Anti-fungal effects of novel N-(tert-butyl)-2-(pyridin-2-yl)imidazo[1,2-a]pyridin-3-amine derivative and it's in-vitro, in-silico, and mode of action against Candida spp.

Imidazoles are a category of azole antifungals that encompass compounds such as ketoconazole, miconazole, esomeprazole, and clotrimazole. In contrast, the triazoles group, which includes fluconazole, voriconazole, and itraconazole, also plays a significant role. The rise of antibiotic resistance in fungal pathogens has evolved into a substantial global public health concern. In this study, two newly synthesized imidazo[1,2-a]pyridine derivative (Probe I and Probe II) molecules were investigated for its antimicrobial potency against of a panel of bacterial (Gram-positive and Gram-negative bacteria) and fungal pathogens. Among the different types of pathogens, we found that Probe II showed excellent antifungal activity against fungal pathogens, based on the preliminary screening the potent molecule further investigated against multidrug-resistance Candida sp. (n = 10) and compared with commercial molecules. In addition, in-silico molecular docking, its dynamics, absorption, distribution, metabolism, excretion and toxicity (ADMET) were analyzed. In this study, the small molecule (Probe II) displayed potent activity only against the Candida spp. including several multidrug-resistant Candida spp. Probe II exhibited minimum inhibitory concentration ranges from 4 to 16 µg/mL and minimum fungicidal concentration in the range 4‒32 µg/mL as the lowest concentration enough to eliminate the Candida spp. The selected molecules inhibit the formation of yeast to mold as well as ergosterol formation by the computational simulation against Sterol 14-alpha demethylase (CYP51) and inhibition of ergosterol biosynthesis by in-vitro model show that the Probe II completely inhibits the formation of ergosterol in yeast cells at 2× MIC. The ADMET analysis Probe II could be moderately toxic to the human being, though the in-vitro toxicity studies will help to understand the real-time toxic level. The novel compound Probe II, which was synthesized during the study, shows promise for development into a new generation of drug treatments aimed at addressing the emerging drug resistance in Candida sp.

Restricted Intramolecular Rotation: A Dual Fluorescence Response to Hg2+ Quenching and Ag+ Enhancement in Live Rhizoctonia Solani Cells.

A novel imidazo[1,2-a]pyridine derivative probe (R) was designed, synthesized, and characterized via various characterization techniques, such as ESI-MS, 1H NMR, 13C NMR, and Dept-135 NMR. The data obtained from single-crystal XRD reveal that probe R has a coplanar configuration and is part of the monoclinic crystal system, designated the P2(1)/n space group. The fluorescence of (R) is further enhanced by silver (I) ions. On the other hand, Hg2+ significantly quenches the fluorescence of probe R. The presence of other common metal ions does not influence the fluorescence of probe R in the CH3CN: H2O (1:1) mixture, as they neither increase nor quench it. From the fluorescence enhancement data, the low detection limit (LOD) for Ag + ions was determined to be 1.24 × 10- 8 M, whereas the quenching caused by Hg2+ resulted in an LOD of 5.69 × 10- 9 M. The complex of probe R with Ag+/Hg2+ exhibited a 1:1 stoichiometry, as confirmed by mass spectrometry and a Job plot. Single-crystal XRD analysis of R and its complex with Hg2+ revealed a loss of coplanarity, which confirmed their nonfluorescent behavior. We present a promising application of probe R in visualizing living Rhizoctonia oryzae cells exposed to silver (I) and mercury (II) ions.

Characterization of anthranilic acid produced by Virgibacillus salarius MML1918 and its bio-imaging application.

Anthranilic acid (AA) holds significant importance in the chemical industry. It serves as a crucial building block for the amino acid tryptophan by manipulating the tryptophan biosynthesis pathway, it is possible to increase the production of anthranilic acid. In this study, we utilized metabolic engineering approaches to produce anthranilic acid from the halophilic bacterium Virgibacillus salarius MML1918. The halophilic bacteria were grown in an optimized production medium, and mass production of secondary metabolites was made in ATCC medium 1097 Proteose peptone-for halophilic bacteria and subjected to column chromatography followed by sub-column chromatography the single band for the purified compound was confirmed. Further, various spectral analyses were made for the partially purified compounds, and fluorescence microscopy for fungal cell observation was performed. The purified compound was confirmed by single crystal X-ray diffraction (XRD) analysis, and it was identified as 2-amino benzoic acid. The Fourier transform infrared Spectroscopy (FT-IR) spectrum and nuclear magnetic resonance (NMR) spectrum also confirm the structural characteristic of 2-amino benzoic acid. The UV-Vis absorption spectrum of AA shows the maximum absorption at 337.86 nm. The emission spectrum of 2-amino benzoic acid showed the maximum emission at 453 nm. The bio-imaging application of 2-amino benzoic acid was examined with fungal mycelium of Rhizoctonia solani. It was effectively bound and emitted the blue color at the concentration of 200 and 300 µg/mL. The halophilic bacterium (V. salarius), may have unique metabolic pathways and requirements compared to non-halophilic organisms, to produce AA effectively. This could have implications for industrial biotechnology, particularly in manufacturing environments where high salt concentrations are present and also it can be used as bio-imaging agent.

Coordination of Distal Carboxylate Anion Alters Metal Ion Specific Binding in Imidazo[1,2-a]pyridine Congeners.

Imidazo[1,2-a]pyridine derivatives have excellent potential for chelation with transition metal ions. Two new imidazo[1,2-a]pyridine-8-carboxylates were synthesized and characterized by 1H NMR, 13C NMR, HRMS, and single crystal-XRD techniques. Methyl carboxylate (probe 1) turns on fluorescence upon coordination with Zn2+, while sodium carboxylate (probe 2) turns off its fluorescence upon coordination with Co2+ or Cu2+ ions present in aqueous acetonitrile medium. 13C NMR study revealed that the change in metal ion specific binding was due to the involvement of carboxylate anion in complex formation with Co2+ or Cu2+ ions. The carboxylate anion at 8-position also enhanced the sensitivity of detection of probe 2 by an order of magnitude (detection limits: 3.804 × 10-7 M, probe 1/Zn2+; 0.420 × 10-7 M, probe 2/Co2+ and 0.304 × 10-7 M, probe 2/Cu2+). The detection limits of probes 1 and 2 comply well with the World Health Organization (WHO) and US Environmental Protection Agency (US-EPA) guidelines for detection of heavy metal ions present in drinking water and ground water. Both the probes form a 1:1 complex with Zn2+, Co2+ or Cu2+, and the stoichiometry was verified by Job plot and ESI-mass analysis. The sensing mechanism is explained using 13C NMR experiments, ESI-mass analytical data and theoretical DFT calculations. The suitability of probes 1 and 2 for on-site detection and quantitative determination of Zn2+, Co2+ and Cu2+ ions present in biological, environmental and industrial samples is demonstrated. In addition, both 1 and 2 are used for detection of intracellular contamination of Zn2+, Co2+ or Cu2+ ions in onion epidermal cells.

Antimicrobial potential of secondary metabolites and DNA gyrase B blocking molecules produced by a halophilic bacterium Virgibacillus salarius (MML1918).

AIM: The present study aims to determine the antimicrobial potential of Virgibacillus salairus (MML1918) against human pathogens and its in-vitro and in-silico properties. METHODS AND RESULTS: In this present study, totally 63 halophilic bacterial cultures were obtained and cultivated in nutrient broth medium containing 8% NaCl and the metabolites, were extracted using ethyl acetate and screened for their antimicrobial property by cell viability assay against 12 pathogenic bacteria and fungi, among 63 halophilic bacteria the Vir. salaries (MML1918) found to be the best producer for secondary metabolites production against clinical pathogens. The optimization of growth for important physiochemical parameters was characterized and applied for different production media and based on its highest activity as 17.5 ± .07 mm zone of inhibition (ZOI) for Bacillus cereus followed by 17.5 ± 00 mm ZOI for Staphylococcus aureus, the production medium ATCC1097 was chosen for mass production. The mass production of secondary metabolites from Vir. salaries MML1918 was carried out in a fermenter under controlled conditions and crude metabolites was extracted and condensed. The antimicrobial activity of crude metabolites showed B. cereus (19.3 ± 0.5 mm ZOI), Staph. aureus, and Candida albicans (18.3 ± 0.5 mm ZOI) as the highest ZOI in production media for halophilic bacteria ATCC1097. Further, the gas chromatography-mass spectrometry analysis showed 24 compounds present in crude metabolites. Among the 24 compounds, four molecules were found to be important based on molecule percentage in crude and structural similarity. The molecular docking studies show that the selected four molecules effectively bind with the active region DNA gyrase B. CONCLUSION: Virgibacillus salarius (MML1918) effectively showed antimicrobial activity against several pathogenic organisms and can be employed as a suitable candidate for producing novel antimicrobial agents.

Antimicrobial Properties of Secondary Metabolites Produced by Halomonas sp.: A Halophilic Bacterium.

Aim It is unknown whether the halotolerant bacterium Halomonas sp. produces a range of secondary metabolites with antimicrobial qualities. In the past few years, there has been a growing interest in the biotechnological capability of halophilic bacteria for the production of antimicrobial compounds. Materials and methods The current review intended to assess the antibacterial and antifungal properties of microbial metabolites, explicitly those produced as secondary metabolites by a putative halophilic bacterium. First, phenotypic and genotypic identification were used to identify and confirm the obtained potent halophilic bacterium as Halomonas sp., and its antioxidant properties and biological compatibility were studied. Results The extracellular metabolites that were obtained exhibit a moderation zone of inhibition against 11 mm of Staphylococcus aureus, 12 mm of Pseudomonas aeruginosa, and 11 mm of Candida albicans. The optimal inhibitory concentration for S. aureus and P. aeruginosa is 256 µg/mL, while the minimum inhibitory concentration (MIC) for C. albicans is 128 µg/mL. The antioxidant property of crude metabolites indicates that 100% scavenging at 512 µg/mL, and the blow at 256 µg/mL, are not reasonable levels of antioxidant activity. Conclusion Secondary metabolites appear to be highly biologically compatible, as there is no hemolytic activity at any of the tested concentrations. According to the study, Halomonas sp.'s secondary metabolites could be a source for the synthesis of novel antimicrobial compounds.

Examining Diagnostic Efficacy: GeneXpert Versus Traditional Staining Techniques With Culture in the Diagnosis of Tuberculosis.

Introduction The tuberculosis (TB) diagnosis involves various methods, such as microscopic examination, culture-based methods, molecular techniques, chest X-rays, serological tests, and interferon-gamma release assays. These methods help identify and confirm TB and its resistance to rifampicin, balancing speed and accuracy for prompt treatment initiation and effective disease management. Aims and objectives To assess the diagnostic accuracy of GeneXpert, Ziehl-Neelsen staining, and fluorescence staining compared to culture media in TB-suspected patients. Materials and methods We analysed 416 patient samples for TB over one year using GeneXpert, Ziehl-Neelsen staining, fluorescence staining, and Löwenstein-Jensen (LJ) medium. Only samples with a suspicion of TB were included in the study. The samples received without clinical history and requests for all four tests were excluded. Results A total of 416 patient samples were categorised into pulmonary and extrapulmonary samples. GeneXpert detected 62 positive cases for TB, out of which 53 were rifampicin-sensitive, seven were rifampicin-indeterminate, and two were rifampicin-resistant. The indeterminate samples were further evaluated using the line probe assay (LPA), of which six were rifampicin-sensitive, and one was rifampicin-resistant. Fluorescent staining detected 44 cases, Ziehl-Neelsen staining detected 40 cases, and LJ culture medium detected 65 cases. Conclusion GeneXpert is superior to staining methods for detecting TB. GeneXpert, combined with microscopy and culture, can enhance TB and multi-drug resistant tuberculosis (MDR-TB) detection and aid in early treatment initiation.

Antimicrobial Potential of Secondary Metabolites Produced by Bacillus sp. and Their Gas Chromatography (GC)-Mass Spectrometry (MS) Analysis.

Aim This study aims to determine the biological activity and explore the antimicrobial compounds produced by a halophilic bacterium, as well as the hemolytic, antioxidant, and antimicrobial properties of extracellular metabolites from Bacillus sp. Methodology The bacterial strain was obtained from the Department of Microbiology at Saveetha Medical College and Hospital, Chennai, India, specifically from the bio-control and microbial product laboratory (BCMPL). The genotype and phenotype of the isolate were characterized while the cultures were maintained in a nutrient broth medium supplemented with 8% sodium chloride (NaCl). The secondary metabolites were extracted using ethyl acetate and concentrated through open evaporation techniques after nine days of growth in the culture medium. Biological compatibility studies were conducted concurrently with the screening of the antimicrobial and antioxidant properties of the secondary metabolites. The chemical composition of the crude metabolites was analyzed using the gas chromatography (GC)-mass spectrometry (MS) technique. Results After phenotypic and genotypic analysis, the obtained potential halophilic bacterium from BCMPL was determined to be Bacillus sp. After the dark brown crude metabolites were extracted, the extracellular metabolites' antimicrobial activity against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Candida albicans (C. albicans) extracellular metabolites was moderately inhibited. Furthermore, the metabolites exhibited a moderate level of hemolytic and antioxidant activity. The GC-MS method depicted the presence of 12 distinct metabolites, each with a distinct retention time. Conclusion To sum up, the halophilic bacteria that were obtained and identified as Bacillus species and their crude metabolites demonstrated noteworthy antioxidant and antimicrobial properties. Further investigation may be helpful in identifying possible compounds that Bacillus sp. produces.

Atypical Multidrug-Resistant Salmonella paratyphi B Infection in a Patient with Uncontrolled Diabetes Mellitus: A Case Report.

Atypical Salmonella infection usually presents with unusual symptoms in addition to gastroenteritis. Such atypical presentations can pose a challenge for diagnosis and treatment as they may be misdiagnosed, leading to delayed care and potential complications. Here we report an unusual case of Salmonella spp. isolated from a wound swab. A 57-year-old male patient with a history of uncontrolled type 2 diabetes presented to the general surgery department with a 25-day history of swelling, ulceration, and purulent discharge on his right foot. A wound swab was collected for culture and sensitivity. Gram staining showed occasional pus cells and a few gram-negative bacilli. Culture was done, and the organism was identified as Salmonella Paratyphi B with the help of other biochemicals. The isolate showed susceptibility to chloramphenicol and cotrimoxazole and resistance to other panels of antibiotics. Routine blood and urine analysis of the patient showed normal findings. Wound dressing was done on an alternative day, followed by administration of antibiotics. The patient was advised to follow up after two weeks. The clinical outcome in the above patient was satisfactory with appropriate antibiotics. We present a case of atypical typhoidal Salmonella as a rare cause of wound infection and not a major threat if diagnosed and treated accordingly.

Antimicrobial Archetypes: Assessing the Knowledge, Attitude, and Practice (KAP) Trends in Antimicrobial Resistance (AMR) and Antimicrobial Stewardship Program (AMSP) Among Faculties, Residents, and Interns in a Tertiary Care Hospital.

Background Antimicrobial resistance (AMR) is caused by inappropriate use of antimicrobials. India's high antibiotic use contributes significantly to AMR. Antimicrobial Stewardship Programs (AMSPs) are crucial for optimizing antimicrobial use. Knowledge, Attitude, and Practice (KAP) studies are essential for evaluating healthcare professionals' beliefs and conduct regarding AMR and AMSPs. Materials and methods A cross-sectional study at Saveetha Medical College and Hospital evaluated doctors' knowledge, attitudes, and practices regarding AMR and stewardship programs. The study involved 202 participants, including faculty members, postgraduates, and interns. Results The study involved 202 participants, with residents being the majority at 51.4%, followed by faculty at 26.7% and interns at 21.7%. Faculty members showed the highest overall knowledge, followed by residents and interns. Despite possessing knowledge, practitioners did not consistently implement their knowledge in their daily practices, with a statistically significant difference of p < 0.01. There was a substantial disparity in attitude between the departments, as evidenced by a statistically significant p-value of less than 0.01. Conclusion Positive trends in knowledge and attitudes exist, but there are areas for improvement in translating attitudes into clinical practices. There is a significant disparity among faculty members, residents, and interns, highlighting the urgent need for interventions to bridge the gap. Implementing antibiotic prescribing guidelines at the institutional level and enhancing knowledge, attitudes, and practices among healthcare professionals are crucial to addressing AMR.

Secondary Metabolites of Halobacillus sp.: Antimicrobial and Antioxidant Activity, Biological Compatibility, and Gas Chromatography-Mass Spectrometry (GC-MS) Analysis.

Background The rise of infectious diseases and the emergence of resistant pathogens pose significant challenges to human health. In response to this global threat, researchers are exploring novel sources of bioactive compounds for effective antimicrobial therapies. One avenue of investigation is the study of halophilic bacteria and their secondary metabolites. These bacteria thrive under extreme conditions and produce valuable bioactive metabolites, which have the potential for therapeutic applications. Methods In this study, the potent bacterial cultures obtained from the Payanur salt pan, Tamil Nadu, were analyzed for the antimicrobial activity of their metabolites. The secondary metabolites were obtained from the halophilic bacteria by culturing the bacteria in 8% NaCl. The resultant secondary metabolites produced were extracted using ethyl acetate and their antimicrobial property was studied using the well diffusion method. The minimum inhibitory concentration (MIC) of these metabolites against five clinical pathogens, namely, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans was determined. Their antioxidant property was studied using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method and biological compatibility was determined by hemolytic assay of the secondary metabolites. Results The potent halophilic bacteria isolated from salt pan bacteria were phenotypically and genotypically identified as Halobacillus sp. The secondary metabolites extracted from these bacteria yielded 110 mg of crude metabolites. The antimicrobial activity of crude metabolites shows a moderate zone of inhibition of 14 mm for P. aeruginosa, 13 mm for E. coli and C. albicans, and 11 mm for S. aureus. The minimum inhibitory concentration was 128 µg/mL for E. coli, P. aeruginosa, and C. albicans, which was found to be the best growth inhibition concentration. The DPPH scavenging activity shows a higher activity till the concentration of 64 µg/mL. The hemolytic activity of 25% is obtained at 128 µg/mL and below 64 µg/mL, there is no hemolytic activity. The gas chromatography-mass spectrometry (GC-MS) analysis of the secondary metabolites shows the presence of 17 compounds. Among them, there were four major compounds: (i) cyclo(L-prolyl-L-valine) (probability of 95.63%), (ii) pyrrolo[1,2-a]pyrazine- 1,4-dione,hexahydro-3-(2-methylpropl) (probability of 94.45%), (iii) 2,5-piperazinedione,3,6-bis(2-methylpropyl) (probability of 71.94%) and (iv) pyrrolo[1,2-a]pyrazine-1,4-dione,hexahydro-3-(phenylmethyl) (probability of 88.01%). Conclusion In conclusion, the isolated bacterium is confirmed to be Halobacillus sp. and the secondary metabolites produced by this bacterium could be the potential source for the development of novel antimicrobial and antioxidant compounds that are highly biologically compatible. Further research may help to develop novel compounds in the pharmaceutical industry.

A fluorescent chemosensor for selective detection of chromium (III) ions in environmentally and biologically relevant samples.

A simple single step one pot multicomponent reaction was performed to synthesize N-(tert-butyl)-2-(furan-2-yl)imidazo[1,2-a]pyridine-3-amine (TBFIPA). The synthesized TBFIPA was subjected to library of cations to study its ability for selective and sensitive detection of specific metal ions. Selective detection of chromium ions by TBFIPA were found from the significant hypsochromic shift (335 nm â†’ 285 nm) in the UV-Visible spectra. The fluorescent TBFIPA displays complete quenching of fluorescence under UV lamp (365 nm) only in the presence of chromium without the interference of common metal ions. Binding constant (ka) obtained from Benesi-Hildebrand plot is 0.21 × 105 M-1, limit of detection (LOD) and limit of quantification (LOQ) of TBFIPA toward Cr3+ ions are 4.70 × 10-7 M and 1.56 × 10-7 M, respectively. The mechanism proposed during complex formation were supported by stoichiometric Job continuous variation plot, 1H NMR titration and ESI-MS spectroscopic data. All the experimental confirmation for complex formation were corroborated with theoretical DFT studies optimized using RB3LYP/6-31G(d) basis set. The selectivity and sensitivity of TBFIPA toward Cr3+ ions are found suitable to design a user-friendly silica based portable test kit. Alongside, TBFIPA was successfully utilized for imaging onion epidermal cells. Furthermore, the results obtained for biological, environmental, and industrial samples provided solid evidence to estimate chromium ions using TBFIPA in these real samples.

Wavelength specific aggregation induced emission in aqueous media permits selective detection of Ag+ and Hg2+ ions.

A new 1,8-naphthalimide derivative (probe 1) adopts V-shaped structure, emits fluorescence and displays the Mie effect and aggregation-induced emission (AIE). Selective interactions of thiophilic Ag+ and Hg2+ ions (10 µM) with 1 (10 µM) resulted in AIEs at 499 and 521 nm, respectively. Both Ag+ and Hg2+ induce the formation of 1:2 complexes with 1, leading to the formation of AIE active aggregates with an average size of 423 and 198 nm, respectively. The formation of crystalline needles with Ag+ and spherical aggregates with Hg2+ results in wavelength specific AIE that permits the naked-eye and fluorometric detection of Ag+ and Hg2+ ions. Probe 1 shows excellent selectivity toward Ag+ and Hg2+ among various metal ions, therefore, 1 is suitable for the selective and quantitative detection of Ag+ and Hg2+ ions. Job plots are used for the determination of the stoichiometry of the complexes formed. It is evident from the fluorescence images of probe 1 in Rhizoctonia oryzae mycelia cells that they can be employed as potential candidates for in-vitro bioimaging.

Chelation of specific metal ions imparts coplanarity and fluorescence in two imidazo[1,2-a]pyridine derivatives: Potential chemosensors for detection of metal ions in aqueous and biosamples.

Synthesis and chelation induced fluorescence emission from two imidazo[1,2-a]pyridine derivatives are described. The nonfluorescent molecule 1 containing N and O donor atoms, achieves coplanarity upon interactions with trivalent cations Al3+, Fe3+ and Cr3+, that favors fluorescence emission. Molecule 2 containing two N donor atoms attains coplanarity upon interaction with the only Zn2+ and becomes fluorescent. Both molecules 1 and 2 form a 1:1 complex with interacting metal ions. Other trivalent metal ions (including Bi3+ and In3+) and common divalent metal ions (including Hg2+ and Cd2+) fail to form any complex with 1 or 2, and they do not interfere in the detection of Zn2+, Al3+, Fe3+ or Cr3+ ions. Noninterference of other metal ions renders 1 and 2 suitable for the detection of fungal cells contaminated with Zn2+, Al3+, Fe3+ or Cr3+ ions.