Synthesis, lipophilicity determination, DFT calculation, antifungal and DPPH radical scavenging activities of tetrahydrothiophen-3-one based thiazoles

Discovery of Lead 2-Thiazolylhydrazones with Broad-Spectrum and Potent Antifungal Activity

Opportunistic fungal infections represent a global health problem, mainly for immunocompromised individuals. New therapeutical options are needed since several fungal strains show resistance to clinically available antifungal agents. 2-Thiazolylhydrazones are well-known as potent compounds against Candida and Cryptococcus species. A scaffold-focused drug design using machine-learning models was established to optimize the 2-thiazolylhydrazone skeleton and obtain novel compounds with higher potency, better solubility in water, and enhanced absorption. Twenty-nine novel compounds were obtained and most showed low micromolar MIC values against different species of Candida and Cryptococcus spp., including Candida auris, an emerging multidrug-resistant yeast. Among the synthesized compounds, 2-thiazolylhydrazone 28 (MIC value ranging from 0.8 to 52.17 μM) was selected for further studies: cytotoxicity evaluation, permeability study in Caco-2 cell model, and in vivo efficacy against Cryptococcus neoformans in an invertebrate infection model. All results obtained indicate the great potential of 28 as a novel antifungal agent.

Current Status and Structure Activity Relationship of Privileged Azoles as Antifungal Agents (2016-2020)

Fungal infections have major contribution to the infectious related deaths in recent century. The issue has gotten worse with the advent of immunity impairing conditions such as HIV epidemic. Eukaryote nature of fungal pathogens leads to harder eradication than bacterial infections. Given the importance of the problem, considerable efforts have been put on the synthesis and biological assessment of azole-based chemical scaffolds and their bioisosteres. The emergence of validated macromolecular targets within different fungal species inspires structure-based drug design strategies toward diverse azole-based agents. Despite of advantageous features, emergence of drug-resistant fungal species restrict the applicability of current azoles as the first-line antifungal agents. Consequently, it appears advisable to elucidate SARs and chemical biodiversity within antifungal azoles. Current contribution was devoted to a brief look at clinically applied drugs, structure-based classification of azole antifungals and their structure activity relationships (SARs). Reviewed molecules belong to the antifungal structures that were reported throughout 2016-2020.

Benzo[b]thiophene-thiazoles as potent anti-Toxoplasma gondii agents: Design, synthesis, tyrosinase/tyrosine hydroxylase inhibitors, molecular docking study, and antioxidant activity

Synthesis and investigation of anti-Toxoplasma gondii activity of novel thiazoles containing benzo [b]thiophene moiety are presented. Among the derivatives, compound 3k with adamantyl group shows exceptionally high potency against Me49 strain with IC₅₀ (8.74 μM) value which is significantly lower than the activity of trimethoprim (IC₅₀ 39.23 μM). In addition, compounds 3a, 3b and 3k showed significant activity against RH strain (IC₅₀ 51.88-83.49 μM). The results of the cytotoxicity evaluation showed that Toxoplasma gondii growth was inhibited at non-cytotoxic concentrations for the mammalian L929 fibroblast (CC₃₀ ∼ 880 μM). The most active compound 3k showed tyrosinase inhibition effect, with IC₅₀ value of 328.5 μM. The binding energies calculated for compounds 3a-3e, 3k are strongly correlated with the experimentally determined values of tyrosinase inhibition activity. Moreover, the binding energies corresponding to the same ligands and calculated for both tyrosinase and tyrosine hydroxylase are also correlated with each other, suggesting that tyrosinase inhibitors may also have an inhibitory effect on tyrosine hydroxylase. Compounds 3j and 3k have also very strong antioxidant activity (IC₅₀ 15.9 and 15.5 μM), respectively, which is ten times higher than well-known antioxidant BHT.

Lipophilicity as a Central Component of Drug-Like Properties of Chalchones and Flavonoid Derivatives

Lipophilcity is an important physico-chemical parameter that influences membrane transport and binding ability to action. Migration distance following complete elution of compounds was used to calculate different lipophilicity-related parameters. The aim of this study is to show that lipophilicity is a central component of thiazole chalcones and flavonoid derivatives regarding their drug-like properties. Experimental and computational methods were used. This study considers 44 previously synthesized compounds (thiazole chalcones, flavanones, flavones, 3-hydroxyflavones, and their acetylated derivatives). The concerned compounds have shown antitumoral hallmarks and antibacterial activity in vitro. The experimental method used to determine compounds’ lipophilicity was the reverse-phase thin layer chromatography (RP-TLC). Lipophilicity related parameters—isocratic retention factor (R_M), relative lipophily (R_M⁰), slope (b), chromatographic hydrophobic index (φ₀), scores of principal components (PC1/R_M)—were determined based on reverse-phase chromatography results.

Synthesis of urea-functionalized chitosan derivatives for potential antifungal and antioxidant applications

In the current study, five novel urea-functionalized chitosan derivatives were synthesized via condensation reactions of chloroacetyl chitosan (CTCS) with urea groups bearing nitrogen-containing heterocycles. In order to identify the structure characteristics of chitosan derivatives, FT-IR, ¹H NMR spectroscopy, and elemental analysis were carried out. The antifungal activity of the derivatives against four species of phytopathogen (Fusarium oxysporum f. sp. niveum, Phomopsis asparagus, Fusarium oxysporum f. sp. cucumebrium Owen, and Botrytis cinerea) was evaluated. Furthermore, the antioxidant activity of chitosan derivatives was tested by hydroxyl-radical scavenging and superoxide-radical scavenging assays. The results indicated that chitosan derivatives bearing urea groups displayed superior bioactivity compared with chitosan. Besides, L929 cells were adopted for cytotoxicity test of chitosan and synthesized samples by CCK-8 assay and all samples showed decreased cytotoxicity. These results suggested that the novel urea-functionalized chitosan derivatives could be an ideal biomaterial for antifungal and antioxidant applications.