New coordination compounds of some rare-earth metal complexes with sulfur and nitrogen Schiff bases and their in vitro antibacterial and antifungal properties

A series of rare-earth metal complexes with Schiff bases have been prepared by the interactions of hydrated lanthanide(III) chloride with the sodium salts of 1-(2-thienyl)ethanone hydrazinecarbothioamide (L¹H) and 1-(2-thienyl)ethanonehydrazinecarboxamide (L²H) in 1:3 molar ratios and characterized by their elemental analyses, molar conductance and IR, NMR (¹H and ¹³C) electronic and EPR spectral studies. The spectral data suggested that the complexes have a hexa-coordinated environment around the central metal atoms. Elemental analyses and NMR spectral data of the ligands and their metal(III) complexes agree with their proposed structures. The synthesized Schiff bases and their new metal complexes have been screened for in vitro antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Pseudomonas cepacicola) bacterial strains and for in vitro antifungal activity against Fusarium oxysporum and Macrophomina phaseolina. All compounds showed significant antibacterial and antifungal activities against microbial species.     

Synthesis,antibacterial and antifungal evaluation of thio- or piperazinyl-substituted 1,4-naphthoquinone derivatives

A series of S-, S,S-, S,O-, N- and N,S-derivatives from 2,3-dichloro-1,4-naphthoquinone compound 1 were synthesized in different reaction media and evaluated for their antibacterial and antifungal activities. The structures of the novel products were characterized by spectroscopic methods, such as microanalysis, ¹H NMR, ¹³C NMR and MS. Among the tested compounds 9, 12 and 18 are the most effective compounds against Candida tenuis as potent antifungal compounds. Compound 9 is also the most effective compound against Staphylococcus aureus as a potent antifungal compound.     

A facile microwave enhanced synthesis of sulfur-containing 5-membered heterocycles derived from 2-mercaptobenzothiazole over ZnCl 2/DMF and antimicrobial activity evaluation

An efficient and extremely fast procedure for the synthesis of 4-thiazolidinones 4a–j by the reaction of arylidene-[(2-benzothiazolylthio)-acetamidyl] 3a–j with thioglycolic acid in DMF in the presence of a catalytic amount of anhydrous ZnCl ₂ under microwave irradiation is described. A considerable increase in the reaction rate has been observed with better yield in microwave technique. All the compounds have been screened for their antifungal activity against Candida albicans (ATCC-64550), Candida krusei (ATCC-14243) and Candida parapsilosis (ATCC-22019) and antibacterial activity against Escherchia coli (Gram?ve) (ATCC-8739), Staphylococcus aureus (Gram+ve) (ATCC-6538) and Bacillus substilis (Gram+ve) (ATCC-6633). The structures of the synthesised compounds 4a–j have been characterized on the basis of their elemental analysis and spectral data.     

Synthesis and antimicrobial activities of some ethyl 2-arylthio-6-arylimidazo[2,1-b]thiazole-3-carboxylates and their sulfones

A series of new 2-arylthio-3-ethoxycarbonyl-6-arylimidazo[2,1-b]thiazoles (4a–4h) and 2-arenesulfonyl-3-ethoxycarbonyl-6-arylimidazo[2,1-b]thiazoles (5a–5h) have been prepared and characterized by analytical and spectral methods. The title compounds 4a–4h and 5a–5h were obtained by the reaction of 2-amino-4-ethoxycarbonyl-5-arylthiothiazoles (2a and 2b)/2-amino-4-ethoxycarbonyl-5-arenesulphonyl-thiazoles (3a and 3b) with various phenacyl bromides in anhydrous ethanol. These newly synthesized compounds (4a–4h and 5a–5h) were screened for their antibacterial activity against Gram-negative bacterium Escherichia coli, Gram-positive bacterium Staphylococcus aureus, and antifungal properties against Aspergillus niger and Candida albicans.     

Comparative study of the influence of active groups of chitosan derivatives on antifungal activity

In this study, series of chitosan derivatives containing active groups were synthesized and evaluated for their antifungal activity against three crop‐threatening fungi, Fusarium oxysporum. f. sp. Vasinfectum, Alternaria solani, and Valsa mali. Schiff bases of carboxymethyl chitosan (As: 2‐(2‐hydroxy‐5‐nitrobenzylideneamino)‐6‐carboxymethyl chitosan; Bs: 2‐(2‐hydroxyl‐5‐chlorobenzaldimino)‐6‐carboxymethyl chitosan), N‐substituted carboxymethyl chitosan (An: 2‐(2‐hydroxyl‐5‐nitrobenzylamino)‐6‐carboxymethyl chitosan; Bn: 2‐(2‐hydroxyl‐5‐chlorobenzylamino)‐6‐carboxymethyl chitosan) and 2‐urea‐carboxymethyl chitosan (Au: 2‐(2‐nitrophenylurea)‐6‐carboxymethyl chitosan; Bu: 2‐(2‐chlorophenylurea)‐6‐carboxymethyl chitosan) were synthesized, and their antifungal activity was comparatively studied by hypha measurement in vitro, respectively. Results obtained from this study revealed that the active groups combined with Schiff bases functional groups (C?N) could strengthen the antifungal activity most effectively among the compounds studied in this work. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Heterogeneous NaHSO4·SiO2 catalyzed ‘one-pot’ synthesis and in vitro antibacterial and antifungal activities of pyridino-1,2,3-thiadiazoles

A ‘one-pot’ synthesis of 5,7-diaryl-4,4-dimethyl-4,5,6,7-tetrahydropyridino[4,3-d]-1,2,3-thiadiazoles (11–15) using NaHSO₄·SiO₂ heterogeneous catalyst in dry media under microwave irradiation by a simple synthetic strategy is described. Among the synthesized 1,2,3-thiadiazoles, compounds having electron withdrawing chloro- and fluoro- functional group on the aryl moiety 14 and 15 exerted a wide range of modest antibacterial and antifungal activity in vitro against the tested organisms. The obtained results may be used as a key step for the building of novel chemical compounds with interesting antimicrobial profiles comparable with that of the standard drugs.     

Promising Antifungal and Antibacterial Agents Based on 5-Aryl-2,2′-bipyridines and Their Heteroligand Salicylate Metal Complexes: Synthesis,Bioevaluation, Molecular Docking

A series of new 5-aryl-2,2′-bipyridines and their (polyfluoro)salicylate complexes of Cu(II), Co(II) and Mn(II) were synthesized. Their antimicrobial activity was evaluated in vitro against six strains of Trichophytons, E. floccosum, M. canis, C. ablicans and Gram-negative bacteria N. gonorrhoeae. Among azo-ligands, Ph-bipy and Tol-bipy showed promising antifungal activity (minimum inhibitory concentration (MIC)<0.8–27 μM). Their antifungal action was found can be realized via binding Fe(III) ions. Tol-bipy suppressed growth of Gram-positive bacteria S. aureus, S. aureus MRSA and their monospecies biofilms (MIC 6–16 μM). Using molecular docking, the anti-staphylococcal action mechanism based on the inhibition of S. aureus DNA gyrase GyrB was proposed for the lead compounds. Among metal complexes, Cu(II) and Mn(II) complexes based on tetrafluorosalicylic acid and Tol-bipy or Ph-bipy had the high antifungal activity (MIC<0.24–32 μM). Mn(SalF₄−2H)₂(Tol-bipy)₂] suppressed the growth of seven Candida strains at MIC 12–24 μM. [Cu(Sal−2H)(Ph-bipy)] and [Cu(SalF₃−2H)(Ph-bipy)₂] showed the promising anti-gonorrhoeae activity (MIC 4.2–5.2 μM). (Cu(SalF_n−2H)(Tol-bipy)₂], [Cu(SalF₄−2H)(Ph-bipy)₂] and [Cu(SalF₃−2H)(Ph-bipy)₂]) were found active against the bacteria of S. aureus, S. aureus MRSA and their biofilms (MIC 2.4–41.4 μM). The most active compounds were tested for toxicity in vitro against human embryonic kidney (HEK-293) cells and in vivo experiments with CD-1 mice.     

Polyprenylated benzophenone-enriched extracts obtained using SC–CO2 from the dry ethanolic extract of Brazilian red propolis

Red propolis is a well-known potent antimicrobial source because of its various bioactive compounds. This work aims to submit a sample of Brazilian red propolis to supercritical CO₂ extraction, with subsequent chemical characterisation by HPLC and UHPLC–MS, and to evaluate the antifungal activity against three strains of Candida glabrata. The method proved to be selective for the extraction of benzophenones. The results demonstrated a correlation between the presence of benzophenones and antifungal activity. The supercritical extract that seems to be the richest in benzophenones was the one obtained with a pressure of 300 bar and was the most active against the C. glabrata strains.

Abbreviations: SFE, Supercritical Fluid Extraction; MIC, Minimal Inhibitory Concentration; SC, Supercritical; BZP, benzophenones     

The Triazole Ring as a Privileged Scaffold for Putative Antifungals: Synthesis and Evaluation of a Series of New Analogues

The significant antifungal activity of a series of novel 1,2,4-triazole derivatives against different strains of Candida albicans, Candida krusei and Aspergillus fumigatus, compared to the commercial fungicides ketoconazole and itraconazole, is reported. Systemic mycosis and invasive fungal infections, whether from immunodeficiency or hospital-acquired infection, have been on an upward trend for several years. The 1,2,4-triazole ring substituted with other aromatic and heteroaromatic systems plays an important role in the field of antifungal drug discovery and development. Thus, an extensive series of 29 triazoles, substituted in different positions with a variety of aromatic rings, has been designed, synthesized, and evaluated for their fungicidal activity. Almost all the agents tested in vitro showed high activity against all examined fungal strains. It is noteworthy that, in the case of A. fumigatus, all the examined compounds achieved equal or higher antifungal activity than ketoconazole, but less activity than itraconazole. Among all the derivatives studied, the dichlorourea analogue and bromo-substituted triazole stand out as the most promising compounds. Quantitative structure-activity relationship (QSAR) models were built for a systematic structure-activity relationship (SAR) profile to explain and potentially explore the potency characteristics of 1,2,4-triazole analogues.     

Synthesis and biological activities of 3-polyamino-5β-cholane-7α,24-diols

A series of 3-polyaminochenodeoxycholic acid derivatives were synthesized and their in vitro antimicrobial and antifungal activities were assessed. The antimicrobial activity was evaluated against Gram-positive and Gram-negative bacteria, and the antifungal activity was assessed against two strains Candida albicans (ATCC MYA-1003) and Aspergillus fumigatus (ATCC 16424). The introduction of an amine group to steroid was accomplished by reductive amination of 3-oxosteroid 9 with Boc-spermidine and Boc-spermine, in the presence of NaBH(OAc)₃. This afforded a high yield of 3-polyaminosteroids of 10–13. The 3β-sperminyl-5β-cholane 6 showed the highest antimicrobial activity against Streptococcus pyogenes 308A, Staphylococcus aureus 503, Escherichia coli DC2 and Pseudomonas aeruginosa 9027 with a MIC value of 3.13 μg/mL.     

Potent Synergy between Spirocyclic Pyrrolidinoindolinones and Fluconazole against Candida albicans

A spiroindolinone, (1S,3R,3aR,6aS)‐1‐benzyl‐6′‐chloro‐5‐(4‐fluorophenyl)‐7′‐methylspiro[1,2,3a,6a‐tetrahydropyrrolo[3,4‐c]pyrrole‐3,3′‐1H‐indole]‐2′,4,6‐trione, was previously reported to enhance the antifungal effect of fluconazole against Candida albicans. A diastereomer of this compound was synthesized, along with various analogues. Many of the compounds were shown to enhance the antifungal effect of fluconazole against C. albicans, some with exquisite potency. One spirocyclic piperazine derivative, which we have named synazo‐1, was found to enhance the effect of fluconazole with an EC₅₀ value of 300 pM against a susceptible strain of C. albicans and going as low as 2 nM against some resistant strains. Synazo‐1 exhibits true synergy with fluconazole, with an FIC index below 0.5 in the strains tested. Synazo‐1 exhibited low toxicity in mammalian cells relative to the concentrations required for antifungal synergy.     

Antifungal Activities and Chemical Composition of Wood and Leaf Essential Oils from Cunninghamia konishii

Abstract

In this study antifungal activities of essential oils from wood and leaf and their constituents of Cunninghamia konishii against four wood decay fungi and six plant pathogenic fungi were investigated. GC and GC-MS analyses show that the major compounds of wood essential oil were cedrol and α-pinene, while those of leaf essential oil were α-pinene and p-cymene. Antifungal tests demonstrated the wood oil from C. konishii used against Trametes versicolor, Lenzites betulina, Laetiporus sulphureus, and Gloeophyllum trabeum and leaf oil from C. konishii used against L. sulphureus had strong antifungal activities. Moreover, wood oil used against Rhizoctonia solani, Fusarium solani, Pestalotiopsis funereal, and Ganoderma australe also had strong antifungal activities. Among the seven constituents of wood oil, cedrol displayed the best antifungal properties, indicating that it may be used as potential antifungal agents for the control of fungal diseases in plants.     

Antifungal Effects of Volatile Compounds from Black Zira (<Emphasis Type="Italic">Bunium persicum</Emphasis>) and Other Spices and Herbs

The dish pack method, which measures growth inhibition or promotion effects of volatile compounds on germinating seeds, was applied to measure the antifungal effects of 52 dried samples of spices and herbs against a soil-borne phytopathogenic fungus, Fusarium oxysporum. Black zira showed the strongest effect, followed by cumin and cardamom. Headspace sampling and gas chromatography–mass spectrometry analysis of black zira identified seven volatile compounds, γ-terpinene, limonene, p-cymene, β-pinene, α-pinene, cuminaldehyde, and myrcene. Among these, cuminaldehyde and p-cymene showed the strongest antifungal activities against F. oxysporum, suggesting roles in the antifungal activity of black zira. The same compounds also showed antifungal activities against another soil-borne phytopathogenic fungus, Verticillium dahliae, and foliar phytopathogenic fungi, Botrytis cinerea and Alternaria mali. The total activity calculated from the concentration of cuminaldehyde contained in black zira and its EC₅₀ against F. oxysporum demonstrated that cuminaldehyde is the main antifungal compound detected in black zira.     

Design, ‘one-pot’ synthesis,characterization, antibacterial and antifungal activities of novel 6-aryl-1,2,4,5-tetrazinan-3-thiones in dry media

A novel ‘one-pot’ synthesis of 6-aryl-1,2,4,5-tetrazinan-3-thiones is carried out by the three-component coupling of thiourea, various structurally diverse aromatic aldehydes and ammonium acetate in the presence of reusable NaHSO₄·SiO₂ heterogeneous catalyst in dry media under microwave irradiation. FT-IR, ¹H NMR, D₂O Exchange, HOMOCOR, ¹³C NMR, MS and elemental analysis characterize all the synthesized compounds. In vitro antibacterial/fungal activities are carried out for all the synthesized eight new compounds. All the compounds are more active against bacterial strains namely Staphylococcus aureus, β-Heamolytic streptococcus, Vibreo cholerae, Salmonella typhii, Shigella felxneri, Klebsiella pneumonia and Pseudomonas except compounds 1 and 6, while compound 6 shows promising activity against Salmonella typhii. Moreover, of all the compounds tested, compounds 3 and 8 are more effectual against all the tested fungal strains.     

s-Triazole systems. Part IV: Novel substituted thio-s-triazole derivatives

Interaction of (3-aryloxymethyl-4-phenyl-striazol-5-yl)thioacethydraz-ide ( la -c) with phenyl isocyanate and/or with methyl/phenyl isothiocyanate gave semicarbazides ( 2a -c) and thiosemicarbazides ( 3a-f ) respectively. Cyclization of ( 3a-f ) yielded s-triazoles ( 4a-f ). Compounds 4b,d,f were easily alkylated giving S-substituted thio-s-triazoles ( 5a-e ). Furthermore, compounds 4b,d,f underwent a Mannich reaction to give the expected Mannich bases ( 6a-f ). All compounds were fully confirmed by elemental and spectral analyses and have been screened in vitro, for antimicrobial activity.     

Synthesis and Properties of Novel Antifungal Gemini Compounds Derived from <Emphasis Type="Italic">N</Emphasis>-Acetyl Diethanolamines

A series of new N-acetylated non-ionic and cationic gemini surfactants (3a–f) having dimeric structures derived from primary and tertiary amines with variably long tails (C₈–C₁₂–C₁₈) were synthesized. In addition, N-acetylated monomeric analogues 6a and 6b were prepared and their antifungal potency and surface properties were also determined. Critical micelle concentration (CMC), effectiveness of surface tension reduction (γ_CMC), surface excess concentration (Γ), and area per molecule at the interface (A) were also determined and the resulting values indicate that the cationic series is characterized by good surface-active and self-aggregation properties. For the first time, all surfactants were tested to evaluate their antifungal properties using the method for the broth macrodilution test (M27-A2, NCCLS). Four microbial strains were used to perform the study: Candida parapsilosis (ATCC 22019), C. albicans (ATCC 64548), and a wild-type strain of C. parasilosis and Saccharomyces cerevisiae (ATCC 9763). The antimicrobial activity was measured by yeast growth inhibition expressed as minimum inhibitory concentration (MIC) values. Results were compared to those obtained for their monomeric analogues and for a commercially available reference compound (Fluconazole). Gemini 3b, 3e and 3f were found to be the most potent compounds. The results show S. cerevisiae as the most sensitive strain. In contrast, the wild strain of C. parapsilosis was resistant.

Lysophospholipids from the Guangxi Sponge Spirastrella purpurea

Four known ( 1 – 4 ) and two new ( 5 and 6 ) lysophospholipids were isolated from the sponge Spirastrella purpurea from Weizhou Island, Guangxi Autonomous Region, China. The structures of the new compounds ( 5 and 6 ) were elucidated by detailed spectroscopic techniques, including 1D and 2D NMR (¹H and ¹³C NMR, ¹H–¹H COSY, HSQC, and HMBC) as well as mass spectrometry and optical rotation experiments. The known compounds ( 1 – 4 ) were identified by comparison of their spectroscopic data and specific optical rotation with those reported in the literature. The isolated compounds displayed various moderate in vitro antifungal activities against four fungi (Cryptococcus neoformans, Candida glabrata, Trichophyton rubrum, and Aspergillus fumigatus), whereas they displayed no neuroprotective activity against Aβ_25‐35‐induced SH‐SY5Y cell damage.     

Synthesis,spectral and structural study of sulfur-containing copper(II) complexes

A series of four new copper(II) complexes [Cu(H₂L)(L¹)] 1, [Cu(H₂L)(PMDT)] 2, [Cu(H₂L)(Dien)] 3 and [Cu(H₂L)(L²)] 4 have been synthesized by template condensation (H₂L=thiodiglycolic acid, L¹=N-[(1)-1-(4-methylphenyl)ethylidene]benzohydrazide, PMDT=N,N,N′,N′,N ^′′-pentamethyldiethylene- triamine, Dien=diethylenetriamine L²=N-[(1)-pyridin-2-ylmethylidene]benzohydrazide). The bonding and stereochemistry of the complexes have been characterized by molar conductance, elemental analysis, magnetic susceptibility, infrared, UV–visible, electron paramagnetic resonance structural studies and electrochemical studies. g-Values were calculated for all complexes in polycrystalline form as well as in DMSO solution. The magnetic and spectral data indicate square pyramidal geometry for 1 and octahedral geometry for 2–4 complexes. Cyclic voltammograms for all the complexes are similar and involve two irreversible redox processes. Their biological properties have also been studied. The thio complexes show more antibacterial activity than the controlled one. The antibacterial activities of the compounds have also been tested against Escherichia coli with different concentrations.     

Synthesis and biological evaluation of some new coumarinyl thiazolopyrimidinones

Two new series of coumarin linked, linear and angularly fused thiazolo-[3,2-a]-pyrimidinones have been synthesized from 3-bromoacetyl coumarins by azole and azine approaches. Regioisomeric 5H and 7H thiazolo-[3,2-a]-pyrimidinones have been clearly distinguished by their IR and UV fluorescence spectral data. All the compounds have been characterized by analytical and spectroscopic methods. Rate and yield enhancements have been achieved using microwave irradiation. The results of in vivo diuretic activity indicate that substituents on coumarin do not enhance the activity. In vitro antimicrobial activities have shown that the compounds are specifically active against Gram-positive but are inactive against Gram-negative bacterial strains. Moderate fungal activity was observed against Candida albicans and Penicillium chrysogenum and all the compounds were found to be inactive against Aspergillus niger.