Antifungal and immunomodulating activities of 1,4-benzothiazine azole derivatives: review

Experimental investigation of the effect of tebuconazole on three biomarkers of innate immunity in the house sparrow (Passer domesticus)

Triazoles are among the most widely used fungicides in the world due to their efficacy against fungal crop diseases and their broad spectrum of action. Intensive use of triazoles has resulted in residual contamination in different compartments of agroecosystems and exposes non-target species to potential sublethal effects. Triazoles are known to be immunomodulators in medicine and therapeutic treatments, but very little data is available on their potential effect on immune parameters of non-target vertebrate species living in agroecosystems. In this study, we experimentally examined the impact of tebuconazole on three immune biomarkers (haemagglutination titre (HA), haemolysis titre (HL), and haptoglobin concentration (Hp)), as well as on the body condition of house sparrows (Passer domesticus). Our results suggest that tebuconazole had very little, if any, effect on the studied immune parameters. However, further studies are needed to better assess the effect of tebuconazole on bird immunity because (1) experimental individuals were kept under optimal conditions and the impact of tebuconazole on immunity may occur under suboptimal conditions, (2) only one concentration of tebuconazole was tested and its effect could be dose-dependent and (3) other complementary immunological biomarkers should be studied, given the complexity of the vertebrate immune system. Current knowledge on the potential effects of triazoles on the immunity of wild farmland vertebrates is still largely insufficient. Further physiological and immune studies should be conducted to better understand the effect of triazole fungicides on farmland birds.

The Multifaceted Opportunities Provided by the Pheomelanin-Inspired 1,4-Benzothiazine Chromophore: A Still-Undervalued Issue

1,4-Benzothiazines are the main building blocks of the naturally occurring pheomelanin pigments, and their chromophoric properties have been strongly related to the well-known phototoxicity of these pigments, partly responsible for the high incidence of melanoma and other skin cancers in red-haired people. However, some peculiar features of the 1,4-benzothiazine chromophore could be functionally exploited in several sectors. Within this context, in this perspective, an overview of the very recently reported applications of the 1,4-benzothiazine chromophore in pH sensing, filter permeability control, smart packaging, electrochromic device fabrication, bioimaging, photocatalysis, and HPLC detection systems is provided, together with a brief presentation of recently developed synthetic approaches to the 1,4-benzothiazine scaffold, with the aim of emphasizing the still-undervalued multifunctional opportunities offered by this class of compounds.

Microwave assisted synthesis and structure-activity relationship of 4-hydroxy-N'-[1-phenylethylidene]-2H/2-methyl-1,2-benzothiazine-3-carbohydrazide 1,1-dioxides as anti-microbial agents

A series of 4-hydroxy-N'-[1-phenylethylidene]-2H/2-methyl, 1,2-benzothiazine-3-carbohydrazide 1,1-dioxides was synthesized from commercially available sodium saccharin. Base catalyzed ring expansion of methyl (1,1-dioxido-3-oxo-1,2-benzisothiazol-2(3H)-yl)acetate followed by ultrasound mediated hydrazinolysis and subsequent reaction with 1-phenylethanones under the influence of microwaves yielded the title compounds. Besides, microwave assisted synthesis of 1,4-dihydropyrazolo[4,3-c][1,2]benzothiazin-3-ol 5,5-dioxide and 4-methyl-1,4-dihydropyrazolo[4,3-c][1,2]benzothiazin-3-ol 5,5-dioxide is also discussed. Most of the synthesized compounds were found to possess moderate to significant anti-microbial (anti-bacterial and anti-fungal) activities. It is found that compounds with greater lipophilicity (N-methyl analogues) possessed higher anti-bacterial activities.

QSPR modeling of the half-wave potentials of benzoxazines by optimal descriptors calculated with the SMILES

Optimal descriptors calculated with Simplified Molecular Input Line Entry System (SMILES) notation have been used in quantitative structure-property relationships (QSPR) modeling electrochemical half-wave potential of benzoxazine derivatives by one-variable correlations.

Synthesis of potential biologically active 1,2-benzothiazin-3-yl-quinazolin-4(3H)-ones

A series of potential biologically active 2-(4-hydroxy-1,1-dioxido-2H-1,2-benzothiazin-3-yl)quinazolin-4(3H)-ones was synthesized in a straight forward manner by condensation of respective 4-hydroxy-1,2-benzothiazine-1,1-dioxides with anthranilamide followed by simple and high throughput cyclization of N-[2-(aminocarbonyl)phenyl]-4-hydroxy-1,2-benzothiazine-3-carboxamide-1,1-dioxides. All the synthesized compounds were subjected to preliminary evaluation for their biological activity against Gram positive and Gram negative bacteria. Some of the assayed compounds showed marked activity against Bacillus subtilis.

Synthesis, antiproliferative and antifungal activities of some 2-(2,4-dihydroxyphenyl)-4H-3,1-benzothiazines

A new method for the synthesis of 4H-3,1-benzothiazine skeleton is described. The compounds were obtained by the reaction of sulfinylbis(2,4-dihydroxythiobenzoyl) with o-substituted anilines bearing an activated methylene group (-CH2OH, -CH2NR1R2), o-aminobenzanilides or 2-aminobenzophenones. The reaction proceeded through thiobenzanilide intermediates, which were converted to the 4H-3,1-benzothiazine fused ring by an endocyclization process. The compounds were tested for their antiproliferative properties against the cells of a human breast cancer T47D line. The activity of some compounds was comparable to that of cisplatin, studied as a control. A strong antifungal effect against the strains of moulds, yeasts and dermatophytes was also found.

Synthesis of 4-octyl-2H-1,4-benzo-thiazin-3-ones

Synthesis, physical and analytical properties of 6-alkylacylamino-4-octyl-2H-1,4-benzo-thiazin-3-ones derivatives are described. These new compounds were prepared by acylation and/or alkylation of the amino group under phase transfer catalysis conditions. Acid hydrolysis of the alkylacylamino-2H-1,4-benzo-thiazin-3-ones afforded N-alkylamino-benzothiazin-3-ones. Some of these compounds were evaluated in vitro for possible bacteriostatic activity.