Kwang-il Kwon

Metformin inhibits P-glycoprotein expression via the NF-κB pathway and CRE transcriptional activity through AMPK activation

BACKGROUND AND PURPOSE The expression of P‐glycoprotein (P‐gp), encoded by the multidrug resistance 1 (MDR1) gene, is associated with the emergence of the MDR phenotype in cancer cells. We investigated whether metformin (1,1‐dimethylbiguanide hydrochloride) down‐regulates MDR1 expression in MCF‐7/adriamycin (MCF‐7/adr) cells.

Purple sweet potato anthocyanins attenuate hepatic lipid accumulation through activating adenosine monophosphate-activated protein kinase in human HepG2 cells and obese mice

Purple sweet potato is a functional food rich in anthocyanins that possess disease-preventive properties. Anthocyanins are known to possess potent antidiabetic properties. However, the effect of the anthocyanin fraction (AF) from purple sweet potato on hepatic lipid metabolism remains unclear. Our hypothesis is that AF inhibits hepatic lipid accumulation through the activation of adenosine monophosphate-activated protein kinase (AMPK) signaling pathways in vitro and in vivo. In this study, we evaluated body weight, liver histology, and hepatic lipid content in high-fat diet (HFD)-fed ICR mice treated with AF. In addition, we characterized the underlying mechanism of AFs effects in HepG2 hepatocytes through Western blot analysis. Anthocyanin fraction (200 mg/kg per day) reduced weight gain and hepatic triglyceride accumulation and improved serum lipid parameters in mice fed an HFD for 4 weeks. Anthocyanin fraction significantly increased the phosphorylation of AMPK and acetyl-coenzyme A carboxylase (ACC) in the liver and HepG2 hepatocytes. In addition, AF down-regulated the levels of sterol regulatory element-binding protein 1 and its target genes including ACC and fatty acid synthase (FAS). The specific AMPK inhibitor compound C attenuated the effects of AF on the expression of lipid metabolism-related proteins such as SREBP-1 and FAS in HepG2 hepatocytes. The beneficial effects of AF on HFD-induced hepatic lipid accumulation are thus mediated through AMPK signaling pathways, suggesting a potential target for the prevention of obesity.

Suppression of EGF-induced tumor cell migration and matrix metalloproteinase-9 expression by capsaicin via the inhibition of EGFR-mediated FAK/Akt, PKC/Raf/ERK, p38 MAPK, and AP-1 signaling.

SCOPE Capsaicin is a cancer-suppressing agent. The aim of our study was to determine the effect of capsaicin on tumor invasion and migration; the possible mechanisms involved in this inhibition were investigated in human fibrosarcoma cells. METHODS AND RESULTS We employed invasion, migration and gelatin zymography assays to characterize the effect of capsaicin on HT-1080 cells. Transient transfection assays and immunoblot analysis were performed to study its molecular mechanisms of action. Capsaicin inhibited the epidermal growth factor (EGF)-induced activation of matrix metalloproteinase (MMP)-9 and MMP-2, and further inhibited cell invasion and migration. Capsaicin decreased the EGF-induced expression of MMP-9, MMP-2, and MT1-MMP, but did not alter TIMP-1 and TIMP-2 levels. Capsaicin suppressed EGF-induced c-Jun and c-Fos nuclear translocation, and also abrogated the EGF-induced phosphorylation of EGF receptor (EGFR), focal adhesion kinase (FAK), protein kinase C (PKC), phosphatidylinositol 3-Kinase (PI3K)/Akt, extracellular regulated kinase (ERK)1/2, and JNK1/2, an upstream modulator of AP-1. Furthermore, the EGFR inhibitor inhibited EGF-induced MMP-9 expression, as well as AP-1 activity and cell migration. CONCLUSION Capsaicin inhibited the EGF-induced invasion and migration of human fibrosarcoma cells via EGFR-dependent FAK/Akt, PKC/Raf/ERK, p38 mitogen-activated protein kinase (MAPK), and AP-1 signaling, leading to the down-regulation of MMP-9 expression. These results indicate the role of capsaicin as a potent anti-metastatic agent, which can markedly inhibit the metastatic and invasive capacity of fibrosarcoma cells.

Pharmacokinetic characterization of decursinol derived from Angelica gigas Nakai in rats

Decursinol is a major coumarin derived from the roots of Angelica gigas and has various pharmacological effects against inflammation, angiogenesis, nociceptive pain and Alzheimer’s disease. In vitro and in vivo studies were conducted to characterize the metabolism and pharmacokinetics of decursinol. Decursinol exhibited high stability to oxidative and glucuronic metabolism in human and rat liver microsomes. In Caco-2 cell monolayers, decursinol showed high permeability (>14 × 10−6 cm/s) at all tested concentrations in the absorptive direction, which saturated at 100 μM. Secretion increased in a concentration-dependent manner, with an efflux ratio of more than 2 at 50 μM, indicating the participation of an active efflux transporter such as P-glycoprotein, multidrug resistance protein 2 or breast cancer resistance protein. The fraction of decursinol not bound to plasma proteins was 25–26% in the rat and 9–18% in humans. In human plasma, but not rat plasma, the percentage of unbound decursinol was concentration dependent. Following intravenous administration in rats, non-linear elimination of decursinol was observed with Km and Vmax values of 2.1 μg/mL and 2.5 mg·h−1·kg−1, respectively. Following oral administration, decursinol exhibited high oral bioavailability (>45%) and rapid absorption (Tmax, 0.4–0.9 h) over the dose range studied. In addition, dose-dependent absorption and elimination were observed at 20 mg/kg.

Advanced method for determination of omeprazole in plasma by HPLC.

An advanced and sensitive high-performance liquid chromatographic (HPLC) method for determination of omeprazole in human plasma has been developed. After omeprazole was extracted from plasma with diethylether, the organic phase was transferred to another tube and trapped back with 0.1 N NaOH solution. The alkaline aqueous layer was injected into a reversed-phase C8 column. Lansoprazole was used as an internal standard. The mobile phase consisted of 30% of acetonitrile and 70% of 0.2 M KH2PO4, pH 7.0. Recoveries of the analytes and internal standard were >75.48%. The coefficients of variation of intra- and inter-day assay were <5.78 and 4.59% for plasma samples. The detection limit in plasma was 2 ng/ml. The clinical applicability of this assay method was evaluated by determining plasma concentration-time courses of the respective analytes in 24 healthy volunteers after oral administration 40 mg of omeprazole. The present assay is considered to be simple, accurate, economical and suitable for the study of the kinetic disposition of omeprazole in the body.

Saponins from the roots of Platycodon grandiflorum suppress ultraviolet A-induced matrix metalloproteinase-1 expression via MAPKs and NF-κB/AP-1-dependent signaling in HaCaT cells

Saponins from the roots of Platycodon grandiflorum (CKS) have been shown to exhibit many pharmacological activities, including anti-cancer and anti-inflammatory activities and antioxidant effects. However, anti-skin photoaging effects of CKS have not yet been reported. In this study, we investigated the protective effects of CKS against UVA damage on immortalized human keratinocytes (HaCaT). We then explored the inhibitory effects of CKS on UVA-induced MMP-1 and investigated the molecular mechanism underlying those effects. CKS increased the cell viability and inhibited reactive oxygen species (ROS) production in HaCaT cells exposed to UVA irradiation. Pre-treatment of HaCaT cells with CKS inhibited UVA-induced production of MMP-1 and MMP-9. In addition, CKS decreased UVA-induced expression of the inflammatory cytokines IL-1β and IL-6. Western blot analysis further revealed that CKS markedly suppressed the enhancement of collagen degradation in UVA-exposed HaCaT cells. CKS also suppressed UVA-induced activation of NF-κB or c-Jun and c-Fos, and the phosphorylation of MAPKs, which are upstream modulators of NF-κB and AP-1.

The Effects of Food on the Bioavailability of Fenofibrate Administered Orally in Healthy Volunteers via Sustained-Release Capsule

ObjectiveTo examine the effects of food on plasma concentration and bioavailability of fenofibrate administered as a sustained-release capsule.MethodsTwenty-four healthy Korean volunteers were enrolled in a randomised, open-label, balanced, three-treatment, three-period, three-sequence, single oral dose, crossover pharmacokinetic study. A single dose of fenofibrate (250mg sustained-release capsule) was administered on three occasions — after overnight fasting, after consumption of a standard breakfast and after a high-fat breakfast. Serial blood samples were collected for the next 72 hours. Plasma fenofibric acid concentrations were measured by high-performance liquid chromatography, and pharmacokinetic parameters were calculated.ResultsThe pharmacokinetic parameters were significantly affected by food intake. The high-fat breakfast affected the rate of absorption of fenofibrate more than the standard breakfast and fasted conditions. Specifically, the area under the plasma concentration-time curve from time zero to infinity (AUC∞) and peak plasma concentration (Cmax) increased 2.45-fold and 2.89-fold, respectively, between the fasted and standard-fed conditions (p < 0.01). In addition, the high-fat meal caused 3.34-fold and 3.82-fold increases compared with the fasted condition in AUC∞ and Cmax, respectively. A one-compartment open model with lag time successfully described the plasma concentrations of fenofibric acid.ConclusionIn healthy volunteers, AUC∞ and Cmax of fenofibrate, when administered via sustained-release capsules immediately after the consumption of food, was increased significantly from the fasting conditions (p < 0.01). The greatest AUC∞ and Cmax occurred when the capsules were taken after a high-fat breakfast.

Cytochrome P450-mediated herb–drug interaction potential of Galgeun-tang

We evaluated the herb-drug interaction potential of Galgeun-tang (GGT) extracts, mediated by cytochrome P450 (CYP) inhibition/induction. Further, the effects of fermentation on the CYP-mediated herb-drug interaction potential of GGT extracts were determined. As measured by LC-ESI/MS/MS, GGT extracts (0-300μg/mL) showed no inhibitory activity toward eight CYP isoforms (1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, and 3A4) in pooled human liver microsomes, suggesting that GGT may have low potential for herb-drug interactions mediated by CYP inhibition. Hepatic CYP expression and activity in rats treated with GGT extracts twice per day for 1week was examined. Among the tested CYP isoforms (1A1, 1A2, 1B1, 2B1, 2C11, 2E1, 3A1, 3A2, and 4A1), CYP1B1 and 4A1 were increased by GGT extracts. Hepatic activities of 7-ethoxyresorufin-O-deethylase, 7-pentoxyresorufin-O-depentylase, and chlorzoxazone 6-hydroxylase, but not midazolam hydroxylase were also elevated. These results raise the possibility that GGT extracts may increase the toxicity of environmental toxicants through the elevating CYP-dependent metabolic activation. Interestingly, the increases in CYP1B1 and CYP4A1 levels, and 7-ethoxyresorufin-O-deethylase, 7-pentoxyresorufin-O-depentylase, and chlorzoxazone 6-hydroxylase activities were attenuated by fermentation of GGT extract using Lactobacillus plantarum KFRI 402, but not 144. Further studies are needed to identify the CYP regulatory component(s) from GGT and determination its metabolism.

Analysis of enantiomers of sibutramine and its metabolites in rat plasma by liquid chromatography-mass spectrometry using a chiral stationary-phase column.

Sibutramine, a monoamine reuptake inhibitor, is used as a racemate, for the treatment of obesity. It is converted in vivo mainly to two desmethyl active metabolites, mono-desmethylsibutramine (MDS) and di-desmethylsibutramine (DDS). In the present study, we introduced a rapid and simple chromatographic method for separating the R(+)- and S(-)-isomers of sibutramine, MDS, and DDS, respectively. The stereoisomers of the three compounds were extracted from rat plasma using diethyl ether and n-hexane under alkaline conditions. After evaporating the organic layer, the residue was reconstituted in the mobile phase (10 mM ammonium acetate buffer adjusted to pH 4.03 with acetic acid:acetonitrile, 94:6, v/v). The enantiomers in the extract were separated on a Chiral-AGP stationary-phase column and were quantified in a tandem mass spectrometry. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. This method was used to measure the concentrations of the enantiomers of sibutramine, MDS, and DDS in plasma after a single oral dose of 10 mg/kg racemic sibutramine in rats.

3-Caffeoyl, 4-dihydrocaffeoylquinic acid from Salicornia herbacea inhibits tumor cell invasion by regulating protein kinase C-δ-dependent matrix metalloproteinase-9 expression.

In this study, we determined the effects of a novel chlorogenic acid, 3-caffeoyl, 4-dicaffeoylquinic acid (CDCQ) isolated from Salicornia herbacea, on tumor invasion and migration in human fibrosarcoma HT-1080 cells and investigated the possible mechanism(s) involved. CDCQ reduced the phorbol myristate acetate (PMA)-induced activation of matrix metalloproteinase (MMP)-9 and MMP-2 and inhibited cell invasion and migration. CDCQ suppressed PMA-induced expression of MMP-9 mRNA and protein by suppressing the transcription factor AP-1, without changing the level of tissue inhibitor of metalloproteinase (TIMP)-1. CDCQ-inhibited PMA-induced MMP-2 expression by suppressing membrane-type 1 MMP (MT1-MMP), but did not alter the TIMP-2 level. CDCQ also inhibited the PMA-induced nuclear translocation of c-Jun and c-Fos, which are upstream of PMA-induced MMP-9 expression. Furthermore, CDCQ strongly repressed PMA-induced phosphorylation of ERK, p38 MAPK, and JNK, which are dependent on the PKCdelta pathway. In conclusion, we demonstrated that the anti-invasive effects of CDCQ occur through the inhibition of AP-1 and signaling pathways involving PKCdelta and three MAPKs, leading to the downregulation of MMP-9 expression. Thus, CDCQ is an effective anti-metastatic agent that functions by downregulating MMP-9 gene expression.