Serial Dilution Method Research Articles

PHYTOCHEMICAL AND MICROBIOLOGICAL ASPECTS OF THE <i>NIGELLA SATIVA</i> L. HERBS STUDY

Nigella sativa L. is a promising plant object, herbal medicinal raw materials of which can be comprehensively used for the development of drugs with an antimicrobial activity.The aim of the study was to screen and compare the antimicrobial activity of water-ethanolic extractions from the Nigella sativa L. herbs with a eucalyptus tincture of as a reference preparation.Materials and methods. Chromatograms of the extracts were obtained by thin layer chromatography in the system of chloroform – ethanol – water (26:16:3). The detection of adsorption zones was carried out in daylight, in the UV light at λ=254 nm and λ=365 nm, as well as by treatment with reagents – a 3% alcohol solution of aluminum chloride and a solution of diazobenzosulfonic acid in a 20% sodium carbonate solution. The next step was to determine the minimum inhibitory concentration by the method of double serial dilutions in Mueller-Hinton nutrient broth (Bio-Rad, USA). As test cultures, the strains of the American Type Culture Collection (ATCC) microorganisms were used: Staphylococcus aureus (ATCC 29213), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), as well as Candida albicans (a clinical strain). Simultaneously, an experiment to establish a “negative” control was carried out. For the comparative evaluation of the studied samples activity, its activity was compared with the reference preparation with a proven antimicrobial activity – a eucalyptus tincture.Results. For all water-ethanolic extractions and the Nigella sativa L. herb tincture, the adsorption zones characteristic of flavonoids with Rf1 = 0.28, Rf2 = 0.15, Rf3 = 0.11 were revealed, and under the action of an alcoholic solution of aluminum chloride, the fluorescence of the adsorption zones was also enhanced, which indicates the phenolic nature of these compounds.In the course of the study, it was found out that all water-ethanolic extractions from the Nigella sativa L. herbs have the greatest antimicrobial effect against the Pseudomonas aeruginosa strain. When compared with the reference preparation – a eucalyptus tincture, it was notified that the specified tincture of the Nigella sativa L. herbs has an advantage in the antimicrobial activity over the strain of Pseudomonas aeruginosa – the action at the 16-fold dilution vs the 4-fold dilution. The action on the Escherichia coli and Candida albicans strains is comparable for the both tinctures.Conclusion. The obtained results of phytochemical and microbiological analyses will be used as a rationale for the introduction of antimicrobial preparations based on the Nigella sativa herbs in medical and pharmaceutical practice.

Synthesis and the Antimicrobial Activity of Salt Carbenoid Compounds

Aim. To synthesize aliphatic and aromatic derivatives of salt carbenoid compounds of the series of imidazole, benzimidazole, pyridine, pyrimidine and 1,3,4-oxadiazole containing fluorophenyl, cetyl or adamantyl substituents, and study their antimicrobial (antibacterial and antifungal) activities.Results and discussion. New derivatives of heterocyclic carbenoid salts and zwitterions based on the imidazole, benzimidazole, pyridine, pyrimidine and 1,3,4-oxadiazole heterocyclic systems containing fluorophenyl, cetyl or adamantyl substituents were synthesized. For this purpose, reactions of cyclization of the corresponding diimines with ethoxymethyl chloride (imidazolium salts), quaternization of the corresponding azoles with cetyl bromide or 1-adamantyl bromide in organic solvents (benzimidazolium, pyridinium and 1,3,4-oxadiazolium salts), cyclization of di(1-adamantylamino)alkanes hydrobromides with the orthoformic ester (4,5-dihydroimidazolium and tetrahydropyridinium salts) were used. Zwitterionic compounds were obtained by the reaction of the corresponding azolium salts with phenyl isothiocyanate in the presence of potassium carbonate. Some macrocyclic and adamantyl substituted heterocyclic compounds showed antifungal and antibacterial activities.Experimental part. The structure of the compounds synthesized was proven by 1H and 13C NMR spectroscopy methods. The antimicrobial activity was studied out by the agar diffusion method to determine diameters of the growth inhibition zones of microorganisms (bacteria and fungi) and by the method of serial dilutions to determine the minimum inhibitory concentration and minimum bactericidal and fungicidal concentrations.Conclusions. The synthesis of new heterocyclic carbenoid salts and zwitterions based on the imidazole, benzimidazole, pyridine, pyrimidine and 1,3,4-oxadiazole heterocyclic systems containing fluorophenyl, cetyl or adamantyl substituents has been performed. Compounds of macrocyclic and adamantyl heterocyclic series with antifungal and antibacterial activities have been found. 1,3-Dicetylimidazolium bromide, macrocyclic bis(decylenebenzimidazolium) bromides, azolium-N-phenylthiocarboximides have been proven to be the most active.

Phyto-assisted Preparation of Fe2O3 Nanoflowers and Their Antimicrobial Studies

Synthetic protocols for the preparation of nanomaterials chemically are expensive, too much time taking and unfriendly to the environment, therefore, phyto-assisted approach has the potential to be a promising alternative strategy for the synthesis of nanomaterials. Herein, Fe2O3 with nanoflower-like architecture (Fe2O3 NFs) was prepared using Moringa oleifera leaf extract, and characterized by employing several analytical techniques. The antimicrobial activity of the prepared Fe2O3 NFs was evaluated against the bacteria viz. Salmonella typhi, Staphylococcus aureus, Bacillus subtilis, Escherichia coli by using the serial dilution method. The results suggested that Fe2O3 NFs possess comparable antimicrobial activity comparable with streptomycin against the used pathogens.

Isolation and identification of Streptomyces tunisiensis from Garmsar salt cave soil with antibacterial and gene expression activity against Pseudomonas aeruginosa

It is known that more than 70% of the current antibiotics have been produced by Streptomyces; therefore, the main goal of the present study was to isolate halophiles Streptomyces to investigate their antimicrobial properties on the expression of the pathogenic genes of clinically resistant Pseudomonas aeruginosa. To this aim, isolation of Streptomyces from soil was performed by serial dilution method, and cultivation on ISP2 and SCA medium. The secondary metabolite was extracted by ethyl acetate method. The presence of exo A, alg D and oprl genes were determined by PCR in 50 clinical isolates of Pseudomonas aeruginosa. The inhibitory effect of active metabolites on gene expression were investigated by employing the real-time PCR technique. The purification of secondary metabolites were performed by employing the HPLC technique. Moreover, the FTIR technique was employed to determine the functional groups to help performing identifications by employing the LC-MS technique. Finally, selected Streptomyces was identified by 16S ribosomal RNA gene. Accordingly, the possible forms of Streptomyces were isolated and identified, in which Streptomyces number 25 had the highest growth inhibition zone against the clinical strains of Pseudomonas aeruginosa. The obtained results of molecular analysis showed 95.4% similarity to Streptomyces tunisiensis. The effect of selected Streptomyces secondary metabolites reduced expressions of both of exo A and algD genes in 1024μg/mL concentration. In this regard, the potent fraction could be known as an isobutyl Nonactin analogue. The concluding remarks of this work showed the antimicrobial activity of halophilus Streptomyces species against the resistant strains of Pseudomonas aeruginosa with the ability of producing antibiotics proposing for running further investigations to determine the active compound structures.

Regioselective synthesis of benzo[b]indeno[1,2-e][1,4]thiazin-11(10aH)-ones and antimicrobial evaluation thereof

Benzo[b]indeno[1,2-e][1,4]thiazin-11(10aH)-ones 8a–h were synthesized regioselectively via cyclocondensation of 2,5-dibromo-2-(substitutedphenyl)-1H-indene-1,3(2H)-diones 4a–c and 2-aminobenzenethiols 7a–e using freshly dried EtOH as solvent with 42–60% yields. The synthesized derivatives were well-characterized by employing different spectral techniques (FTIR, 1H and 13C NMR, and HRMS) and X-ray crystallographic analysis. All the derivatives were examined for their preliminary in vitro antimicrobial activity against two Gram-positive bacterial strains, i.e., Bacillus subtilis, and Staphylococcus aureus, two Gram-negative bacterial strains, i.e., Pseudomonas aeruginosa and Escherichia coli, and two fungal strains, i.e., Candida albicans and Rhizopus oryzae employing serial dilution method taking Ciprofloxacin and Fluconazole as standard reference drugs for antibacterial and antifungal activities, respectively. Among all the tested derivatives, 8h was found to exhibit significant inhibition against all the microbial strains under study.

Respiratory Stress of Sub-Lethal Concentration of Chlorine on Oreochromis niloticus

In aquatic environment, one of the most significant manifestations of the toxic stress on aquatic organisms, especially fishes are the over stimulation or depression of respiratory activities. These variations in respiratory activities have been used as in indicator of environmental stress. This study was aimed to assess the sub-lethal toxicity of chlorine through respiratory stress on Oreochromis niloticus. It was noticed that in all dosage experiments as the concentration increased rate of gill movement decreased. The rate of gill movement during the first minute after the dosage in control was 128 per minute. Serial dilution method employed in this study helped to assess the LC50 of chlorine and the value noted was 2 ppm. The minimum number of gill movement noted was in 20ppm dosage and the value was 98 per minute whereas the maximum noted was in 5ppm dosage and the value was 101 per minute. In 60th minutes after dosage also the control showed a value of 126 per minute and 20 ppm dosage showed a very low value such as 32 per minute whereas 5ppm dosage of chlorine showed a reasonably good value of 61 per minute. It was noted that in the case of average gill movement, control showed a very high value such as 127 per minute, whereas 5ppm dosage of chlorine showed a reasonably good value such as 84 per minute, and 20 ppm dosage showed a low value 72 per minute. When a comparison was made between control and differently dosed fishes, it was observed that in all dosed cases the average gill movement was very low when compared with control. A significant difference exists between gill movement in the dosed group and control (P<0.05). Consumption of oxygen increased with an increase in dosage and decreased with increased period of exposure. In control the average oxygen consumption was 0.012 mg/ml/gm body weight, in 5ppm it was 0.014 mg/ml/gm body weight, in 10 ppm it was 0.0155 mg/ml/gm body weight, in 15 ppm it was 0.021 mg/ml/gm body weight and in 20ppm it was0.022 mg/ml/gm body weight.

Enhanced Biodegradation of Battery-Contaminated Soil Using Bacillus sp. (MZ959824) and Its Phytotoxicity Study

Batteries that have been used and thrown away are potential threats to the environment. The aim of the present study is to explore the bacterial bioremediation of the battery-contaminated soil. The battery contaminated soil sample was collected from the municipal compost yard, Vellalore, Coimbatore, Tamil Nadu, India. The Bacillus sp was isolated by the serial dilution method. The Bacillus strain was identified based on the colony morphology as well as the 16s ribosomal ribonucleic acid partial gene sequence and was designated the name HVRCBNR. It was deposited in the GenBank under the accession number Bacillus sp MZ959824. The bacterial growth was evaluated by measuring the optical density of the media (OD600), while the degradation was determined by FTIR analysis. The phytotoxic analysis was performed using Trigonella foenum-graecum to assess the toxicity of the battery waste before and after bacterial treatment. The spectroscopic study showed that the strain HVRCBNR achieved 83.6% degradation. The growth indexes of Trigonella foenum-graecum showed that the biodegraded soil was nonphytotoxic in comparison with the control. This study supports the degradability of the strain HVRCBNR, and this could pave a way for sustainable solution to battery contaminated soil treatment.

Antibacterial and antibiofilm activity of polyfunctional benzimidazole derivatives

Introduction. Compounds based on fused imidazole derivatives can become the basis for the development of a new generation of clinical therapeutic agents for more effective treatment of resistant human bacterial infections. This requires research, including the design, synthesis, and screening of biologically active compounds of this group.The aim. To study the effect of polyfunctional benzimidazole derivatives on the survival of Escherichia coli AB1157 culture and its ability to form biofilms.Methods. The antibacterial activity of the studied compounds was evaluated using the serial dilution method. Modeling of the formation of biofilms was carried out in the wells of an immunological plate with subsequent staining of the biomass with crystal violet.Results. The inhibitory activity of some of the studied compounds on the formation of biofilms by the Gram-negative bacterium E. coli AB1157 was demonstrated. The most pronounced inhibitory effect on E. coli AB1157 biofilms was exerted by 5-bromo-2-(trifluoromethyl)-1-H-benzimidazole. The level of biofilm formation decreased by 2–4 times in the area of concentrations of 15–60 µg/ml and by 8–10 times at concentrations of 125 µg/ml and above.Conclusion. The presented work expands the knowledge about the biological activity of benzimidazoles. The obtained results show that benzimidazole derivatives are good candidates for the development of new drugs against biofilms. The data obtained are of practical interest and need further study.

Effect of subinhibitory concentrations of biocides on formation of adaptive resistance of clinical isolates of Klebsiella pneumoniae

The purpose of the research is to study the effect of subinhibitory concentrations of biocides on the formation of adaptive resistance of clinical isolates of K. pneumoniae. The study analyzes the effect of chlorhexidine, benzalkonium chloride, povidone iodine, ethanol, glycolic acid, polyhexamethylene guanidine on the formation of adaptive resistance of clinical isolates of Kl. pneumoniae (n=9), isolated in 2021 from patients undergoing treatment in various departments of the oncological hospital in Minsk. Determination of the sensitivity of bacteria to biocides was carried out with the serial dilutions method in a dense nutrient medium and with the serial microdilutions method in a liquid nutrient medium, using a twofold dilution of each antimicrobial substance. Throughout the course of the research, it was found that subcultivation of clinical isolates of K. pneumoniae on media with subinhibitory concentrations of chlorhexidine and benzalkonium chloride led to 60 and 40 times increase in bacterial resistance to them, respectively. It was shown that variability which does not affect the bacterial genome makes the maximum contribution to the development of resistance of K. pneumoniae clinical isolates to chlorhexidine, and both phenotypic and mutational variability to benzalkonium chloride. Povidone iodine, ethanol and glycolic acid did not cause the development of adaptive resistance of microorganisms. The results obtained indicate that the irrational and uncontrolled use of antiseptic and disinfectants containing chlorhexidine and benzalkonium chloride as active substances can lead to the development of adaptive resistance of microorganisms and thereby reduce the effectiveness of preventive and therapeutic measures.

BAKTERI PENGHASIL AMILASE YANG DIISOLASI DARI EKOENZIM LIMBAH BUAH-BUAHAN

Many of potential enzymes can be found in the ecoenzyme, one of them is amylase. Amylase is an enzyme that is able to hydrolize the glycoside bonds of starch or starch into dextrin, glucose and maltose which is widely used in various industries such as beverages. This study aims to isolate the ecoenzyme bacteria and test their ability to produce amylase. Isolation of ecoenzyme bacteria was carried out using serial dilution methods 10-1, 10-3, 10-5. A total of 0.1 ml of each dilution series was pipetted and spread on the Nutrient agar (NA) medium. The bacterial isolates that grew were then purified and identified by morphological observation, Gram staining and their enzymatic activity was tested using Starch Agar (SA) media qualitatively. The results of this study showed there were 39 bacterial isolates from ecoenzyme with different morphological characteristics. The amylase activity test were found that 34 isolates had a positive activity to hydrolize the starch in the SA media which was indicated by the formation of a clear zone around the bacterial colonies. Each bacterial isolate had a different hydrolysis index value, which ranged from 9.45 to 23.65. The highest clear zone diameter index value from starch hydrolysis was EJM 15 isolate.

Comparison of Use of Concentrated Saliva with Serial Dilution Method in Determination of Candida Colonies in Oral Samples

Fungal infections have been commonly observed in the oral cavity with the most common being Candida albicans but with time, new species of candida have been observed and isolated from the oral cavity. Identification of new strains is necessary not only because of their ability to cause infection but also due to their susceptibility toward antifungal agents. The use of concentrated saliva or serial dilution method has been used for these culture tests, with each method having its own advantage and disadvantage. Hence, the aim of the study was to quantitatively analyze effectiveness of both these methods on samples from the oral cavity.

Characterization of Halophilic Bacteria Isolated from Khewra Salt Mines

Halophilic bacteria can populate every niche of earth. These halophiles have a great potential of exopolysaccharides production that is of considerable importance in various industries. To screen EPS producing halophiles, saline soil samples were collected from Khewra salt mines, Jehlum, Pakistan. Twenty-two morphologically different bacterial strains were isolated by serial dilution method. All strains were considered as moderate halophilic bacteria as they could grow at 3-15% of NaCl concentration whereas only three strains could grow at 15% of NaCl, which belonged to the genus Bacillus and Pseudomonas. For screening of EPS production, P-medium was used. While for the estimation of slime production, congo-red agar was used that exhibited positive results by appearance of black colored colonies by many strains. Moreover, EPS production was analyzed quantitatively and qualitatively. Isolated Staphylococcus and Bacillus species produced high amount of EPS (20g/L). “Moderate halophiles” play an important role in therapeutics, bioremediation, food and medicine, petroleum and tanning industries by producing EPS. Recently, growth of many agriculture crops has been improved by using beneficial halophiles in saline soils. Consequently, with the help of these beneficial halophiles we can give benefit to mankind

INFLUENCE OF THE COMPLEX BACTERIAL PREPARATION AZOGRAN ON THE DEVELOPMENT OF SPROUTS OF CULTIVATED PLANTS

Objective. To investigate the effect of seed treatment of cultivated plants with the complex bacterial preparation Azogran (based on Bacillus subtilis IMB B-7023 and Azotobacter vinelandii IMB B-7076) on the initial stages of ontogenesis under laboratory conditions. Methods. Microbiological (cultivation of microorganisms was carried out under periodic culture conditions — A. vinelandii IMB B-7076 in Ashby liquid digest medium, Bacillus subtilis IMB B-7023 — in a mineral medium with glucose; the number of viable cells in suspensions was determined by the method of serial dilutions followed by sowing on the surface of the relevant agarized media), physiological (with different dilutions of biopreparation suspensions for seed inoculation), statistical. Results. Bacterization of Ukraina variety buckwheat seeds, Podolianka variety winter wheat and Marharyta variety common tare with a liquid complex bacterial preparation Azogran had a positive effect on germination energy, germination, sprout length and their weight compared to the control (water treatment). The best results at the initial stages of plant ontogenesis were found for buckwheat and wheat. The positive effect of inoculation was more pronounced when diluting the biopreparation suspension with water in ratios of 1:10 and 1:100, which indicates intensive production of biologically active substances by bacteria. Treatment of seeds of different corn varieties with an aqueous suspension of the granular complex bacterial preparation Azogran had a positive effect on the development of sprouts, and also contributed to the reduction of their damage by phytopathogenic micromycetes. Conclusion. The complex bacterial preparation Azogran has a positive effect on the energy of germination, germination and the weight of sprouts of the investigated plant species, reduces the degree of seed damage by micromycetes and is recommended for the treatment of seeds of agricultural plants before sowing in the soil.

ISOLASI DAN IDENTIFIKASI Streptomyces sp. PADA KOLAM TANAH DI DESA TENGGUR TULUNGAGUNG JAWA TIMUR

Tenggur Village, Rejotangan District, Tulungagung Regency is a village where the majority of its residents work as fish farmers. Currently, one of the diseases that attack fish is thought to be caused by infection with Aeromonas hydrophila bacteria, the fish's body parts will bleed, especially the chest, abdomen and at the base of the fins, and the fish will die even though the pond is well maintained. Fish disease control is currently still using chemicals so that the impact of beneficial bacteria will be destroyed in the pond environment and residues of compounds in fish that will be harmful to health if consumed. Streptomyces bacteria are bacteria that are able to produce enzymes and antibiotics that can be used as biocontrol agents for several diseases caused by bacteria. The purpose of this study was to isolate and identify Streptomyces bacteria from soil ponds in Tenggur Tulungagung Village, East Java. Isolation was carried out using the serial dilution method. Streptomyces were isolated from an earthen pond with a depth of 15 cm from the soil surface and planted on Yeast Extract Malt Agar (ISP4) media. The growing colonies were observed macroscopically and microscopically, as well as biochemical tests using the Guide to the Classification and Identification of the Actinomycetes and Their antibiotics from Lechevalier and Waksman (1973). The results showed 4 isolates of Streptomyces sp.1, Streptomyces sp.2, Streptomyces sp.3, Streptomyces sp.4. The four isolates will later be tested against Aeromonas hydrophyla bacteria, which is the cause of Motile Aeromonas septicemia.

Isolation, Screening, and Active Metabolites Identification of Anti-Vibrio Fungal Strains Derived From the Beibu Gulf Coral.

The Beibu Gulf harbors abundant underexplored marine microbial resources, which are rich in diversified secondary metabolites. The genera Vibrio is a well-known pathogenic bacterium of aquatic animals. In this study, 22 fungal strains were isolated and identified from the Beibu Gulf coral via the serial dilution method and internal transcribed spacer (ITS) sequence analysis, which were further divided into three branches by phylogenetic tree analysis. The crude extracts of them via small-scale fermentation were selected for the screening of inhibitory activity against Vibrio alginalyticus, Vibrio coralliilyticus, Vibrio harveyi, Vibrio parahaemolyticus, Vibrio owensii, and Vibrio shilonii. The results showed that eight fungal extracts displayed anti-Vibrio activity via the filter paper disk assay. Several of them showed strong inhibitory effects. Then, two tetramic acid alkaloids, equisetin (1) and 5′-epiequisetin (2), were identified from Fusarium equiseti BBG10 by bioassay-guided isolation, both of which inhibited the growth of Vibrio spp. with the MIC values of 86–132 μg/ml. The scanning electron microscope results showed that cell membranes of Vibrio became corrugated, distorted or ruptured after treatment with 1 and 2. Taken together, this study provided eight fungal isolates with anti-Vibrio potentials, and two alkaloid-type antibiotics were found with anti-Vibrio effects from the bioactive strain F. equiseti BBG10. Our findings highlight the importance of exploring promising microbes from the Beibu Gulf for the identification of anti-Vibrio for future antibiotic development.

Attractive study of the antimicrobial, antiviral, and cytotoxic activity of novel synthesized silver chromite nanocomposites

Antibiotic resistance is a global problem. This is the reason why scientists search for alternative treatments. In this regard, seven novel silver chromite nanocomposites were synthesized and assayed to evaluate their antimicrobial, antiviral, and cytotoxic activity. Five bacterial species were used in this study: three Gram-positive (Bacillus subtilis, Micrococcus luteus, and Staphylococcus aureus) and two Gram-negative (Escherichia coli and Salmonella enterica). Three fungal species were also tested: Candida albicans, Aspergillus niger, and A. flavus. The MIC of the tested compounds was determined using the bifold serial dilution method. The tested compounds showed good antibacterial activity. Maximum antibacterial activity was attained in the case of 15 N [Cobalt Ferrite (0.3 CoFe2O4) + Silver chromite (0.7 Ag0.5Cr2.5O4)] against M. luteus. Concerning antifungal activity, C. albicans was the most susceptible fungal species. The maximum inhibition was recorded also in case of 15 N [Cobalt Ferrite (0.3 CoFe2O4) + Silver chromite (0.7 Ag0.5Cr2.5O4)]. The most promising antimicrobial compound 15 N [Cobalt Ferrite (0.3 CoFe2O4) + Silver chromite (0.7 Ag0.5Cr2.5O4)] was assayed for its antiviral and cytotoxic activity. The tested compound showed weak antiviral activity. The cytotoxic activity against Mammalian cells from African Green Monkey Kidney (Vero) cells was detected. The inhibitory effect against Hepatocellular carcinoma cells was detected using a MTT assay. The antimicrobial effect of the tested compounds depends on the tested microbial species. The tested compounds could be attractive and alternative antibacterial compounds that open a new path in chemotherapy.

Antimicrobial Effects of L-Chg10-Teixobactin against Enterococcus faecalis In Vitro.

Objective: Teixobactin and its analogues are a new class of antibiotics that have no detectable bacterial resistance. This study was designed to determine the antibacterial and antibiofilm activities of a novel teixobactin analogue, L-Chg10-teixobactin, against two strains of Enterococcus faecalis (E. faecalis). Materials and Methods: The efficacy of L-Chg10-teixobactin against two strains of E. faecalis (ATCC 29212 and 47077) was determined using Clinical and Laboratory Standards Institute methods. L-Chg10-teixobactin was prepared at a stock concentration of 1 mg/mL in 5% DMSO. The minimum inhibitory concentration (MIC) was calculated using a two-fold serial broth dilution method, utilizing a 96-well plate. The minimum bactericidal concentration (MBC) was determined by plating the bacteria onto agar to define the concentration that resulted in 99.9% of bacterial death. Ampicillin was used as the control. The effect of L-Chg10-teixobactin on the inhibition of ATCC 47077 strain biofilm formation was determined by measuring the minimum biofilm inhibitory concentration (MBIC) using the safranin assay, while the eradication of the preformed biofilm was determined by measuring the minimum biofilm eradication concentration (MBEC) using the XTT assay. For nonlinear data, the log dose–response curve was plotted to calculate the optimum concentration using Excel (version 16.51, Microsoft® excel. 2021, Microsoft Corporation, Reymond, WA, USA). The data are presented as mean ± standard deviation (SD). Results: The MIC and MBC values of L-Chg10-teixobactin against both strains of E. faecalis were 0.8 μg/mL. The MIC of ampicillin was 1.25 μg/mL for ATCC 29212 and ranged from 1.25 to 5 μg/mL for ATCC 47077. The MBC of ampicillin for ATCC 29212 and ATCC 47077 was 10 and 20 μg/mL, respectively. The MIC and MBC of ampicillin were much higher compared with those of L-Chg10-teixobactin. The MBEC80 of L-Chg10-teixobactin was 4.60 μg/mL for ATCC 47077, which was much lower than that of ampicillin (20 μg/mL). Conclusions: L-Chg10-teixobactin demonstrated potent antibacterial and antibiofilm effects against E. faecalis, suggesting its potential role an effective antibacterial and antibiofilm agent in endodontic treatment.

Viola betonicifolia-Mediated Biosynthesis of Silver Nanoparticles for Improved Biomedical Applications.

We report the biosynthesis of silver (Ag) nanoparticles (NAPs) (LEVB-Ag NAPs) by an environmentally friendly green synthesis approach using the phytoconstituents of Viola betonicifolia leaf extract. The spectroscopic techniques were employed to characterize biosynthesized LEVB-Ag NAPs successfully. Biosynthesized LEVB-Ag NAPs were assessed for antibacterial and antimycotic activities against bacterium and mycological strains (H. pylori, S. epidermidis, C. tropicalis, and T. rubrum) using the serial dilution method. They were also evaluated for their biofilm inhibiting potential against both bacterial and fungi species. They were further assessed for the cytobiocompatible potential with two normal cell lines (293T and hMSC). The results demonstrate that the biosynthesized LEVB-Ag NAPs showed superior log10 reduction in bacterial and fungal growth and presented more than 99.50% killing efficiency. Moreover, biosynthesized LEVB-Ag NAPs excellently inhibited the biofilm formation of bacterial (Gram-positive and Gram-negative) and mycological strains and presented more than 80% biofilm inhibiting percentage compared to both plant extract and CHE-Ag NAPs. They further presented good cytobiocompatibility in vitro with 293T and hMSC cells compared to CHE-Ag NAPs. Biosynthesized LEVB-Ag NAPs presented superior antibacterial, antimycotic, biofilm inhibition, and cytobiocompatible results that might be attributed to the synergistic effect of the NAPs’ physiochemical properties and the immobilized phytoconstituents from plant leaf extract on their surface. Hence, biosynthesized LEVB-Ag NAPs may be a promising contender for a variety of therapeutic applications.

Antimicrobial evaluation and QSAR studies of 3,6-disubstituted-11H-benzo[5,6][1,4]thiazino[3,4-a]isoindol-11-ones

The antimicrobial evaluation of a series of twenty 3,6-disubstituted-11H-benzo[5,6][1,4]thiazino[3,4-a]isoindol-11-ones 8a–t was done against two Gram-positive bacterial strains viz. Bacillus subtilis (MTCC 441) and Staphylococcus epidermidis (MTCC 6880), two Gram-negative bacterial strains viz. Escherichia coli (MTCC 1652) and Pseudomonas aeruginosa (MTCC 424), and two fungal strains viz. Candida albicans (MTCC 227) and Aspergillus niger (MTCC 8189) employing serial dilution method. Ciprofloxacin and Fluconazole were used as reference drugs for antibacterial and antifungal activities, respectively. The results of antimicrobial assay were reported in terms of Minimum Inhibitory Concentrations (MIC, μmol/mL). Structure Activity Relationships (SAR) were established for both antibacterial and antifungal inhibitory abilities of the compounds 8a–t under study. Further, Quantitative Structure Activity Relationships (QSAR) was accomplished to correlate the biological activity data with structural properties of compounds, using linear regression. The quality of models was determined by using parameters like R-squared (R2), root mean squared error (RMSE) and Pearson correlation coefficient (Pcor) along with scatter plot and residual plot. But, the best model was obtained for P. aeruginosa with excellent internal predictivity because of randomly distribution in the residual plot around the zero-error line. Thus, this model proved helpful for further synthesis of new derivatives of this series.

Evaluation of possible biological control of Fusarium concentricum sp. using plant extracts and antagonistic species of microbes in vitro.

Background:Fusariumconcentricum is one of the most devastating fungi responsible for fruit and vegetable crops rot worldwide. The present study was designed to find an ecofriendly control measure for pathogenic Fusariumconcentricum, using suitable bioagents. Methods: Medicinal plant extracts were evaluated or their antifungal activities against Fusariumconcentricum using the poisoned food and serial dilution methods. Antagonistic potency of some nonpathogenic microbes was also assessed on Fusariumconcentricum using the dual culture method. Results: Highest inhibitionofgrowth of Fusarium concentricum wasobservedwith 68.1% (0.389 mg per 90 mm Petri plate) of mycelia on Coccinia grandis plant leaf extract, in comparison to the control grown with 100.0% (1.22 mg/dish). The tested plants extract showed MIC values rages of 80-150 µg/ml on the isolated fungus. The highest inhibition of radial growth was observed using Trichoderma viride on Fusariumconcentricum (46.01% inhibition). Conclusions: The findings of present study would be benevolent for antifungal drug development to control Fusariumconcentricum causing fruit and vegetable rot.