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

Exploration of thiazine Schiff bases as promising urease inhibitors: Design, synthesis, enzyme inhibition, kinetic analysis, ADME/T evaluation, and molecular docking studies

Urease catalyzes the hydrolysis of urea, leading to an increase in stomach pH and supporting Helicobacter pylori survival, which is linked to several gastrointestinal disorders. In this study, thiazine-based Schiff bases were explored as promising urease inhibitors. Various spectroscopic techniques characterized the synthetic library of thiazine Schiff bases 2-36 and also evaluated for their inhibitory activities against urease. The derivatives demonstrated significant inhibitory potential with IC50 values ranging from 0.14 ± 0.08 to 3.66 ± 0.21 μM, outperforming the standard inhibitor thiourea (IC50 = 19.43 ± 0.18 μM). Structure-activity relationship (SAR) studies revealed that specific substitutions (type and positions) on the aryl ring significantly affect the inhibition potential. The most potent derivative, compound 7, possessed 2-methoxy-5-trifluoromethyl substitutions and exhibited an IC50 of 0.14 ± 0.08 μM. Enzyme kinetics studies revealed that the most potent derivatives function as competitive inhibitors. Additionally, molecular docking studies provided insights into the binding interactions between the molecule and the urease active site, highlighting key residues involved in inhibitor binding. These findings highlight the therapeutic potential of thiazine-based Schiff bases as urease inhibitors and provide insights for the development of new anti-ulcer agents.

Transition-metal-free intramolecular double hydrofunctionalization of alkyne to access 6/7/5-fused heterocyclic skeletons

We describe a novel intramolecular double hydrofunctionalization cyclization of alkyne with nitrogen and oxygen nucleophilic groups to construct valuable 6/7/5-fused heterocyclic products. This post-Groebke-Blackburn-Bienaymé (GBB) reaction introduces a new class of functionalized isocyanides. Transition-metal-free cyclization, broad substrate scope, and high atom economy were some features of the present protocol.

Green Synthetic Methods of Oxazine and Thiazine Scaffolds as Promising Medicinal Compounds: A Mini-review

Medical researchers have paid close attention to the green synthesis of oxazine and thiazine derivatives since they provided a lead molecule for the creation of numerous possible bioactive compounds. This review provides more information on green synthesis, which will be very helpful to researchers in creating the most effective, affordable, and clinically significant thiazine and oxazine derivatives that are anticipated to have strong pharmacological effects. This has resulted in the identification of several substances with a wide range of intriguing biological functions. This article's goal is to examine the numerous green chemical processes used to create oxazine and thiazine derivatives and their biological activity. We anticipate that researchers interested in oxazine and thiazine chemicals will find this material to be useful. We anticipate that medicinal chemists looking for new active medicinal components for drug discovery and advance progress will find this review of considerable interest.

Isolation of oligostilbenes from Iris lactea Pall. var. chinensis (Fisch.) Koidz and their anti-inflammatory activities

Iris lactea Pall. var. chinensis (Fisch.) Koidz (Iris lactea) is an herbaceous perennial widely distributed in China, India, and South Korea. Iris lactea has been extensively used in traditional Chinese medicine. The present study isolated a new oligostilbene (compound 1), together with three known oligostilbenes (compounds 2, 3 and 4) from the seeds of Iris lactea. The structures of these compounds were elucidated by HRESIMS, NMR, and chemical analyses. The network-based pharmacologic analysis platform was used to predict the target proteins related to inflammation of isolated compounds. Furthermore, the isolated compounds were tested for their anti-inflammatory effects in LPS-stimulated RAW 264.7 cells. In this network, 138 candidate targets of compounds related to its therapeutic effect on inflammation were identified. In addition, compounds 1, 2, 3 and 4 significantly decreased NO content and the IL-6 levels as well as the expression of COX-2 in LPS-stimulated RAW 264.7 cells.

Effect of tricyclic 1,2-thiazine derivatives in neuroinflammation induced by preincubation with lipopolysaccharide or coculturing with microglia-like cells

Background

Alzheimer’s disease (AD) is considered the most common cause of dementia among the elderly. One of the modifiable causes of AD is neuroinflammation. The current study aimed to investigate the influence of new tricyclic 1,2-thiazine derivatives on in vitro model of neuroinflammation and their ability to cross the blood–brain barrier (BBB).

Methods

The potential anti-inflammatory effect of new tricyclic 1,2-thiazine derivatives (TP1, TP4, TP5, TP6, TP7, TP8, TP9, TP10) was assessed in SH-SY5Y cells differentiated to the neuron-like phenotype incubated with bacterial lipopolysaccharide (5 or 50 μg/ml) or THP-1 microglial cell culture supernatant using MTT, DCF-DA, Griess, and fast halo (FHA) assays. Additionally, for cultures preincubated with 50 µg/ml lipopolysaccharide (LPS), a cyclooxygenase (COX) activity assay was performed. Finally, the potential ability of tested compounds to cross the BBB was evaluated by computational studies. Molecular docking was performed with the TLR4/MD-2 complex to assess the possibility of binding the tested compounds in the LPS binding pocket. Prediction of ADMET parameters (absorption, distribution, metabolism, excretion and toxicity) was also conducted.

Results

The unfavorable effect of LPS and co-culture with THP-1 cells on neuronal cell viability was counteracted with TP1 and TP4 in all tested concentrations. Tested compounds reduced the oxidative and nitrosative stress induced by both LPS and microglia activation and also reduced DNA damage. Furthermore, new derivatives inhibited total COX activity. Additionally, new compounds would cross the BBB with high probability and reach concentrations in the brain not lower than in the serum. The binding affinity at the TLR4/MD-2 complex binding site of TP4 and TP8 compounds is similar to that of the drug donepezil used in Alzheimer's disease. The ADMET analysis showed that the tested compounds should not be toxic and should show high intestinal absorption.

Conclusions

New tricyclic 1,2-thiazine derivatives exert a neuroregenerative effect in the neuroinflammation model, presumably via their inhibitory influence on COX activity and reduction of oxidative and nitrosative stress.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43440-022-00414-8.