Synthesis and antifungal activity of thiadiazole-functionalized chitosan derivatives

Polysaccharides and lipoproteins as reactants for the synthesis of pharmaceutically important scaffolds: A review

The growing number of diseases in the past decade has once again highlighted the need for extensive research on the development of novel drugs. There has been a major expansion in the number of people suffering from malignant diseases and types of life-threatening microbial infections. The high mortality rates caused by such infections, their associated toxicity, and a growing number of microbes with acquired resistance necessitate the need to further explore and develop the synthesis of pharmaceutically important scaffolds. Chemical entities derived from biological macromolecules like carbohydrates and lipids have been explored and observed to be effective agents in the treatment of microbial infections and diseases. These biological macromolecules offer a variety of chemical properties that have been exploited for the synthesis of pharmaceutically relevant scaffolds. All biological macromolecules are long chains of similar atomic groups which are connected by covalent bonds. By altering the attached groups, the physical and chemical properties can be altered and molded as per the clinical applications and needs, this ring them potential candidates for drug synthesis. The present review establishes the role and significance of biological macromolecules by articulating various reactions and pathways reported in the literature.

Development of a chitosan derivative bearing the thiadiazole moiety and evaluation of its antifungal and larvicidal efficacy

A new chitosan derivative bearing a new thiadiazole compound was developed, and its antifungal and larvicidal activities were investigated. The chitosan derivative (coded here as PTDz-Cs) was synthesized by the reaction between the carboxylic derivative of the thiadiazole moiety and chitosan. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (1H/13C-NMR), gas chromatography–mass spectrometry (GC–MS), elemental analysis, X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) were used to characterize the developed derivatives. Compared to chitosan, the PTDz-Cs derivative has a less crystalline structure and less thermal stability. The antifungal results revealed that PTDz-Cs exhibited potential activity against Rhizopus microspores, Mucor racemosus, Lichtheimia corymbifera, and Syncephalastrum racemosum where inhibition zones were 17.76, 20.1, 38.2, and 18.3 mm, respectively. The larvicidal efficacy of the PTDz-Cs derivative against A. stephensi larvae was tested, and the results exposed that the LC50 and LC90 values (first instar) were 5.432 and 10.398 ppm, respectively, indicating the high susceptibility of early instar mosquito larvae to PTDz-Cs. These results emphasize that this study provided a new chitosan derivative that could be potentially used in the biomedical fields.

New thiadiazole modified chitosan derivative to control the growth of human pathogenic microbes and cancer cell lines

The emergence of multidrug-resistant microbes and the propagation of cancer cells are global health issues. The unique properties of chitosan and its derivatives make it an important candidate for therapeutic applications. Herein, a new thiadiazole derivative, 4-((5-(butylthio)-1,3,4-thiadiazol-2-yl) amino)-4-oxo butanoic acid (BuTD-COOH) was synthesized and used to modify the chitosan through amide linkages, forming a new thiadiazole chitosan derivative (BuTD-CH). The formation of thiadiazole and the chitosan derivative was confirmed by FT-IR, ¹H/¹³C-NMR, GC-MS, TGA, Elemental analysis, and XPS. The BuTD-CH showed a high antimicrobial effect against human pathogens Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, and Candida albicans with low MIC values of 25-50 μg ml^-1 compared to unmodified chitosan. The in-vitro cytotoxicity of BuTD-CH was evaluated against two cancer cell lines (MCF-7 and HepG2) and one normal cell (HFB4) using the MTT method. The newly synthesized derivatives showed high efficacy against cancerous cells and targeted them at low concentrations (IC₅₀ was 178.9 ± 9.1 and 147.8 ± 10.5 μg ml^-1 for MCF-7 and HepG2, respectively) compared with normal HFB4 cells (IC₅₀ was 335.7 ± 11.4 μg ml^-1). Thus, low concentrations of newly synthesized BuTD-CH could be safely used as an antimicrobial and pharmacological agent for inhibiting the growth of human pathogenic microbes and hepatocellular and adenocarcinoma therapy.

Synthesis of Water-Soluble Sulfonated Chitin Derivatives for Potential Antioxidant and Antifungal Activity

Chitin is a natural renewable and useful biopolymer limited by its insolubility; chemical derivatization can enhance the solubility and bioactivity of chitin. The purpose of this study was to synthesize novel water-soluble chitin derivatives, sulfo-chitin (SCT) and sulfopropyl-chitin (SPCT), as antioxidant and antifungal agents. The target derivatives were characterized by means of elemental analysis, FTIR, 13C NMR, TGA and XRD. Furthermore, the antioxidant activity of the chitin derivatives was estimated by free radical scavenging ability (against DPPH-radical, hydroxyl-radical and superoxide-radical) and ferric reducing power. In addition, inhibitory effects against four fungi were also tested. The findings show that antioxidant abilities and antifungal properties were in order of SPCT > SCT > CT. On the basis of the results obtained, we confirmed that the introduction of sulfonated groups on the CT backbone would help improve the antioxidant and antifungal activity of CT. Moreover, its efficacy as an antioxidant and antifungal agent increased as the chain length of the substituents increased. This derivatization strategy might provide a feasible way to broaden the utilization of chitin. It is of great significance to minimize waste and realize the high-value utilization of aquatic product wastes.

Pyridine-Based NNS Tridentate Chitosan Thiosemicarbazones and Their Copper(II) Complexes: Synthesis, Characterization, and Anticancer Activity

Chitosan-functionalized pyridine-based thiosemicarbazones and their copper(II) complexes have been found to own a substantial antiproliferative activity against the tumorigenic Madin Darby canine kidney (MDCK) and MCF-7 cancer cell lines. In the current study, chitosan oligosaccharide (CS) (87% DDA, M_w < 3000 Da) and crab shell chitosan (CCS) (67% DDA, M _w 350 kDa) were functionalized as chitosan pyridine-2-thiosemicarbazones and chitosan 2-acetyl pyridine-2-thiosemicarbazones, and their copper(II) complexes were synthesized. The formation of chitosan thiosemicarbazones and their NNS tridentate behavior to give the square planar copper(II) chitosan thiosemicarbazone complexes were established by spectroscopic studies, powder X-ray diffraction, elemental analysis, and magnetic moment measurements. The thermal study showed a marked stability of these derivatives before the outset of chitosan backbone degradation at 200 °C. The colorimetric MTT assay revealed a higher activity of CS thiosemicarbazones, viz., CSTSC series (IC₅₀ 375-381 μg mL^-1 in the MDCK cell line and 281-355 μg mL^-1 in the MCF-7 cell line) than that of high-molecular-weight CCS thiosemicarbazones, viz., CCSTSC series (IC₅₀ 335-400 μg mL^-1 in the MDCK cell line and 365-400 μg mL^-1 in the MCF-7 cell line), showing an enhanced activity with a decrease in M_w and an increase in DDA of constituent chitosan, a higher activity of both of these series of thiosemicarbazones than that of their native chitosan, viz., CS (IC₅₀ 370 μg mL^-1 in the MCF-7 cell line and >400 μg mL^-1 in the MDCK cell line) and CCS (IC50 > 400 μg mL^-1 in both cell lines), and a higher activity of the Cu-CSTSC complexes (IC₅₀ 322-342 μg mL^-1 in the MDCK cell line and 278-352 μg mL^-1 in the MCF-7 cell line) and Cu-CCSTSC complexes (IC₅₀ 274-400 μg mL^-1 in the MDCK cell line and 231-352 μg mL^-1 in the MCF-7 cell line) than that of their respective ligands.

Exploring the Antiparasitic Activity of Tris-1,3,4-Thiadiazoles against Toxoplasma gondii-Infected Mice

Nitrogen-containing atoms in their core structures have been exclusive building blocks in drug discovery and development. One of the most significant and well-known heterocycles is the 1,3,4-thidiazole nucleus, which is found in a wide range of natural products and therapeutic agents. In the present work, certain tris-1,3,4-thiadiazole derivatives (6, 7) were synthesized through a multi-step synthesis approach. All synthesized compounds were characterized using different spectroscopic tools. Previously, thiadiazole compounds as anti-Toxoplasma gondii agents have been conducted and reported in vitro. However, this is the first study to test the anti-Toxoplasma gondii activity of manufactured molecular hybrids thiadiazole in an infected mouse model with the acute RH strain of T. gondii. All the observed results demonstrated compound (7)’s powerful activity, with a considerable reduction in the parasite count reaching 82.6% in brain tissues, followed by liver and spleen tissues (65.35 and 64.81%, respectively). Inflammatory and anti-inflammatory cytokines assessments proved that Compound 7 possesses potent antiparasitic effect. Furthermore, docking tests against TgCDPK1 and ROP18 kinase (two major enzymes involved in parasite invasion and egression) demonstrated compound 7’s higher potency compared to compound 6 and megazol. According to the mentioned results, tris-1,3,4-thiadiazole derivatives under test can be employed as potent antiparasitic agents against the acute RH strain of T. gondii.

Novel Chitosan Derivatives and Their Multifaceted Biological Applications

Chitosan is a rather attractive material, especially because of its bio-origins as well as generation from exoskeletal waste. As the mantle has been effectively transferred from chitin to chitosan, so has it been extrapolated to in-house synthesized novel chitosan derivatives. This review comprehensively lists the available novel chitosan derivatives (ChDs) and summarizes their biological applications. The fact that chitosan derivatives do comprise multifaceted biological applications is attested by the voluminous reports on their varied contributions. However, this review points out to the fact that there has been selective focus on bio functions such as antifungal, antioxidant, antibacterial, whereas other biomedical applications and antiviral applications remain relatively less explored. With their current functionality record, there is definitely no doubt that the plethora of synthesized ChDs will have a profound impact on the unexplored biological aspects. This review points out this lacuna as room for future exploration.

An overview on the synthetic urease inhibitors with structure-activity relationship and molecular docking

Urease is a kind of enzyme which could be found in various bacteria, fungi, plants, and algae, which can quickly catalyze the hydrolysis of urea into ammonia and carbon dioxide. With the ammonia concentration increasing, the activity of Helicobacter pylori has got an obvious enhancement and leads to mucosal damage in the stomach, gastroduodenal infection, peptic ulcers, and gastric cancer. The infectious diseases caused by Helicobacter pylori can be controlled to a certain extent by inhibiting urease activity with urease inhibitors. Hence, studies of urease inhibitors have attracted great attention all over the world and a variety of effective urease inhibitors have been synthesized in recent years. In this review, we will draw summaries for these inhibitors including urease inhibitory activity, inhibition kinetics, structure-activity relationship, and molecular docking. The collected information is expected to provide rational guidance and effective strategy to develop novel, potent, and safe urease inhibitors for better practical applications in the future.

Crystal structure of (3E,3′E)-3,3′-((1,3,4-thiadiazole-2,5-diyl)bis(sulfanediyl))bis(4-hydroxy-4-phenylbut-3-en-2-one), C22H18N2O4S3

C22H18N2O4S3, monoclinic, P21/c (no. 14), a = 9.632(2) Å, b = 10.000(3) Å, c = 22.760(6) Å, β = 93.196(18)°, V = 2188.9(10) Å3, Z = 4, R gt(F) = 0.0354, wR ref(F 2) = 0.0933, T = 293(2) K.

Chitin/Chitosan and Its Derivatives: Fundamental Problems and Practical Approaches

In this review, we present the data on the natural occurrence of chitin and its partially or fully deacetylated derivative chitosan, as well as their properties, methods of modification, and potential applications of derivatives with bactericidal, fungicidal, and antioxidant activities. The structure and physicochemical characteristics of the polymers, their functions, and features of chitin microbial synthesis and degradation, including the processes occurring in nature, are described. New data on the hydrolytic microorganisms capable of chitin degradation under extreme conditions are presented. Special attention is focused on the effect of physicochemical characteristics of chitosan, including molecular weight, degree of deacetylation, polydispersity index, and number of amino group derivatives (quaternized, succinyl, etc.) on the antimicrobial and antioxidant properties of modified polymers that can be of particular interest for biotechnology, medicine, and agriculture. Analysis of the available literature data confirms the importance of fundamental research to broaden our knowledge on the occurrence of chitin and chitosan in nature, their role in global biosphere cycles, and prospects of applied research aimed at using chitin, chitosan, and their derivatives in various aspects of human activity.

Cationic chitosan derivatives as potential antifungals: A review of structural optimization and applications

The increasing resistance of pathogen fungi poses a global public concern. There are several limitations in current antifungals, including few available fungicides, severe toxicity of some fungicides, and drug resistance. Therefore, there is an urgent need to develop new antifungals with novel targets. Chitosan has been recognized as a potential antifungal substance due to its good biocompatibility, biodegradability, non-toxicity, and availability in abundance, but its applications are hampered by the low charge density results in low solubility at physiological pH. It is believed that enhancing the positive charge density of chitosan may be the most effective approach to improve both its solubility and antifungal activity. Hence, this review mainly focuses on the structural optimization strategy of cationic chitosan and the potential antifungal applications. This review also assesses and comments on the challenges, shortcomings, and prospect of cationic chitosan derivatives as antifungal therapy.

Synthesis, Antioxidant and Anti-inflammatory Activities of 5-((styrylsulfonyl) methyl)-1,3,4-Oxadiazol / Thiadiazol-2-amine Derivatives

Background:

A new class of 5-(styrylsulfonylmethyl)-1,3,4-oxadiazol-2-amine and 5- (styrylsulfonylmethyl)-1,3,4-thiadiazol-2-amine derivatives were prepared by derivatization of amino function.

Methods:

All the synthesized compounds were tested for antioxidant and anti-inflammatory activities.

Results:

The 2-amino-3-chloro-N-(5-(4-methylstyrylsulfonylmethyl)-1,3,4-oxadiazol-2-yl)-propanamide (12b) and 3-chloro-N-(5-(4-methylstyrylsulfonylmethyl)-1,3,4-oxadiazol-2-yl)-butanamide (14b) displayed significant antioxidant activity, greater than the standard Ascorbic acid.

Conclusion:

Moreover, 12b and 14b also exhibited promising anti-inflammatory activity

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.

Synthesis, Characterization, and Antifungal Activity of Schiff Bases of Inulin Bearing Pyridine ring

As a renewable, biocompatible, and biodegradable polysaccharide, inulin has a good solubility in water and some physiological functions. Chemical modification is one of the important methods to improve the bioactivity of inulin. In this paper, based on 6-amino-6-deoxy-3,4-acetyl inulin (3), three kinds of Schiff bases of inulin bearing pyridine rings were successfully designed and synthesized. Detailed structural characterization was carried out using FTIR, ¹³C NMR, and ¹H NMR spectroscopy, and elemental analysis. Moreover, the antifungal activity of Schiff bases of inulin against three plant pathogenic fungi, including Botrytis cinerea, Fusarium oxysporum f.sp.niveum, and Phomopsis asparagi, were evaluated using in vitro hypha measurements. Inulin, as a natural polysaccharide, did not possess any antifungal activity at the tested concentration against the targeted fungi. Compared with inulin and the intermediate product 6-amino-6-deoxy-3,4-acetyl inulin (3), all the synthesized Schiff bases of inulin derivatives with >54.0% inhibitory index at 2.0 mg/mL exhibited enhanced antifungal activity. 3NS, with an inhibitory index of 77.0% exhibited good antifungal activity against Botrytis cinerea at 2.0 mg/mL. The synthesized Schiff bases of inulin bearing pyridine rings can be prepared for novel antifungal agents to expand the application of inulin.

Synthesis, Characterization, and Antifungal Activity of Pyridine-Based Triple Quaternized Chitosan Derivatives

In this study, a series of triple quaternized chitosan derivatives, including 6-O-[(2-hydroxy-3-trimethylammonium)propyl]-2-N-(1-pyridylmethyl-2-ylmethyl)-N,N-dimethyl chitosan chloride (7), 6-O-[(2-hydroxy-3-trimethylammonium)propyl]-2-N-(1-pyridylmethyl-3-yl- methyl)-N,N-dimethyl chitosan chloride (8), and 6-O-[(2-hydroxy-3-trimethylammonium)propyl]- 2-N-(1-pyridylmethyl-4-ylmethyl)-N,N-dimethyl chitosan chloride (9) were successfully designed and synthesized via reacting epoxypropyl trimethylammonium chloride with the N-pyridinium double quaternized chitosan derivatives. Detailed structural characterization was carried out using FT-IR and ¹H-NMR spectroscopy, and elemental analysis. Besides, the activity of the triple quaternized chitosan derivatives against three common plant pathogenic fungi, Watermelon fusarium, Fusarium oxysporum, and Phomopsis asparagi, was investigated in vitro. The results indicated that the triple quaternized chitosan derivatives had enhanced antifungal activity when compared to double quaternized chitosan derivatives and chitosan, especially at 1.0 mg/mL, which confirmed the theory that the higher density of positive charge contributed to the antifungal activity. Moreover, 8 with an almost 99% inhibitory index showed the better antifungal activity against Watermelon fusarium. Moreover, the cytotoxicity of the products was also evaluated in vitro on 3T3-L1 cells and all the triple quaternized chitosan derivatives exhibited low cytotoxicity. These results suggested that triple quaternized chitosan derivatives may be used as good antifungal biomaterials.

Synthesis, characterization, and antifungal property of starch derivatives modified with quaternary phosphonium salts

Four novel starch derivatives modified with quaternary phosphonium salts were designed and successfully synthesized, including trimethylphosphonium acetyl starch chloride, tributylphosphonium acetyl starch chloride, tricyclohexylphosphonium acetyl starch chloride, triphenylphosphonium acetyl starch chloride, and characterized by FTIR, UV, ¹H NMR, ¹³C NMR, and ³¹P NMR spectra. Their antifungal activities against four kinds of phytopathogens were evaluated using the radial growth assay and minimum inhibitory concentration procedure. The fungicidal assessment revealed that the synthesized starch derivatives had superior antifungal activity compared with starch. Especially, the inhibitory indices of triphenylphosphonium acetyl starch chloride against these four kinds of plant pathogens were higher than 70% at 1.0mg/mL. The results indicated that quaternary phosphonium groups should be high-efficiency antifungal function groups, and meanwhile longer alkyl chain lengths or the stronger electron-withdrawing groups were responsible for enhanced antifungal versatility and efficacy. The cytotoxicity of starch and starch derivatives bearing quaternary phosphonium salts was evaluated in vitro on HEK-293T cells. As novel quaternary phosphonium functionalized starch derivatives could be prepared efficiently and exhibited superduper antifungal activity, this synthetic strategy might provide an effective way and notion to prepare novel antifungal biomaterials.

Novel Amino-Pyridine Functionalized Chitosan Quaternary Ammonium Derivatives: Design, Synthesis, and Antioxidant Activity

Chemical modification of chitosan is increasingly studied for its potential of providing new applications of chitosan. Here, a group of novel chitosan quaternary ammonium derivatives containing pyridine or amino-pyridine were designed and successfully synthesized through chemical modification of chitosan. Pyridine and amino-pyridine were used as functional groups to improve the antifungal activity of chitosan derivatives. The chitosan derivatives' antioxidant activity against hydroxyl-radical and 1,1-Diphenyl-2-picrylhydrazyl (DPPH)-radical was tested in vitro. The results showed that chitosan derivatives had better water solubility and stronger antioxidant activity compared with chitosan in all assays. Especially, compounds 3C and 3E (with 3-amino pyridine and 2,3-diamino pyridine as substitute respectively) exhibited stronger hydroxyl-radical and DPPH-radical scavenging ability than other synthesized compounds. These data demonstrated that the synergistic effect of the amino group and pyridine would improve the antioxidant activity of chitosan derivatives, and the position of the amino group on pyridine could influence the antioxidant property of chitosan derivatives.

An update on polysaccharide-based nanomaterials for antimicrobial applications

Scientific community has made a lot of efforts to combat the infectious diseases using antimicrobial agents, but these are associated with problems of development of multi-drug resistance and their adverse side effects. To tackle these challenges, nanocarrier-based drug delivery system using polysaccharides has received enormous attention in the past few years. These antimicrobial agents can become more efficacious when adsorbed, entrapped, or linked to polysaccharides. In addition, these nanocarrier-based systems provide an increase in the surface area of the drug and are able to achieve the targeted drug delivery as well as used for the synthesis of packaging materials with improved mechanical strength, barrier, and antimicrobial properties. This review focuses on potential therapeutic applications of nanocarrier-based drug delivery systems using polysaccharides for antimicrobial applications.

Synthesis of Novel 2,5-Disubstituted-1,3,4-thiadiazoles Clubbed 1,2,4-Triazole, 1,3,4-Thiadiazole, 1,3,4-Oxadiazole and/or Schiff Base as Potential Antimicrobial and Antiproliferative Agents

In the present study, a new series of 2,5-disubstituted-1,3,4-thiadiazole tethered 1,2,4-triazole, 1,3,4-thiadiazole, 1,3,4-oxadiazole and Schiff base derivatives were synthesized and characterized by IR, ¹H-NMR, ¹³C-NMR, MS and elemental analyses. All compounds were screened for their antibacterial, antifungal and antiproliferative activity. Some of the synthesized derivatives have displayed promising biological activity.