Anti-inflammatory effects of the Zingiber officinale roscoe constituent 12-dehydrogingerdione in lipopolysaccharide-stimulated Raw 264.7 cells.

Ginger has long been used worldwide as a spice, seasoning, and wine and is also used as a traditional medicine. There have been no previous studies of the potential beneficial effects of the ginger constituent 12-dehydrogingerdione (12-DHGD). We investigated the anti-inflammatory effect of 12-DHGD on lipopolysaccharide (LPS)-stimulated Raw 264.7 cells. The cytotoxicity of 12-DHGD was measured using the MTT assay, and production of prostaglandin E2 (PGE2 ) and the inflammatory cytokines interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)-α was measured by ELISA. Production of nitric oxide (NO) was measured using Griess reagent and expression of cyclooxygenase-2 (COX-2) and inducible NO (iNOS) enzymes was assessed by reverse transcriptase-polymerase chain reaction. Treatment of Raw 264.7 cells with 12-DHGD significantly inhibited LPS-stimulated production of NO (at 12-DHGD concentrations of 150 and 200 ng/ml), IL-6 (at 50, 100, 150, and 200 ng/ml), and PGE2 (at 200 ng/ml). Consistent with the effects on NO and PGE2 production, 12-DHGD treatment also inhibited the LPS-stimulated increase in iNOS and COX-2 mRNA levels. However, 12-DHGD did not affect production of IL-1ß or TNF-α in response to LPS. 12-DHGD, a constituent of ginger, is a potent inhibitor of proinflammatory mediator production in Raw 264.7 macrophage cells.

In vitro BACE-1 inhibitory activity of resveratrol oligomers from the seed extract of Paeonia lactiflora.

A new resveratrol oligomer (1) together with eight related components (2- 9) were isolated from the seed extract of Paeonia lactiflora (Paeoniaceae) as active principles responsible for the inhibition of beta-site APP-cleaving enzyme 1 (BACE-1) in vitro. The chemical structure of 1 was established as (-)-7a,8a- CIS- ε-viniferin with the aid of spectroscopic analyses including NOESY experiments. All isolated resveratrol oligomers (1- 9) demonstrated significant inhibition on baculovirus-expressed BACE-1 in a dose-dependent manner, which was assessed by the FRET assay using Rh-EVNLDAEFK as a substrate in vitro.

A nonthiazolidinedione peroxisome proliferator-activated receptor α/γ dual agonist CG301360 alleviates insulin resistance and lipid dysregulation in db/db mice.

Activation of peroxisome proliferator-activated receptors (PPARs) have been implicated in the treatment of metabolic disorders with different mechanisms; PPARα agonists promote fatty acid oxidation and reduce hyperlipidemia, whereas PPARγ agonists regulate lipid redistribution from visceral fat to subcutaneous fat and enhance insulin sensitivity. To achieve combined benefits from activated PPARs on lipid metabolism and insulin sensitivity, a number of PPARα/γ dual agonists have been developed. However, several adverse effects such as weight gain and organ failure of PPARα/γ dual agonists have been reported. By use of virtual ligand screening, we identified and characterized a novel PPARα/γ dual agonist, (R)-1-(4-(2-(5-methyl-2-p-tolyloxazol-4-yl)ethoxy)benzyl)piperidine-2-carboxylic acid (CG301360), exhibiting the improvement in insulin sensitivity and lipid metabolism. CG301360 selectively stimulated transcriptional activities of PPARα and PPARγ and induced expression of their target genes in a PPARα- and PPARγ-dependent manner. In cultured cells, CG301360 enhanced fatty acid oxidation and glucose uptake and it reduced pro-inflammatory gene expression. In db/db mice, CG301360 also restored insulin sensitivity and lipid homeostasis. Collectively, these data suggest that CG301360 would be a novel PPARα/γ agonist, which might be a potential lead compound to develop against insulin resistance and hyperlipidemia.

A new specific BACE-1 inhibitor from the stembark extract of Vitis vinifera.

A new resveratrol dimer, (+)-vitisinol E (1) which demonstrated inhibitory activity on BACE-1 (beta-site APP-cleaving enzyme 1) in vitro, was isolated from the stembark extract of Vitis vinifera (Vitaceae) together with four known resveratrol oligomers, (+)-epsilon-viniferin (2), (+)-ampelopsin A (3), (+)-vitisin A (4) and (-)-vitisin B (5). The chemical structure of 1 was established by MR spectroscopic analyses, including HMBC. All isolated resveratrol derivatives (1-5) demonstrated significant inhibition on baculovirus-expressed BACE-1 in a dose-dependent manner, which was assessed with the FRET assay using Rh-EVNLDAEFK as a substrate in vitro.

Trisindoline synthesis and anticancer activity.

Expression of a Rhodococcus-derived oxygenase gene in Escherichia coli yielded indigo metabolites with cytotoxic activity against cancer cells. Bioactivity-guided fractionation of these indigo metabolites led to the isolation of trisindoline as the agent responsible for the observed in vitro cytotoxic activity against cancer cells. While the cytotoxicity of etoposide, a common anticancer drug, was dramatically decreased in multidrug-resistant (MDR) cancer cells compared with treatment of parental cells, trisindoline was found to have similar cytotoxicity effects on both parental and MDR cell lines. In addition, the cytotoxic effects of trisindoline were resistant to P-glycoprotein overexpression, one of the most common mechanisms of drug resistance in cancer cells, supporting its use to kill MDR cancer cells.

Capsiate improves glucose metabolism by improving insulin sensitivity better than capsaicin in diabetic rats.

Red peppers and red pepper paste are reported to have anti-obesity, analgesic and anti-inflammatory effects in animals and humans due to the capsaicin in red pepper. We investigated whether consuming capsaicin and capsiate, a nonpungent capsaicin analogue, modifies glucose-stimulated insulin secretion, pancreatic ß-cell survival and insulin sensitivity in 90% pancreatectomized (Px) diabetic rats, a moderate and non-obese type 2 diabetic animal model. Px diabetic rats were divided into 3 treatment groups: 1) capsaicin (Px-CPA), 2) capsiate (Px-CPI) or 3) dextrose (Px-CON) and provided high fat diets (40 energy % fat) containing assigned components (0.025% capsaicin, capsiate, or dextrose) for 8 weeks. Both capsaicin and capsiate reduced body weight gain, visceral fat accumulation, serum leptin levels and improved glucose tolerance without modulating energy intake in diabetic rats. In comparison to the control, both capsaicin and capsiate potentiated first and second and phase insulin secretion during hyperglycemic clamp. Both also increased ß-cell mass by increasing proliferation and decreasing apoptosis of ß-cells by potentiating insulin/IGF-1 signaling. However, only capsiate enhanced hepatic insulin sensitivity during euglycemic hyperinuslinemic clamp. Capsiate reduced hepatic glucose output and increased triglyceride accumulation in the hyperinsulinemic state and capsiate alone significantly increased glycogen storage. This was related to enhanced pAkt→PEPCK and pAMPK signaling. Capsaicin and capsiate reduced triglyceride storage through activating pAMPK. In conclusion, capsaicin and capsiate improve glucose homeostasis but they differently enhance insulin sensitivity in the liver, insulin secretion patterns, and islet morphometry in diabetic rats. Capsiate has better anti-diabetic actions than capsaicin.

HPLC-ELSD analysis of 18 platycosides from balloon flower roots (Platycodi Radix) sourced from various regions in Korea and geographical clustering of the cultivation areas.

An effective HPLC method to analyse platycosides from the balloon flower root was developed using ELSD. The optimum resolution of the platycosides was achieved on an ODS column with gradient elution of eluent A, 30mM ammonium acetate buffer (pH 4.81): methanol: acetonitrile=75:5:20 (v/v/v), and B, 69:5:26 (v/v/v). Amongst 18 platycosides, platycoside E showed the highest content, followed by polygalacin D2 and 3″-O-acetylplatyconic acid A. The sum of these three compounds was recommended for quality control of balloon flower root for medicinal purposes. The samples could be clustered into groups based on platycoside content. Group I, characterised by a high concentration of platycosides, was located near the west coast of Korea, whereas group II, characterised by a low concentration of platycosides, was located inland or in mountainous area. The method could be used to control the quality of balloon flower root.

Yeast α-glucosidase inhibition by isoflavones from plants of Leguminosae as an in vitro alternative to acarbose.

In the course of searching for new classes of α-glucosidase inhibitors originated from natural resources, 11 kinds of isoflavones, i.e., medicarpin (1), formononetin (2), mucronulatol (3), (3R)-calussequinone (5), (3R)-5'-methoxyvestitol (6), tectorigenin (7), biochanin A (8), tuberosin (9), calycosin (10), daidzein (11), and genistein (12), as well as a flavone, liquritigenin (4), were isolated as active principles responsible for the yeast α-glucosidase inhibitory activity from two leguminous plant extracts, i.e., the heartwood extract of Dalbergia odorifera and the roots extract of Pueraria thunbergiana. Each components (1-12) demonstrated a significantly potent inhibition on yeast α-glucosidase in a dose dependent manner when the p-nitrophenyl-α-D-glucopyranoside was used as a substrate in vitro. The concentration required for 50% enzyme inhibition (IC50) were calculated as 2.93 mM (1), 0.51 mM (2), 3.52 mM (7) 0.35 mM (8), 3.52 mM (9), 0.85 mM (11), and 0.15 mM (12) when that of reference drug acarbose was evaluated as 9.11 mM, in vitro. However, isoflavone glycosides, i.e., puerarin (13), daidzin (14), formononetin-7-O-ß-glucopyranoside (15), and genistin (16), exhibited a relatively poor inhibitory activity on yeast α-glucosidase as compared with the corresponding isoflavone (2, 11, 12), respectively.

In vitro BACE-1 inhibitory phenolic components from the seeds of Psoralea corylifolia.

A new isoflavone, neocorylin ( 1) was isolated from the seeds extract of Psoralea corylifolia L. (Fabaceae), together with eight known constituents ( 2 - 9), i. e., bakuchiol ( 2), psoralen ( 3), bavachromene ( 4), isobavachromene ( 5), bavachalcone ( 6), isobavachalcone ( 7), 7,8-dihydro-8-(4-hydrophenyl)-2,2-dimethyl-2 H,6 H-[1,2- B:5,4- B']dipyran-6-one ( 8), and bavachinin ( 9). The structure of the new isoflavone 1 was elucidated as 7-hydroxy-3-[2-methyl-2-(4-methylpenten-3-yl)-2 H-chromen-6-yl]-4 H-chromen-4-one by spectroscopic analyses. Neocorylin ( 1) as well as related compounds 2, 4 - 6, 8 and 9 exhibited a significant inhibitory effect on baculovirus-expressed BACE-1 in vitro.

Cardiovascular effects of lignans isolated from Saururus chinensis.

Saururus chinensis has been widely used as a traditional medicine for the treatment of beriberi, hypertension, pneumonia, edema, jaundice and gonorrhea. However, there is only limited information on the cardiovascular effects of S. chinensis extract or its single compounds. The present study was performed to investigate the effects of active lignans isolated from the extract of S. chinensis on vascular responses and heart functions. The vasorelaxant activity-guided fractionation of roots extract of S. chinensis led to the isolation of eight lignans as active principles. These lignans produced concentration-dependent relaxations of the endothelium-intact aortic preparations of rat aorta. Particularly, saucerneol ( 1), saucerneol D ( 2) and machilin D ( 8) exhibited distinctive vasorelaxant activity (EC (50) values: 2.2, 12.7 and 17.8 microM, respectively), which were significantly inhibited by removal of functional endothelium or pretreatment with N(G)-nitro-L-arginine methyl ester. Saucerneol ( 1) and saucerneol D ( 2) caused a significant decrease in left ventricular pressure, +dP/dt (max) and heart rate in isolated hearts. These results suggest that several lignans including saucerneol ( 1), saucerneol D ( 2) and machilin D ( 8), isolated from the ethanol extract of the roots of S. chinensis, have significant cardiovascular effects such as vasorelaxant and negative inotropic actions.

Vasorelaxant effect of stilbenes from rhizome extract of rhubarb (Rheum undulatum) on the contractility of rat aorta.

The vascular relaxant effect of the rhizome extract of Rheum undulatum was evaluated with isolated rat thoracic aorta preparations. The methanol extract of the rhizome induced a concentration-dependent relaxation of aortic preparations precontracted with 0.3 microm phenylephrine (EC50 value: 5.8 microg/mL). The activity-guided fractionation of the extract led to the isolation of seven hydroxystilbene components as active principles, i.e. piceatannol, resveratrol, desoxyrhapontigenin, rhapontigenin, piceid, rhaponticin and epsilon-viniferin. Of these, piceatannol, a tetrahydroxystilbene, exhibited the most potent vascular relaxant effect in rat aortic preparations (EC50 value 2.4 microm). The vasorelaxant effect of piceatannol on endothelium-intact aorta rings was diminished completely by the removal of functional endothelium or by pretreatment of the aortic tissues with N(G)-nitro-l-arginine methyl ester. These results suggest that piceatannol may be the major mediator responsible for the vasorelaxing properties of the rhizome extract of Rheum undulatum and the vasorelaxant effects of the piceatannol may be mediated via endothelium-dependent nitric oxide signaling pathway.

Vasorelaxant effect of the rootbark extract of Paeonia moutan on isolated rat thoracic aorta.

The vascular relaxant effect of the rootbark extract of Paeonia moutan was evaluated in isolated rat thoracic aorta. The methanolic extract of the rootbark showed a vasorelaxant activity in rat aortic preparations precontracted with 0.3 microM phenylephrine (IC50 value: 16.8 microg/mL). The activity-guided fractionation of the extract led to the isolation of five active principles such as paeoniflorin (1), paeonidanin (2), methylpaeoniflorin (4), tetragalloylglucose (5) and pentagalloylglucose (6), and these active ingredients potently relaxed phenylephrine-induced contraction of rat aortic preparations in a concentration-dependent manner (IC50 values: 19.4, 7.9, 10.1, 5.1 and 3.6 microM, respectively). These results suggest that pinane glycosides and galloylglucoses might be the components responsible for the vasorelaxant properties of the rootbark extract of P. moutan, and their vasorelaxant effects may be mediated through increases in the release of nitric oxide from endothelial cells.

PTP-1B inhibitors: cyclopenta[d][1,2]-oxazine derivatives.

A series of novel cyclopenta[d][1,2]-oxazine derivatives was prepared and evaluated for their inhibitory activity toward protein tyrosine phosphatase 1B (PTP-1B). Compound 6s was found to be an inhibitor of PTP-1B with nanomolar IC(50) value and high level of selectivity over other recombinant phosphatases.