Novel benzene sulfonamide-piperazine hybrid compounds: design, synthesis, antioxidant, enzyme inhibition activities and docking, ADME profiling studies.

Benzene sulfonamides are an important biological substituent for several activities. In this study, hybridization of benzene sulfonamide with piperazine derivatives were investigated for their antioxidant capacity and enzyme inhibitory potencies. Six molecules were synthesized and characterized. DPPH, ABTS, FRAP, CUPRAC, chelating and phosphomolybdemum assays were applied to evaluate antioxidant capacities. Results show that compounds have high antioxidant capacity and compound 4 has the best antioxidant activity among them. Compound 4 has higher antioxidant activity than references for FRAP (IC50: 0.08 mM), CUPRAC (IC50: 0.21 mM) and phosphomolybdenum (IC50: 0.22 mM) assays. Besides this, compound 4 has moderate DPPH and ABTS antioxidant capacity. Furthermore, enzyme inhibition activities of these molecules were investigated against AChE, BChE, tyrosinase, α-amylase and α-glucosidase enzymes. It was revealed that all compounds have good enzyme inhibitory potential except for α-amylase enzyme. The best inhibitory activities were observed for AChE with compound 5 the same value (IC50: 1.003 mM), for BChE with compounds 2 and 5 the same value (IC50: 1.008 mM), for tyrosinase compound 4 (IC50: 1.19 mM), and for α-glucosidase with compound 3 (IC50: 1.000 mM). Docking studies have been conducted with these molecules, and the results correlate well with the inhibitory assays.

Piperazine and piperidine-substituted 7-hydroxy coumarins for the development of anti-inflammatory agents.

Coumarins (2H-1-benzopyran-2-one), derivatives that can be isolated from several plants, have been reported for their anticoagulant, antimicrobial, anti-inflammatory, or anticancer activity. Some of these structures are currently approved for the treatment of cardiovascular diseases, as antibiotics or as an anticancer drug. Given the great potential of this structure and the limited number of studies that focus on molecules derived from carbon 8 of the benzopyranone heterocycle, we synthesized in this project 38 coumarin derivatives by substituting carbon 8 of the benzopyran ring with some aromatic and aliphatically substituted piperidines and piperazines. As a few of these structures were already shown to exhibit some carbonic anhydrase (CA) inhibition and as CA enzymes are reported to be closely related to inflammation, the synthesized derivatives were evaluated for their anti-inflammatory activity in vitro. The results indicated that compounds 20 and 31 revealed promising anti-inflammatory activity, as they demonstrated better activity than the reference drugs.

Novel 8-Substituted Coumarins That Selectively Inhibit Human Carbonic Anhydrase IX and XII.

A novel series of 8-substituted coumarin-based compounds, characterized by the presence of alkylpiperazine and arylpiperazine chains, were synthesized and tested for their inhibitory activity against four human carbonic anhydrase (hCA) isoforms. All compounds displayed nanomolar potency against the cancer-related hCA IX and hCA XII; moreover, they were shown to be devoid of any inhibitory activity toward the cytosolic hCA I and hCA II up to 10 µM concentration in the assay system. Therefore, the synthesized coumarin ligands demonstrated to be potent and selective hCA IX/XII inhibitors, and were shown to be as potent as the reference inhibitor acetazolamide against hCA XII, with single-digit nanomolar Ki values. Molecular modeling studies provided a rationale for explaining the selectivity profile of these non-classic hCA inhibitors and their interactions with the enzymes, according to their specific mechanism of action, thus paving the way for future structure-based lead optimization studies.

The cysteine releasing pattern of some antioxidant thiazolidine-4-carboxylic acids.

Oxidative stress that corresponds to a significant increase in free radical concentration in cells can cause considerable damage to crucial biological macromolecules if not prevented by cellular defense mechanisms. The low-molecular-weight thiol glutathione (GSH) constitutes one of the main intracellular antioxidants. It is synthesized via cysteine, an amino acid found only in limited amounts in cells because of its neurotoxicity. Thus, to ensure an efficient GSH synthesis in case of an oxidative stress, cysteine should be provided extracellularly. Yet, given its nucleophilic properties and its rapid conversion into cystine, its corresponding disulfide, cysteine presents some toxicity and therefore is usually supplemented in a prodrug approach. Here, some thiazolidine-4-carboxylic acids were synthesized and evaluated for their antioxidant properties via the DDPH and CUPRAC assays. Then, the cysteine releasing capacity of the obtained compounds was investigated in aqueous and organic medium in order to correlate the relevant antioxidant properties of the molecules with their cysteine releasing pattern. As a result, the structures' antioxidative properties were not only attributed to cysteine release but also to the thiazolidine cycle itself.

Gold(I)/Zn(II) catalyzed tandem hydroamination/annulation reaction of 4-yne-nitriles.

The tandem hydroamination-annulation reaction of 4-pentyne-nitriles in the presence of amine nucleophiles and a cooperatively operating catalyst system, consisting of Ph(3)PAuCl and Zn(ClO(4))(2), provides an efficient route to 2-aminopyrroles. Two regioisomeric 2-aminopyrroles were formed in moderate to good yields.