New azole antifungal agents with novel modes of action: Synthesis and biological studies of new tridentate ligands based on pyrazole and triazole

Exploring the Antimicrobial Potential of Novel 1,2,4-Triazole Conjugates with Pyrazole: Synthesis, Biological Activity and In Silico Docking

In the present study, a new series of 1,2,4-triazole linked pyrazole hybrids (5 a-5 l) were synthesized from dimethyl amino pyrazole (1) in good yield by three-step reaction. The chemical structures of the resulted compounds were thoroughly elucidated using spectral analyses such as IR, 1H-NMR, 13C-NMR, mass spectra and elemental analysis. The target compounds were screened for their antimicrobial activity against the various standard pathogenic Gram-(-ve) (E. coli, P. aeruginosa, K. pneumoniae, A. baumannii), and Gram-(+ve) (S. aureus, S. faecalis) microorganisms. According to the results obtained, in particular, compounds 5 b, 5 f, 5 h and 5 j was effective at inhibiting the antibacterial growth of all the bacteria's, having MIC values ranging 0.983-14.862 mg/mL and compared to moxifloxacin (1.391-22.01 mg mL-1). The most active compounds were chosen to interact with the DNA gyrase and topoisomerase-IV targets via molecular docking. These selected ligands interacted with 2XCO, 1S16 targets and docked into the active site of amino acids Ala-269, Gly-413, Asn-405, Ser-1182, Thr-1185, His-1186, His-1186, Lys-1189, and Trp-1213. Computational studies were carried out to design the precursor compounds to support the experimental part of the study. The pharmacokinetic properties, stability, and drug-likeness parameters of all target molecules were estimated using SwissADME and PkCSM protocols. The current study used in silico approaches combining e-pharmacophore modeling and structure-based molecular docking of targets to identify antimicrobial agents.

Inhibitive effect and mechanism of cinnamaldehyde on growth and OTA production of Aspergillus niger in vitro and in dried red chilies

Mould and mycotoxin contamination is an ongoing issue in agriculture and food industry. Production by Aspergillus niger DTZ-12 in Guizhou dried red chilies was found, leading to significant economic losses. In this study, the inhibitive efficacy (Effective Concentration, EC) of cinnamaldehyde (CIN), eugenol (EUG), carvacrol (CAR), and linalool (LIN) against A. niger DTZ-12 were evaluated. CIN with the best antifungal capacity was then investigated for the comprehensive inhibitory activity against A. niger DTZ-12 including mycelia, spores, and physiological activities. Results showed that CIN can effectively retard mycelial growth, spore germination, and OTA production of A. niger DTZ-12 in vitro and in dried red chilies during storage. At physiological level, CIN can increase cell membrane permeability by reducing the ergosterol, decrease ATP content and ATPase activity, and promote the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in cell. These results suggested that CIN displayed a great potential to be employed as a natural and effective alternative preservative during dried red chili storage.

Applications of Choline Chlorine based Deep Eutectic Solvents as Sustainable Media and catalyst in the synthesis of Heterocyclic Scaffolds

Abstract:

Deep eutectic solvents (DESs), also referred to as low transition temperature mixtures (LTTMs), have emerged as sustainable and cheap alternatives to conventional organic solvents in organic synthesis. This is attributed to their exceptional characteristics viz. easy preparation with readily available cheap materials, water compatibility, non-flammability, non-toxicity, biocompatibility, biodegradability, etc. All these properties label them as versatile and cost-effective green solvents. The first reported DES, choline chloride urea mixture has appeared as an innocuous solvent and catalyst in many organic transformations. This prospective DES combination has been applied extensively to the synthesis of a wide range of heterocyclic compounds including quinolones, spirooxindoles, etc. The conditions employed are relatively mild and do not require additional acid catalysts or organic solvents. This eco-friendly blend for the synthesis of heterocycles reports excellent yields of products with shorter reaction times and a simple workup procedure. Evaluating these merits, this review focuses on the recent literature published on the use of choline chlorine-based DESs in the synthesis of a few important heterocyclic compounds.

Toxic Mechanism and Biological Detoxification of Fumonisins

Food safety is related to the national economy and people's livelihood. Fumonisins are widely found in animal feed, feed raw materials, and human food. This can not only cause economic losses in animal husbandry but can also have carcinogenicity or teratogenicity and can be left in animal meat, eggs, and milk which may enter the human body and pose a serious threat to human health. Although there are many strategies to prevent fumonisins from entering the food chain, the traditional physical and chemical methods of mycotoxin removal have some disadvantages, such as an unstable effect, large nutrient loss, impact on the palatability of feed, and difficulty in mass production. As a safe, efficient, and environmentally friendly detoxification technology, biological detoxification attracts more and more attention from researchers and is gradually becoming an accepted technique. This work summarizes the toxic mechanism of fumonisins and highlights the advances of fumonisins in the detoxification of biological antioxidants, antagonistic microorganisms, and degradation mechanisms. Finally, the future challenges and focus of the biological control and degradation of fumonisins are discussed.

New 1,2,3-Triazole-Appended Bis-pyrazoles: Synthesis, Bioevaluation, and Molecular Docking

The present work describes design of a small library of new 1,2,3-triazole-appended bis-pyrazoles by using a molecular hybridization approach, and the synthesized hybrids were evaluated for their antifungal activity against different fungal strains, namely, Candida albicans, Cryptococcus neoformans, Candida glabrata, Candida tropicalis, Aspergillus niger, and Aspergillus fumigatus. All the compounds exhibited broad-spectrum activity against the tested fungal strains with excellent minimum inhibitory concentration values. The molecular docking study against sterol 14α-demethylase (CYP51) could provide valuable insights into the binding modes and affinity of these compounds. Furthermore, these compounds were also evaluated for their antioxidant activity, which also resulted in promising data.

Methyl linked pyrazoles: Synthetic and Medicinal Perspective

Pyrazoles, an important and well known class of the azole family, have been found to show a large number of applications in various fields specially of medicinal chemistry. Among pyrazole derivatives, particularly, methyl substituted pyrazoles have been reported as the potent medicinal scaffolds that exhibit a wide spectrum of biological activities. The present review is an attempt to highlight the detailed synthetic approaches for methyl substituted pyrazoles along with in depth analysis of their respective medical significances till March2021. It is hoped that literature sum-up in the form of present review article would certainly be a great tool to assist the medicinal chemists for generating new leads possessing pyrazole nucleus with high efficacy and less microbial resistance.

Competency of Clove and Cinnamon Essential Oil Fumigation against Toxigenic and Atoxigenic Aspergillus flavus Isolates

Aspergillus flavus is a frequent contaminant of maize grain. We isolated this fungus, determined the colony morphology and species (by internal transcribed spacer sequencing) and measured the aflatoxin content. The selected A. flavus fungi were placed into two groups, toxigenic and atoxigenic; both appeared similar morphologically, except that the atoxigenic group lacked sclerotia. An essential oil fumigation test with clove and cinnamon oils as antifungal products was performed on fungal conidial discs and fungal colonies in Petri plates. Cinnamon oil at 2.5 to 5.0 μL/plate markedly inhibited the mycelial growth from conidial discs of both strains, whereas clove oil showed less activity. The oils had different effects on fungal mycelia. The higher clove fumigation doses of 10.0 to 20.0 μL/plate controlled fungal growth, while cinnamon oil caused less inhibition. Compared with atoxigenic groups, toxigenic A. flavus responded stably. Within abnormal A. flavus hyphae, the essential oils degenerated the hyphal morphology, resulting in exfoliated flakes and shrinkage, which were related to fungal membrane injury and collapse of vacuoles and phialide. The treatments, especially those with cinnamon oil, increased the electroconductivity, which suggested a weak mycelium membrane structure. Moreover, the treatments with essential oils reduced the ergosterol content in mycelia and the aflatoxin accumulation in the culture broth. The fumigations with clove and cinnamon oils inhibited the development of both conidia and colonies of A. flavus in dose-dependent manners.

Broad-Spectrum Antifungal Agents: Fluorinated Aryl- and Heteroaryl-Substituted Hydrazones

Fluorinated aryl- and heteroaryl-substituted monohydrazones displayed excellent broad-spectrum activity against various fungal strains, including a panel of clinically relevant Candida auris strains relative to a control antifungal agent, voriconazole (VRC). These monohydrazones displayed less hemolysis of murine red blood cells than that of VRC at the same concentrations, possessed fungicidal activity in a time-kill study, and exhibited no mammalian cell cytotoxicity. In addition, these monohydrazones prevented the formation of biofilms that otherwise block antibiotic effectiveness and did not trigger the development of resistance when exposed to C. auris AR Bank # 0390 over 15 passages.

Synthesis and Antibacterial Evaluation of Mannich Bases Derived from 1,2,4-Triazole

The series of novel Mannich bases were synthesized and evaluated for their in vitro antibacterial activity against Gram-positive and Gram-negative bacterial strains. The results showed that all compounds were less active than the drugs used as reference, but some of them had moderate potency against Staphylococcus epidermidis ATCC 12228 and Bacillus subtilis ATCC 6633. The presence of a phenyl ring in the position 4 of piperazine seems to be necessary for antibacterial activity in this class of compounds.

Essential oils and their bioactive compounds as green preservatives against fungal and mycotoxin contamination of food commodities with special reference to their nanoencapsulation

Fungal and mycotoxin contamination of stored food items is of utmost concern throughout the world due to their hazardous effects on mammalian systems. Most of the synthetic chemicals used as preservatives have often been realised to be toxic to humans and also cause adverse environmental effects. In this respect, use of different plant products especially essential oils (EOs) and their bioactive compounds has been recognized as a green strategy and safer alternatives to grey synthetic chemicals in view of their long traditional use. The current nanoencapsulation technology has strengthened the prospective of EOs and their bioactive compounds in food preservation by enhancing their bioactivity and mitigating other problems regarding their large-scale application. Although, the antimicrobial potential of EOs and their bioactive compounds has been reviewed time to time by different food microbiologists, but very less is known about their mode of action. Based on these backgrounds, the present article provides an account on the antifungal and antimycotoxigenic mode of action of EOs as well as their bioactive compounds. In addition, the article also deals with the application of currently used nanoencapsulation approach to improve the stability and efficacy of EOs and their bioactive compounds against mycotoxigenic fungi causing deterioration of stored food items so as to recommend their large-scale application for safe preservation and enhancement of shelf life of food items during storage.

Antifungal effects of thymol and salicylic acid on cell membrane and mitochondria of Rhizopus stolonifer and their application in postharvest preservation of tomatoes

This study investigated effects of the simultaneous application of thymol and salicylic acid (SIM_TSA) on the target sites of Rhizopus stolonifer, as well as the defenceenzymes of postharvest tomato, when applied as edible coating. SIM_TSA induced the changes of ultrastructure and membrane integrity of R. stolonifer. When the concentrations of the fungistat increased, cells stained with propidium iodide and leakage of 260/280 nm-absorbing materials increased while ergosterol synthesis decreased, suggesting damage of cell membrane. Furthermore, SIM_TSA treatment significantly reduced the citric acid content and the activities of enzymes related to the tricarboxylic acid cycle, and increased the mitochondrial membrane potential and the reactive oxygen species, indicating damage of mitochondrial-related functions. Moreover, SIM_TSA edible coating increased the defence enzyme activities in tomato. Based on the results, SIM_TSA can be used as a potential preservation method for tomato as it showed a targeted effect on the cell membrane and mitochondria of R. stolonifer.

Rosmarinus officinalis L. (rosemary) as therapeutic and prophylactic agent

Rosmarinus officinalis L. (rosemary) is a medicinal plant native to the Mediterranean region and cultivated around the world. Besides the therapeutic purpose, it is commonly used as a condiment and food preservative. R. officinalis L. is constituted by bioactive molecules, the phytocompounds, responsible for implement several pharmacological activities, such as anti-inflammatory, antioxidant, antimicrobial, antiproliferative, antitumor and protective, inhibitory and attenuating activities. Thus, in vivo and in vitro studies were presented in this Review, approaching the therapeutic and prophylactic effects of R. officinalis L. on some physiological disorders caused by biochemical, chemical or biological agents. In this way, methodology, mechanisms, results, and conclusions were described. The main objective of this study was showing that plant products could be equivalent to the available medicines.

N,N'-diaryl-bishydrazones in a biphenyl platform: Broad spectrum antifungal agents

N,N'-Diaryl-bishydrazones of [1,1'-biphenyl]-3,4'-dicarboxaldehyde, [1,1'-biphenyl]-4,4'-dicarboxaldehyde, and 4,4'-bisacetyl-1,1-biphenyl exhibited excellent antifungal activity against a broad spectrum of filamentous and non-filamentous fungi. These N,N'-diaryl-bishydrazones displayed no antibacterial activity in contrast to previously reported N,N'-diamidino-bishydrazones and N-amidino-N'-aryl-bishydrazones. The leading candidate, 4,4'-bis((E)-1-(2-(4-fluorophenyl)hydrazono)ethyl)-1,1'-biphenyl, displayed less hemolysis of murine red blood cells at concentrations at or below that of a control antifungal agent (voriconazole), was fungistatic in a time-kill study, and possessed no mammalian cytotoxicity and no toxicity with respect to hERG inhibition.

Synthesis of a Series of Chalcones and Related Flavones and Evaluation of their Antibacterial and Antifungal Activities

Background:

A series of chalcones and flavones were synthesized from 2’-hydroxyacetophenone and substituted aromatic aldehydes via Simmons-Schmidt condensation followed by oxidative cyclization.

Methods:

Characterization of the obtained structures was established on the basis of their spectroscopic data. The synthesized compounds were screened for their antimicrobial activities against five bacterial strains (Citrobacter freundii, Staphylococcus aureus, Listeria monocytogenes, Salmonella braenderup, Escherichia coli.) and two fungal strains (Candida albicans, Candida krusei).

Results:

The in vitro bioassay results indicated that some target compounds displayed moderate (4d, 4e) to high (4a) antifungal activity against the pathogenic fungi C. albicans and C. krusei.

Conclusion:

For the antibacterial activity, only products 3d and 4d showed a weak antibacterial activity. These compounds can lead to the design of new drugs with specific antifungal activity.

Development of Antibacterial and Antifungal Triazole Chromium(III) and Cobalt(II) Complexes: Synthesis and Biological Activity Evaluations

In this work, six complexes (2⁻7) of Cr(III) and Co(II) transition metals with triazole ligands were synthesized and characterized. In addition, a new ligand, 3,5-bis(1,2,4-triazol-1-ylmethyl)toluene (1), was synthesized and full characterized. The complexes were obtained as air-stable solids and characterized by melting point, electrical conductivity, thermogravimetric analysis, and Raman, infrared and ultraviolet/visible spectroscopy. The analyses and spectral data showed that complexes 3⁻7 had 1:1 (M:L) stoichiometries and octahedral geometries, while 2 had a 1:2 (M:L) ratio, which was supported by DFT calculations. The complexes and their respective ligands were evaluated against bacterial and fungal strains with clinical relevance. All the complexes showed higher antibacterial and antifungal activities than the free ligands. The complexes were more active against fungi than against bacteria. The activities of the chromium complexes against Candida tropicalis are of great interest, as they showed minimum inhibitory concentration 50 (MIC₅₀) values between 7.8 and 15.6 μg mL^-1. Complexes 5 and 6 showed little effect on Vero cells, indicating that they are not cytotoxic. These results can provide an important platform for the design of new compounds with antibacterial and antifungal activities.

Risk management of ochratoxigenic fungi and ochratoxin A in maize grains by bioactive EVOH films containing individual components of some essential oils

Aspergillus steynii and Aspergillus tubingensis are possibly the main ochratoxin A (OTA) producing species in Aspergillus section Circumdati and section Nigri, respectively. OTA is a potent nephrotoxic, teratogenic, embryotoxic, genotoxic, neurotoxic, carcinogenic and immunosuppressive compound being cereals the first source of OTA in the diet. In this study bioactive ethylene-vinyl alcohol copolymer (EVOH) films containing cinnamaldehyde (CINHO), linalool (LIN), isoeugenol (IEG) or citral (CIT) which are major components of some plant essential oils (EOs) were produced and tested against A. steynii and A. tubingensis growth and OTA production in partly milled maize grains. Due to the favourable safety profile, these bioactive compounds are considered in the category "GRAS". The study was carried out under different water activity (0.96 and 0.99 a_w), and temperature (24 and 32 °C) conditions. ANOVA showed that class of film, fungal species, a_w and temperature and their interactions significantly affected growth rates (GR), ED₅₀ and ED₉₀ and the doses for total fungal growth inhibition and OTA production. The most effective EVOH films against both species were those containing CINHO. ED₅₀, ED₉₀ and doses for total growth and OTA inhibition were 165-405, 297-614, 333-666 μg of EVOH-CINHO/plate (25 g of maize grains), respectively, depending on environmental conditions. The least efficient were EVOH-LIN films. ED₅₀, ED₉₀ and doses for total growth and OTA inhibition were 2800->3330, >3330 and >3330 μg of EVOH-LIN/plate (25 g of maize grains), respectively. The effectiveness of the bioactive films increased with increasing doses. Overall, A. tubingensis was less sensitive to treatments than A. steynii. Depending on the species, a_w and temperature affected GR and OTA production in a different way. In A. steynii cultures, optimal growth occurred at 0.96 a_w and 32 °C while optimal OTA production happened at 0.99 a_w and 32 °C. In A. tubingensis cultures optimal growth happened at 0.99 a_w and 32 °C, although the best conditions for OTA production were 0.99 a_w and 24 °C. Thus, these species can be very competitive in warm climates and storage conditions. The EVOH-CINHO films followed by EVOH-IEG and EVOH-CIT films, designed in this study and applied in vapour phase, can be potent antifungal agents against A. steynii and A. tubingensis and strong inhibitors of OTA biosynthesis in maize grains at very low doses. This is the first study on the impact that interacting environmental conditions and bioactive films containing individual components of EOs have on the growth of these ochratoxigenic fungi and on OTA production in maize grains.

1,2,3-Triazole–quinazolin-4(3H)-one conjugates: evolution of ergosterol inhibitor as anticandidal agent

The present study describes the synthesis of 1,2,3-triazole–quinazolinone conjugates (5a–q) from ethyl 4-oxo-3-(prop-2-ynyl)-3,4-dihydroquinazoline-2-carboxylate and phenyl azide/substituted phenyl azides employing Cu(i) catalysed Huisgen 1,3-dipolar cycloaddition. The corresponding acids (6a–q) were obtained by hydrolysis of esters (5a–q) to study the effect of these functionalities on the biological activity. All synthesized compounds were screened for in vitro anticandidal evaluation against Candia albicans, Candida glabrata and Candida tropicalis strains. The results indicated that compound 5n showed potent anticandidal activity with IC₅₀ in the range of 8.4 to 14.6 μg mL⁻¹. Hemolytic activity using human red blood cells (hRBCs) and cytotoxicity by MTT assay on human embryonic kidney (HEK-293) cells revealed the non-toxic nature of the selected compounds. Growth kinetic study with compound 5n showed its fungicidal nature as no significant growth of Candida cells was observed even after 24 h. Cellular ergosterol content was determined in the presence of different concentrations of 5n to measure the activity of lanosterol 14α-demethylase indirectly. The results showed significant disruption of the ergosterol biosynthetic pathway through inhibition of lanosterol 14α-demethylase activity supported by docking studies (PDB: 5v5z). Overall, this study demonstrates the anticandidal potential of 5n which can serve as the lead for further structural optimization and SAR studies.

The present study elicits the synthesis of 1,2,3-triazole–quinazolinone conjugates (5a–q) as ergosterol inhibitors for Candida infections.

Antibiofilm and Antihyphal Activities of Cedar Leaf Essential Oil, Camphor, and Fenchone Derivatives against Candida albicans

Candida albicans can form biofilms composed of yeast, hyphal, and pseudohyphal elements, and C. albicans cells in the hyphal stage could be a virulence factor. The present study describes the chemical composition, antibiofilm, and antihyphal activities of cedar leaf essential oil (CLEO), which was found to possess remarkable antibiofilm activity against C. albicans but not to affect its planktonic cell growth. Nineteen components were identified in CLEO by gas chromatography/mass spectrometry, and phenolics were the main constituents. Of these, camphor, fenchone, fenchyl alcohol, α-thujone, and borneol significantly reduced C. albicans biofilm formation. Notably, treatments with CLEO, camphor, or fenchyl alcohol at 0.01% clearly inhibited hyphal formation, and this inhibition appeared to be largely responsible for their antibiofilm effects. Transcriptomic analyses indicated that camphor and fenchyl alcohol downregulated some hypha-specific and biofilm related genes (ECE1, ECE2, RBT1, and EED1). Furthermore, camphor and fenchyl alcohol reduced C. albicans virulence in a Caenorhabditis elegans nematode model. These results demonstrate CLEO, camphor, and fenchyl alcohol might be useful for controlling C. albicans infections.

Crystal structure of N′-(4-(dimethylamino)benzylidene)-5-phenyl-1H-pyrazole-3-carbohydrazide, C19H19N5O

C19H19N5O, triclinic, P1̅ (no. 2), a = 11.8865(6) Å, b = 12.6289(7) Å, c = 13.5579(7) Å, α = 74.552(2)°, β = 83.174(2)°, γ = 62.534(2)°, V = 1740.56(16) Å3, Z = 4, Rgt(F) = 0.0610, wRref(F2) = 0.1713, T = 100 K.

Inhibitory effect of essential oils on Aspergillus ochraceus growth and ochratoxin A production

Ochratoxin A (OTA) is a mycotoxin which is a common contaminant in grains during storage. Aspergillus ochraceus is the most common producer of OTA. Essential oils play a crucial role as a biocontrol in the reduction of fungal contamination. Essential oils namely natural cinnamaldehyde, cinnamon oil, synthetic cinnamaldehyde, Litsea citrate oil, citral, eugenol, peppermint, eucalyptus, anise and camphor oils, were tested for their efficacy against A. ochraceus growth and OTA production by fumigation and contact assays. Natural cinnamaldehyde proved to be the most effective against A. ochraceus when compared to other oils. Complete fungal growth inhibition was obtained at 150-250 µL/L with fumigation and 250-500 µL/L with contact assays for cinnamon oil, natural and synthetic cinnamaldehyde, L. citrate oil and citral. Essential oils had an impact on the ergosterol biosynthesis and OTA production. Complete inhibition of ergosterol biosynthesis was observed at ≥ 100 µg/mL of natural cinnamaldehyde and at 200 µg/mL of citral, but total inhibition was not observed at 200 µg/mL of eugenol. But, citral and eugenol could inhibit the OTA production at ≥ 75 µg/mL and ≥ 150 µg/mL respectively, while natural cinnamaldehyde couldn't fully inhibit OTA production at ≤ 200 µg/mL. The inhibition of OTA by natural cinnamaldehyde is mainly due to the reduction in fungal biomass. However, citral and eugenol could significant inhibit the OTA biosynthetic pathway. Also, we observed that cinnamaldehyde was converted to cinnamic alcohol by A. ochraceus, suggesting that the antimicrobial activity of cinnamaldehyde was mainly attributed to its carbonyl aldehyde group. The study concludes that natural cinnamaldehyde, citral and eugenol could be potential biocontrol agents against OTA contamination in storage grains.

Antifungal activity and inhibition of fumonisin production by Rosmarinus officinalis L. essential oil in Fusarium verticillioides (Sacc.) Nirenberg

The chemical composition of Rosmarinus officinalis L. essential oil (REO) was analysed by gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. The main compounds of the REO were 1.8 cineole (52.2%), camphor (15.2%) and α-pinene (12.4%). The mycelial growth of Fusarium verticillioides (Sacc.) Nirenberg was reduced significantly by 150 μg/mL of REO. Significant microscopic morphological changes were visualised, such as the rupture of the cell wall and the leakage of cytoplasm at 300 μg/mL of REO. At lower concentrations of REO, the effects on the production of ergosterol and the biomass of mycelium varied, as did the effects on the production of fumonisins, but at ≥300 μg/mL of REO, these processes were significantly inhibited, showing the effectiveness of the REO as an antifungal agent. The results suggested that the REO acts against F. verticillioides by disrupting the cell wall and causing the loss of cellular components, subsequently inhibiting the production of fumonisins and ergosterol.

Effect of Zingiber officinale essential oil on Fusarium verticillioides and fumonisin production

The antifungal activity of ginger essential oil (GEO; Zingiber officinale Roscoe) was evaluated against Fusarium verticillioides (Saccardo) Nirenberg. The minimum inhibitory concentration (MIC) of GEO was determined by micro-broth dilution. The effects of GEO on fumonisin and ergosterol production were evaluated at concentrations of 500-5000 μg/mL in liquid medium with a 5mm diameter mycelial disc of F. verticillioides. Gas chromatography-mass spectrometry showed that the predominant components of GEO were α-zingiberene (23.9%) and citral (21.7%). GEO exhibited inhibitory activity, with a MIC of 2500 μg/mL, and 4000 and 5000 μg/mL reduced ergosterol biosynthesis by 57% and 100%, respectively. The inhibitory effect on fumonisin B1 (FB1) and fumonisin B2 (FB2) production was significant at GEO concentrations of 4000 and 2000 μg/mL, respectively. Thus, the inhibition of fungal biomass and fumonisin production was dependent on the concentration of GEO. These results suggest that GEO was able to control the growth of F. verticillioides and subsequent fumonisin production.

Synthesis of bis-acyclonucleoside analogues bearing benzothienyl-1,2,4-Triazol-3-Yl-disulfide under conventional and microwave methods

The oxidation of 5-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole-3-thiol (1) with a solution of iodine and potassium iodide at room temperature afforded [5-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole-3-yl]disulfide (2). In contrast, when the reaction mixture was heated or irradiated by MW, an unexpected additional product was obtained and identified as 3-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole (3); the ratio of products was 3:1. The preferred conformer of 2 was deduced from the theoretical calculation. The alkylation of compounds 2 and 3 with epichlorohydrin and hydroxyalkylating agents gave the corresponding N,N-bis- and N-acyclonucleosides analogues 8-15.