Experimental and theoretical observations of alkylated EOSIN based “turn-on” superoxide sensor as well as its anti-microbial study

The alkylating as well as alkoxylating behavior of dialkyl sulfites are well presented in the literature. In the present work dialkyl sulphites behavior has been investigated towards EOSIN Y (tetrabrominated fluorescein). The products of the reactions (dialkylated eosin Y) reveal that alkylation takes place at the both active sites (at hydroxyl and carboxyl functionalities) in a single step through sulphur-centred Arbuzov type rearrangement. Density functional theory (DFT) has been used as a tool to analyze the role of the halogen groups present at the periphery of the xanthene moiety in alkylation at hydroxyl and carboxy positions of EOSIN Y. Furthermore, in photo-physical study, it was observed that compound C acts as a superoxide sensor specifically with the detection limit 63μM. Its anti-microbial activity was checked against the E. coli and S-aureus using the agar well diffusion assay and, it was observed that it could be used as better antimicrobial agent.

Bacteria Are New Targets for Inhibitors of Human Farnesyltransferase

Farnesyltransferase inhibitors (FTIs) are focus for the treatment of several diseases, particularly in the field of cancer therapy. Their potential, however, goes even further, as a number of studies have evaluated FTIs for the treatment of infectious diseases such as malaria, African sleeping sickness, leishmaniosis, and hepatitis D virus infection. Little is known about protein prenylation mechanisms in human pathogens. However, disruption of IspA, a gene encoding the geranyltranstransferase of Staphylococcus aureus (S. aureus) leads to reprogramming of cellular behavior as well as impaired growth and decreased resistance to cell wall-targeting antibiotics. We used an agar well diffusion assay and a time kill assay and determined the minimum inhibitory concentrations of the FTIs lonafarnib and tipifarnib. Additionally, we conducted cell viability assays. We aimed to characterize the effect of these FTIs on S. aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis (S. epidermidis), Escherichia coli (E. coli), Enterococcus faecium (E. faecium), Klebsiella pneumoniae (K. pneumoniae), Pseudomonas aeruginosa (P. aeruginosa), and Streptococcus pneumoniae (S. pneumoniae). Both the FTIs lonafarnib and tipifarnib were capable of inhibiting the growth of the Gram-positive bacteria S. aureus, MRSA, S. epidermidis, and S. pneumoniae, whereas no effect was observed on Gram-negative bacteria. The analysis of the impact of lonafarnib and tipifarnib on common human pathogens might lead to novel insights into their defense mechanisms and therefore provide new therapeutic targets for antibiotic-resistant bacterial infections.

Bis-Thiourea Quaternary Ammonium Salts as Potential Agents against Bacterial Strains from Food and Environmental Matrices

In recent years, the phenomenon of antibiotic resistance in hospitals, communities and the environment has increasingly grown, so antibiotic resistance has become an urgent problem that requires a decisive and global intervention. Incorrect/unnecessary use of antibiotics contributes to increase the ability of microorganisms to develop resistance faster and faster. Research efforts must, therefore, be made to ensure a future in which antibiotic drugs will still be useful in combating infectious diseases. The search for new antibacterial compounds is fundamental. In this study, the antimicrobial activity of the compounds was evaluated against selected bacterial strains from food and environmental matrices by using the Agar Well Diffusion Assay. A total of thirty-six Gram-positive and Gram-negative bacteria were employed to determine the action spectrum and the antimicrobial effectiveness of a small series of thiourea derivatives. Results showed that the highest activities were found for compounds 1 and 4. The important role of the alkyl chain length and/or guanidine moiety in the width of action spectrum was evidenced. Further studies will allow evaluating the efficacy of the inhibiting action and the molecular mechanisms underlying this activity in order to identify compounds capable of counteracting the phenomenon of antibiotic resistance and to identify possible future applications of these newly synthesized compounds that have shown a high bactericidal action potential.

Lactic acid bacterial bacteriocins and their bioactive properties against food-associated antibiotic-resistant bacteria

Purpose Incidence of foodborne diseases and growing resistance of pathogens to classical antibiotics is a major concern in the food industry. Consequently, there is increasing demand for safe foods with fewer chemical additives but natural products which are not harmful to the consumers. Bacteriocins, produced by lactic acid bacteria (LAB), is of interest because they are active in a nanomolar range, do not have toxic effects, and are readily available in fermented food products. Methods In this research, LAB were isolated from fufu, gari, kunu, nono, and ogi using De Mann, Rogosa, and Sharpe agar. Cell-free supernatants were prepared from 18-24 h LAB culture grown on MRS broth. Effect of organic acid was eliminated by adjusting the pH of the supernatants to 7.0 with 1M NaOH while the effect of hydrogen peroxide was eliminated by treating with Catalase enzyme. The supernatant was then filter-sterilized using a membrane filtration unit with a 0.2-μm pore size millipore filter and subjected to agar well diffusion assay against foodborne antibiotic-resistant bacteria. Result A total of 162 isolates were obtained from the food samples. The antimicrobial sensitivity test yielded positive results for 45 LAB isolates against Staphylococcus aureus ATCC 25923 while 52 LAB isolates inhibited Escherichia coli ATCC 25922. On confirmation of the bacteriocinogenic nature of the inhibitory substance, 4 of the LAB isolates displayed a remarkable degree of inhibition to Leuconostoc mesenteroides, Salmonella typhimurium, and Bacillus cereus. Agar well diffusion assay was also performed against antibiotic-resistant foodborne pathogens using the cell-free supernatant (CFS) obtained from Lactobacillus fermentum strain NBRC15885 (Limosilactobacillus fermentum), Lactobacillus fermentum strain CIP102980 (Limosilactobacillus fermentum), Lactobacillus plantarum strain JCM1149 (Lactiplantibacillus garii), and Lactobacillus natensis strain LP33 (Companilactobacillus nantensis). The foodborne pathogens exhibited a notable level of resistance to antibiotics, with B. cereus exhibiting a resistance profile of 40%, S. aureus (50%), K. pnuemoniae (70%), E. coli (60%), and S. typhi (40%). The (CFS) was able to inhibit the growth of B. cereus, Klebsiella pneumonia, S. typhimurium, S. aureus, and E. coli. Conclusion Therefore, it portends that the bacteriocins produced by the LAB isolated from these food products could act as probiotics for effective inhibition of the growth of antibiotic-resistant foodborne pathogens.

Insight Into the Beneficial Role of Lactiplantibacillus plantarum Supernatant Against Bacterial Infections, Oxidative Stress, and Wound Healing in A549 Cells and BALB/c Mice

Lactiplantibacillus plantarum MTCC 2621 is a well-characterized probiotic strain and is reported to possess many health benefits. However, the wound healing potential of this probiotic is yet to be explored. Here, we have assessed the antibacterial, antioxidant, and wound healing activities of cell-free supernatant of Lactiplantibacillus plantarum MTCC 2621 (Lp2621). Lp2621 exhibited excellent antibacterial activity against the indicator bacteria in the agar well diffusion assay. Lp2621 did not show any hemolytic activity. The safety of Lp2621 gel was established using the skin irritation assay in BALB/c mice, and no dermal reactions were observed. The supernatant showed 60–100% protection of A549 cells against H2O2-induced stress. In the scratch assay, Lp2621 accelerated wound healing after 24 h of treatment. The percent wound healing was significantly higher in cells treated with Lp2621 at 18–24 h posttreatment. In an excision wound healing in mice, topical application of Lp2621 gel showed faster healing than the vehicle- and betadine-treated groups. Similar wound healing activity was observed in wounds infected with Staphylococcus aureus. Histological examination revealed better wound healing in Lp2621-treated mice. Topical treatment of the wounds with Lp2621 gel resulted in the upregulation of pro-inflammatory cytokine IL-6 in the early phase of wound healing and enhanced IL-10 expression in the later phase. These findings unveil a protective role of Lp2621 against bacterial infection, oxidative stress, and wound healing.

The synthesis, antimicrobial activity and docking studies of 6-(1H-benzimidazol-2-yl)-5-methylthieno[2,3-d]pyrimidin- 4(3H)-ones with acetamide and 1,2,4-oxadiazol-5-ylmethyl substituents

Aim. To synthesize, study the antimicrobial activity and suggest antimicrobial activity mechanism for the novel derivatives of 6-(1H-benzimidazol-2-yl)-5-methylthieno[2,3-d]pyrimidin-4(3H)-one. Results and discussion. As the result of the targeted modification of 6-(1H-benzimidazol-2-yl)-5-methylthieno[2,3-d]-pyrimidin-4(3H)-one in position 3 with acetamide and 1,2,4-oxadiazol-5-ylmethyl substituents, the compounds, which demonstrated better antimicrobial activity in the agar well diffusion assay than the reference drug Streptomycin, were obtained. To elucidate the mechanism of action of the novel compounds, the docking studies were con-ducted to the active site of the 16S subunit of ribosomal RNA, the proven target for aminoglycoside antibiotics, as well as tRNA (Guanine37-N1)-methyltransferase (TrmD), which inhibitors were considered as a new potential class of antibiotics. Experimental part. By the interaction of 6-(1H-benzimidazol-2-yl)-5-methylthieno[2,3-d]pyrimidin-4(3H)-one with a series of N-arylchloroacetamides and 3-aryl-5-(chloromethyl)-1,2,4-oxadiazoles in DMF in the presence of K2CO3 the target compounds were obtained. The antimicrobial activity was assessed by the agar well diffusion method. The concentration of microbial cells was determined by the McFarland standard; the value was 107 cells in 1 mL of the media. The 18 – 24 hour culture of microorganisms was used for tests. For the bacteria cultivation, Müller-Hinton agar was used, Sabouraud agar was applied for C. albicans cultivation. The compounds were tested as the DMSO solution with the concentration of 100 µg/mL; the volume of the solution was 0.3 mL, the same volume was used for Streptomycin (the concentration 30 µg/mL). The docking studies were performed using Autodock Vina. Crystallographic data for the complexes of Streptomycin with the 16S subunit of ribosomal RNA (1NTB) and its active site, as well as for tRNA (Guanine37-N1)-methyltransferase (EC 2.1.1.228; TrmD) (5ZHN) and its active site were obtained from the Protein Data Bank.Conclusions. It has been determined that 2-[6-(1H-benzimidazol-2-yl)-5-methyl-4-oxothieno[2,3-d]pyrimidin-3(4H)-yl]-N-[4-(ethoxy)phenyl]acetamide, which is the most active as an antimicrobial agent among the compounds tested, also shows the best binding activity towards the active site of tRNA (guanine37-N1)-methyltransferase.

Preparation of Nanostructured Lipid Carriers (NLCs) Loading Violacein Extract for Anti-Acne Products

The objective of this research is to evaluate the antimicrobial activity of Nanostructured Lipid Carriers (NLCs) loading violacein extract. The extract was tested for the antimicrobial activities against 3 strains of pathogenic bacteria; namely Cutibacterium acnes ATCC 6919, Staphylococcus aureus ATCC 6538 and Staphylococcus epidermidis ATCC 12228 by agar well diffusion assay. The result indicated that the violacein extract from Chromobacterium violaceum ATCC 12472 has strongest antibacterial effect against C. acnes, S. aureus and S. epidermidis with MIC values in range of 0.0146-0.4688 mg/mL with the lowest MBC value of 0.0146 mg/mL against C. acnes. Violacein extract loaded Nanostructured Lipid Carriers (NLCs) for anti-acne products were prepared by using melt-emulsification technique. The studied factors are the ratio of liquid lipid and solid lipid (LL:SL), surfactant concentration and sonication time. The Ratio of Oleic acid and Compritol® 888 ATO (3:1) with Tween 20 (1.5% w/w) and sonication time of 10 minute (F8 formulation) are an optimizing condition for NLC-Base. The resulted formulations showed the NLC-Base had average particle size of 213.7±2.42 nm with a polydispersity index of 0.239±0.003 and Zeta potential of -26.6±0.45 mV. After that, violacein extract (2% w/w) was loaded into the NLCs (VIO-NLCs). Antibacterial activity of VIO-NLCs 2 % was determined by using agar dilution. The result showed that VIO-NLCs 2 % can inhibit the growth of C. acnes for 60 days during storage. Furthermore, VIO-NLCs 2 % can also act as S. aureus and S. epidermidis inhibitor within 30 days shelf life.

Initial Evaluation of Antioxidant and Antibacterial Activities of Medicinal Plant Extracts in Vietnam

The diversity of medicinal plants in Vietnam is a rich source to develop novel health products. This study evaluated the antioxidant and antimicrobial activities of ethanolic extracts of Pluchea indica, Drynaria fortunei, Stephania glabra, lemongrass and lime mixture, and ginger and kumquat mixture. The extract of ginger and kumquat mixture showed the highest percentage of free radical scavenging (85% at the concentration of 0.1 mg/ml), following by the extract of P. indica leaves and stem (60%). The plant extracts displayed antibacterial activity against Bacillus cereus, Staphylococcus aureus, and Vibrio parahaemolyticus at different levels in the agar well diffusion assay. The extract of S. glabra inhibited the growth of all bacterial strains. The mean of inhibition zone diameter, produced by S. glabra extract, was similar to or even significantly higher than that of control at particular concentrations.

Compounds from Vernonia arborea Buch.-Ham. Inhibit Microbes that Impair Wound Healing

Aims: To identify the antimicrobial potency of the leaf fractions of Vernonia arborea against selected wound microbes viz., Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Stenotrophomonas maltophilia. Background: Wound healing is often delayed due to the presence of polymicrobial load, that have to be abolished to facilitate the healing process. A major class of antimicrobial phytocompound reported to occur in Vernonia arborea species include sesquiterpenes. Reports on the wound healing potency of V. arborea in wound models of Wistar rats however did not report antimicrobial activity of the aqueous or methanolic extracts. Methodology: The column fractions of the hexane leaf extract were tested against the selected strains by agar well diffusion assay and the zone of inhibition confirmed with TLC bioautography at specific Rf. The minimum inhibitory concentration (MIC) of the bioactive fractions was identified using resazurin microtiter assay (REMA) and the minimum bactericidal concentration (MBC) was determined. HPTLC quantification was also performed. Results: Out of the 30 pooled fractions, six showed antimicrobial potency against all the five tested wound microbes. The minimum inhibitory concentrations of these fractions were determined, ranging from 15.62 µg/mL to 500 µg/mL for the different microbes. Quantitative High-Performance Thin Layer Chromatography (HPTLC) revealed two compounds (a and b) in the bioactive fraction10 with yields of 633 mg (63%) and 97 mg (9.7%) per gram of the extract. Conclusion: The findings suggest the potential use of the bioactive compound in chronic infectious wound management therapy.

Evaluation of antibacterial potentials of Parthenium hysterophorus L. leaf extract against some pathogenic and nonpathogenic bacteria

Background: The herb, P. hysterophorus L. has been used in folk medicine for many years to treat neurological disorders, inflammation, fever and malaria. This study aimed to evaluate the antibacterial activity of P. hysterophorus L. leaf extracts against some pathogenic and nonpathogenic bacterial strains. Methods: Methanol and chloroform extracts of P. hysterophorus L. leaf were applied against pathogenic Vibrio (V.) parahaemolyticus ATCC 17802, Escherichia coli 0157 ATCC 43894, Sarcina (S.) lutea IFO 3232) and nonpathogenic Bacillus (B.) subtilis IFO 3026 strains by agar well diffusion assay. Visible zones of inhibition were measured. Results: The methanol and chloroform extracts of P. hysterophorus leaf exhibited remarkable antibacterial activity against all three pathogenic (V. parahaemolyticus, E. coli 0157, S. lutea) and nonpathogenic (B. subtilis) bacterial strains. Chloroform solvent extract of P. hysterophorus leaves showed highest zone of inhibition (23 mm) against gram positive pathogenic S. lutea and methanolic leaf extract showed highest zone of inhibition (26 mm) against B. subtilis. The lowest zone of inhibition was observed for gram negative pathogenic V. parahaemolyticus in the response of methanolic (9 mm) and the chloroform (10mm) leaf extract. Conclusion: The findings of this study suggest that, leaf extracts of Parthenium hysterophorus L. could be a potential source of antibacterial agents to cope with antibiotic resistance and new drug discovery.