New Meloxicam Derivatives-Synthesis and Interaction with Phospholipid Bilayers Measured by Differential Scanning Calorimetry and Fluorescence Spectroscopy

The purpose of the present paper was to assess the ability of five newly designed and synthesized meloxicam analogues to interact with phospholipid bilayers. Calorimetric and fluorescence spectroscopic measurements revealed that, depending on the details of the chemical structure, the studied compounds penetrated bilayers and affected mainly their polar/apolar regions, closer to the surface of the model membrane. The influence of meloxicam analogues on the thermotropic properties of DPPC bilayers was clearly visible because these compounds reduced the temperature and cooperativity of the main phospholipid phase transition. Additionally, the studied compounds quenched the fluorescence of prodan to a higher extent than laurdan, what pointed to a more pronounced interaction with membrane segments close to its surface. We presume that a more pronounced intercalation of the studied compounds into the phospholipid bilayer may be related to the presence of the molecule of a two-carbon aliphatic linker with a carbonyl group and fluorine substituent/trifluoromethyl group (compounds PR25 and PR49) or the three-carbon linker together with the trifluoromethyl group (PR50). Moreover, computational investigations of the ADMET properties have shown that the new meloxicam analogues are characterized by beneficial expected physicochemical parameters, so we may presume that they will have a good bioavailability after an oral administration.

Interaction of Oxicam Derivatives with the Artificial Models of Biological Membranes-Calorimetric and Fluorescence Spectroscopic Study

The modified 1,2-benzothiazine analogues designed as new drug candidates and discussed in this paper are oxicam derivatives. Oxicams are a class of non-steroidal anti-inflammatory drugs (NSAIDs). Their biological target is cyclooxygenase (COX), a membrane protein associated with the phospholipid bilayer. In recent decades, it has been proven that the biological effect of NSAIDs may be closely related to their interaction at the level of the biological membrane. These processes are often complicated and the biological membranes themselves are very complex. Therefore, to study these mechanisms, simplified models of biological membranes are used. To characterize the interaction of six oxicam derivatives with DPPC, DMPC and EYPC, artificial models of biological membranes (multi-bilayers or liposomes), differential scanning calorimetry (DSC) and fluorescence spectroscopy techniques were applied. In spectroscopic measurements, two fluorescent probes (Laurdan and Prodan) localized in different membrane segments were used. All tested oxicam derivatives interacted with the lipid bilayers and may penetrate the artificial models of biological membranes. They intercalated into the lipid bilayers and were located in the vicinity of the polar/apolar membrane interface. Moreover, a good drug candidate should not only have high efficiency against a molecular target but also exhibit strictly defined ADMET parameters, therefore these activities of the studied compounds were also estimated.

Modulating Properties of Piroxicam, Meloxicam and Oxicam Analogues against Macrophage-Associated Chemokines in Colorectal Cancer

The mechanisms underlying the antineoplastic effects of oxicams have not been fully elucidated. We aimed to assess the effect of classic and novel oxicams on the expression/secretion of macrophage-associated chemokines (RTqPCR/Luminex xMAP) in colorectal adenocarcinoma cells, and on the expression of upstream the non-steroidal anti-inflammatory drug (NSAID)-activated genes NAG1, NFKBIA, MYD88, and RELA, as well as at the chemokine profiling in colorectal tumors. Meloxicam downregulated CCL4 9.9-fold, but otherwise the classic oxicams had a negligible/non-significant effect. Novel analogues with a thiazine ring substituted with arylpiperazine and benzoyl moieties significantly modulated chemokine expression to varying degree, upregulated NAG1 and NFKBIA, and downregulated MYD88. They inhibited CCL3 and CCL4, and their effect on CCL2 and CXCL2 depended on the dose and exposure. The propylene linker between thiazine and piperazine nitrogens and one arylpiperazine fluorine substituent characterized the most effective analogue. Only CCL19 and CXCL2 were not upregulated in tumors, nor was CXCL2 in tumor-adjacent tissue compared to normal mucosa. Compared to adjacent tissue, CCL4 and CXCL2 were upregulated, while CCL2, CCL8, and CCL19 were downregulated in tumors. Tumor CCL2 and CCL7 increased along with advancing T and CCL3, and CCL4 along with the N stage. The introduction of arylpiperazine and benzoyl moieties into the oxicam scaffold yields effective modulators of chemokine expression, which act by upregulating NAG1 and interfering with NF-κB signaling.

Synthesis of New Tricyclic 1,2-Thiazine Derivatives with Anti-Inflammatory Activity

New, tricyclic compounds containing a sulfonyl moiety in their structure, as potential safer COX inhibitors, were designed and synthesized. New derivatives have three conjugated rings and a sulfonyl group. A third ring, i.e., an oxazine, oxazepine or oxazocin, has been added to the 1,2-benzothiazine skeleton. Their anti-COX-1/COX-2 and cytotoxic effects in vitro on NHDF cells, together with the ability to interact with model membranes and the influence on reactive oxygen species and nitric oxide, were studied. Additionally, a molecular docking study was performed to understand the binding interaction of the compounds with the active site of cyclooxygenases. For the abovementioned biological evaluation of new tricyclic 1,2-benzothiazine derivatives, the following techniques and procedures were employed: the differential scanning calorimetry, the COX colorimetric inhibitor screening assay, the MTT, DCF-DA and Griess assays. All of the compounds studied demonstrated preferential inhibition of COX-2 compared to COX-1. Moreover, all the examined tricyclic 1,2-thiazine derivatives interacted with the phospholipid model membranes. Finally, they neither have cytotoxic potency, nor demonstrate significant influence on the level of reactive oxygen species or nitric oxide. Overall, the tricyclic 1,2-thiazine derivatives are good starting points for future pharmacological tests as a group of new anti-inflammatory agents.

Synthesis and biological evaluation as well as in silico studies of arylpiperazine-1,2-benzothiazine derivatives as novel anti-inflammatory agents

Novel arylpiperazine-1,2-benzothiazine derivatives have been designed and synthesized as potential anti-inflammatory agents. Their structure and properties have been studied using spectroscopic techniques (¹H NMR, ¹³C NMR, FT-IR), MS, elemental analyses, and single-crystal X-ray diffraction (SCXRD, for compound 7b). This study aimed to evaluate the inhibitory activity of new derivatives against both cyclooxygenase isoforms COX-1 and COX-2 due to the similarity of new compounds to oxicams drugs from the NSAIDs group. All new compounds were divided into two series - A and B - with a different linker between thiazine and piperazines nitrogens. Series A included the three-carbon aliphatic linker and series B - two-carbon with a carbonyl group. According to in vitro and molecular docking studies all new compounds exhibited cyclooxygenase inhibitory activity. The series of A compounds included COX-1 inhibitors only. In contrast, the B series showed inhibition of both COX-1 and COX-2, which suggested the importance of the acetoxy linker for COX-2 inhibition. Moreover, the most selective compound 7b, towards COX-2, was non-toxic for the normal human cell line (in concentration of 10 µM) comparable to reference drug meloxicam. Additionally, investigation of influence on model membranes confirmed the ability of the compound 7b to penetrate lipid bilayers which seemed to be important to the influence with membrane protein-cyclooxygenase.

Synthesis and pharmacological evaluation of novel arylpiperazine oxicams derivatives as potent analgesics without ulcerogenicity

Gastrotoxicity continues to be a major issue in therapy with nonsteroidal anti-inflammatory drugs (NSAIDs). Medicine is yet to develop absolutely safe analgesics. Numerous strategies are employed to discover new, safer NSAIDs, for example selective inhibition of cyclooxygenase-2, new molecular targets (e.g. microsomal prostaglandin E₂ synthase-1), incorporation of cytoprotective compounds in the drug molecule or modification of the classic NSAIDs currently available on the market. The research presented in this paper is indicative of a current worldwide trend in this area of science, and is an example of the fourth strategy noted above. Two series of new arylpiperazine derivatives of the classic NSAID - piroxicam, were developed by conventional synthesis. The full range of compounds obtained proved to be between two and five times analgesically more potent than the reference drug and, most importantly, they did not show any ulcerogenic activity.