Enhancing antifungal properties of chitosan by attaching isatin-piperazine-sulfonyl-acetamide pendant groups via novel imidamide linkage

World health organization listed fungi as priority pathogens in 2022 to counter their adverse effects on human well-being. The use of antimicrobial biopolymers is a sustainable alternative to toxic antifungal agents. In this study, we explore chitosan as an antifungal agent by grafting a novel compound N-(4-((4-((isatinyl)methyl)piperazin-1-yl)sulfonyl)phenyl) acetamide (IS). The acetimidamide linkage of IS to chitosan herein was confirmed by ¹³C NMR and is a new branch in chitosan pendant group chemistry. The modified chitosan films (ISCH) were studied using thermal, tensile, and spectroscopic methods. The ISCH derivatives strongly inhibit fungal pathogens of agricultural and human importance, namely Fusarium solani, Colletotrichum gloeosporioides, Myrothecium verrucaria, Penicillium oxalicum, and Candida albicans. ISCH80 showed an IC₅₀ value of 0.85 μg/ml against M. verrucaria and ISCH100 with IC₅₀ of 1.55 μg/ml is comparable to the commercial antifungal IC₅₀ values of Triadiamenol (3.6 μg/ml) and Trifloxystrobin (3 μg/ml). Interestingly, the ISCH series remained non-toxic up to 2000 μg/ml against L929 mouse fibroblast cells. The ISCH series showed long-standing antifungal action, superior to our lowest observed antifungal IC₅₀ values of plain chitosan and IS at 12.09 μg/ml and 3.14 μg/ml, respectively. ISCH films are thus suitable for fungal inhibition in an agricultural setting or food preservation.

Five-Membered Heterocyclic Sulfonamides as Carbonic Anhydrase Inhibitors

The development of heterocyclic derivatives has progressed considerably over the past decades, and many new carbonic anhydrase inhibitors (CAIs) fall into this field. In particular, five-membered heterocyclic sulfonamides have been generally shown to be more effective inhibitors compared to six-membered rings ones. Despite the importance of oxygen and nitrogen five-membered heterocyclic aromatic rings in medicinal chemistry, the installation of sulfonamide moiety on such heterocycles has not received much attention. On the other hand, 1,3,4-thiadiazole/thiadiazoline ring-bearing sulfonamides are the scaffolds which have been widely used in a variety of pharmaceutically important CAIs such as acetazolamide, metazolamide and their many derivatives obtained by using the tail approach. Here, we reviewed the field focusing on the diverse biological activities of these CAIs, such as antiglaucoma, antiepileptic, antitumor and antiinfective properties. This review highlights developments involving five-membered heterocyclic sulfonamides over the last years, with a focus on their pharmacological/clinical applications.

Piceatannol Protects against High Glucose-Induced Injury of Renal Tubular Epithelial Cells via Regulating Carbonic Anhydrase 2

INTRODUCTION

We here evaluated the efficacy of piceatannol (PIC) in high glucose (HG)-induced injury of renal tubular epithelial cells HK-2.

METHODS

After the establishment of an HG-induced cell injury model and the treatment with PIC at both high and low concentrations and/or acetazolamide (ACZ, the inhibitor of carbonic anhydrase 2 [CA2]), MTT and flow cytometry assays were carried out to confirm the viability and apoptosis of HK-2 cells. The levels of oxidative stress markers lactate dehydrogenase (LDH), malondialdehyde (MDA), and reactive oxygen species (ROS), the ratio of glutathione/oxidized glutathione (GSH/GSSG), and the CA2 activity were determined. Both quantitative reverse-transcription polymerase chain reaction and Western blot were used to calculate the expressions of CA2 (the predicted target gene of PIC via intersecting the data from bioinformatic analyses) and AKT pathway-related (phosphatase and tensin homolog [PTEN], phosphorylated [p]-AKT, AKT) and apoptosis-related proteins (Bcl-2 and cleaved caspase-3).

RESULTS

HG suppressed cell viability and the levels of GSH/GSSG ratio, CA2, pThr308-AKT/AKT, pSer473-AKT/AKT, and Bcl-2, while promoting cell apoptosis, the levels of LDH, MDA, and ROS, and the expressions of PTEN and cleaved caspase-3. All effects of HG were reversed by PIC at a high concentration. CA2 was predicted and identified as the target of PIC. In HG-treated HK-2 cells, additionally, ACZ reversed the effects of PIC on the viability, apoptosis, and levels of both oxidative stress markers and AKT pathway- and apoptosis-related factors.

CONCLUSION

PIC protects against HG-induced injury of HK-2 cells via regulating CA2.

Detecting Key Functional Components Group and Speculating the Potential Mechanism of Xiao-Xu-Ming Decoction in Treating Stroke

Stroke is a cerebrovascular event with cerebral blood flow interruption which is caused by occlusion or bursting of cerebral vessels. At present, the main methods in treating stroke are surgical treatment, statins, and recombinant tissue-type plasminogen activator (rt-PA). Relatively, traditional Chinese medicine (TCM) has widely been used at clinical level in China and some countries in Asia. Xiao-Xu-Ming decoction (XXMD) is a classical and widely used prescription in treating stroke in China. However, the material basis of effect and the action principle of XXMD are still not clear. To solve this issue, we designed a new system pharmacology strategy that combined targets of XXMD and the pathogenetic genes of stroke to construct a functional response space (FRS). The effective proteins from this space were determined by using a novel node importance calculation method, and then the key functional components group (KFCG) that could mediate the effective proteins was selected based on the dynamic programming strategy. The results showed that enriched pathways of effective proteins selected from FRS could cover 99.10% of enriched pathways of reference targets, which were defined by overlapping of component targets and pathogenetic genes. Targets of optimized KFCG with 56 components can be enriched into 166 pathways that covered 80.43% of 138 pathways of 1,012 pathogenetic genes. A component potential effect score (PES) calculation model was constructed to calculate the comprehensive effective score of components in the components-targets-pathways (C-T-P) network of KFCGs, and showed that ferulic acid, zingerone, and vanillic acid had the highest PESs. Prediction and docking simulations show that these components can affect stroke synergistically through genes such as MEK, NFκB, and PI3K in PI3K-Akt, cAMP, and MAPK cascade signals. Finally, ferulic acid, zingerone, and vanillic acid were tested to be protective for PC12 cells and HT22 cells in increasing cell viabilities after oxygen and glucose deprivation (OGD). Our proposed strategy could improve the accuracy on decoding KFCGs of XXMD and provide a methodologic reference for the optimization, mechanism analysis, and secondary development of the formula in TCM.

Synthesis and Anti-Trypanosoma cruzi Biological Evaluation of Novel 2-Nitropyrrole Derivatives

Human American trypanosomiasis, called Chagas disease, caused by T. cruzi protozoan infection, represents a major public health problem, with about 7000 annual deaths in Latin America. As part of the search for new and safe anti-Trypanosoma cruzi derivatives involving nitroheterocycles, we report herein the synthesis of ten 1-substituted 2-nitropyrrole compounds and their biological evaluation. After an optimization phase, a convergent synthesis methodology was used to obtain these new final compounds in two steps from the 2-nitropyrrole starting product. All the designed derivatives follow Lipinski’s rule of five. The cytotoxicity evaluation on CHO cells showed no significant cytotoxicity, except for compound 3 (CC₅₀ = 24.3 µM). Compound 18 appeared to show activity against T. cruzi intracellular amastigotes form (EC₅₀ = 3.6 ± 1.8 µM) and good selectivity over the vero host cells. Unfortunately, this compound 18 showed an insufficient maximum effect compared to the reference drug (nifurtimox). Whether longer duration treatments may eliminate all parasites remains to be explored.

Synthesis, Crystal Structure, Inhibitory Activity and Molecular Docking of Coumarins/Sulfonamides Containing Triazolyl Pyridine Moiety as Potent Selective Carbonic Anhydrase IX and XII Inhibitors

In this work, two classes of Carbonic Anhydrase (CA) inhibitors, sulfonamide and coumarin derivatives linked to pyta moiety (2a-b) and their corresponding rhenium complexes (3a-b), were designed. These compounds were synthesized and fully characterized by classical analytical methods and X-ray diffraction. All the synthesized compounds were evaluated for their inhibitory activity against the hCA isoforms I, II, IX and XII. They exhibited high inhibitory activities in the range of nanomolar for both hCA IX and hCA XII isoforms. The sulfonamide compound 2a showed the strongest inhibition against the tumour-associated hCA IX isoform with a Ki of 11.7 nM. The tumour-associated isoforms hCA IX and hCA XII were selectively inhibited by all the coumarin derivatives, with inhibition constants ranging from 12.7 nM (2b) to 44.5 nM (3b), while the hCA I and II isoforms were slightly inhibited (in the micromolar range), as expected. In terms of selectivity, compared to previously published rhenium complex-based CA inhibitors, complex 3b showed one of the highest selectivities against hCA IX and hCA XII compared to the off-target isoforms hCA I and hCA II, making it a potential anti-cancer drug candidate. Molecular docking calculations were performed to investigate the inhibition profiles of the investigated compounds at the tumour-associated hCA IX active site and to rationalize our results.

Developments of small molecules as inhibitors for carbonic anhydrase isoforms

Carbonic anhydrases are ubiquitous, and their role in the hydration of carbon dioxide is essential for the survival of many tissues and organs. However, their association with many pathological diseases, especially in glaucoma, Alzheimer's, obesity, epilepsy, and tumorigenesis, has prompted the design and synthesis of novel carbonic anhydrase inhibitors (CAIs). Herein we describe (1) approaches used in the design of CAIs and (2) synthesis of small molecules as CAIs within the last five years. Despite the active research in this area, there are still more avenues to explore, especially selective inhibition of CA I, CA IX, and XII. These isoforms would continue to open up a diversity of carbonic anhydrase inhibitors containing 1,2,3-triazoles, imidazolone, pyrrolidone, thiadiazole, isatin, and glycoconjugates as part of their molecular frameworks.