Limonene inhibits virulence associated traits in Candida albicans: In-vitro and in-silico studies

Features of the rare pathogen Meyerozyma guilliermondii strain SO and comprehensive in silico analyses of its adherence-contributing virulence factor agglutinin-like sequences

Meyerozyma guilliermondii is a rare yeast pathogen contributing to the deadly invasive candidiasis. M. guilliermondii strain SO, as a promising protein expression host, showed 99% proteome similarity with the clinically isolated ATCC 6260 (type strain) in a recent comparative genomic analysis. However, their in vitro virulence features and in vivo pathogenicity were uncharacterized. This study aimed to characterize the in vitro and in vivo pathogenicity of M. guilliermondii strain SO and analyze its Als proteins (MgAls) via comprehensive bioinformatics approaches. M. guilliermondii strain SO showed lower and higher sensitivity towards β-mercaptoethanol and lithium, respectively than the avirulent S. cerevisiae but exhibited the same tolerance towards cell wall-perturbing Congo Red with C. albicans. With 7.5× higher biofilm mass, M. guilliermondii strain SO also demonstrated 75% higher mortality rate in the zebrafish embryos with a thicker biofilm layer on the chorion compared to the avirulent S. cerevisiae. Being one of the most important Candida adhesins, sequence and structural analyses of four statistically identified MgAls showed that MgAls1056 was predicted to exhibit the most conserved amyloid-forming regions, tandem repeat domain and peptide binding cavity (PBC) compared to C. albicans Als3. Favoured from the predicted largest ligand binding site and druggable pockets, it showed the highest affinity towards hepta-threonine. Non-PBC druggable pockets in the most potent virulence contributing MgAls1056 provide new insights into developing antifungal drugs targeting non-albicans Candida spp. Virtual screening of available synthetic or natural bioactive compounds and MgAls1056 deletion from the fungal genome should be further performed and validated experimentally.

Monoterpenes as potential antifungal molecules against Candida cell membranes: in-vitro and in-silico studies

Azoles are the frequently used antifungal drugs that target the enzyme lanosterol 14 α-demethylase (erg11p). This enzyme plays a vital role in ergosterol biosynthesis and hence maintainenance of cell membrane fluidity and integrity. The emergence of resistance to azoles and their fungistatic nature against several fungal pathogens is the major challenge to combat invasive candidiasis. Therefore, there is an urgent need to discover new antifungals with better efficacy. This study targets erg11 protein using in silico approach and identifies the monoterpene compounds (α-terpineol, carveol, and terpinene-4-ol) based on docking score and ligand interaction analysis. Further dynamic behavior of best-docked compounds with erg11p was analyzed by various parameters of MD simulation. The binding free energy of selected compounds towards the definitive pocket was also calculated. To further investigate the antifungal activity of selected compounds, in vitro studies were conducted on C. albicans. Studies thus suggest that the proposed the mechanism of antifungal action of test compounds involves targeting the ergosterol biosynthetic pathway. The compounds were explored for their effect on the disruption of membrane integrity by studying ERG11gene expression analysis, scanning electron microscopy, PI uptake (fluorescence microscopy,) and H+-extrusion. The results suggest that the selected monoterpenes are safer natural antifungals that disrupt membrane integrity by inhibiting ergosterol biosynthesis and other membrane associated structures.

1,3,4-oxadiazole derivatives: synthesis, characterization, antifungal activity, DNA binding investigations, TD-DFT calculations, and molecular modelling

1,3,4-Oxadiazole-based heterocyclic analogs (3a-3m) were synthesized via cyclization of Schiff bases with substituted aldehydes in the presence of bromine and acetic acid. The structural clarification of synthesized molecules was carried out with various spectroscopic techniques such as FT-IR,1H and 13C-NMR, UV-visible spectroscopy, and mass spectrometry. In-vitro antifungal activity was performed against C. albicans, C. glabrata and C. tropicalis and analogs 3g, 3i, and 3m showed potent MIC at 200 µg/ml and excellent ZOI measurements of 17-21 nm. The cell viability on Huh7 for lead molecules 3g, 3i, and 3m was found to be 99.5%, 92.3%, and 86.9% at 20, 10, and 20 μM, respectively. The antioxidant activity of molecules 3 g, 3i, and 3 m was estimated and exhibited great IC50 values of 0.104 ± 0.021, 0.145 ± 0.05, and 0.165 ± 0.018 μg/mL with DPPH and 0.107 ± 0.04, 0.191 ± 0.12, and 0.106 ± 0.08 with H2O2, respectively. The binding interaction mode for the lead molecules was also carried out with Ct-DNA using the absorption, emission, CV, CD, and Time resolve fluorescence techniques. The results showed good binding constant (Kb) values of 9.1 × 105, 9.94 × 105, and 9.32 × 105 M-1 for 3g, 3i, and 3m, respectively. TD-DFT study of compounds 3g, 3i, and 3m was done to find out HOMO/LUMO energy levels, surface study of the molecular electrostatic potential, Mulliken population analysis, and natural bond orbitals showing the linkages between the donors and acceptors.Molecular docking of three lead analogs with PDB ID: 1BNA and molecular modelling of compounds 3g, 3i, and 3m with C. albicans CYP51 protein (PDB ID: 5FSA) were carried out.Communicated by Ramaswamy H. Sarma.

Different essential oils can inhibit Candida albicans biofilm formation on acrylic resin by suppressing aspartic proteinase: In vitro and in silico approaches

INTRODUCTION

Cymbopogon martini, Syzygium aromaticum, and Cupressus sempervirens are used for antimicrobial purposes in the worldwide. Both their extracts and essential oil contents are rich in active ingredients.

OBJECTIVE

The aim of this study was to investigate the inhibitory effect of Cymbopogon martini essential oil (CMEO), Syzygium aromaticum essential oil (SAEO) and Cupressus sempervirens essential oil (CSEO) on Candida albicans biofilm formation on heat-polymerized polymethyl methacrylate (PMMA) samples in vitro and in silico.

MATERIALS AND METHODS

Essential oil contents with anticandidal potential were determined by Gas Chromatography-Mass Spectrometry. Following C. albicans adhesion, PMMA samples were treated independently with Corega® and each essential oil. The anticandidal activity of the essential oils was determined by spectrophotometric absorbance measurement at 600 nm, taking into account the cultures of each sample. The cytotoxicity evaluation of essential oils was performed by MTT Colorimetric assay. The software package AutoDockTools (1.5.6) was used for the in silico studies. The effect of essential oil content on the inhibition of Secreted aspartic proteinase (SAP2) was evaluated considering the Ligand@SAP2 complex formation.

RESULTS

2% of CMEO and 5% of SAEO exhibited higher anticandidal activity than Corega® (p < 0.05), whereas Corega® had higher anticandidal activity than 2% and 5% of CSEO (p < 0.05). The cytotoxicity of essential oils on NIH/3T3 cells after 24 h was found to be 2.41 for CSEO, 2.84 for CMEO, and 2.85 µg/mL for SAEO. The results of the in silico study showed that citronellol from CMEO, chavibetol (m-eugenol) from SAEO and β-pinene from CSEO each had the highest effect on the inhibition of SAP2. The highest binding affinity value was found for citronellol at -5.3 kcal/mol.

CONCLUSIONS

The biofilm formation of C. albicans onto acrylic resin was inhibited by CMEO, SAEO and CSEO at a concentration of 2% through in vitro assay. The most effective inhibition was determined to be due to citronellol in CMEO through in silico analysis.

A Convenient One-Pot Synthesis of Novel Benzimidazole-Thiazinone Derivatives and Their Antimicrobial Activity

Background: The increasing prevalence of antimicrobial resistant highlights the urgent need for the new therapeutic agents. This study aimed to design and synthesize fused tricyclic benzimidazole-thiazinone derivatives (CS1-CS10) through a convenient method and evaluate their antimicrobial activity against various microorganisms. Methods: A series of fused tricyclic benzimidazole-thiazinone derivatives was rationally designed and synthesized in one pot by the reaction between trans substituted acrylic acids and 1H-benzo[d]imidazole-2-thiol using coupling reagent TBTU (2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate). The structure of these compounds was confirmed through various spectroscopic techniques like IR, 1H and 13C NMR, the DEPT and 2D-HMQC NMR techniques were also performed to confirm the relation of both carbon and proton. Further, the compounds were in vitro evaluated for their effectiveness against the Candida species and a panel of standard bacterial isolates. Results: The synthesized compounds showed moderate antimicrobial activity. Among all of the compounds, CS4 exhibited potent inhibition against Pseudomonas aeruginosa and Escherichia coli at 256 and 512 μg/mL concentrations, respectively. Additional research indicated that compound CS4 demonstrated a synergistic effect after combining with the standard antibacterial drug ciprofloxacin. Conclusions: These results suggest that CS4 is the best-synthesized antibacterial agent particularly in combination therapies. These findings highlight its promise for further development as a novel antibacterial agent.

Enhancing environmental sustainability: Butea monosperma leaves as a key component in WO3-based composites for water purification and therapeutic applications

In this research, a novel nano-biocomposite material, namely, tungsten trioxide-Butea monosperma leaf powder (WO3@BLP), is an effective and eco-friendly adsorbent used for the mitigation of congo red (CR) and crystal violet (CV) dyes from its aqueous phase. The as-prepared WO3@BLP was characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), DLS analysis, and TGA. Many factors such as solution pH, WO3@BLP dose, temperature, contact time, and initial CR/CV dye concentrations were exploited to monitor the adsorption efficiency of WO3@BLP composites. The biosorption of both CR and CV dyes followed the Langmuir isotherm, with maximum adsorption capacities (qmax) reaching 84.91 mg g-1 for CR at pH 2.3 and 162.75 mg g-1 for CV at pH 8, fitting of kinetics data to the PSO model with closed values of qeexp (mg g-1) and qecal (mg g-1), i.e., 25.69 to 25.38 mg g-1 for CR dye and 29.06 to 29.08 mg g-1 for CV dye. The interaction mechanism behind the adsorption of CR and CV dyes onto the WO3@BLP bionanocomposite includes electrostatic interaction and surface complexation. The synthesized materials were tested for antifungal activity against three different Candida cells, i.e., C. albicans ATCC 90028, C. glabrata ATCC 90030, and C. tropicalis ATCC 750, by using broth dilution method on the minimum inhibiting concentration (MIC). Furthermore, the cytotoxicity of nano-formulated WO3@BLP was studied by in vitro hemolytic assay on a human host. Overall, this research presents a pioneering nano-biocomposite, WO3@BLP, as a sustainable adsorbent for CR and CV dye removal, adhering to Langmuir isotherm and pseudo-second-order kinetics. Its multifaceted approach includes elucidating interaction mechanisms, demonstrating antifungal activity, and assessing cytotoxicity, marking a significant advancement in environmental remediation.

Pharmacological potential of limonene against opportunistic fungi: Impact on Candida virulence

The present article aims to evaluate the antifungal and antivirulence effect of the phytoconstituent Limonene against Candida spp. Antifungal assays were performed, where the concentration capable of inhibiting 50 % of fungal growth, the growth inhibition curve, the minimum fungicidal concentration, the evaluation of the modifying effect with fluconazole, the inhibitory effect of the substances on the morphological transition of Candida spp. and the statistical analysis of the results were determined. With this study, it was seen that limonene demonstrated growth inhibition for the strains tested and when associated the natural compound with Fluconazole, there was potentiation of the effect of the drug, since the inhibition of growth by the combination occurred at lower concentrations against all strains tested, when compared to the drug alone, which inhibited growth at the highest concentration. In the test to determine the Minimum Fungicidal Concentration of the products tested alone and in combination, it was found that in the case of Candida strains, growth inhibition by limonene occurred at a concentration of 1024 μg/mL. For Fluconazole, growth impairment ranged from > 1024 μg/mL to 256 μg/mL for the strains. And when combined, limonene potentiated the action of FCZ, making fungal colonization unfeasible at concentrations below 1024 μg/mL. Regarding the morphological transition from yeast to hyphae, limonene was used at concentrations of 1024 μg/mL and 512 μg/mL, and it was found that, for CA and CK, the filaments were reduced in number and size at the highest concentration and against CT, the morphological transition from yeast to hyphae/pseudohyphae was totally inhibited, and if compared to the growth control, limonene was able to reduce fungal growth at concentrations greater than 512 μg/mL. This compound has antimicrobial activity described, due to its ability to interfere in the gene expression of the fungus, the limited therapeutic options and the recent emergence of multidrug-resistant Candida species represent a significant challenge for human medicine and highlight the need for new therapeutic approaches, and in this study a great potential of limonene was revealed in relation to the perspective of increasing the efficiency of commercial drug. This work can bring an important contribution to the scientific database, while emphasizing that in-depth studies and tests on the subject, in order to better investigate its effectiveness and mechanisms by which they exert their effects, are still necessary.

Citrus limon Essential Oil: Chemical Composition and Selected Biological Properties Focusing on the Antimicrobial (In Vitro, In Situ), Antibiofilm, Insecticidal Activity and Preservative Effect against Salmonella enterica Inoculated in Carrot

New goals for industry and science have led to increased awareness of food safety and healthier living in the modern era. Here, one of the challenges in food quality assurance is the presence of pathogenic microorganisms. As planktonic cells can form biofilms and go into a sessile state, microorganisms are now more resistant to broad-spectrum antibiotics. Due to their proven antibacterial properties, essential oils represent a potential option to prevent food spoilage in the search for effective natural preservatives. In this study, the chemical profile of Citrus limon essential oil (CLEO) was evaluated. GC-MS analysis revealed that limonene (60.7%), β-pinene (12.6%), and γ-terpinene (10.3%) are common constituents of CLEO, which prompted further research on antibacterial and antibiofilm properties. Minimum inhibitory concentration (MIC) values showed that CLEO generally exhibits acceptable antibacterial properties. In addition, in situ antimicrobial research revealed that vapour-phase CLEO can arrest the growth of Candida and Y. enterocolitica species on specific food models, indicating the potential of CLEO as a preservative. The antibiofilm properties of CLEO were evaluated by MIC assays, crystal violet assays, and MALDI-TOF MS analysis against S. enterica biofilm. The results of the MIC and crystal violet assays showed that CLEO has strong antibiofilm activity. In addition, the data obtained by MALDI-TOF MS investigation showed that CLEO altered the protein profiles of the bacteria studied on glass and stainless-steel surfaces. Our study also found a positive antimicrobial effect of CLEO against S. enterica. The anti-Salmonella activity of CLEO in vacuum-packed sous vide carrot samples was slightly stronger than in controls. These results highlight the advantages of the antibacterial and antibiofilm properties of CLEO, suggesting potential applications in food preservation.

Bibliometric analysis and thematic review of Candida pathogenesis: Fundamental omics to applications as potential antifungal drugs and vaccines

Invasive candidiasis caused by the pathogenic Candida yeast species has resulted in elevating global mortality. The pathogenicity of Candida spp. is not only originated from its primary invasive yeast-to-hyphal transition; virulence factors (transcription factors, adhesins, invasins, and enzymes), biofilm, antifungal drug resistance, stress tolerance, and metabolic adaptation have also contributed to a greater clinical burden. However, the current research theme in fungal pathogenicity could hardly be delineated with the increasing research output. Therefore, our study analysed the research trends in Candida pathogenesis over the past 37 years via a bibliometric approach against the Scopus and Web of Science databases. Based on the 3993 unique documents retrieved, significant international collaborations among researchers were observed, especially between Germany (Bernhard Hube) and the UK (Julian Naglik), whose focuses are on Candida proteinases, adhesins, and candidalysin. The prominent researchers (Neils Gow, Alistair Brown, and Frank Odds) at the University of Exeter and the University of Aberdeen (second top performing affiliation) UK contribute significantly to the mechanisms of Candida adaptation, tolerance, and stress response. However, the science mapping of co-citation analysis performed herein could not identify a hub representative of subsequent work since the clusters were semi-redundant. The co-word analysis that was otherwise adopted, revealed three research clusters; the cluster-based thematic analyses indicated the severeness of Candida biofilm and antifungal resistance as well as the elevating trend on molecular mechanism elucidation for drug screening and repurposing. Importantly, the in vivo pathogen adaptation and interactions with hosts are crucial for potential vaccine development.

Naphthyl bearing 1,3,4-thiadiazoleacetamides targeting the parasitic folate pathway as anti-infectious agents: in silico, synthesis, and biological approach

Malaria is still a complex and lethal parasitic infectious disease, despite the availability of effective antimalarial drugs. Resistance of malaria parasites to current treatments necessitates new antimalarials targeting P. falciparum proteins. The present study reported the design and synthesis of a series of a 2-(4-substituted piperazin-1-yl)-N-(5-((naphthalen-2-yloxy)methyl)-1,3,4-thiadiazol-2-yl)acetamide hybrids for the inhibition of Plasmodium falciparum dihydrofolate reductase (PfDHFR) using computational biology tools followed by chemical synthesis, structural characterization, and functional analysis. The synthesized compounds were evaluated for their in vitro antimalarial activity against CQ-sensitive PfNF54 and CQ-resistant PfW2 strain. Compounds T5 and T6 are the most active compounds having anti-plasmodial activity against PfNF54 with IC50 values of 0.94 and 3.46 μM respectively. Compound T8 is the most active against the PfW2 strain having an IC50 of 3.91 μM. Further, these active hybrids (T5, T6, and T8) were also evaluated for enzyme inhibition assay against PfDHFR. All the tested compounds were non-toxic against the Hek293 cell line with good selectivity indices. Hemolysis assay also showed non-toxicity of these compounds on normal uninfected human RBCs. In silico molecular docking studies were carried out in the binding pocket of both the wild-type and quadruple mutant Pf-DHFR-TS to gain further insights into probable modes of action of active compounds. ADME prediction and physiochemical properties support their drug-likeness. Additionally, they were screened for antileishmanial activity against L. donovani promastigotes to explore broader applications. Thus, this study provides molecular frameworks for developing potent antimalarials and antileishmanial agents.

In Vitro Screening of Antimicrobial and Anti-Coagulant Activities, ADME Profiling, and Molecular Docking Study of Citrus limon L. and Citrus paradisi L. Cold-Pressed Volatile Oils

Citrus, which belongs to the Rutaceae family, is a very widespread genus in the Mediterranean Basin. In Tunisia, various parts of these spontaneous or cultivated plants are used in common dishes or in traditional medicine. The purpose of this work was to investigate C. limon and C. paradisi essential oil (EO). The samples were studied for their chemical composition using SPME/MS, as well as their antibacterial and antifungal activities. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) methods were used to evaluate the anticoagulant potentialities. The obtained results show that both essential oils are rich in monoterpenes hydrocarbons, whereby limonene is the main compound in C. paradisi EO (86.8%) and C. limon EO (60.6%). Moreover, C. paradisi EO contains β-pinene (13.3%), sabinene (2.2%) and α-pinene (2.1%). The antibacterial assay of the essential oils showed important bactericidal and fungicidal effects against all strains tested. In fact, the MICs values of C. limon EO ranged from 0.625 to 2.5 mg/mL against all Gram-positive and Gram-negative bacteria, and from 6.25 to 12.5 mg/mL for Candida spp. strains, while C. paradisi EO was more active against all bacteria with low MICs values ranging from 0.192 to 0.786 mg/mL, and about 1.5 mg/mL against Candida species. Both tested Citrus EOs exhibited interesting anticoagulant activities as compared to heparin. The molecular docking approach was used to study the binding affinity and molecular interactions of all identified compounds with active sites of cytidine deaminase from Klebsiella pneumoniae (PDB: 6K63) and the C (30) carotenoid dehydrosqualene synthase from Staphylococcus aureus (PDB: 2ZCQ). The obtained results show that limonene had the highest binding score of -4.6 kcal.mol-1 with 6K63 enzyme, and -6.7 kcal.mol-1 with 2ZCQ receptor. The ADME profiling of the major constituents confirmed their important pharmacokinetic and drug-like properties. Hence, the obtained results highlight the potential use of both C. limon and C. paradisi essential oils as sources of bioactive compounds with antibacterial, antifungal, and anti-coagulant activities.

Current and Potential Applications of Monoterpenes and Their Derivatives in Oral Health Care

Plant products have been employed in medicine for centuries. As the world becomes more health-conscious, there is a growing interest in natural and minimally processed products for oral health care. This has led to an increase in research into the bioactive compounds found in plant products, particularly monoterpenes. Monoterpenes are known to have beneficial biological properties, but the specific mechanisms by which they exert their effects are not yet fully understood. Despite this, some monoterpenes are already being used in oral health care. For example, thymol, which has antibacterial properties, is an ingredient in varnish used for caries prevention. In addition to this, monoterpenes have also demonstrated antifungal, antiviral, and anti-inflammatory properties, making them versatile for various applications. As research continues, there is potential for even more discoveries regarding the benefits of monoterpenes in oral health care. This narrative literature review gives an overview of the biological properties and current and potential applications of selected monoterpenes and their derivatives in oral health care. These compounds demonstrate promising potential for future medical development, and their applications in future research are expected to expand.

Chemical Composition and Anti-Candida Activity of Mentha suaveolens Ehrh. Essential Oils Obtained by Different Distillation Processes

A comparative study on essential oils extracted from Mentha suaveolens Ehrh. from Italy is reported. Two extraction procedures were investigated: hydrodistillation and steam distillation, carried out as a continuous and fractionated procedure. Fresh and dried plant material from two harvests was used. The hydrodistillation method yielded a higher amount of essential oil. The dried plant was significantly richer in essential oil per kg of starting plant material. Gas chromatography-mass spectrometry analysis of 112 samples showed that the essential oils belong to the piperitenone oxide-rich chemotype. In addition, piperitenone, p-cymen-8-ol, and limonene were among the most abundant compounds in the different samples. A higher amount of piperitenone oxide was obtained by hydrodistillation, while steam distillation gave a higher percentage of piperitenone and limonene. The essential oils were characterized for their anti-Candida albicans activity; higher potency was observed for the samples rich in piperitenone oxide, with MIC values ranging from 0.39 to 0.78 mg·mL-1 (0.039% and 0.078% p/v). The results of this work provide a deep insight into the methodology of essential oil extraction and the associated chemical variability of M. suaveolens Ehrh. Some of the essential oils are potent against C. albicans and could be considered for potential use in therapy.

d-Limonene complexed with cyclodextrin attenuates cardiac arrhythmias in an experimental model of doxorubicin-induced cardiotoxicity: Possible involvement of calcium/calmodulin-dependent protein kinase type II

BACKGROUND

Arrhythmias are one manifestation of the cardiotoxicity that results from doxorubicin (Doxo) administration. Although cardiotoxicity is an anticipated outcome in anticancer therapies, there is still a lack of treatment options available for its effective management. This study sought to evaluate the possible cardioprotective effect of complex d-limonene (DL) plus hydroxypropyl-β-cyclodextrin (HβDL) during treatment with Doxo, focusing on the arrhythmic feature.

METHODS

Cardiotoxicity was induced in Swiss mice with Doxo 20 mg/kg, with 10 mg/kg of HβDL being administered 30 min before the Doxo. Plasma CK-MB and LDH levels were analyzed. Cellular excitability and susceptibility to cardiac and cardiomyocyte arrhythmias were evaluated using in vivo (pharmacological cardiac stress) and in vitro (burst pacing) ECG protocols. Ca2+ dynamics were also investigated. The expression of CaMKII and its activation by phosphorylation and oxidation were evaluated by western blot, and molecular docking was used to analyze the possible interaction between DL and CaMKII.

RESULTS

Electrocardiograms showed that administration of 10 mg/kg of HβDL prevented Doxo-induced widening of the QRS complex and QT interval. HβDL also prevented cardiomyocyte electrophysiological changes that trigger cellular arrhythmias, such as increases in action potential duration and variability; decreased the occurrence of delayed afterdepolarizations (DADs) and triggered activities (TAs), and reduced the incidence of arrhythmia in vivo. Ca2+ waves and CaMKII overactivation caused by phosphorylation and oxidation were also decreased. In the in silico study, DL showed potential inhibitory interaction with CaMKII.

CONCLUSION

Our results show that 10 mg/kg of βDL protects the heart against Doxo-induced cardiotoxicity arrhythmias, and that this is probably due to its inhibitory effect on CaMKII hyperactivation.

Synthesis, antifungal evaluation, and molecular docking studies of steroidal thiazolopyrimidines

A series of steroidal thiazolopyrimidine derivatives were developed and evaluated for their antifungal properties against Candida species using steroid as the basic skeletonand a thiazolopyrimidine heterocycle as a pharmacophore in the D-ring. Dehydroepiandrosterone, aromatic aldehydes, and 2-aminothiazole were used in a one-pot multicomponent reaction with silica sulphuric acid to generate the target molecules. Additionally, molecular docking studies were conducted to determine how synthesized steroidal derivatives interacted with the amino acid residues of CYP51 ofCandida albicans.

Identification of new oxospiro chromane quinoline-carboxylate antimalarials that arrest parasite growth at ring stage

Malaria still threatens half the globe population despite successful Artemisinin-based combination therapy. One of the reasons for our inability to eradicate malaria is the emergence of resistance to current antimalarials. Thus, there is a need to develop new antimalarials targeting Plasmodium proteins. The present study reported the design and synthesis of 4, 6 and 7-substituted quinoline-3-carboxylates 9(a-o) and carboxylic acids 10(a-b) for the inhibition of Plasmodium N-Myristoyltransferases (NMTs) using computational biology tools followed by chemical synthesis and functional analysis. The designed compounds exhibited a glide score of -9.241 to -6.960 kcal/mol for PvNMT and -7.538 kcal/mol for PfNMT model proteins. Development of the synthesized compounds was established via NMR, HRMS and single crystal X-ray diffraction study. The synthesized compounds were evaluated for their in vitro antimalarial efficacy against CQ-sensitive Pf3D7 and CQ-resistant PfINDO lines followed by cell toxicity evaluation. In silico results highlighted the compound ethyl 6-methyl-4-(naphthalen-2-yloxy)quinoline-3-carboxylate (9a) as a promising inhibitor with a glide score of -9.084 kcal/mol for PvNMT and -6.975 kcal/mol for PfNMT with IC50 values of 6.58 µM for Pf3D7 line. Furthermore, compounds 9n and 9o exhibited excellent anti-plasmodial activity (Pf3D7 IC50 = 3.96, 6.71 µM, and PfINDO IC50 = 6.38, 2.8 µM, respectively). The conformational stability of 9a with the active site of the target protein was analyzed through MD simulation and was found concordance with in vitro results. Thus, our study provides scaffolds for the development of potent antimalarials targeting both Plasmodium vivax and Plasmodium falciparum.Communicated by Ramaswamy H. Sarma.

Oxadiazole Schiff Base as Fe3+ Ion Chemosensor: "Turn-off" Fluorescent, Biological and Computational Studies

Compound, (E)-5-(4-((thiophen-2-ylmethylene)amino)phenyl)-1,3,4-oxadiazole-2-thiol (3) was synthesized via condensation reaction of 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol with thiophene-2-carbaldehyde in ethanol. For the synthesis and structural confirmation the FT-IR, ¹H, ¹³C-NMR, UV-visible spectroscopy, and mass spectrometry were carried out. The long-term stability of the probe (3) was validated by the experimental as well as theoretical studies. The sensing behaviour of the compound 3 was monitored with various metal ions (Ca²⁺, Cr³⁺, Fe³⁺, Co²⁺, Mg²⁺, Na⁺, Ni²⁺, K⁺) using UV- Vis. and fluorescence spectroscopy techniques by various methods (effect of pH and density functional theory) which showing the most potent sensing behaviour with iron. Job's plot analysis confirmed the binding stoichiometry ratio 1:1 of Fe³⁺ ion and compound 3. The limit of detection (LOD), the limit of quantification (LOQ), and association constant (K_a) were calculated as 0.113 µM, 0.375 µM, and 5.226 × 10⁵ respectively. The sensing behavior was further confirmed through spectroscopic techniques (FT-IR and ¹H-NMR) and DFT calculations. The intercalative mode of binding of oxadiazole derivative 3 with Ct-DNA was supported through UV-Vis spectroscopy, fluorescence spectroscopy, viscosity, cyclic voltammetry, and circular dichroism measurements. The binding constant, Gibb's free energy, and stern-volmer constant were find out as 1.24 × 10⁵, -29.057 kJ/mol, and 1.82 × 10⁵ respectively. The cleavage activity of pBR322 plasmid DNA was also observed at 3 × 10^-5 M concentration of compound 3. The computational binding score through molecular docking study was obtained as -7.4 kcal/mol. Additionally, the antifungal activity for compound 3 was also screened using broth dilution and disc diffusion method against C. albicans strain. The synthesized compound 3 showed good potential scavenging antioxidant activity against DPPH and H₂O₂ free radicals.

Antifungal Effect and Inhibition of the Virulence Mechanism of D-Limonene against Candida parapsilosis

Yeasts from the Candida parapsilosis complex are clinically relevant due to their high virulence and pathogenicity potential, such as adherence to epithelial cells and emission of filamentous structures, as well as their low susceptibility to antifungals. D-limonene, a natural compound, emerges as a promising alternative with previously described antibacterial, antiparasitic, and antifungal activity; however, its mechanisms of action and antivirulence activity against C. parapsilosis complex species have not been elucidated. Therefore, in the present study, we aimed to evaluate the antifungal and antivirulence action, as well as the mechanism of action of D-limonene against isolates from this complex. D-limonene exhibited relevant antifungal activity against C. parapsilosis complex yeasts, as well as excellent antivirulence activity by inhibiting yeast morphogenesis and adherence to the human epithelium. Furthermore, the apoptotic mechanism induced by this compound, which is not induced by oxidative stress, represents an important target for the development of new antifungal drugs.