RESUMEN
Catechin polyphenols are the major bioactive ingredients in green tea with various human health benefits. Extraction of catechins from green tea (GTE) leaves at optimized standard conditions is still a challenging approach. An optimized, rapid, and economic extraction method is industrially needed. We hypothesized that certain extraction techniques in the presence of natural polymers and antioxidants might improve GTE catechin extraction yield and its biological activity. The effect of microwave (30-60 seconds irradiation in a typical kitchen microwave) assisted extraction (MAE) and ultrasonic assisted extraction (UAE) techniques were evaluated separately and in combination. To study the effect of the extraction solvent, nine edible green solvent combinations were investigated namely water, ascorbic acid, chitosan/ascorbic acid, carboxymethylcellulose /ascorbic acid, methylcellulose /ascorbic acid, chitosan/methylcellulose/ascorbic acid, methylcellulose, chitosan/acetic acid, and ethanol. The amounts of extracted catechins from green tea leaves were quantified with HPLC-UV. Data showed that the use of MAE & UAE technique was the optimal in producing a higher extraction yield of catechins. Chitosan/ascorbic acid was the optimized solvent with high extraction efficiencies of catechins. Studies in high fat diet fed animals demonstrated significant reduction of total cholesterol and LDL-C by GTE after 3 weeks of oral daily administration. In conclusion, efficient extraction, and stabilization of catechins from green tea leaves demonstrated a significant lowering of high fat diet-mediated elevation in blood cholesterol and LDL-C levels.
RESUMEN
The risk of serious bleeding is a major liability of anticoagulant drugs that are active-site competitive inhibitors targeting the Factor Xa (FXa) prothrombin (PT) binding site. The present work identifies several new classes of small molecule anticoagulants that can act as nonactive site inhibitors of the prothrombinase (PTase) complex composed of FXa and Factor Va (FVa). These new classes of anticoagulants were identified, using a novel agnostic computational approach to identify previously unrecognized binding pockets at the FXa-FVa interface. From about three million docking calculations of 281,128 compounds in a conformational ensemble of FXa heavy chains identified by molecular dynamics (MD) simulations, 97 compounds and their structural analogues were selected for experimental validation, through a series of inhibition assays. The compound selection was based on their predicted binding affinities to FXa and their ability to successfully bind to multiple protein conformations while showing selectivity for particular binding sites at the FXa/FVa interface. From these, thirty-one (31) compounds were experimentally identified as nonactive site inhibitors. Concentration-based assays further identified 10 compounds represented by four small-molecule families of inhibitors that achieve dose-independent partial inhibition of PTase activity in a nonactive site-dependent and self-limiting mechanism. Several compounds were identified for their ability to bind to protein conformations only seen during MD, highlighting the importance of accounting for protein flexibility in structure-based drug discovery approaches.
Asunto(s)
Descubrimiento de Drogas , Inhibidores Enzimáticos/farmacología , Tromboplastina/antagonistas & inhibidores , Humanos , Modelos MolecularesRESUMEN
Maintaining cholesterol and triglyceride (TG) levels within healthy limits is critical for decreasing the risk of heart disease. Dyslipidemia refers to the abnormal levels of lipids in the blood, including low high-density lipoprotein cholesterol (HDL-C), also known as good cholesterol, high low-density lipoprotein cholesterol (LDL-C), also known as bad cholesterol, and/or high TG levels that contribute to the development and progression of atherosclerosis. In this article we reviewed some of the current therapeutic targets for the treatment of dyslipidemia, with a primary focus on endothelial lipase and lecithin cholesterol acyl transferase for raising HDL-C, and the proprotein convertase subtilisin-like kexin type 9 (PCSK9), microsomal triglyceride transfer protein, and the messenger RNA of apolipoprotein B for lowering LDL-C. In addition, we reviewed the role of apolipoprotein AI (apoAI) in raising HDL-C, where we discuss three apoAI-based drugs under development. These are its mutated dimer (apoAI-Milano), a complex with phospholipids, and a mimetic peptide. Atherosclerosis, mainly because of dyslipidemia, is a leading cause of cardiovascular disease. Regarding the title of this article, the 'good' refers to HDL-C, the 'bad' refers to LDL-C, and the 'ugly' refers to atherosclerosis.
Asunto(s)
Colesterol/metabolismo , Dislipidemias/metabolismo , Triglicéridos/metabolismo , Animales , Apolipoproteína A-I/metabolismo , Apolipoproteínas B/metabolismo , Aterosclerosis/fisiopatología , Enfermedades Cardiovasculares/fisiopatología , Colesterol/sangre , HDL-Colesterol/sangre , LDL-Colesterol/sangre , Dislipidemias/genética , Humanos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Lipasa/genética , Lipasa/metabolismo , Fosfatidilcolina-Esterol O-Aciltransferasa/biosíntesis , Fosfatidilcolina-Esterol O-Aciltransferasa/genética , Proproteína Convertasa 9 , Proproteína Convertasas/genética , Proproteína Convertasas/metabolismo , Serina Endopeptidasas/genética , Serina Endopeptidasas/metabolismo , Triglicéridos/sangreRESUMEN
Human coagulation factor XIa (FXIa), a serine protease activated by site-specific cleavage of factor XI by thrombin, FXIIa, or autoactivation, is a critical enzyme in the amplification phase of the coagulation cascade. To investigate the potential of FXIa inhibitors as safe anticoagulants, a series of potent, selective peptidomimetic inhibitors of FXIa were designed and synthesized. Some of these inhibitors showed low nanomolar FXIa inhibitory activity with >1000-fold FXa selectivity and >100-fold thrombin selectivity. The X-ray structure of one of these inhibitors, 36, demonstrates its unique binding interactions with FXIa. Compound 32 caused a doubling of the activated partial thromboplastin time in human plasma at 2.4 microM and was efficacious in a rat model of venous thrombosis. These data suggest that factor XIa plays a significant role in venous thrombosis and may be a suitable target for the development of antithrombotic therapy.
Asunto(s)
Anticoagulantes/farmacología , Diseño de Fármacos , Factor XIa/antagonistas & inhibidores , Inhibidores del Factor Xa , Fragmentos de Péptidos/síntesis química , Inhibidores de Serina Proteinasa/farmacología , Animales , Anticoagulantes/síntesis química , Anticoagulantes/química , Sitios de Unión , Cristalografía por Rayos X , Humanos , Concentración 50 Inhibidora , Masculino , Estructura Molecular , Tiempo de Tromboplastina Parcial , Fragmentos de Péptidos/química , Fragmentos de Péptidos/farmacología , Unión Proteica , Conformación Proteica , Ratas , Ratas Sprague-Dawley , Inhibidores de Serina Proteinasa/síntesis química , Inhibidores de Serina Proteinasa/química , Relación Estructura-Actividad , Trombina/antagonistas & inhibidores , Trombosis de la Vena/tratamiento farmacológicoRESUMEN
A series of functionalized aryl boronic acids were synthesized and evaluated as potential inhibitors of factor XIa. Crystal structures of the protein-inhibitor complexes led to the design and synthesis of second generation compounds showing single digit micromolar inhibition against FXIa and selectivity against thrombin, trypsin, and FXa.
Asunto(s)
Anticoagulantes/síntesis química , Ácidos Borónicos/síntesis química , Ácidos Borónicos/farmacología , Factor XIa/antagonistas & inhibidores , Anticoagulantes/farmacología , Sitios de Unión , Cristalografía por Rayos X , Diseño de Fármacos , Humanos , Concentración 50 Inhibidora , Unión Proteica , Conformación Proteica , Inhibidores de Serina Proteinasa/síntesis química , Inhibidores de Serina Proteinasa/farmacología , Relación Estructura-ActividadRESUMEN
Using an alpha-ketothiazole arginine moiety as a key recognition element, a series of small peptidomimetic molecules was designed and synthesized, and their co-crystal structures with factor XIa were studied in an effort to develop smaller, less peptidic inhibitors as antithrombotic agents.