Lowest Minimum Inhibitory Concentration Value Research Articles

COMPARATIVE STUDY OF QUERCETIN & LEMON PEEL EXTRACT ON MULTIPLE DRUG RESISTANT BACTERIA

The current investigation explores the antibacterial properties of Quercetin, a flavonoid found in plants, and lemon peel extract, renowned for its rich bioactive content, against multiple drug resistant bacteria. The study method involved the identification of multidrug-resistant bacteria through antimicrobial susceptibility testing (AST). Nine standard bacterial strains exhibited resistance to different antibiotics, with a MAR index exceeding 0.10, including Ampicillin, Vancomycin, Polymyxin B, Nitrofurantoin, Trimethoprim, and penicillins.In the present study bioactive compounds from lemon peel were extracted using two solvents, methanol and water, and their efficacy was assessed against drug-resistant bacteria. Minimum Inhibitory Concentration (MIC) values, determined by using the well plate method, revealed lower MIC values for the water extract (LPWE) compared to the methanol extract (LPME) and quercetin. For instance, the MIC for LPWE against E. hermanniensis ATCC 700323 was 140 mg/ml, whereas it was 50 mg/ml for quercetin & 1 mg/ml for LPME. From the results, it can be interpreted that Methanol extract was most effective against drug-resistant bacteria when compared to water extract and quercetin.Furthermore, GC-MS analysis was performed to analyze the chemical entities present in each extract. Given the activity of LPME, LPWE, and Quercetin against both Gram-negative bacteria and Gram-positive bacteria, these extracts hold promise as broad-spectrum antibacterial agents applicable in various fields such as medicine, food, and cosmetics.

Quantitative Analysis of Swertiamarin Content from Fagraea fragrans Leaf Extract using HPLC Technique and its Correlation to Antibacterial Activity

The rise in drug resistance poses escalating challenges for antibacterial medications, leading to an urgent demand for the exploration and innovation of new antibacterial drugs. Fagraea fragrans Roxb., belonging to the Gentianaceae family, is one of the common herbal medicines which can be found abundantly in Southeast Asia. The secoiridoid glucoside swertiamarin, one of the major compounds in F. fragrans leaf, exhibits antimicrobial effects. To guarantee the medicinal effectiveness of F. fragrans leaves, it is essential to identify a standardized analytical method for quantifying the active compound. In this study, the optimized HPLC method following ICH guideline was validated for the quantitative analysis of swertiamarin content in F. fragrans leaf in terms of linearity (y = 5733.5x - 369.1; R2 = 0.9999), accuracy (93.57-96.39% recovery), precision (0.91% RSD for repeatability precision; 1.19% RSD for intermediate precision), limit of detection (0.73 µg/mL), limit of quantitation (2.23 µg/mL), specificity (peak purity index = 0.999995) and robustness (% RSD <1).The maximum wavelength of swertiamarin was found to be at 238 nm. The amount of swertiamarin content in F. fragrans leaf extract conducted from the validated HPLC method was found to be 0.0259 ± 0.0005 g/100 g crude drug. The leaf extract exhibited antimicrobial activity against clinical isolates of Enterobacter cloacae, Klebsiella pneumonia, and Escherichia coli at 0.125 mg/mL, and Pseudomonas aeruginosa at 0.5, showing minimum inhibitory concentration (MIC) values. Whereas swertiamarin exhibited even lower MIC values. The developed HPLC analysis effectively determines swertiamarin content as a chemical marker to ensure the antimicrobial potential of F. fragrans leaves.

Synthesis, characterization, antibacterial efficacy, and Cytotoxicity of monoclinic KMg3(Al0.5B0.5)Si3O10F2: A novel material for anticariogenic applications

Fluorophlogopite is a well-known fluorosilicate glass-ceramic derivative known for its bioactivity, machinability and optimal mechanical properties. There is limited information regarding its antibacterial and biocompatible properties. This research paper presents the synthesis and characterization of a novel Boron-doped Fluorphlogopite [KMg3(Al0.5B0.5)Si3O10F2] aiming to improve its antibacterial properties intended for anticariogenic applications. The combustion synthesis method was employed, with oxalyl dihydrazide (ODH) (C2H6N4O2) serving as the fuel. X-ray Diffraction (XRD) analyses unveiled a monoclinic crystal system, showcasing a P21 space group, and an average crystallite size of approximately 28 nm. Morphological scrutiny divulged clustered, irregularly shaped, cluster-like structures. The energy gap was determined to be around 4.97 ± 0.0062 eV. Fourier-Transform Infrared (FTIR) spectroscopy depicted the presence of characteristic bonds. BET analysis indicated the presence of a large surface area and porous structure (mesopores), which may contribute to lower MIC and MBC values, enhancing antibacterial effectiveness. The antibacterial activity, evaluated via agar well diffusion, yielded an 8 mm zone of inhibition. Furthermore, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) against S mutans were determined to be 2 mg/ml and 16 mg/ml, respectively. The biocompatibility of the synthesized KMg3(Al0.5B0.5)Si3O10F2 was assessed through the MTT assay, indicating non-toxic behavior at a concentration of 12 μg/ml with 98 % cell viability, while showing moderate toxicity with 61 % viable cells at its highest concentration of 200 μg/ml.

Silencing of Resistance Mechanism in Vancomycin-Resistance Enterococci Using Antisense RNA of vanA Gene

The World Health Organization has included the problem of antibiotic resistance among the top 10 important health problems in the world. Treatment of infectious diseases has become more difficult due to the spread of antibiotic resistance between bacteria via transposable elements. Vancomycin-resistant enterococci (VRE) are of critical medical and public health importance due to their association with serious nosocomial infections and high risk of death. One of the most important features of VREs is that they have multiple antibiotic resistance and treatment options are reduced. Therefore, new treatment methods are needed. The vanA gene constitutes the building block of the vancomycin resistance mechanism and causes high resistance to vancomycin. In this study, it was aimed to investigate the neutralization of the vancomycin resistance mechanism by creating vanA antisense RNA (asRNA). The vanA positive VRE50 strain in our culture collection which was isolated from the clinical sample, was used to amplify the vanA gene by polymerase chain reaction (PCR). The amplified vanA amplicon was inserted inversely into the pUC19 plasmid by means of the enzyme cutting sites in the primers used. The resulting plasmid was combined with the pAT392 plasmid which can replicate in gram-positive bacteria and a fusion plasmid was created. The fusion plasmid whose orientation was confirmed, was transferred to the wild strain VRE50 by electroporation method. Minimum inhibitory concentration (MIC) values of transformed VRE (tVRE50) and wild type VRE50 strains used as control were determined by the E-Test method. The vancomycin MIC value of the wild type VRE50 strain was determined as 1024 µg/mL and that of the tVRE50 strain was 32 µg/mL and it was determined that the vancomycin resistance of the tVRE50 strain decreased with asRNA (antisense RNA). Antisense RNA technology is an important method for neutralizing the expression of genes. This study showed that neutralization of the vancomycin resistance gene may provide a lower MIC value in a vancomycin-resistant enterococcus strain and lead to increased susceptibility. This new approach provides a new method for VRE treatment by neutralizing the vancomycin resistance mechanism. The result obtained in this study needs to be supported by in vivo tests.

Molecular insights into quercetin-enhanced crystalline silver nanoparticles: Implications for breast cancer cell cytotoxicity and antibacterial action in Kyllinga nemoralis

Amidst the ongoing global health crisis posed by cancer and antibiotic-resistant infections, innovative solutions are in high demand. The utilization of Kyllinga nemoralis leaf (KNL) extracts for synthesizing silver nanoparticles (AgNPs) represents a novel approach, with the potential to deliver profound advancements in healthcare, benefitting society on a broad scale. Successful synthesis of AgNPs by KNL extracts for treating breast cancer cells, specifically MDA-MB-231 cells, is recorded in this report. The adsorption mechanism of quercetin (Q) on Ag and its optimized structural characteristics were computed at the DFT level. According to FTIR analysis, quercetin, one of the flavonoids found in KNL extract, acts as a reducing and stabilizing agent for the conversion of Ag+ ions to Ag0, and carboxylates serve as ligands that cap the AgNPs. The small-sized (7 nm), spherical particles, which are uniform in size and monodispersed, exhibit regulation over the size of the AgNPs due to being shielded by enough flavonoids and gallic acid absorbed into the extract. The observed negative zeta potential of −20 mV indicates the moderate stability of the AgNPs colloid. It is noted that AgNPs prepared at higher concentrations of KNL extract showed lower minimum inhibitory concentration (MIC) values (80 µg/mL) and larger inhibition zones (22 mm) against Pseudomonas aeruginosa. The cell viability rate of MDA-MB-231 cell lines decreases with increasing concentration of AgNPs. The antibacterial and anticancer activity of AgNPs is observed in a size-dependent manner. This research raises the possibility of using plant-based, small-sized AgNPs therapeutically for breast cancer and as antibacterial agents.

Phytochemistry and antimicrobial activity of Moroccan Origanum compactum and Ruta montana essential oils against nosocomial bacteria

Introduction: Healthcare-associated infections are a global public health issue with farreaching individual and economic repercussions. The microorganism’s multi-resistance frequently increases the risk that can be lowered by using biomolecules of medicinal plant essential oils (EOs). This study investigated the phytochemical components and antimicrobial potential of the EOs of Moroccan Origanum compactum and Ruta montana gathered from Taza Region. Methods: The EOs’ chemical analysis was performed by GC/MS and their antimicrobial effects were assessed by the microplate dilution method against eight nosocomial resistantbacterial strains. Results: The main constituents of O. compactum EO were Thymol (29.56%), carvacrol (26.44%), γ-terpinene (18.86%) and p-cymene (12.01%), while those of R. montana EO were 2-undecanone (85.76%), 2-nonanone (3.95%), 2-decanone (3.67%) and 2-dodecanone (1.94%). The O. compactum EO had important antimicrobial effects on all bacteria experienced. The lower minimum inhibitory concentration (MIC) values were obtained for the tested Staphylococcus species (0.062%, 0.125% (v/v)) while the highest one (2% (v/v)) was obtained for Klebsiella pneumonia and Pantoea spp. The R. montana EO showed MIC values of 4% (v/v) for Pantoea spp. and 8% (v/v) for the other tested strains except K. pneumonia for which no effect was shown. Conclusion: Therefore, these EOs, especially the O. compactum one, have an interesting antibacterial potential against nosocomial infections and might be used to develop new antimicrobial agents.

Antibiotic Susceptibility of Staphylococcus Aureus with VanA and MecA Genes.

Staphylococcus aureus (S.aureus) is an emerging antibiotic resistant bacterium responsible for various infections in human. Resistance to methicillin and vancomycin are of prime concern in S. aureus. The study aims to determine the minimum inhibitory concentration (MIC) of Vancomycin and evaluate the existence of mecA and vanA genes, associated with antibiotic resistance. Clinical specimens from three Kathmandu hospitals were processed and S. aureus was identified using conventional microbiological procedures. MRSA was phenotypically identified with cefoxitin (30µg) disc diffusion, while vancomycin susceptibility was assessed using the Ezy MICTM stripes. The mecA and vanA genes were detected by polymerase chain reaction (PCR). Out of 266 S. aureus samples from various clinical specimen subjected for analysis, 77 (28.9%) were found methicillin-resistant (MRSA) and 10 (3.8%) were observed vancomycin-resistant (VRSA). Vancomycin resistant isolates showed a significant correlation between resistance to ampicillin, chloramphenicol, and cefoxitin. The mecA gene was found in 39 of the MRSA isolates, having 50.64% of MRSA cases, while the vanA gene was detected in 4 of the VRSA cases, constituting 40% of VRSA occurrences. The strains with higher vancomycin minimum inhibitory concentration values (≥ 1.5 μg/ml) displayed increased resistance rates to various antibiotics compared to strains with lower minimum inhibitory concentration values (< 1.5 μg/ml). The presence of vanA genes was strongly associated (100%) with vancomycin resistance, while the 10.3% mecA gene was identified from MRSA having resistance towards vancomycin also.

Bee chitosan nanoparticles loaded with apitoxin as a novel approach to eradication of common human bacterial, fungal pathogens and treating cancer.

Antimicrobial resistance is one of the largest medical challenges because of the rising frequency of opportunistic human microbial infections across the globe. This study aimed to extract chitosan from the exoskeletons of dead bees and load it with bee venom (commercially available as Apitoxin [Api]). Then, the ionotropic gelation method would be used to form nanoparticles that could be a novel drug-delivery system that might eradicate eight common human pathogens (i.e., two fungal and six bacteria strains). It might also be used to treat the human colon cancer cell line (Caco2 ATCC ATP-37) and human liver cancer cell line (HepG2ATCC HB-8065) cancer cell lines. The x-ray diffraction (XRD), Fourier transform infrared (FTIR), and dynamic light scattering (DLS) properties, ζ-potentials, and surface appearances of the nanoparticles were evaluated by transmission electron microscopy (TEM). FTIR and XRD validated that the Api was successfully encapsulated in the chitosan nanoparticles (ChB NPs). According to the TEM, the ChB NPs and the ChB NPs loaded with Apitoxin (Api@ChB NPs) had a spherical shape and uniform size distribution, with non-aggregation, for an average size of approximately 182 and 274 ± 3.8 nm, respectively, and their Zeta potential values were 37.8 ± 1.2 mV and - 10.9 mV, respectively. The Api@ChB NPs had the greatest inhibitory effect against all tested strains compared with the ChB NPs and Api alone. The minimum inhibitory concentrations (MICs) of the Api, ChB NPs, and Api@ChB NPs were evaluated against the offer mentioned colony forming units (CFU/mL), and their lowest MIC values were 30, 25, and 12.5 μg mL-1, respectively, against Enterococcus faecalis. Identifiable morphological features of apoptosis were observed by 3 T3 Phototox software after Api@ChB NPs had been used to treat the normal Vero ATCC CCL-81, Caco2 ATCC ATP-37, and HepG2 ATCC HB-8065 cancer cell lines for 24 h. The morphological changes were clear in a concentration-dependent manner, and the ability of the cells was 250 to 500 μg mL-1. These results revealed that Api@ChB NPs may be a promising natural nanotreatment for common human pathogens.

Staphylococcus aureus small colony variants: A potentially underestimated microbiological challenge in peritoneal dialysis

IntroductionPeritonitis remains the major infectious complication in the setting of peritoneal dialysis (PD). Despite known only moderate pathogenicity, the most frequently detected pathogens in PD-related peritonitis are surprisingly coagulase-negative staphylococci. However, this could be explained, at least in part, by Staphylococcus aureus small colony variants (SCVs) induced by PD fluids (PDFs) and misidentified by routinely used microbiological methods. Material and methodsBacteria were exposed to commonly used PDFs in various regimens designed to simulate daily use as closely as possible. Wild-type isolates and SCVs were subsequently used to determine minimum inhibitory concentrations (MICs), in vitro biofilm formation capacities, and auxotrophies. Underlying genetic alterations were investigated using whole-genome sequencing, and various microbial identification methods were tested to determine their performance for wild-types and SCVs. ResultsStable SCVs could be isolated most successfully after exposure to glucose-containing PDFs alone. The reading of MICs was significantly affected by the reduced growth of SCVs, resulting in lower MIC values in 44% of all tests. Nonsynonymous mutations were found in all but one SCV, while only two isolates showed typical auxotrophic responses. While MALDI-TOF, PCR and Pastorex Staph-Plus correctly identified all S. aureus SCVs, API-Staph and VITEK-2 yielded identification rates of only 40% and 10%, respectively. ConclusionsOverall, the present study has shown that commercially available PDFs induce S. aureus SCVs in vitro, which are difficult to identify and test for antimicrobial susceptibility and can potentially lead to recurrent or persistent infections. Thus, they represent a potentially underappreciated challenge not only for microbiologists, but also for clinicians.

In vitro activity of tedizolid against 43 species of Nocardia species

The purpose of the present study was to evaluate the in vitro activity of tedizolid against several clinically significant species of Nocardia by comparing with that of linezolid. A total of 286 isolates of Nocardia species, including 236 clinical isolates recovered from patients in Japan and 50 strains (43 species) purchased from NITE Biological Resource Center, were studied. Antimicrobial susceptibility testing was performed using the broth microdilution method. For the 286 Nocardia isolates, the minimal inhibitory concentration (MIC)50 and MIC90 values of tedizolid were 0.25 and 0.5 μg/ml, and those of linezolid were 2 and 2 μg/ml, respectively. The distribution of the linezolid/tedizolid ratios (MICs of linezolid/MICs of tedizolid) showed that tedizolid had four- to eight-fold higher activity than linezolid in 96.1% (275/286) of Nocardia isolates. Both the tedizolid and linezolid MIC90 values for Nocardia brasiliensis were two-fold higher than those for the other Nocardia species. Both tedizolid and linezolid had low MIC values, 0.25–1 μg/ml and 0.5–4 μg/ml, respectively, even against nine isolates (five species) that were resistant to trimethoprim/sulfamethoxazole. One Nocardia sputorum isolate showed reduced susceptibility to tedizolid (4 μg/ml). Bioinformatics analysis suggests different resistance mechanisms than the oxazolidinone resistance seen in enterococci and staphylococci.

Anti-bacterial Effects of Allium atroviolaceum Hydroalcoholic Extract on Oral Bacteria of Streptococcus viridans Groups

: In light of the escalating global concern over antibiotic resistance, this study aimed to evaluate the antimicrobial activity of the hydroalcoholic extract of Allium atroviolaceum and compare it with 0.2% chlorhexidine using the well diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods against Streptococcus mitis (ATCC 6249), Streptococcus mutans (PTCC 16836), Streptococcus sanguinis (PTCC 1449), and Streptococcus salivarius (PTCC 1448). The well diffusion method revealed the inhibitory effect of the extract, with the highest activity observed against Streptococcus salivarius. Subsequently, MIC and MBC values were determined, indicating that the hydroalcoholic extract had MIC and MBC values of 3.12 mg/mL against Streptococcus sanguinis and 6.25 mg/mL against other strains (Streptococcus mitis, Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius). Chlorhexidine exhibited significantly lower MIC and MBC values of 0.0003%. Based on literature reviews, Allium species exhibit antimicrobial properties. The findings highlight the potential of Allium atroviolaceum extract as an alternative or complementary antimicrobial agent and warrant further investigation to identify its bioactive components and explore their mechanisms of action. This study contributes to understanding natural antimicrobial agents and their potential applications against bacterial infections.

Antifungal Susceptibility Profile of Clinical and Environmental Isolates of Aspergillus Species From a Tertiary Care Center in North India.

Aspergillus species are ubiquitously found in the environment worldwide and are important causative agents for infection. Drug resistance among Aspergillus species is emerging, hencethe present study was undertaken to look for antifungal susceptibility profiles of clinical and environmental isolates of Aspergillus species. During the period from January 2018 to June 2019, a total of 102 Aspergillus isolates (40 clinical, 40 hospital, and 22 community environment) were tested for antifungal susceptibility testing for determination of minimum inhibitory concentration (MIC)/minimum effective concentration (MEC) as per Clinical and Laboratory Standards Institute(CLSI) M38-A3 method for itraconazole, voriconazole, amphotericin B, and caspofungin. Out of these 102 Aspergillus isolates, A. flavus was the most common species present. Aspergillus species were found to have low MIC values to azoles such as itraconazole and voriconazole except for one clinical isolate, which showed a MIC value of 2 μg/ml to voriconazole. Two isolates were non-wild-type for amphotericin B, but all isolates were wild-type for caspofungin. Antifungal susceptibility testing among clinical Aspergillus isolates and environmental surveillance studies in view of emerging drug resistance should be undertaken at a larger scale.

Mechanistic insight into the membrane disrupting properties of thymol in Candida species

Candida infection is a major problem in immunocompromised patients and has become a significant public health concern in recent years due to high toxicity, multidrug resistance and unfavourable side effects of conventional antifungal drugs. This study aims to investigate the antifungal efficacy of thymol, a natural monoterpenoid, on the membrane integrity of Candida albicans, Candida glabrata and Candida tropicalis. Minimum inhibitory concentrations (MICs) of thymol were 32 µg/ml, 63 µg/ml, and 125 µg/ml for C. albicans, C. tropicalis and C. glabrata, respectively. The minimum fungicidal concentrations (MFC) were 64 µg/ml, 110 µg/ml and 240 µg/ml, respectively. At MIC, thymol treated cells showed complete suppression of cell growth (growth kinetics, disc diffusion), altered morphology (scanning electron microscopy), leakage of intracellular macromolecules (absorption at 260 nm), significant reduction in ergosterol levels and inhibition of plasma membrane H+-ATPase (Pma1) activity. The disruption of the fungal membranes by thymol was further confirmed by propidium iodide uptake using flow cytometry and confocal microscopy. In silico studies with membrane-bound proteins (lanosterol 14-α demethylase (LDM) and Pma1), showed good binding affinity of −6.3 kcal/mol and −6.7 kcal/mol, respectively, and formed hydrogen bonds with crucial amino acid residues at the active site of target proteins. With low MIC values, negligible host toxicity, desirable ADME properties, thymol has immense potential as a potent antifungal drug that can be used for developing mechanism-based drugs as it has specific binding affinity for specific target proteins. Studies using animal models are required for further validation.

Antioxidant and antimicrobial activities of mango peel and radish peel-a comparative investigation

The present study investigated the antioxidant and antimicrobial activities of Bao mango and daikon radish peel (Thai variety) ethanolic extracts. The percentage extraction yield of radish peel was higher compared to the mango peel (p &amp;lt; 0.05). However, Mango peel extract (MPE) contained higher total phenolic content (TPC) than radish peel extract (RPE) (p &amp;lt; 0.05). Similar to the TPC value, antioxidant activities including DPPH radical scavenging activity, reducing power, and peroxidation inhibition were higher in the MPE, compared to the RPE, except for metal chelating activity. The antimicrobial analyses suggested that the MPE showed lower minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values compared to the RPE (p &amp;lt; 0.05) against Gram-positive and Gram-negative bacteria. High-performance liquid chromatography (HPLC) revealed that mangiferin was the major phenolic compound present in MPE, followed by 3, 4 dihydroxybenzoic acid. Therefore, MP could be used as a promising natural antioxidant and antimicrobial agent for food applications.

Comparison Between Moxifloxacin and Chloramphenicol for the Treatment of Bacterial Eye Infections

Background: Moxifloxacin is a bactericidal methoxyquinolone used for the treatment of conjunctivitis and prophylactic therapy in cataract and refractive surgeries. Chloramphenicol is a bacteriostatic organochlorine introduced into clinical practice in 1948 and used mainly in topical preparations because of its known toxicity. Objectives: The study aimed to evaluate the in vitro antibacterial effect and the ocular cytotoxicity of these broad-spectrum antibiotics. Methods: Antimicrobic activity was tested on four bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis), and determined through calculation of Minimum Inhibitory Concentration (MIC) and IC50 for each microorganism. Antibacterial activity was determined by microdilution method after 24 hours incubation with 2-fold serial dilutions (2.5 mg/ml to 4.883 µg/ml) of moxifloxacin and chloramphenicol. Disk diffusion test were performed according to EUCAST methodology. Biofilm formation inhibition (BIC) and biofilm Eradication Concentration (BEC) assay were conducted for P. aeruginosa and S. epidermidis using the microdilution method. Cytotoxicity of antibiotics was evaluated by MTT colorimetric assay on human corneal cell (HCE-2). Results: Cytotoxicity of antibiotics was evaluated on human epithelial corneal cells after 4 hours treatment by viability assay. Results showed that corneal cell viability was significantly higher after moxifloxacin treatment compared to Chloramphenicol (p<0.01). Moxifloxacin is characterized by a significantly lower MIC and IC50 values and a larger inhibition zone for all the strain tested, with high performance in controlling gram-negative growth, compared to Chloramphenicol. Moreover, Moxifloxacin showed higher activity compared to Chloramphenicol in the inhibition of biofilm formation and in the disruption of biofilm, especially against S. epidermidis biofilm. Conclusions: The lower corneal cell toxicity and the broader spectrum of antibacterial activity observed with Moxifloxacin suggests its use in ophthalmic solution for the treatment of bacterial eye infections.

Citrus sinensis Seed-Mediated Gold Nanoparticles for Combating Diabetes and Bacterial Infections: A Promising Multifunctional Nano Formulation

This investigation explores the successful synthesis and comprehensive characterization of Citrus sinensis seed-mediated gold nanoparticles designated as C-AuNPs. Visual confirmation of synthesis was achieved through a distinct ruby red color change in the reaction mixture, followed by UV-Visible spectroscopy, which revealed a characteristic peak absorbance at 522 nm due to the Surface Plasmon Resonance (SPR) phenomenon associated with gold nanoparticles. Transmission Electron Microscopy (TEM) analysis demonstrated uniform, spherical nanoparticles with an average size of 19 nm, ideal for biomedical applications. Dynamic Light Scattering (DLS) revealed a hydrodynamic size of 55 nm in the hydrated state, while a negative zeta potential of −17 mV indicated colloidal stability. C-AuNPs exhibited significant antibacterial activity against both Gram-negative and Gram-positive bacterial strains, surpassing the performance of levofloxacin. Lower Minimum Inhibitory Concentration (MIC) values against bacterial strains further supported their enhanced efficacy, potentially due to interactions with bacterial cell membranes. Furthermore, C-AuNPs demonstrated potent inhibition of α-amylase and α-glucosidase enzymes involved in glucose metabolism, with IC50 values comparable to the anti-diabetic drug acarbose. This suggests their potential as anti-diabetic agents, with the ability to regulate blood sugar levels. C-AuNPs exhibit unique optical, structural, and electrostatic properties, making them promising candidates for diverse biomedical applications. Their small size, stability, antibacterial efficacy, and anti-diabetic properties position C-AuNPs as valuable assets in the realm of nanomedicine and therapeutics, warranting further exploration and development.

The development, preparation and characterisation of novel pyran derivatives and their biological assessment

We have synthesized some novel derivatives of 4-(1-(2, 4-dinitrophenyl)-3-phenyl-1H-pyrazol-4-yl)-7,7-dimet hyl-2-(methylamino)-3nitro-6,7,8,8a-tetrahydro-4H-chromen-5(4aH)-one by the multicomponent reaction of pyrazole aldehydes derivatives, N-methyl-1-(methylthio)-2-nitroethenamine (NMSM) and 5,5-dimethylcyclohexane-1,3-dione. The synthesised compounds are confirmed by 1H NMR, IR and Mass Spectroscopy and they were then tested for antioxidant activities. In terms of antioxidant activity, compounds C-7 and C-1 were found to have the greatest and lowest levels respectively. Against Enterobacter aerogenes, compound C-5 exhibited the lowest minimum inhibitory concentration value.

In vitro characterization and molecular epidemiology of Cryptococcus spp. isolates from non-HIV patients in Guangdong, China.

The burden of cryptococcosis in mainland China is enormous. However, the in vitro characterization and molecular epidemiology in Guangdong, a key region with a high incidence of fungal infection in China, are not clear. From January 1, 2010, to March 31, 2019, clinical strains of Cryptococcus were collected from six medical centres in Guangdong. The clinical information and characteristics of the strains were analysed. Furthermore, molecular types were determined. A total of 84 strains were collected, mostly from male and young or middle-aged adult patients. Pulmonary and cerebral infections (82.1%) were most common. All strains were Cryptococcus neoformans, grew well at 37°C and had capsules around their cells. One melanin- and urea- and one melanin+ and urea- variants were found. Although most strains exhibited a low minimum inhibitory concentration (MIC) value for voriconazole (mean: 0.04 μg/mL) and posaconazole (mean: 0.12 μg/mL), the results for these isolates showed a high degree of variation in the MIC values of fluconazole and 5-fluorocytosine, and resistance was observed for 4 out of 6 drugs. A significant proportion of these strains had MIC values near the ECV values, particularly in the case of amphotericin B. The proportion of strains near the clinical breakpoints was as follows: fluconazole: 3.66%; voriconazole: 3.66%; itraconazole: 6.10%; posaconazole: 13.41%; amphotericin B: 84.15%; 5-fluorocytosine: 2.44%. These strains were highly homogeneous and were dominated by the Grubii variant (95.2%), VNI (94.0%), α mating (100%), and ST5 (89.3%) genotypes. Other rare types, including ST4, 31, 278, 7, 57 and 106, were also found. Phenotypically variant and non-wild-type strains were found in Guangdong, and a significant proportion of these strains had MIC values near the ECV values towards the 6 antifungal drugs, and resistance was observed for 4 out of 6 drugs. The molecular type was highly homogeneous but compositionally diverse, with rare types found. Enhanced surveillance of the aetiology and evolution and continuous monitoring of antifungal susceptibility are needed to provide references for decision-making in the health sector and optimization of disease prevention and control.

Antibacterial and biofilm disruptive nonribosomal lipopeptides from Streptomyces parvulus against multidrug-resistant bacterial infections

BackgroundIn recent years, new drugs for the treatment of various diseases, thereby the emergence of antimicrobial resistance tremendously increased because of the increased consumption rate of various drugs. However, the irrational use of antibiotics increases the microbial resistance along with that the frequency of mortality associated with infections is higher. Broad-spectrum antibiotics were effectively against various bacteria and the unrestricted application of antibiotics lead to the emergence of drug resistance. The present study was aimed to detect the antibacterial properties of lipopeptide novel drug producing Streptomyces parvulus. MethodsA lipopeptide-producing S. parvulus was isolated from the soil sample. The inhibitory effect of lipopeptide was detected against Gram-positive and Gram-negative bacteria. Bactericidal activity and minimum inhibitory concentration (MIC) were assayed. The IC50 value was analysed against ovarian and human melanoma cell lines. The experimental mouse model was infected withKlebsiella pneumoniae and treated with lipopeptide and bactericidal activity was determined. ResultsThe results indicated that the antibacterial activity of lipopeptide ranges from 13 ± 1 mm to 32 ± 2 mm against Gram-positive and Gram-negative strains. The lowest MIC value was noted as 1.5 ± 0.1 µg/mL against K. pneumoniae and the highest against E. aerogenes (7.5 ± 0.2 µg/mL). The IC50 value was considerably high for the ovarian cell lines and human melanoma cell lines (426 µg/mL and 503 µg/mL). At 25 µg/mL concentration of lipopeptide, only 16.4% inhibition was observed in the ovarian cell line whereas 20.2% inhibition was achieved at this concentration in the human melanoma cell line. Lipopeptide inhibited bacterial growth and was completely inhibited at a concentration of 20 µg/mL. Lipopeptide reduced bacterial load in experimental mice compared to control (p < 0.05). ConclusionLipopeptide activity and its non-toxic nature reveal that it may serve as a lead molecule in the development of a novel drug.

Psidium guajava extract-mediated iron, vanadium, and silver ternary oxide nanoparticles for sustainable antibacterial applications

This study investigated the antimicrobial potential and structural characteristics of Fe-Ag-V nanoparticles synthesized from Psidium guajava leaves extract. The nanoparticles demonstrate significant antimicrobial efficacy against bacterial strains, including Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Bacillus cereus, with low Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values. Synthesized eco-consciously, they offer promise in combating infections while supporting sustainability goals. Structural analysis via X-ray diffraction (XRD) and Dynamic Light Scattering (DLS) confirms their face-centered cubic (FCC) crystal structure and rod-like morphology with internal pores, suggesting diverse applications. DLS revealed an average particle diameter of approximately 94.59 nm, enhancing reactivity in catalysis and drug delivery. This study emphasizes the antimicrobial efficacy and structural attributes of Psidium guajava Extract-Derived Fe-Ag-V nanoparticles, suggesting their potential across scientific disciplines, from medicine to materials science, for combating infectious diseases sustainably.