demonstrated that among the plant preparations analyzed, B. orellana L., C. recutita L., I. paraguariensis A. St.-Hil. and M. sylvestris L. were capable of inhibiting the in vitro growth of H. pylori.

Use of the gene of antimicrobial peptide cecropin P1 for producing marker-free transgenic plants

The marker-free transgenic tobacco plants carrying a synthetic gene encoding the antimicrobial peptide cecropin P1 (cecP1) under the control of the cauliflower mosaic virus 35S RNA promoter were produced. The binary vector pBM, free of any selective genes of resistance to antibiotics or herbicides intended for selecting transgenic plants, was used for transformation. The transformants were screened on a nonselective medium by detecting cecropin P1 in plant cells according to the antibacterial activity of plant extracts and enzyme immunoassay. According to the two used methods, 2% of the analyzed regenerants were transformants. The resulting marker-free plants displayed a considerably increased resistance to microbial phytopathogens-the bacterium Erwinia carotovora and fungus Sclerotinia sclerotiorum. Thus, the gene cecP1 can be concurrently used as a target gene and a screening marker. The utility of cecP1 as a selective gene for direct selection of transformed plants is discussed.

In-vitro antibacterial activity of selected medicinal plants from Longisa region of Bomet district, Kenya.

Current strategies to overcome the global problem of antimicrobial resistance include research in finding new and innovative antimicrobials from plants. This study was carried out to determine the antibacterial activity of plant extracts of Olea africana stem-bark, Psidium guajava leaves, Vernonia amygdalina leaves, Lantana camara leaves and Mangifera indica leaves which are used in folklore medicine to treat infections of microbial origin in Longisa region of Bomet District, Kenya. Methanol extracts were derived and screened. Standard cultures of Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 25923 were used in the study. The antibacterial tests used were the agar well diffusion assays at concentration 1 gm/ml. Minimum Inhibition Concentration (MIC) was determined in the plant extract that showed some efficacy against the tested microorganisms. Gentamicin (10 microg) was used as a positive control. The methanol extracts showed weak antibacterial activity against the study organisms compared to Gentamicin. All extracts exhibited a significant bactericidal activity against S. aureus while L. camara and V. amygdalina lacked efficacy against P.aeruginosa and E. coli. O. africana and P. guajava presented the lowest MIC against S.aureus (62.5 mg/ml and 250 mg/ml respectively P. guajava and M. indica showed analogous MICs against P.aeruginosa (250 mg/ml). P. guajava exhibited a better MIC against E.coli (500 mg/ml). This in-vitro study corroborated the antimicrobial activity of the selected plants used in folklore medicine. The plants could be potential sources of new antimicrobial agent.

Efficacy of some antibacterial agents on Staphylococcus aureus isolated from various burn cases

The present study aimed to determine the major bacterial types from various burn cases and a study of antibacterial activity of plant extracts against Staphylococcus aureus isolated from burn cases in comparison with standard antibiotics.A total of 35 specimens were collected from burned patients (both sex, various degrees of burns) in burns unit of Al-Basrah General Hospital and Alsader Teaching Hospital in Basrah city during October 2006 to August 2007. Aqueous extracts from leaves and fruits of Zizyphus spine christi L. and Olea europaea L. were used as antibacterial agents against Staphylococcus aureus isolated from burned patients in comparison with standard antibiotics.The predominant bacterial types arePseudomonas sp. (74.19%) (23 isolates) followed by Staphylococcus aureus (54.83%) (17 isolates), another types distributed in various percentages from burn cases. The greatest effect of plant extracts was for 1000 µg/ml of leaves of Z. spain-christi which gave 20 mm of inhibition zone; the fruit of O. europaea: 1000 Mg/ml gave 16 mm; while the standard antibiotics gave the following diameters of growth inhibition zones: kanamycin and gentamicin (26 mm), neomycin (25 mm), cephalexin (24 mm), fusidic acid (22 mm), tobramycin (16 mm).Various burns are highly infected with diversity of bacterial pathogens, the plant extracts shows a variable activity against S. aureus . Key words: Staphylococcus aureus, antibiotics, burn cases

Antibacterial activity of plant extracts from Brazil against fish pathogenic bacteria

Antibacterial activity of plant extracts from Brazil against fish pathogenic bacteria

Foundation and perspectives of the use of plant extracts as performance enhancers in broilers

Feed is responsible for about 70% of broilers production costs, leading to an increasing number of studies on alternative dietary products that benefit bird performance and lower production costs. Since the 1950s, antimicrobial additives are the most frequently used performance enhancers in animal production and their positive results are observed even in high-challenge conditions. Since the 1990s, due to the ban of the use of some antibiotics as growth promoters and the growing trend of the public to consume natural products, plant extracts have been researched as alternatives to antibiotic growth promoters. The first study that evaluated the antibacterial activities of plant extracts was carried out in 1881; however, they started to be used as flavor enhancers only during the next decades. With the emergence of antibiotics in the 1950s, the use of plant extracts as antimicrobial agents almost disappeared. There are several studies in literature assessing the use of plant extracts, individually or in combination, as antimicrobials, antioxidants, or digestibility enhancers in animal feeds. Research results on the factors affecting their action, such as plant variety, harvest time, processing, extraction, as well as the technology employed to manufacture the commercial product and dietary inclusion levels show controversial results, warranting the need of further research and standardization for the effective use of plant extracts as performance enhancers, when added to animal feeds. This article aims at presenting plant extracts as alternatives to antibiotics, explaining their main modes of action as performance enhancers in broiler production.

Antibacterial activity of plant extracts from Brazil against fish pathogenic bacteria.

The aim of this work was to evaluate the antibacterial activity of Brazilian plants extracts against fish pathogenic bacteria. Forty six methanolic extracts were screened to identify their antibacterial properties against Streptococcus agalactiae, Flavobacterium columnare and Aeromonas hydrophila. Thirty one extracts showed antibacterial activity.

The Antibacterial Activity of Plant Extracts Containing Polyphenols against Streptococcus mutans

The minimum inhibitory concentrations (MIC) of commercially available and 70% aqueous propanone (P70) extracts from plants chosen for polyphenol content on Streptococcus mutans and other bacteria were determined using a standard susceptibility agar dilution technique to investigate their potential use as anticariogenic agents. The effects on adhesion of S. mutans to glass were also studied. The lowest MICs were for the P70 extracts of red grape skin (0.5 mg ml^–1) and green tea and sloe berry skin (2 mg ml^–1). The commercial extracts generally had a lower activity with a minimum MIC of 2 mg ml^–1 for tea extracts, grape seed extracts and Pynogenol® (extract of maritime pine). All other extracts had MICs of ≧4 mg ml^–1. Unfermented cocoa had greater antimicrobial activity than fermented cocoa and the activity of the fractionated extract increased with the extent of epicatechin polymerization. Epicatechin polymer had an MIC of 1 mg ml^–1 and an MBC of 64 mg ml^–1. Selected extracts were tested against other oral bacteria and showed activity against Gram-positive organisms. P70 extracts of unfermented cocoa, epicatechin polymer fraction, green tea and red grape seed were bacteriostatic and prevented acid production when added at the MIC to cultures of S. mutans grown in a chemically defined medium supplemented with either glucose or sucrose. There was a reduction in viability which was greater when added to washed cells, but there were some viable cells after 24 h. The extracts also reduced adherence of S. mutans to glass.

A study of antibacterial activity of plant extracts on bacterial pathogens isolated from Eye infections (conjunctivitis)

Isolation of bacterial pathogens from eye infections ( conjunctivitis ) was carried out in this study . 49 specimens (77.7%) gave positive bacterial cultures from totally (63 samples). The double mode of isolation has a highly rate of 34.6%. Staph.aureus is the predominant pathogen in percentage ( 53.06), followed by other bacterial types. Activity of aqueous and alcoholic extracts of Zizyphus spina christi , and Olea europaea (leaves and fruits) were also evaluated in the present study. Most aqueous extracts are not effected on Staph.aureus while alcoholic extracts have excellent activity against these bacteria. The biggest inhibition zone (20mm) recorded for 1000mcg /ml of Zizyphus extract. The MICs in all extracts ranged between 200-800 mcg / ml . We also used some standard antibiotics to compare their activities with the activity of plant extracts.

Antibacterial activity of plant extracts from northwestern Argentina

To determine the antibacterial and cytotoxic activities of aqueous and ethanolic extracts of northwestern Argentinian plants used in folk medicine. To compare the mentioned activities with those of five commercial antibiotics. To identify the compounds responsible for the antibacterial activity. Plant extracts were prepared according to traditional uses in northwestern Argentina. Antibacterial activity was assayed by agar dilution in Petri dishes and broth dilution in 96-well plates. Lethal dose 50 (LD(50)) was determined by the Artemia salina assay. Phytochemical analysis was performed by sample adsorption on silica gel, thin-layer chromatography (TLC), bioautography and UV-visible spectra. The results showed that Tripodanthus acutifolius aqueous extracts have lower minimal inhibitory concentrations (MIC) (502 and 506 microg of extracted material (EM) per ml for infusion and decoction, respectively) than cefotaxim MIC (640 microg ml(-1)) against Acinetobacterfreundii (303). These data were lower than their LD(50). Tripodanthus acutifolius tincture showed lower MIC (110 microg of EM per ml) and minimal bactericidal concentration (MBC) (220 microg of EM per ml) than cefotaxim (MIC and MBC of 320 microg ml(-1)) for Pseudomonasaeruginosa. This extract also showed a MIC/MBC of 110/220 microg of EM per ml, lower than oxacillin (MIC/MBC of 160/220 microg ml(-1)) for Staphylococcus aureus (ATCC 25923). The cytotoxicity of all extracts were compared with that of commercial antibiotics. Rutin (3,3',4',5,7-pentahydroxyflavone 3-beta-rhamnosilglucoside), iso-quercitrin (3,3',4',5,7-pentahydroxyflavone 3-beta-glucoside) and a terpene would be partially responsible for the antibacterial activity of T. acutifolius infusion. Tripodanthus acutifolius extracts had the ability to inhibit bacterial growth. The antibacterial activity differs with the applied extractive method, and it could be partially attributed to glycoflavonoids. This paper contributes to the knowledge of antibacterial capacity of plants from northwestern Argentina. These antibacterial activities support further studies to discover new chemical structures that can contribute to alleviate or cure some illnesses.

Antibacterial activity of plant extracts from Brazilian southeast region

A screening was conducted with 26 plants collected in the Brazilian southeast region, to identify plant extracts with antibacterial properties against Aeromonas hydrophila, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus. Initially, the agar diffusion method was employed. Then, those extracts presenting activity were submitted to a broth microdilution assay to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). It was observed that 13 of the tested extracts showed antibacterial activity. The best results were obtained with those from Lantana lilacina and Phyllanthus tenellus.

Evaluation of antibacterial activity of different mangrove plant extracts

Antibacterial activity of mature leaves, tender leaves and bark extracts of Avicennia marina, Avicennia officinalis and Bruguiera sexangula were evaluated using Soxhelt extraction method. Petroleum ether, chloroform, ethyl acetate and ethanol were used as solvents in order to get the plant extracts. The antibacterial activity was screened by using agar diffusion technique against pathogenic bacteria species of Staphylococcus sp. (from urine), Proteus sp. (from a wound), Escherichia coli (from infected blood), Shigella sp. (from a wound) and Pseudomonas sp. (from a wound). The length of inhibition zone was measured in millimeters from the edge of the well to the edge of the inhibition zone. Twelve different plant extracts in A. marina, A. officinalis and B. sexangula exhibited different degree of growth inhibition against tested bacterial strains. Mature leaf extracts of A. marina and tender leaf extracts of A. officinalis in ethyl acetate exhibited promising antibacterial activity than other plant extracts. All plant extracts in ethyl acetate showed strong inhibition compared to other extracts on all tested bacterial strains. Among all bacterial strains, Pseudomonas sp. and E. coli showed considerable growth inhibition against almost all plant extracts. Mature leaf extract of only A. marina was used for further investigations since a large amount of tender leaves of A. officinalis was not readily available. Charcoal treated mature leaf extracts of A. marina showed more inhibition for all tested bacterial strains than untreated plant extracts. Combinations of mature leaf extracts of A. marina in different solvents failed to exhibit synergistic activity against tested bacterial strains. Most combinations showed antagonistic effect against Proteus sp., E. coli and Shigella sp. Antibacterial activity of plant extracts of A. marina gradually declined during 4 months after extraction, for all tested bacterial strains. Components of mature leaf extracts of A. marina in chloroform, ethyl acetate and ethanol were separated by Analytical Thin Layer Chromatography (ATLC) when the eluents were hexane and diethyl ether. Isolated components in Preparative Thin Layer Chromatography (PTLC) exhibited moderate antibacterial activity against Pseudomonas sp., Shigella sp. and E. coli. Separated components did not show any antibacterial activity against Proteus sp. and Staphylococcus sp. Phytochemical screening revealed that mature leaf of A. marina contained alkaloids, steroids, triterpenoids and flavonoids.

Antibacterial activity of plant extracts from azuki beans (Vigna angularis) in vitro

This study was undertaken to examine the antimicrobial property of azuki beans (Vigna angularis). The water extracts of green, black and red colored azuki beans showed antibacterial effects against Staphylococcus aureus, Aeromonas hydrophila and Vibrio parahaemolyticus. In contrast, the extract of white azuki beans showed no inhibition towards any of the microorganisms examined. The extracts of colored azuki beans contained larger amounts of polyphenols including proanthocyanidins than the extracts of white azuki beans. The counts of S. aureus cells, inoculated in the medium containing the extracts of colored azuki beans, were significantly reduced in comparison with those of control and white azuki beans after 24 h (p < 0.05). These results suggest that polyphenols including proanthocyanidins in colored azuki beans may be responsible for their antibacterial activity.

Antibacterial activity of plant extracts and phytochemicals on antibiotic-resistant bacteria

The antimicrobial activity of plant extracts and phytochemicals was evaluated with antibiotic susceptible and resistant microorganisms. In addition, the possible synergistic effects when associated with antibiotics were studied. Extracts from the following plants were utilized: Achillea millifolium (yarrow), Caryophyllus aromaticus (clove), Melissa offficinalis (lemon-balm), Ocimun basilucum (basil), Psidium guajava (guava), Punica granatum (pomegranate), Rosmarinus officinalis (rosemary), Salvia officinalis (sage), Syzygyum joabolanum (jambolan) and Thymus vulgaris (thyme). The phytochemicals benzoic acid, cinnamic acid, eugenol and farnesol were also utilized. The highest antimicrobial potentials were observed for the extracts of Caryophyllus aromaticus and Syzygyum joabolanum, which inhibited 64.2 and 57.1% of the tested microorganisms, respectively, with higher activity against antibiotic-resistant bacteria (83.3%). Sage and yarrow extracts did not present any antimicrobial activity. Association of antibiotics and plant extracts showed synergistic antibacterial activity against antibiotic-resistant bacteria. The results obtained with Pseudomonas aeruginosa was particularly interesting, since it was inhibited by clove, jambolan, pomegranate and thyme extracts. This inhibition was observed with the individual extracts and when they were used in lower concentrations with ineffective antibiotics.

Chemical composition and antibacterial activity of Suaeda fruticosa Forsk From Cholistan, Pakistan

Proximate chemical composition, mineral constituents and antibacterial activity of Suaeda fruticosa (Kali Lani) was carried out. Determination of chemical constituents showed the presence of total carbohydrates 0.66 per cent (0.34 per cent reducing and 0.32 per cent non-reducing), moisture contents 87.9 per cent and ash contents 6.0 percent. Ether extract of the plant showed acid value 0.56, iodine value 0.02, refractive index 1.36 and pH value 8.0. The percentage of mineral constituents was, sodium 1.40, potassium 0.55, calcium 2.40, magnesium 2.04, carbonates 0.12, bicarbonates 0.85 and chlorides 1.40. Results of antibacterial activity of plant extracts in water, acetone, ethanol and ether against Klebsiella, Staphylococcus and E.Coli indicated that plant possesses potent antibacterial activity. E.Coli showed resistance to the standard antibiotic 1. e. Streptomycin while its growth was inhibited by acetone and ether extracts.

Antibacterial activity of plant extracts used externally in traditional medicine

Plants of 28 families, selected on the basis of medicinal folklore reports and literature data, were studied in a screening program. Aqueous extracts of plants used externally for the treatment of infected skin lesions were tested for their antibacterial potential. The results indicated that about 60% of the plant extracts tested exhibited some level of antibacterial action.

Preliminary screening of far-eastern ethnomedicinal plants for antibacterial activity

The results of antibacterial screening of 308 ethanol extracts from 250 wild far-eastern plants belonging to 77 families are reported. Antibacterial activity of plant extracts was tested in vitro by the filter-paper disc assay method. The plants screened were reported to be used by the population of the Soviet Far East against some bacterial infections. Activity against grampositive as well as gram-negative groups of microorganisms was tested.