Novel Insights on CAI-CORM Hybrids: Evaluation of the CO Releasing Properties and Pain-Relieving Activity of Differently Substituted Coumarins for the Treatment of Rheumatoid Arthritis

Pain control is among the most important healthcare services in patients affected by rheumatoid arthritis (RA), but the current therapeutic options (i.e., disease-modifying anti-rheumatic drugs) are limited by the risk of the side effects. In this context, we proposed an innovative approach based on the hybridization between carbonic anhydrase inhibitors (CAIs) and CO releasing molecules (CORMs). The resulting CAI-CORM hybrids were revealed to possess strong anti-inflammatory effects in in vitro models of diseases and to relieve ache symptoms in an in vivo RA rat model. In this work, we have deepened the study of these promising hybrids, designing a library of coumarin-based compounds, also including internal dicobalt hexacarbonyl systems. The results obtained from the CO releasing study, the CA inhibitory activity, and the in vivo pain-relief efficacy evaluation in the RA rat model confirmed the success of this strategy, allowing us to consider CAI-CORM hybrids promising anti-nociceptive agents against arthritis.

Intestinal inflammation increases convulsant activity and reduces antiepileptic drug efficacy in a mouse model of epilepsy

We studied the effects of intestinal inflammation on pentylenetetrazole (PTZ)-induced seizures in mice and the effects thereon of some antiepileptic and anti-inflammatory treatments to establish if a link may exist. The agents tested were: alpha-lactoalbumin (ALAC), a whey protein rich in tryptophan, effective in some animal models of epilepsy and on colon/intestine inflammation, valproic acid (VPA), an effective antiepileptic drug in this seizure model, mesalazine (MSZ) an effective aminosalicylate anti-inflammatory treatment against ulcerative colitis and sodium butyrate (NaB), a short chain fatty acid (SCFA) normally produced in the intestine by gut microbiota, important in maintaining gut health and reducing gut inflammation and oxidative stress. Intestinal inflammation was induced by dextran sulfate sodium (DSS) administration for 6 days. Drug treatment was started on day 3 and lasted 11 days, when seizure susceptibility to PTZ was measured along with intestinal inflammatory markers (i.e. NF-κB, Iκ-Bα, COX-2, iNOS), histological damage, disease activity index (DAI) and SCFA concentration in stools. DSS-induced colitis increased seizure susceptibility and while all treatments were able to reduce intestinal inflammation, only ALAC and NaB exhibited significant antiepileptic properties in mice with induced colitis, while they were ineffective as antiepileptics at the same doses in control mice without colitis. Interestingly, in DSS-treated mice, VPA lost part of its antiepileptic efficacy in comparison to preventing seizures in non-DSS-treated mice while MSZ remained ineffective in both groups. Our study demonstrates that reducing intestinal inflammation through ALAC or NaB administration has specific anticonvulsant effects in PTZ-treated mice. Furthermore, it appears that intestinal inflammation may reduce the antiepileptic effects of VPA, although we confirm that it decreases seizure threshold in this group. Therefore, we suggest that intestinal inflammation may represent a valid antiepileptic target which should also be considered as a participating factor to seizure incidence in susceptible patients and also could be relevant in reducing standard antiepileptic drug efficacy.

Modifications on the Amino-3,5-dicyanopyridine Core To Obtain Multifaceted Adenosine Receptor Ligands with Antineuropathic Activity

A new series of amino-3,5-dicyanopyridines (1-31) was synthesized and biologically evaluated in order to further investigate the potential of this scaffold to obtain adenosine receptor (AR) ligands. In general, the modifications performed have led to compounds having high to good human (h) A₁AR affinity and an inverse agonist profile. While most of the compounds are hA₁AR-selective, some derivatives behave as mixed hA₁AR inverse agonists/A_2A and A_2B AR antagonists. The latter compounds (9-12) showed that they reduce oxaliplatin-induced neuropathic pain by a mechanism involving the alpha7 subtype of nAchRs, similar to the nonselective AR antagonist caffeine, taken as the reference compound. Along with the pharmacological evaluation, chemical stability of methyl 3-(((6-amino-3,5-dicyano-4-(furan-2-yl)pyridin-2-yl)sulfanyl)methyl)benzoate 10 was assessed in plasma matrices (rat and human), and molecular modeling studies were carried out to better rationalize the available structure-activity relationships.

Synthesis and Evaluation of Carbonic Anhydrase Inhibitors with Carbon Monoxide Releasing Properties for the Management of Rheumatoid Arthritis

Carbon monoxide (CO) is a gas endogenously produced in humans, reported to exhibit anti-inflammatory and cytoprotective effects at low concentration. In this context, CO releasing molecules (CORMs) are attracting enormous interest. Herein, we report a series of small-molecule hybrids consisting of a carbonic anhydrase (CA; EC 4.2.1.1) inhibitor linked to a CORM tail section (CAI-CORMs). All compounds were screened in vitro for their inhibition activity against the human (h) CA I, II, IV, IX, and XII isoforms. On selected CAI-CORM hybrids, the CO releasing properties were evaluated, along with their pain-relieving effect, in a model of rheumatoid arthritis. One CAI-CORM hybrid (5b) induced a higher pain-relieving effect compared to the one exerted by the single administration of CAI (5a) and CORM (15b) fragments, shedding light on the possibility to enhance the pain relief effect of CA inhibitors inserting a CO releasing moiety on the same molecular scaffold.

Design, synthesis and X-ray crystallography of selenides bearing benzenesulfonamide moiety with neuropathic pain modulating effects

A series of selenides bearing benzensulfonamide were investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). Potent inhibitory action, in the low nanomolar range, was detected against isoforms hCA II and VII, which are known to be involved in neuropathic pain modulation. These selenides showed on the other hand moderate inhibition against the cytosolic isoforms hCA I and transmembrane hCA IX. X-ray crystallographic data of two derivatives bound to hCA II allowed us to rationalize the excellent inhibitory data. In a mice model of neuropathic pain induced by oxaliplatin, some of the strong CA II/VII inhibitors induced a long lasting pain relieving effect.

Design, Synthesis, and X-ray of Selenides as New Class of Agents for Prevention of Diabetic Cerebrovascular Pathology

A series of novel selenides bearing benzenesulfonamide moieties was synthesized and investigated for their inhibition on six human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms such as the physiologically relevant hCA I, II, VA, VB, VII, and IX and the X-ray complex in adduct with hCA II for some of them investigated. These enzymes are involved in a variety of diseases including glaucoma, retinitis pigmentosa, epilepsy, arthritis, metabolic disorders, and cancer. The investigated compounds showed potent inhibitory action against hCA VA, VII, and IX, in the low nanomolar range, thus making them of interest for the development of isoform-selective inhibitors and as candidates for various biomedical applications.