Lowest Minimum Bactericidal Concentration Research Articles

Antibacterial activity of extract and fractions from branches of Protium spruceanum and cytotoxicity on fibroblasts

The crude ethanol extract (CEE) and fractions from branches of Protium spruceanum were subjected to antibacterial and cytotoxicity assays. Compounds of the most active fraction were identified by GC-MS and LC-MS. CEE was active against 19 bacteria and the ethyl acetate fraction (EAF) showed the lowest minimum bactericidal concentration (MBC 0.3–80.0 mg/mL). Through time-kill assay was observed that EAF induced rapid bactericidal effect against Staphylococcus saprophyticus. The cytotoxicity tests against L929 fibroblasts showed great potential of EAF on the treatment of infections caused by five bacteria (MBC < IC50). The results provide in vitro scientific support to the possible application of branches of P. spruceanum as antimicrobial agent that may contribute for treatment of infections.

In vitro antibacterial activities of the leaf extracts of Aloe macrocarpa Tod (Aloaceae)

IntroductionInfectious diseases have been threats to public health across the globe. The use of the leaves of Aloe macrocarpa Tod used for the treatment of infected wounds has been a common practice in North Gondar, Ethiopia. The objective of the study was to investigate the in vitro antibacterial activities of the leaf extracts of Aloe macrocarpa. MethodsMaintaining sterile conditions, the latex and gel of Aloe macrocarpa were collected and dried at room temperature. The crude gel was further extracted using 80% methanol. Then, antibacterial test was conducted against Staphylococcus aureus, Streptococcus pneumonia, and Streptococcus pyogenes and four Gram negative bacterial strains: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, and Salmonella typhi by agar well diffusion and broth dilution methods. ResultsThe three extracts showed different degrees of inhibitory activities against tested bacteria at 2, 1 and 0.5mg/ml concentrations in a dose dependent manner with statistically significant values (P≤0.05). For all tested bacteria, the zone of inhibition ranged from 0.00 to 23.00±0.577mm. The minimum inhibitory concentration (MIC) values ranged from 31.25 to 4000, 31.25 to 2000 and 62.5 to 8000μg/ml for the latex, hydroachoholic gel extract and crude gel, respectively. The lowest minimum bactericidal concentration (MBC) was 31.25μg/ml for the latex against Salmonella typhi. ConclusionFrom this study it can be concluded that the latex and gel extracts of the leaf of Aloe macrocarpa showed an inhibitory activity against tested bacteria. Therefore, the results demonstrated the traditional claims of this plant for the treatment of infected wounds.

Prospective, randomised, controlled study evaluating early modification of oral microbiota following admission to the intensive care unit and oral hygiene with chlorhexidine.

Chlorhexidine (CHX) is the most commonly used oral hygiene product for the prevention of ventilator-associated pneumonia (VAP) in patients undergoing mechanical ventilation (MV). The change in dental plaque (DP) microbiota following CHX use in patients under MV has not been described previously. The aim of this study was to evaluate the incidence of pathogenic bacteria associated with VAP and the coverage of DP within the oral cavity in patients administered CHX. This was a prospective, randomised, controlled, double-blind study in patients (n=16) under MV who were mouth-rinsed with either CHX or placebo. Microbiology samples were collected from the oral mucosa (OM) and DP after admission to the ICU and on Days 3, 5, 7 and 10. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of CHX were determined. Upon admission, the occurrence of multidrug-resistant (MDR) bacteria, including carbapenem-resistant Klebsiella pneumoniae, was reported. The CHX group had a lower incidence of methicillin-resistant Staphylococcus aureus (MRSA) compared with the placebo group for the OM (RR=0.51, 95% CI 0.27-0.98; P=0.011). There was high agreement between the culture results of OM and DP (κ=0.825). VAP developed in six patients. The species identified following tracheal aspiration of VAP patients were similar to those found in the OM for four cases. The strains showed low MICs and MBCs for CHX (<0.039mg/mL). Although DP is rapidly colonised by MDR bacteria, use of 2% CHX reduced the incidence of S. aureus colonisation.

Production of Chitosan/Zinc Oxide Complex by Ultrasonic Treatment with Antibacterial Activity

This study was conducted with the objective of investigating the physical and antimicrobial properties of structured zinc oxide compounds in chitosan submitted to different times of ultrasonic treatment. Zinc oxide particles were dispersed in water and coated with medium molar mass chitosan and two other sonicated samples, following a simple methodology. Before drying, the chitosan/zinc oxide water suspensions were characterized by rheological tests. Their rheological behavior depended on the period of time during which the chitosan sample was submitted to ultrasound. After drying, the microparticles were characterized by infrared spectroscopy, atomic absorption spectrophotometry and scanning electron microscopy (SEM). The microparticles were investigated as for their particle size distribution (PSD). SEM and PSD results revealed that the chitosan/zinc oxide microparticles had a multimodal dispersion. The antibacterial activity of the neat zinc oxide nanoparticles and of the microparticles was evaluated against Escherichia coli and Staphylococcus aureus. The results showed that the ZnO nanoparticles had a lower minimum bactericidal concentration (500 μm/mL against E. coli and 650 μm/mL against S. aureus) than the chitosan-coated/ZnO microparticles. The microparticles with the lowest average particle size and the highest homogeneity exhibited the highest antibacterial activity against both bacteria. This result was attributed to the additional antibacterial activity of soluble zinc ions and of the chitosan sample.

In vitro Antioxidant and Antibacterial Efficacy of Condensed Tannins Containing Tree Leaves Extract of Jammu Province

The present study was conducted to assess the antioxidant potential and antibacterial efficacy of lyophilized condensed tannins (CT) extract from locally available tree leaves (Acacia nilotica, Eugenia jambolana, Ficus religiosa, Leucaenea leucocephala and Psidium guajava) against bacterial species (viz. Enterococcus faecalis, Escherichia coli, Salmonella enteritidis and Staphylococcus aureus). Antioxidant activity was determined by 1, 1-Diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging and total reducing power assays. Lyophilized CT extracts of P. guajava and E. jambolana showed significantly (P<0.05) higher antioxidant potential compared to standard ascorbic acid and other CT sources. Antibacterial efficacy was determined by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using micro dilution method. The MIC and MBC values of CT extracts were significantly (P<0.05) higher for F. religiosa and L. leucocephalla then that of A. nilotica, E. jambolana and P. guajava. The MBC value for S. enteritidis was lower than E. coli and. S. aureus. Lower MIC and MBC values against E. coli, S. aureus and S. enteritidis in CT extracts of different sources showed better results compared to E. faecalis which showed statistically non-significant difference among all CT sources. It may be concluded that all CT sources possess antioxidant and antibacterial efficacy and were found to be effective against E. coli, S. aureus and S. enteritidis except E. faecalis and the comparison among the CT sources, E. jambolana and P. guajava were found to be most potent CT source as well as potent alternative antioxidant and antibacterial agents.

Antibacterial and anti-adherence effects of a plant extract mixture (PEM) and its individual constituent extracts (Psidium sp., Mangifera sp., and Mentha sp.) on single- and dual-species biofilms.

BackgroundPlant extracts mixture (PEM) and its individual constituent plant extracts(Psidium sp., Mangifera sp., Mentha sp.) are known to have an anti-adhering effect towards oral bacteria in the single-species biofilm. To date, the adhering ability of the early and late plaque colonisers (Streptococcus sanguinis and Streptococcus mutans) to PEM-treated experimental pellicle have not been investigated in dual-species biofilms.MethodsFresh leaves of these plants were used in the preparation of the respective aqueous extract decoctions. The minimum inhibitory concentration (MIC) of the extracts towards S. sanguinis ATCC BAA-1455 and S. mutans ATCC 25175 was determined using a two-fold serial microdilution method. The sum of fractional inhibitory concentration (ΣFIC) index of PEM and its constituent plant extracts was calculated using the MIC values of the plants. The minimum bactericidal concentration (MBC) of the plant extracts was also determined. The anti-adherence effect of the plant extracts (individually and mixed) was carried out by developing simulated S. sanguinis and S. mutans respectively in single- and dual-species of biofilms in the Nordini’s Artificial Mouth (NAM) model system in which the experimental pellicle was pretreated with the plant extract before bacterial inoculation. The bacterial population in the respective biofilms was quantified using ten-fold serial dilutions method and expressed as colony forming unit per ml (CFU/ml). The bacterial population was also viewed using Scanning Electron Microscope (SEM). All experiments were done in triplicate.ResultsThe PEM compared with its respective constituent plants showed the lowest MIC towards S. sanguinis (3.81 mg/ml) and S. mutans (1.91 mg/ml) and exhibited a synergistic effect. The Psidium sp. (15.24 mg/ml) and, PEM and Psidium sp. (30.48 mg/ml) showed the lowest MBC towards S. sanguinis and S. mutans respectively. The anti-adherence effect of the PEM and its respective constituent plants (except Psidium sp.) was different for the two bacteria in the single-species biofilm. In the dual-species biofilms, PEM demonstrated similar anti-adherence effect towards S. sanguinis and S. mutans. The proportions of the bacterial population viewed under SEM appeared to be in agreement with the quantified population.DiscussionThe combination of the active constituents of the individual plant extracts in PEM may contribute to its low MIC giving rise to the synergistic effect. The different anti-adherence effect towards S. sanguinis and S. mutans in both single- and dual-species biofilms could be due to the different proportion of the active constituents of the extracts and the interaction between different bacteria. The better adhering ability of S. sanguinis towards the PEM-treated pellicle when present together with S. mutans in the dual-species biofilms may suggest the potential of PEM in controlling the balance between the early and late colonisers in biofilms.

Evaluation of phytochemical and antibacterial properties of &lt;i&gt;Terminalia avicennioides&lt;/i&gt; crude extract against selected bacteria from diarrhoeic patients

Phytochemical screening of aqueous and ethanol crude extracts of the different plant parts of Terminalia avicennioides was carried out using standard chemical evaluation methods. The antibacterial effects of aqueous and ethanol crude extracts of Terminalia avicennioides against E.coli and S.typhimurium clinical and reference isolates from diarrhoeic patients were also evaluated using agar-well diffusion method. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of aqueous and ethanol crude extracts were evaluated by broth dilution techniques. The result revealed the presence of carbohydrates, alkaloids, tannins, flavonoids saponins, triterpens and glycosides. All bacteria were found to be susceptible to the extracts which were indicated by the various zones of inhibition. The activity of extracts was concentration dependent. The reference strains were less susceptible to all extracts at low concentrations of 12.5mg/ml, but highly susceptible to extracts at varied concentrations of 25, 50 and 100mg/ml. However, all test bacteria were more susceptible to the ethanol extracts compared to the aqueous extracts with mean zones of inhibition ranging between 0.68 + 2.54 mm to 22.08 + 1.75 mm on E. coli clinical isolates, 0.0 + 0.0 mm to 20.00+0.mm on E. coli reference isolate, 3.08 + 6.0 mm to 21.50 + 0.00 mm on S. typhimurium clinical isolates and 0.00 + 0.mm to 20.00 + 0.0 mm on S. typhimurium reference isolate. The ethanol crude extracts exhibited lower MICs (12.5 to 25mg/ml) and MBCs (25 to 50mg/ml) values indicating higher efficacy of ethanol extracts, with the leaf extract demonstrating the highest activity against all the bacterial isolates. The important bioactive compounds present in the plant may be responsible for the observed antibacterial activity of the plant and hence its potential use as an antibacterial agent.Keywords: Phytochemical, Antibacterial effect, Terminalia avicennioides, diarrhoeaic patients.

Effect of Punica granatum on the virulence factors of cariogenic bacteria Streptococcus mutans

Dental caries is caused by acids produced by biofilm-forming Streptococcus mutans from fermentable carbohydrates and bacterial byproducts. Control of these bacteria is important in the prevention of dental caries. This study investigated the effect of the fruit peel of Punica granatum on biofilm formation, acid and extracellular polysaccharides production (EPS) by S. mutans. Pomegranate fruit peels crude extracts were prepared. The Minimum bactericidal concentrations (MBC) were determined against S. mutans. At 3 sub-bactericidal concentrations, the effect on the acid production, biofilm formation and EPS production was determined. The results were analysed using Kruskal-Wallis and Wilcoxon Rank Sum Tests. The lowest MBC was 6.25 mg/mL. Punica granatum significantly inhibited acid production (p < 0.01). After 6 and 24 h, it significantly reduced biofilm-formation by 91% and 65% respectively (p < 0.01). The plant extract did not inhibit the production of soluble EPS in either the biofilm or the planktonic growth. However, it significantly reduced the insoluble EPS in the biofilm and the plantktonic (p = < 0.01) form of S. mutans. The crude extract of P. granatum killed cariogenic S. mutans at high concentrations. At sub-bactericidal concentrations, it reduced biofilm formation, acid and EPS production. This suggests that P. granatum extract has the potential to prevent dental caries.

Organic thyme oil emulsion as an alternative washing solution to enhance the microbial safety of organic cantaloupes

Emulsions of organic essential oils may be used as postharvest alternative washing solutions in fresh produce production. In the present study, organic thyme oil was emulsified with whey protein concentrate, gum arabic, lecithin, or their equal mass mixtures without using specialized equipment. The stability of these emulsions was monitored by measuring hydrodynamic diameter during ambient storage up to 7 days. The antimicrobial activity of these emulsions against Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes was evaluated by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). All emulsions had lower MIC and MBC than free thyme oil pre-dissolved in ethanol. Thyme oil emulsified with gum arabic had the smallest and most stable hydrodynamic diameter (156–239 nm) and was chosen as the washing solution to evaluate its efficacy in reducing pathogens on organic cantaloupes. Cantaloupes inoculated with pathogens were immersed in 0.1%, 0.2%, or 0.5% emulsified or free thyme oil for 2 min. The counts of the three cultures inoculated on cantaloupes were reduced by either 0.2% or 0.5% thyme oil and the emulsions were more effective than free thyme oil (P < 0.05). Organic load (2% or 5%) had no effect on their antimicrobial efficacy (P > 0.05). During ambient storage (21 °C) up to 10 days, the counts for all three bacteria gradually declined for all treatments and the emulsion treatment had consistently lower populations than unwashed and water-washed treatments. Therefore, emulsions of organic essential oils have potential applications as postharvest washing solutions to improve the microbiological safety of organic fresh produce.

Synergistic antibacterial and antibiofilm activity of silver nanoparticles biosynthesized by lignin-degrading fungus

The fabrication of silver nanoparticles (Ag-NPs) through green chemistry is an emerging area in the field of medical nanotechnology. Ag-NPs were fabricated by enzymatic reduction of AgNO3 using two lignin-degrading fungus Aspergillus flavus (AfAg-NPs) and Emericella nidulans (EnAg-NPs). The prepared Ag-NPs were characterized by different spectroscopic techniques. Antibacterial activity of prepared Ag-NPs was demonstrated against selected Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive (Staphylococcus aureus) bacteria in the term of minimum bactericidal concentration (MBC) and susceptibility constant (Z). The synergistic antibacterial activity of Ag-NPs with four conventional antibiotics was also determined by the fractional inhibitory concentration index (FICI) using the checkerboard microdilution method. The antibiofilm potential of Ag-NPs was also tested. The plasmon surface resonance of biosynthesized Ag-NPs shows its characteristic peaks at UV and visible region (~450 and 280 nm). Fourier transform infrared spectrometer (FTIR) analysis confirms the nature of the capping agents as protein (enzyme) and indicates the role of protein (enzyme) in reduction of silver ions. The average particle size and charge of synthesized Ag-NPs was ~100 nm and ~−20 mV, respectively. X-ray diffraction (XRD) and TEM analysis confirmed the purity, shape, and size (quasi-spherical, hexagonal, and triangular) of Ag-NPs. Energy-dispersive X-ray spectroscopy (EDX) data validate the biological synthesis of Ag-NPs. Low MBC and high susceptibility constant indicate the high antimicrobial strength of biosynthesized Ag-NPs. The antibacterial analysis demonstrates the synergistic antimicrobial activity of Ag-NPs with antibiotics. This study also shows that biosynthesized Ag-NPs have ability to inhibit the biofilm formation by 80–90 %. The Aspergillus flavus and Emericella nidulans-mediated biosynthesized Ag-NPs have significant antimicrobial activity and demonstrate synergistic effect in combination with antibiotics. It suggests that nanoparticles can be effectively used in combination with antibiotics to improve the efficacy of antibiotics against pathogenic microbes. The substantial antibiofilm efficiency of biosynthesized Ag-NPs would also be helpful against sensitive and multidrug-resistant strains.

Effects of Ethyl Acetate Extracts from the Polycephalomyces nipponicus Isolate Cod-MK1201 (Ascomycetes) against Human Pathogenic Bacteria and a Breast Cancer Cell Line.

This study aimed to identify a suitable organic solvent for extracting bioactive compounds from Polycephalomyces nipponicus and to evaluate the antibacterial and anticancer activities of the extracts obtained. Only extracts obtained with ethyl acetate exhibited antibacterial activity, so ethyl acetate was chosen for large-scale extraction. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Gram-positive and Gram-negative human pathogenic bacteria of the 3 ethyl acetate-derived extracts-ethyl acetate extract from P. nipponicus (PN-ME), ethyl acetate extract after defatting (PN-ME*), and ethyl acetate extract after refluxation (PN-ME')-were determined. PN-ME' exhibited the most potent activity, inhibiting 12 of the 18 test bacteria, especially Bacillus cereus ATCC 11778 and Vibrio cholera (O1) DMST 9700, with low MIC and MBC values. PN-ME* showed greater inhibitory activity than PN-ME. The effects of the extracts on bacterial cell morphology were also determined. After 120 minutes of treatment with PN-ME* or PN-ME', B. cereus ATCC 11778 exhibited an abnormal rod-shaped cell structure, with some cells elongated to multiple times their original size and others appearing collapsed. V cholera (O1) DMST 9700 cells showed shrinkage and the formed subsurface cavities. PN-ME* and PN-ME' also inhibited the growth of MCF-7 breast cancer cells. In conclusion, the fungal isolate P. nipponicus Cod-MK1201 represents a source of antibacterial and anti-breast cancer compounds.

The Comparative Evaluation of the Antimicrobial Effect of Propolis with Chlorhexidine against Oral Pathogens: An In Vitro Study

This study aimed to compare the antimicrobial effectiveness of ethanolic extract of propolis (EEP) to chlorhexidine gluconate (CHX) on planktonic Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, Lactobacillus salivarius subsp. salivarius, Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Staphylococcus aureus, Enterococcus faecalis, Actinomyces israelii, Candida albicans, and their single-species biofilms by agar dilution and broth microdilution test methods. Both agents inhibited the growth of all planktonic species. On the other hand, CHX exhibited lower minimum bactericidal concentrations than EEP against biofilms of A. actinomycetemcomitans, S. aureus, and E. faecalis whereas EEP yielded a better result against Lactobacilli and P. intermedia. The bactericidal and fungicidal concentrations of both agents were found to be equal against biofilms of Streptecocci, P. gingivalis, A. israelii, and C. albicans. The results of this study revealed that propolis was more effective in inhibiting Gram-positive bacteria than the Gram-negative bacteria in their planktonic state and it was suggested that EEP could be as effective as CHX on oral microorganisms in their biofilm state.

Assessment in Vitro of Antibacterial Activity of Manipulated Product, on Solution Form, Obtained from Dry Extract of Leaves of Psidium guajava L.

&lt;p class="Default"&gt;The &lt;em&gt;Psidium guajava L&lt;/em&gt;. specie is a perennial shrub, belonging to the &lt;em&gt;Myrtaceae&lt;/em&gt; family and it is popularly known as guava, its leaves are used in therapy for treating various diseases. The study aims to evaluate the antibacterial activity &lt;em&gt;in vitro &lt;/em&gt;of manipulated product obtained from dried extract of the leaves of &lt;em&gt;P. guajava &lt;/em&gt;L. front standard bacteria ATCC and clinical isolates. The tests were conducted on bacterial samples: &lt;em&gt;Staphylococcus aureus &lt;/em&gt;(ATCC 25923), &lt;em&gt;Pseudomonas aeruginosa &lt;/em&gt;(ATCC 27883), &lt;em&gt;Escherichia coli &lt;/em&gt;(ATCC 25922), &lt;em&gt;Salmonella spp&lt;/em&gt;, &lt;em&gt;Acinetobacter baumannii&lt;/em&gt;, &lt;em&gt;Proteus mirabilis&lt;/em&gt;, &lt;em&gt;Shigella flexneri&lt;/em&gt;, &lt;em&gt;Staphylococcus epidermidis&lt;/em&gt;, &lt;em&gt;Staphylococcus haemolyticus&lt;/em&gt;, &lt;em&gt;Streptococcus agalactiae, Streptococcus mutans&lt;/em&gt;. Among the tests can be mentioned phytochemical of the ethanol extract (EE), microbiological control and physical-chemical analysis of the product and microbiological tests such as agar diffusion method (wells), minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), an evaluation test of hemolytic capacity of the solution and in vitro assay cytotoxic activity were performed, . The best result of the product in the agar diffusion method was front &lt;em&gt;Staphylococcus epidermidis&lt;/em&gt;, while the lower MIC and MBC were front &lt;em&gt;Staphylococcus aureus &lt;/em&gt;(ATCC 25923). The product showed no hemolytic activity and no cytotoxic activity at the tested concentrations. According to the test results, it is believed on the possibility of the production of a pharmaceutical formulation derived from the dry extract of &lt;em&gt;Psidium guajava&lt;/em&gt;, since it showed great antibacterial activity.&lt;/p&gt;

Potential Study of Kopasanda (Chromolaena odorata L.) Leaves as Antibacterial Against Vibrio harveyi, Disease Causative Agent of Tiger Shrimp (Penaeus monodon Fabricius) Post Larvae

Vibriosis caused by Vibrio harveyi is still being a serious bacterial disease problem in the black tiger shrimp Penaeus monodon aquaculture. Due to this disease, the mortality of tiger shrimp post larvae can reach 100%. Attempt has been made for this bacterial disease prevention by using mangrove associates secondary metabolites. This study aims to determine potential of kopasanda (C. odorata L.) leaves as natural antibacterial against Vibrio harveyi. Potential study was carried out by determinination of the best solvent used to extract the bioactive secondary metabolites of kopasanda leaves, determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Toxicity study was also done by using soaking method to determine the save concentrations of C. odorata leaves on tiger shrimp post larvae. C. odorata leaves was extracted with methanol to extract all the active components, then, partitioned into n-hexane, ethyl acetate, methanol and aqueous extract. The highest antibacterial activity against V. harveyi was shown by methanol extract. The results suggest that C. odorata leaves have a potential to be developed as a raw material source for vibriosis prevention. It is due to its strong anti-vibrio activity showed by the low MIC and MBC of 0.625 and 1.250 mg/ml, respectively. Furthermore, the methanol extract did not show any toxicon tiger shrimp (P. monodon) post larvae up to 2.500 mg/ml.

Isolation and identification of anti-methicillin resistant Staphylococcus aureus compounds from Phyllanthus columnaris stem bark

Aim: Phyllanthus columnaris Mull.Arg. was found to possess anti-methicillin resistant Staphylococcus aureus (antiMRSA) activities. This study aimed at isolating, identifying and evaluating the active compounds from the stem bark of Phyllanthus columnaris Mull.Arg. against MRSA. Methodology and results: Stem bark extracts (methanol, acetone and aqueous) of Phyllanthus columnaris were subjected to anti-MRSA screening by disc diffusion method. MIC and MBC tests were carried out to compare the lowest concentration to inhibit and kill the sixteen MRSA tested among the three extracts. TLC bioautography were performed to detect the bioactive compounds. Isolation of the two active compounds was performed by means of preparative TLC. Morphological and ultra-structure alterations of the MRSA treated with bioactive compounds after 24 h were revealed by scanning and transmission electron microscopy. Both methanol and acetone extracts exhibited good anti-MRSA activity with the lowest minimum inhibitory concentration (MIC) value for both extracts were 0.78 mg/mL and the lowest minimum bactericidal concentration (MBC) were 1.56 mg/mL. Bioassay-guided chromatography by bioautography revealed two active anti-MRSA compounds from both tannin-free methanol and acetone extracts and characterized as stigmasterol and lupeol by nuclear magnetic resonance (NMR) spectral data. Scanning and transmission electron microscopy of MRSA treated with stigmasterol and lupeol showed cell wall disruption, release of cytoplasmic compounds and decreased in cellular volume. Conclusion, significance and impact of study: Results obtained herein, may suggest that the stem bark of Phyllanthus columnaris possess anti-MRSA and the two of the active compounds isolated were stigmasterol and lupeol. Their anti-MRSA effects up to the morphological and ultra-structure studies were not reported earlier.

The Essential Oil Profiles and Antibacterial Activity of Six Wild Cinnamomum species

The essential oil composition of six species of wild Cinnamomum found in Borneo was investigated. The oils were obtained from bark by hydrodistillation and the volatile chemical profile was obtained via Gas Chromatography-Mass Spectrometry (GCMS). A total of 65 volatile constituents were identified, where the essential oils of the studied specimens contained high contents of oxygenated monoterpenes. Eucalyptol (1.2-31.1%), terpinen-4-ol (7.9-22.1%), eugenol (0.4-37.9%) and α-cadinol (0.4-1.8%) were detected consistently in the specimens studied. The oils of C. cuspidatum and C. crassinervium exhibited significant inhibition against Listeria monocytogenes, specifically the latter, which displayed a lower minimum bactericidal concentration (MBC) value against Staphylococcus aereus and L. monocytogenes. This result had highlighted the possible usage of the essential oil derived from wild cinnamom species against food borne pathogens.

Evaluation of antibacterial activity of N-phosphonium chitosan as a novel polymeric antibacterial agent

N-phosphonium chitosans (NPCSs) with different degrees of substitution (3%, 13% and 21%) were synthesized and evaluated as novel polymeric antibacterial agents. Their antibacterial activities compared with hydroxypropyltrimethyl ammonium chloride chitosan (HACC), parent chitosan and (5-carboxypentyl) triphenylphosphonium bromide (CTPB) were tested against Escherichia coli and two strains of drug-resistance Staphylococcus aureus by minimal inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and biofilm prevention assays. The results show that the NPCS with 3% or 13% substitution has lower MIC and MBC values and stronger ability to inhibit biofilm formation of all the three bacteria than HACC, chitosan and CTPB. In addition, the antibacterial activity of NPCSs increases with their substitution decreasing from 21% to 3%. Overall, the antibacterial activity of NPCS with 3% or 13% substitution is better than that of NPCS with 21% substitution, HACC with 22% substitution, chitosan and CTPB. It can be considered that NPCS with appropriate degree of substitution has favorable antibacterial activity and is a potential polymeric antibacterial agent.

Antibacterial activity of northern Ontario medicinal plant extracts

Hassan, H. M., Jiang, Z.-H., Asmussen, C., McDonald, E. and Qin, W. 2014. Antibacterial activity of northern Ontario medicinal plant extracts. Can. J. Plant Sci. 94: 417–424. In the present study, the antibacterial activity (in vitro) of the leaf and/or flower crude extracts of Anaphalis margaritacea (L.) Benth &amp; Hook.f., Grindelia squarrosa (Pursh) Dunal, Apocynum androsaemifolium L., Arctostaphylos uva-ursi (L.) Spreng, Cornus canadensis L. and Xanthium strumarium L. medicinal plants was analyzed through the hole-plate diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays against Escherichia coli, Aeromonas caviae, Paenibacillus alvei, Micrococcus luteus, Mycobacterium avium subsp. avium and Bacillus cereus bacteria. In addition, the time-kill dynamic processes of these extracts against A. caviae, B. cereus, P. alvei, and M. luteus bacteria were also tested. The leaf and flower extracts of Anap. margaritacea and G. squarrosa possess significant antibacterial activity against all the bacteria tested, with inhibition of A. caviae, P. alvei and M. luteus within 1–12 h of incubation at MBC. Particularly, at higher concentrations of the Anap. margaritacea flower crude extract (2–3×MBC), inhibition of A. caviae, B. cereus, P. alvei, and M. luteus bacteria is achieved between 0.5 and 4 h of incubation. In addition, these extracts exhibit high inhibition diameters (majority &gt; 18 mm) and low MIC and/or MBCs (majority=1.25 mg mL−1). In contrast, the leaf extracts of Arct. uva-ursi, X. strumarium, Apoc. androsaemifolium and C. canadensis plants demonstrate moderate to low activity. These results indicate that extracts from Anap. margaritacea and G. squarrosa could be a source of novel antimicrobial scaffolds, compounds or pharmacophores with implications in the pharmaceutical industry and medicine.

Antimicrobial Activity ofCladonia verticillarisLichen Preparations on Bacteria and Fungi of Medical Importance

Cladonia verticillarislichen lectin (ClaveLL) was purified using a previously established protocol and then evaluated for its potential antimicrobial activity. Initially, the autochthonous lichen was submitted to extraction with sodium phosphate buffer pH 7.0, followed by filtration and centrifugation to obtain crude extract. A salt fractionation was performed with 30% ammonium sulfate. After centrifugation, the protein fraction was loaded onto molecular exclusion chromatography using Sephadex G-100 matrix to purify active lectin. ClaveLL showed antibacterial activity against Gram-positive (Bacillus subtilis,Staphylococcus aureus, andEnterococcus faecalis) and Gram-negative (Escherichia coliandKlebsiella pneumoniae) assayed strains, with greater inhibitory effect on growth ofE. coli(MIC of 7.18 μg mL−1). The lowest minimum bactericidal concentration (MBC, 57.4 μg mL−1) was detected againstE. faecalis. The antifungal assay performed withTrichophyton mentagrophytes,Microsporum gypseum,Trichophyton rubrum,Trichosporon cutaneum, andTrichosporon asahievaluated crude extract, fraction, and ClaveLL preparations. ClaveLL was the most active againstT. rubrumwith an inhibition percentage of 35% compared to negative control (phosphate buffer). Extract and fraction showed better activity on growth inhibition ofT. mentagrophytes(35%). The results indicate the potential of ClaveLL and otherC. verticillarispreparations as antimicrobial agents useful for applications focusing on human health.

ANTIBACTERIAL EFFICACY OF MANIBADRA CHOORNAYA AND ITS INDIVIDUAL INGREDIENTS

The present study was carri ed out in order to find out the antibacterial activi ty of hot and cold extracts of M anibadr a C hoornaya and its ingredients; fruits of Embelia ribes , Terminalia chebula and Emblica officinalis and root of Operculina turpethum against St aphylococcus aureus ( NCTC6571) and Escherichia coli (ATCC25922). Streptomycin and sterile distilled water were used as sta ndard and control respectively. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the extracts were determined by macro broth dilution method. Phytochemical analysis was done to identify the presence of chemicals in each extracts. Quantitative and comparative evaluation of antibacterial properties showed that the hot and cold extracts of Terminalia chebula revealed si gnificantly (P < 0.05) highest activity on both of the tested bacteria . Except Operculina turpethum , all the tested hot extracts including Manibadra C hoornaya extracts exhibited better effect on Escherichia coli when compared with respective cold extracts. The same tendency was produced on Staphylococcus aureus by Terminalia chebula and the Manibadra Choornaya . Terminalia chebula hot extract showed the lowest MIC (7.8125 mg / ml) on both of the test bacteria and lowest MBC (15.625 mg / ml) on E. coli . Most of the remaining extracts had 31.25 mg / ml as their MIC and 62.5 mg / ml as MBC . The phytochemical analysis revealed the presence of tannins in all test extracts where as glycoside, saponins, phlobatannins, resins and terpenoids were found in some of the extracts. Pres ent study prove the antibacterial activity of Manibadra Choornaya and its individual ingredients, further studies could provide more evidences for developing antimicrobial compounds from these extracts.