New quinoxalinone inhibitors targeting secreted phospholipase A2 and α-glucosidase

Synthesis, biological evaluation, and molecular modelling of novel quinoxaline-isoxazole hybrid as anti-hyperglycemic

In our effort to develop potent anti-hyperglycemic compounds with inhibitory activity against α-amylase and α-glucosidase, a series of novel quinoxaline-isoxazole moieties were synthesized. The novel quinoxaline-isoxazole derivatives were assessed in vitro for their anti-hyperglycemic activities on α-amylase and α-glucosidase inhibitions. The results revealed promising IC50 values compared to acarbose as a positive control for α-amylase and α-glucosidase. Among them, N-Ethyl-7-chloro-3-((3-phenylisoxazol-5-yl)methoxy)quinoxalin-2-amine 5b showed dual inhibitory with IC50 of 24.0 µM for α-amylase and 41.7 µM for α-glucosidase. In addition, N-Ethyl-7-methoxy-3-((3-(2-chlorophenyl)isoxazol-5-yl)methoxy)quinoxalin-2-amine 5j also had dual bioactivities against α-amylase and α-glucosidase with IC50 of 17.0 and 40.1 µM, respectively. Nevertheless, two more compounds N-Ethyl-7-cyano-3-((3-phenylisoxazol-5-yl)methoxy)quinoxaline-2-amine 5e showed strong mono-inhibition for α-glucosidase with IC50 of 16.6 µM followed by N-Ethyl-7-methoxy-3-((3-phenylisoxazol-5-yl)methoxy)quinoxalin-2-amine 5 f with IC50 of 18.6 µM. The molecular docking study for α-glucosidase inhibitor provided the binding energy ranging from 8.3 to 9.1 kcal/mol and α-amylase inhibitor showed the binding energy score at 8.4 and 8.5 kcal/mol. The dual inhibitions nature of 5b and 5j were further analyzed and confirmed via molecular dynamics including the stability of the compound, interaction energy, binding free energy, and the interaction residue analysis using the MM-GBSA approach. The results showed that compound 5j was the most potent compound. Lastly, the drug-likeness properties were also evaluated with all synthesized compounds 5a-5j and the results reveal that all potent compounds meet Lipinski's rules of five.

Functionalized quinoxalinones as privileged structures with broad-ranging pharmacological activities

Quinoxalinones are a class of heterocyclic compounds which attract extensive attention owing to their potential in the field of organic synthesis and medicinal chemistry. During the past few decades, many new synthetic strategies toward the functionalization of quinoxalinone based scaffolds have been witnessed. Regrettably, there are only a few reports on the pharmacological activities of quinoxalinone scaffolds from a medicinal chemistry perspective. Therefore, herein we intend to outline the applications of multifunctional quinoxalinones as privileged structures possessing various biological activities, including anticancer, neuroprotective, antibacterial, antiviral, antiparasitic, anti-inflammatory, antiallergic, anti-cardiovascular, anti-diabetes, antioxidation, etc. We hope that this review will facilitate the development of quinoxalinone derivatives in medicinal chemistry.

Synthesis of 2-styryl-quinazoline and 3-styryl-quinoxaline based sulfonate esters via sp3 C-H activation and their evaluation for α-glucosidase inhibition

Synthesis of 2-styryl-quinazolines and 3-styryl-quinoxaline based sulfonates is reported via sp3 C-H functionalization in the presence of triethylamine (10 mol%). The resulting compounds were tested for the α-glucosidase enzyme inhibition...

Design, Synthesis, and Biological Activity of Conformationally Restricted Analogues of Silibinin

Silibinin (Sib), one of the main components of milk thistle extract, has attracted considerable attention because of its various biological activities, which include antioxidant activity and potential effects in diabetes and Alzheimer's disease (AD). In a previous study, we synthesized catechin analogues by constraining the geometries of (+)-catechin and (-)-epicatechin. The constrained analogues exhibited enhanced bioactivities, with the only major difference between the two being their three-dimensional structures. The constrained geometry in (+)-catechin resulted in a high degree of planarity (PCat), while (-)-epicatechin failed to maintain planarity (PEC). The three-dimensional structure of Sib may be related to its ability to inhibit aggregation of amyloid beta (Aβ). We therefore introduced PCat and PEC into Sib to demonstrate how the constrained molecular geometry and differences in three-dimensional structures may enhance such activities. Introduction of PCat into Sib (SibC) resulted in effective inhibition of Aβ aggregation, α-glucosidase activity, and cell growth, suggesting that not only reduced flexibility but also the high degree of planarity may enhance the biological activity. SibC is expected to be a promising lead compound for the treatment of several diseases.

Recent advances in micro- and nano-bubbles for atherosclerosis applications

Micro- and nano-bubbles have been developed as powerful multimodal theranostic agents for atherosclerosis treatment.

Small-molecule inhibitors as potential therapeutics and as tools to understand the role of phospholipases A2

Phospholipase A2 (PLA2) enzymes are involved in various inflammatory pathological conditions including arthritis, cardiovascular and autoimmune diseases. The regulation of their catalytic activity is of high importance and a great effort has been devoted in developing synthetic inhibitors. We summarize the most important small-molecule synthetic PLA2 inhibitors developed to target each one of the four major types of human PLA2 (cytosolic cPLA2, calcium-independent iPLA2, secreted sPLA2, and lipoprotein-associated LpPLA2). We discuss recent applications of inhibitors to understand the role of each PLA2 type and their therapeutic potential. Potent and selective PLA2 inhibitors have been developed. Although some of them have been evaluated in clinical trials, none reached the market yet. Apart from their importance as potential medicinal agents, PLA2 inhibitors are excellent tools to unveil the role that each PLA2 type plays in cells and in vivo. Modern medicinal chemistry approaches are expected to generate improved PLA2 inhibitors as new agents to treat inflammatory diseases.

In Silico and In Vitro Study of the Bromelain-Phytochemical Complex Inhibition of Phospholipase A2 (Pla2)

Phospholipase A2 (Pla2) is an enzyme that induces inflammation, making Pla2 activity an effective approach to reduce inflammation. Therefore, investigating natural compounds for this Pla2 inhibitory activity has important therapeutic potential. The objective of this study was to investigate the potential in bromelain-phytochemical complex inhibitors via a combination of in silico and in vitro methods. Bromelain-amenthoflavone displays antagonistic effects on Pla2. Bromelian-asiaticoside and bromelain-diosgenin displayed synergistic effects at high concentrations of the combined compounds, with inhibition percentages of more than 70% and 90%, respectively, and antagonistic effects at low concentrations. The synergistic effect of the bromelain-asiaticoside and bromelain-diosgenin combinations represents a new application in treating inflammation. These findings not only provide significant quantitative data, but also provide an insight on valuable implications for the combined use of bromelain with asiaticoside and diosgenin in treating inflammation, and may help researchers develop more natural bioactive compounds in daily foods as anti-inflammatory agent.