Synthesis of Moracin C and Its Derivatives with a 2-arylbenzofuran Motif and Evaluation of Their PCSK9 Inhibitory Effects in HepG2 Cells.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key factor in several cardiovascular diseases, as it is responsible for the elevation of circulating low-density lipoprotein cholesterol (LDL-C) levels in blood plasma by direct interaction with the LDL receptor. The development of orally available drugs to inhibit this PCSK9-LDLR interaction is a highly desirable objective. Here, we report the synthesis of naturally occurring moracin compounds and their derivatives with a 2-arylbenzofuran motif to inhibit PCSK9 expression. In addition, we discuss a short approach involving the three-step synthesis of moracin C and a divergent method to obtain various analogs from one starting material. Among the tested derivatives, compound 7 (97.1%) was identified as a more potent inhibitor of PCSK9 expression in HepG2 cells than berberine (60.9%). These results provide a better understanding of the structure-activity relationships of moracin derivatives for the inhibition of PCSK9 expression in human hepatocytes.

Novel linked butanolide dimer compounds increase adiponectin production during adipogenesis in human mesenchymal stem cells through peroxisome proliferator-activated receptor γ modulation.

Compounds inducing adiponectin production have therapeutic potential for metabolic diseases. During screening, heme oxygenase-1-inducing marliolide derivatives were identified as adiponectin-inducing compounds. Although some marliolide derivatives were directly bound to peroxisome proliferator-activated receptor γ (PPARγ), the adiponectin-inducing activity did not correlate with the PPARγ binding affinity. The most potent adiponectin inducing compound, (E,4S,5S)-3-butylidene-dihydro-4-hydroxy-5-methylfuran-2(3H)-one (1a), exhibited the weakest PPARγ binding activity. A docking simulation suggested that two 1a molecules can be present in two different sites within the PPARγ-ligand-binding pocket (LBP). Based on the docking model, novel linked butanolide dimer compounds were synthesized. A linked butanolide dimer compound, (3E,3'E,4S,4'S,5S,5'S)-3,3'-(decane-1,10-diylidene)bis(4-hydroxy-5-methyldihydrofuran-2(3H)-one) (3a), promoted adiponectin production in human bone marrow mesenchymal stem cells (hBM-MSCs) as a novel PPARγ full agonist (EC50, 4.34 µM). This linked butanolide dimer study provides novel insight into PPARγ biology, suggesting that small molecules can form multiple ligand interactions within the PPARγ-LBP and thereby affect the functional outcomes of PPARγ activation.

Discovery of Flavonoids from Scutellaria baicalensis with Inhibitory Activity Against PCSK 9 Expression: Isolation, Synthesis and Their Biological Evaluation.

Nine flavonoids were isolated and identified from a chloroform-soluble fraction of the roots of Scutellaria baicalensis through a bioactivity-guided fractionation using a proprotein convertase subtilisin/kexin type 9 (PCSK9) monitoring assay in HepG2 cells. All structures were established by interpreting the corresponding spectroscopic data and comparing measured values from those in the literature. All compounds were assessed for their ability to inhibit PCSK9 mRNA expression; compounds 1 (3,7,2'-trihydroxy-5-methoxy-flavanone) and 4 (skullcapflavone II) were found to suppress PCSK9 mRNA via SREBP-1. Furthermore, compound 1 was found to increase low-density lipoprotein receptor protein expression. Also, synthesis of compound 1 as a racemic mixture form (1a) was completed for the first time. Natural compound 1 and synthetic racemic 1a were evaluated for their inhibitory activities against PCSK9 mRNA expression and the results confirmed the stereochemistry of 1 was important.