Inhibition of Monilinia fructicola sporulation and pathogenicity through eucalyptol-mediated targeting of MfCat2 by Streptomyces lincolnensis strain JCP1-7.

Peach brown rot, attributed to Monilinia fructicola, presents a significant threat to postharvest peach cultivation, causing losses of up to 80%. With an increasing number of countries, spearheaded by the European Union, imposing bans on chemical agents in fruit production, there is a growing interest in mining highly active antibacterial compounds from biological control strains for postharvest disease management. In this study, we highlight the unique ability of Streptomyces lincolnensis strain JCP1-7 to inhibit M. fructicola sporulation, despite its limited antimicrobial efficacy. Through GC-MS analysis, eucalyptol was identified as the key compound. Fumigation of diseased fruits with eucalyptol at a concentration of 0.0335 µg cm-3 demonstrated an in vivo inhibition rate against M. fructicola of 93.13%, completely suppressing spore formation. Transcriptome analysis revealed the impact of eucalyptol on multiple pathogenesis-related pathways, particularly through the inhibition of catalase 2 (Cat2) expression. Experiments with a MfCat2 knockout strain (ΔMfCat2) showed reduced pathogenicity and sensitivity to JCP1-7 and eucalyptol, suggesting MfCat2 as a potential target of JCP1-7 and eucalyptol against M. fructicola. Our findings elucidate that eucalyptol produced by S. lincolnensis JCP1-7 inhibits M. fructicola sporulation by regulating MfCat2, thereby effectively reducing postharvest peach brown rot occurrence. The use of fumigation of eucalyptol offers insights into peach brown rot management on a large scale, thus making a significant contribution to agricultural research.

Antibacterial Meroterpenoids, Merochlorins G-J from the Marine Bacterium Streptomyces sp.

Four new chlorinated meroterpenoids, merochlorins G-J (1-4), and 10, a dihydronaphthalenedione precursor, along with known merochlorins A (5) and C-F (6-9), were obtained from cultivation of the bacterium strain Streptomyces sp. CNH-189, which was isolated from marine sediment. The planar structures of compounds 1-4 and 10 were elucidated by interpretation of MS, UV, and NMR spectroscopic data. The relative configurations of compounds 1-4 were determined via analysis of nuclear Overhauser effect (NOE) spectroscopic data, after which their absolute configurations were established by comparing the experimental electronic circular dichroism (ECD) spectra of compounds 1-4 to those of previously reported possible enantiomer models and DP4 calculations. Compound 3 displayed strong antibacterial activities against Bacillus subtilis, Kocuria rhizophila, and Staphylococcus aureus, with MIC values of 1, 2, and 2 µg/mL, respectively, whereas compound 1 exhibited weak antibacterial effects on these three strains, with a 16-32 µg/mL MIC value range.

Discovery and evaluation on the antibacterial and cytotoxic activities of a novel antifungalmycin N2 produced from Streptomyces sp. strain N2.

Antifungalmycin N2 (3-methyl-3,5-amino-4-vinyl-2-pyrone, C6H7O2N) was a novel metabolite produced from Streptomyces sp. strain N2, and the present study aimed to evaluate its antibacterial and cytotoxic properties. By using Oxford cup method, the obtained results revealed that antifungalmycin N2 exhibited a significant antibacterial activity against the pathogenic bacteria such as Staphylococcus aureus, Escherichia coli, and Micrococcus kristinae, especially the Gram-positive S. aureus. Meanwhile, the MTT assay showed that antifungalmycin N2 could exert a marked inhibitory action on tumor cell lines, such as the cell lines of BEL-7402 (human hepatocellular carcinoma), Hela (human cervical carcinoma), HCT116 (human colon cancer), and SW620 (human colon cancer). And the IC50 values antifungalmycin N2 against the above cell lines ranged from 11.23 to 15.37 µg/mL. In conclusion, the antibacterial and cytotoxic activities suggested that the novel antifungalmycin N2 was a promising active structure to be developed as new drug for treating infectious diseases and cancers.

Half of 'Micrococcus spp.' cases identified by conventional methods are revealed as other life-threatening bacteria with different drug susceptibility patterns by 16S ribosomal RNA gene sequencing.

Bacterial infection during chemotherapy is a fatal complication, therefore precise identification of the pathogenic microorganism is required for treatment. We report that 2 of 4 pediatric patients with malignancy who were diagnosed with Micrococcus spp. infection by conventional methods were finally revealed to have Kytococcus schroeteri and Kocuria marina infection by 16S ribosomal RNA gene sequence analysis (16S rRNA analysis). Although K. schroeteri is morphologically similar to Micrococcus spp., its drug susceptibility profile is quite different from that of Micrococcus spp. K. schroeteri is resistant to penicillin and cephalosporin, which are effective for Micrococcus spp. In fact, penicillin-resistant lethal pneumonia caused by K. schroeteri has been reported in compromised hosts. Based on our results, Micrococcus spp. determined by conventional methods could contain other life-threatening bacteria with different drug susceptibility patterns from Micrococcus spp. To develop an effective empirical treatment for immunocompromised hosts, accumulation of pathogen data by 16S rRNA analysis is required.

Fermentation conditions optimization, purification, and antioxidant activity of exopolysaccharides obtained from the plant growth-promoting endophytic actinobacterium Glutamicibacter halophytocola KLBMP 5180.

In this study, an endophytic actinobacterium Glutamicibacter halophytocola KLBMP 5180, was investigated for the production and antioxidant activity of exopolysaccharides (EPSs). First, the suitable fermentation time, temperature, inoculation volume, pH value, and the carbon and nitrogen sources for EPSs production were obtained using the one variable at a time method (OVAT). Then, a central composition design was used for fermentation conditions optimization to obtain the maximum EPS yield. The optimal medium and condition were as follows: 100 mL broth in 250 mL Erlenmeyer flasks, including 3.65 g/L maltose, 9.88 g/L malt extract, 3.40 g/L yeast extract, 1.41 g/L MnCl2, pH 7.5, culture temperature 28 °C, and 200 rpm for 7 days, which increased the yield of EPSs to 2.89 g/L. Two purified EPSs, 5180EPS-1 (MW 58.9 kDa) and 5180EPS-2 (10.5 kDa), comprising rhamnose, galacturonic acid, glucose, glucuronic acid, xylose, and arabinose, were obtained for chemical analysis and antioxidant evaluation. The scavenging ability and reducing power of the superoxide anion and hydroxyl radicals demonstrated the moderate in vitro antioxidant activities of the two EPSs, thus indicating their potential to be a new source of natural antioxidants. However, further structure elucidation and functional studies need to be continued.

Benzophenone Compounds, from a Marine-Derived Strain of the Fungus Pestalotiopsis neglecta, Inhibit Proliferation of Pancreatic Cancer Cells by Targeting the MEK/ERK Pathway.

Pancreatic cancer, which has an extremely poor prognosis, is one of the most fatal human cancers. Chemotherapy is the main palliative treatment for advanced cancer patients and also plays an indispensable role in postoperative treatments for surgical patients. Therefore, there is an urgent need to develop more innovative anticancer drugs to fight against this fatal disease. Here, we investigate the potential of benzophenone derivatives, obtained from a marine-derived strain of the fungus Pestalotiopsis neglecta, as antiproliferative lead compounds for the treatment of pancreatic cancer. The compounds, seven new (1-7) and two known (8 and 9) halogenated benzophenone derivatives, were obtained by bioactivity-guided fractionation from the cultures of Pestalotiopsis neglecta. The structures were defined by spectroscopic methods including X-ray crystallographic analysis. Using the commonly used pancreatic cancer cell line PANC-1, 2 and 4 were found to suppress cell proliferation and induce apoptosis in the low micromolar range of 7.6 and 7.2 µM, respectively. Mechanistically, benzophenone derivatives not only inhibit MEK activity in the cytoplasm but also suppress ERK activity in the cytoplasm and nucleus. An in silico study suggests that benzophenone derivatives could potentially inhibit MEK activity by binding to the allosteric pocket in MEK. Benzophenones could serve as new lead compounds for the treatment of pancreatic cancer.

Kocuria kristinae: an emerging pathogen in medical practice.

Introduction. Kocuria kristinae is becoming a growing public health challenge, especially for its ability to cause infections in immunocompromised patients. This bacterium is a Gram+coccus, catalase+, coagulase, and it is a common inhabitant of skin and oral mucosa.Aim. To investigate the spectrum of infections caused by K. K ristinae.Methodology. Between January-March 2018, we carried out a systematic search in PubMed utilizing the key search term 'Kocuria kristinae'. The selection criteria for studies were studies reporting cases of human infections due to K. kristinae, case-control and cohort studies and studies published in English or Spanish.Results. The literature search yielded 48 publications: after title, abstract and full-text analysis, 20 papers were consistent with the selection criteria. These studies were carried out in the period 2001-2017 in the USA, Japan, Taiwan, Hong Kong, Ukraine, Egypt, Bahrain, Serbia, India, Italy, Spain, Turkey and Mexico. K. kristinae was involved in 17 cases of central venous catheter-related bacteremia, four infective endocarditis, three acute peritonitis, one abdominal abscess, umbilical sepsis, acute cholecystitis and urinary tract infection. Additionally, K. kristinae was found in 40 % of carious cavities, although it is not clear whether they are directly involved in the development of caries. Antibiotic susceptibility testing has sometimes revealed multi-drug resistance.Conclusions. The clinical spectrum of K. kristinae infections has recently widened. The increasing spread of this underestimated bacterium and its resistance to antibiotics represent a new challenge for public health, which requires specific actions to limit it.

Mycousfurans A and B, Antibacterial Usnic Acid Congeners from the Fungus Mycosphaerella sp., Isolated from a Marine Sediment.

Mycousfurans (1 and 2), two new usnic acid congeners, along with (-)-mycousnine (3), (-)-placodiolic acid (4), and (+)-usnic acid (5), were isolated using high-performance liquid chromatography-ultraviolet (HPLC-UV)-guided fractionation of extracts of Mycosphaerella sp. isolated from a marine sediment. The planar structures of 1 and 2 were elucidated using 1D and 2D NMR spectra. The relative configurations of the stereogenic carbons of 1 and 2 were established via analysis of their nuclear Overhauser spectroscopy (NOESY) spectra, and their absolute configurations were determined using a comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compounds 1 and 2 were found to have antibacterial activity, showing moderate activity against Kocuria rhizophila and Staphylococcus aureus.

Variation in Streptomycin Resistance Mechanisms in Clavibacter michiganensis.

Clavibacter michiganensis is the causal agent of bacterial canker of tomato, which causes significant economic losses because of the lack of resistant tomato varieties. Chemical control with streptomycin or cupric bactericides is the last defensive line in canker disease management. Streptomycin is an aminoglycoside antibiotic that inhibits protein synthesis and targets the 30S ribosomal protein RpsL. Streptomycin has been used to control multiple plant bacterial diseases. However, identification and characterization of streptomycin resistance in C. michiganensis have remained unexplored. In this study, a naturally occurring C. michiganensis strain TX-0702 exhibiting spontaneous streptomycin resistance was identified, with a minimum inhibitory concentration of 128 µg/ml. Additionally, an induced streptomycin-resistant strain BT-0505-R was generated by experimental evolution of the sensitive C. michiganensis strain BT-0505. Genome sequencing and functional analyses were used to identify the genes conferring resistance. A point mutation at the 128th nucleotide in the rpsL gene of strain BT-0505-R is responsible for conferring streptomycin resistance. However, in TX-0702, resistance is not attributed to mutation of rpsL, streptomycin inactivation enzymes, or multidrug efflux pumps. The mechanism of resistance in TX-0702 is independent of previously reported bacterial loci. Taken together, these data highlight diverse mechanisms used by a Gram-positive plant pathogenic bacterium to confer antibiotic resistance.

Characterization and mode of action of a potent bio-preservative from food-grade Bacillus licheniformis MCC 2016.

The antibacterial peptide of Bacillus licheniformis MCC 2016 have potential biopreservative efficacy. Here, we report the purification process, properties, and mode of action of this antibacterial peptide for its potential application in the food industry. The antibacterial peptide from the cell-free supernatant was purified using a sequence of purification steps. The purified antibacterial peptide showed a specific activity of 68817 AU mg-1 and 0.4% yield. Liquid chromatography-mass spectroscopy analysis showed an mz-1 value of 279.28 for the active peptide. The SDS-PAGE analysis confirmed the antibacterial peptide is low-molecular weight and the size is between 3.0 and 3.5 kDa. Scanning electron microscopy, Fourier transform infrared spectroscopy, ß-gal induction assay and release of UV-absorbing materials indicated that the antibacterial peptide targets the cell wall of pathogens. Minimum inhibitory concentration of the antibacterial peptide against Listeria monocytogenes Scott A and others (Kocuria rhizophila ATCC 9341, Staphylococcus aureus FRI 722 and Salmonella typhimurium MTCC 1251) was found to be 1600 and 800 AU mL-1, respectively. The antibacterial peptide is temperature and pH stable, proteolytic-enzyme-sensitive, low-molecular weight, cell wall active class I bacteriocin and exhibits remarkable antibacterial activity against pathogens, suggesting its application as a potential biopreservative in the food industry.

Antimicrobial treatment of Kocuria kristinae invasive infections: Systematic review.

Objective of this systematic review was to establish whether and what invasive infections in humans were caused by Kocuria kristinae, and to evaluate outcomes of administered antibiotic treatment. MEDLINE, EBSCO, SCOPUS, SCINDEKS and GOOGLE SCHOLAR were systematically searched for primary case reports or case series describing invasive infections with K. kristinae. K. kristinae is a pathogen microorganism that could cause invasive infections of various tissues in patients of any age. Majority of the patients had K. kristinae isolated from blood. It was also found in peritoneal fluid, pus, sputum, synovial fluid, bile, fluid from abdominal abscess, throat swab, urine catheter tip and mid-stream urine. Antibiotic treatment was almost universally effective, with only one death reported. Susceptibility was highest to vancomycin, linezolid, rifampicin, teicoplanin, tigecycline, cefotaxime, ampicillin/sulbactam, minocycline and meropenem. Initial treatment of Kocuria kristinae infections should involve parenteral vancomycin in combination with some other antibiotic to which it is susceptible.

Variability in nitrate-reducing oral bacteria and nitric oxide metabolites in biological fluids following dietary nitrate administration: An assessment of the critical difference.

There is conflicting evidence on whether dietary nitrate supplementation can improve exercise performance. This may arise from the complex nature of nitric oxide (NO) metabolism which causes substantial inter-individual variability, within-person biological variation (CVB), and analytical imprecision (CVA) in experimental endpoints. However, no study has quantified the CVA and CVB of NO metabolites or the factors that influence their production. These data are important to calculate the critical difference (CD), defined as the smallest difference between sequential measurements required to signify a true change. The main aim of the study was to evaluate the CVB, CVA, and CD for markers of NO availability (nitrate and nitrite) in plasma and saliva before and after the ingestion of nitrate-rich beetroot juice (BR). We also assessed the CVB of nitrate-reducing bacteria from the dorsal surface of the tongue. It was hypothesised that there would be substantial CVB in markers of NO availability and the abundance of nitrate-reducing bacteria. Ten healthy male participants (age 25 ±â€¯5 years) completed three identical trials at least 6 days apart. Blood and saliva were collected before and after (2, 2.5 and 3 h) ingestion of 140 ml of BR (∼12.4 mmol nitrate) and analysed for [nitrate] and [nitrite]. The tongue was scraped and the abundance of nitrate-reducing bacterial species were analysed using 16S rRNA next generation sequencing. There was substantial CVB for baseline concentrations of plasma (nitrate 11.9%, nitrite 9.0%) and salivary (nitrate 15.3%, nitrite 32.5%) NO markers. Following BR ingestion, the CVB for nitrate (plasma 3.8%, saliva 12.0%) and salivary nitrite (24.5%) were lower than baseline, but higher for plasma nitrite (18.6%). The CD thresholds that need to be exceeded to ensure a meaningful change from baseline are 25, 19, 37, and 87% for plasma nitrate, plasma nitrite, salivary nitrate, and salivary nitrite, respectively. The CVB for selected nitrate-reducing bacteria detected were: Prevotella melaninogenica (37%), Veillonella dispar (35%), Haemophilus parainfluenzae (79%), Neisseria subflava (70%), Veillonella parvula (43%), Rothia mucilaginosa (60%), and Rothia dentocariosa (132%). There is profound CVB in the abundance of nitrate-reducing bacteria on the tongue and the concentration of NO markers in human saliva and plasma. Where these parameters are of interest following experimental intervention, the CD values presented in this study will allow researchers to interpret the meaningfulness of the magnitude of the change from baseline.

Consistency evaluation between matrix components ratio and microbiological potency of tylosin major components.

BACKGROUND: The aim of our research work was to investigate the relative potencies of matrix components of tylosin, a multi-component antibiotic, and establishing a quantitative relationship between content and potency of each component. METHODS: The potencies of tylosin matrix components were determined by using three bioassay methods. The content of tylosin components (tylosin A, B, C, and D) in different tylosin samples were determined by using high pressure liquid chromatography (HPLC) technique and their theoretical potencies were calculated. Equivalency of theoretical and microbiological potencies for each sample was evaluated using statistical analysis. RESULTS: The highest amount of tylosin B content was found in tylosin phosphate and tartrate (up to 19%). Tylosin D content in all tylosin samples varied in the range of 0.03 to 18.73%. Tylosin A, B, and C showed similar sensitivity to the Kocuria rhizophila, the test organism in agar-diffusion method, while the potency of tylosin D was 39% of A. In the turbidimetric methods by Staphylococcus aureus, tylosin D and B responses to A component were ranged from 22.5 to 22.8% and 77.3 to 79.3%, respectively, while potencies of tylosin C and A were almost equal. The biopotency conversion factors were not resulted to a single factor, due to the different antibacterial activity of tylosin components. CONCLUSION: Our findings indicated that defining individual limit for the low active matrix components and for the total of other components with similar high activity could improve the accuracy of potency results. Graphical abstract ᅟ.

Study of marine bacteria inactivation by photochemical processes: disinfection kinetics and growth modeling after treatment.

The importance of seawater treatment in order to avoid microbiological pollution related to aquaculture or ballast water management has increased during the last few years. Bacterial indicators used for the evaluation of different disinfection treatments are usually related with both waste and drinking water, these standards are not usual microorganisms found in seawater. Thus, it is thought necessary to study the behavior of different marine-specific organisms in regard to improve the disinfection processes in seawater. In this study, three different bacteria have been selected among major groups of bacterial community from marine waters: two water-associated, Roseobacter sp. and Pseudomonas litoralis, and one sediment-associated, Kocuria rhizophila. A kinetic inactivation model together with a post-treatment growth tendency has been obtained after the application of UV-C and UV/H2O2 processes. According to the first kinetic rate constant, different responses were obtained for the different bacterial groups. Once the treatment was applied, modeling of growth curves revealed high recover within the first 3 days after treatment, even when UV/H2O2 was applied. This study introduces a sensitivity index, in which results show different levels of resistance for both treatments, being Roseobacter sp. the most sensitive bacteria, followed by P. litoralis and K. rhizophila.

Hexavalent chromium reduction potential of Cellulosimicrobium sp. isolated from common effluent treatment plant of tannery industries.

Present study deals with the isolation and characterization of a bacterium capable for the effective reduction of Cr(VI) from tannery wastewater. Based on the 16S rRNA gene sequence analysis, this bacterium was identified as Cellulosimicrobium sp. (KX710177). During the Cr(VI) reduction experiment performed at 50, 100, 200,and 300mg/L of Cr(VI) concentrations, the bacterium showed 99.33% and 96.98% reduction at 50 and 100mg/L at 24 and 96h, respectively. However, at 200 and 300mg/L concentration of Cr(VI), only 84.62% and 62.28% reduction was achieved after 96h, respectively. The SEM analysis revealed that bacterial cells exposed to Cr(VI) showed increased cell size in comparison to unexposed cells, which might be due to either the precipitation or adsorption of reduced Cr(III) on bacterial cells. Further, the Energy Dispersive X-ray (EDX) analysis showed some chromium peaks for cells exposed to Cr(VI), which might be either due to the presence of precipitated reduced Cr(III) on cells or complexation of Cr(III) with cell surface molecules. The bacterium also showed resistance and sensitivity against the tested antibiotics with a wide range of MIC values ranging from 250 to 800mg/L for different heavy metals. Thus, this multi-drug and multi-metal resistant bacterium can be used as a potential agent for the effective bioremediation of metal contaminated sites.

In Vitro Antibacterial Activity of Pomegranate Juice and Peel Extracts on Cariogenic Bacteria.

AIM: To evaluate the antimicrobial activity of hydroalcoholic extracts of pomegranate (Punica granatum L.) peel and juice, against the microorganisms considered the main etiologic agents of dental caries. METHODS: The values of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined against Streptococcus mutans Clarke ATCC® 25175™ strain and Rothia dentocariosa clinical isolate. RESULTS: Peel extracts inhibit effectively the growth and survival of S. mutans ATCC 25175 strain and R. dentocariosa clinical isolate with MIC and MBC values of 10 µg/µl and 15 µg/µl, respectively. Furthermore, the pomegranate juice extract showed high inhibitory activity against S. mutans ATCC 25175 strain with a MIC value of 25 µg/µl and a MBC value of 40 µg/µl, whereas, against R. dentocariosa, it has displayed a moderate inhibitory activity, with MIC and MBC values of 20 µg/µl and 140 µg/µl, respectively. CONCLUSIONS: In vitro microbiological tests demonstrate that the hydroalcoholic extracts of pomegranate juice and peel are able to contrast the main cariogenic bacteria involved in tooth decay. Although being preliminary data, our results suggest that pomegranate polyphenolic compounds could represent a good adjuvant for the prevention and treatment of dental caries.

1-Methoxypyrrole-2-carboxamide-A new pyrrole compound isolated from Streptomyces griseocarneus SWW368.

A new pyrrole compound, 1-methoxypyrrole-2-carboxamide, was obtained from a culture broth of Streptomyces griseocarneus SWW368, which was isolated from the rhizospheric soil under a Para rubber tree (Hevea brasiliensis). The chemical structure was elucidated by 1D NMR, 2D NMR, and MS, as a pyrrole ring with a N-methoxy group and a primary amide group. It exhibited antibacterial properties against Kocuria rhizophila, Staphylococcus aureus and Xanthomonas campestris pv. oryzae; however, cytotoxicity of the compound at 714 µM against several mammalian tumor cell lines, i.e. A549, PANC1, HT29, HT1299 and HeLa S3, were not detected.

Volatile organic compounds produced by a soil-isolate, Bacillus subtilis FA26 induce adverse ultra-structural changes to the cells of Clavibacter michiganensis ssp. sepedonicus, the causal agent of bacterial ring rot of potato.

Rhizobacterial volatile organic compounds (VOCs) play an important role in the suppression of soil-borne phytopathogens. In this study, the VOCs produced by a soil-isolate, Bacillus subtilis FA26, were evaluated in vitro for their antibacterial activity against Clavibacter michiganensis ssp. sepedonicus (Cms), the causal agent of bacterial ring rot of potato. The VOCs emitted by FA26 inhibited the growth of Cms significantly compared with the control. Scanning and transmission electron microscopy analyses revealed distorted colony morphology and a wide range of abnormalities in Cms cells exposed to the VOCs of FA26. Varying the inoculation strategy and inoculum size showed that the production and activity of the antibacterial VOCs of FA26 were dependent on the culture conditions. Headspace solid-phase microextraction/gas chromatography-mass spectrometry analyses revealed that FA26 produced 11 VOCs. Four VOCs (benzaldehyde, nonanal, benzothiazole and acetophenone) were associated with the antibacterial activity against Cms. The results suggested that the VOCs produced by FA26 could control the causal agent of bacterial ring rot of potato. This information will increase our understanding of the microbial interactions mediated by VOCs in nature and aid the development of safer strategies for controlling plant disease.

[Unusually infected sebaceous cyst by Dermabacter hominis]. / Un caso inusual de quiste sebáceo infectado por Dermabacter hominis.

Dermabacter hominis species is constituted by Gram positive facultative anaerobic coryneform rods being part of the resident microbiota human skin, and exceptionally associated to infections in immunocompromised or severely debilitated patients. An immunocompetent young adult woman with a neck sebaceous cyst infected by D. hominis as unique etiologic agent is presented. Phenotypic identification of the causative agent was achieved through simple tests, based on the originally scheme proposed by Funke and Bernard, and feasible to be performed in a hospital Microbiology Laboratory. Phenotypic characteristics as coccoid morphology, the acrid/spermatic odor, esculin hydrolysis, the production of pyrrolidonyl-arylamidase, lysine and ornithine decarboxylase, are key tests to identify D. hominis. The matrix-asisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) confirmed the phenotypic identification.

Facile Synthesis of Azaarene-Substituted Hydroxycoumarins Possessing High Biological Activities via Three-Component C(sp(3))-H Functionalization.

An unprecedented three-component C(sp(3))-H functionalization of 2-alkylazaarenes with aryl aldehydes and 4-hydroxycoumarins was realized, providing azaarene-substituted 3-benzyl-4-hydroxycoumarins in good to excellent yields. These new target compounds displayed broad-spectrum antibacterial activities, providing a new type of antibacterial skeleton.