Hyo Kon Chun

HEPATOPROTECTIVE EFFECTS OF 18β-GLYCYRRHETINIC ACID ON CARBON TETRACHLORIDE-INDUCED LIVER INJURY: INHIBITION OF CYTOCHROME P450 2E1 EXPRESSION

The protective effects of 18beta-glycyrrhetinic acid (GA), the aglycone of glycyrrhizin (GL) derived from licorice, on carbon tetrachloride-induced hepatotoxicity and the possible mechanisms involved in this protection were investigated in mice. Pretreatment with GA prior to the administration of carbon tetrachloride significantly prevented an increase in serum alanine, aspartate aminotransferase activity and hepatic lipid peroxidation in a dose-dependent manner. In addition, pretreatment with GA also significantly prevented the depletion of glutathione (GSH) content in the livers of carbon tetrachloride-intoxicated mice. However, reduced hepatic GSH levels and glutathione-S-transferase activities were unaffected by treatment with GA alone. Carbon tetrachloride-induced hepatotoxicity was also prevented, as indicated by a liver histopathologic study. The effects of GA on the cytochrome P450 (P450) 2E1, the major isozyme involved in carbon tetrachloride bioactivation, were also investigated. Treatment of mice with GA resulted in a significant decrease of the P450 2E1-dependent hydroxylation of p-nitrophenol and aniline in a dose-dependent manner. Consistent with these observations, the P450 2E1 expressions were also decreased, as determined by immunoblot analysis. GA also showed antioxidant effects upon FeCl(2)-ascorbate-induced lipid peroxidation in mice liver homogenate and upon superoxide radical scavenging activity. These results show that protective effects of GA against the carbon tetrachloride-induced hepatotoxicity may be due to its ability to block the bioactivation of carbon tetrachloride, primarily by inhibiting the expression and activity of P450 2E1, and its free radical scavenging effects.

Tungtungmadic acid, a novel antioxidant, fromSalicornia herbacea

Tungtungmadic acid (3-caffeoyl-4-dihydrocaffeoyl quinic acid) is a new chlorogenic acid derivative that was isolated from theSalicornia herbacea. The structure of tungtungmadic acid was determined using chemical and spectral analysis. The antioxidant activity of tungtungmadic acid was evaluated using various antioxidant assays, including free radical scavenging, lipid peroxidation and hydroxyl radical-induced DNA strand breaks assays. Tungtungmadic acid (IC50=5.1 μM and 9.3 μM) was found to have higher antioxidant activity in the DPPH scavenging assay as well as in the iron-induced liver microsomal lipid peroxidation system. In addition, the tungtungmadic acid was also effective in protecting the plasmid DNA against strand breakage induced by hydroxyl radicals.

Protective mechanisms of 3-caffeoyl, 4-dihydrocaffeoyl quinic acid from Salicornia herbacea against tert-butyl hydroperoxide-induced oxidative damage

Salicornia herbacea has been used as a folk medicine for disorders such as constipation, obesity, diabetes, and cancer. Recent studies have shown that S. herbacea has antioxidative, anti-inflammatory, immunomodulatory, antihyperglycemic, and antihyperlipidemic activities. In the present work, we investigated the protective effects of the chlorogenic acid derivative, 3-caffeoyl, 4-dihydrocaffeoyl quinic acid (CDCQ), which was isolated from S. herbacea, against tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity in Hepa1c1c7 cells. Pretreatment of Hepa1c1c7 cells with CDCQ significantly reduced t-BHP-induced generation of ROS, caspase-3 activation, and subsequent cell death. Also, CDCQ up-regulated heme oxygenase-1 (HO-1) expression, which conferred cytoprotection against oxidative injury induced by t-BHP. Moreover, CDCQ-induced nuclear translocation of the transcription factor NF-E2-related factor 2 (Nrf2), which is upstream of CDCQ-induced HO-1 expression, and PI3K/Akt activation, a pathway that is involved in induced Nrf2 nuclear translocation. Taken together, these results suggest that the protective effects of CDCQ against t-BHP-induced hepatotoxicity may be due, at least in part, to its ability to scavenge ROS and to regulate the antioxidant enzyme HO-1 via the PI3K/Akt-Nrf2 signaling pathways.

3-Caffeoyl, 4-dihydrocaffeoylquinic acid from Salicornia herbacea attenuates high glucose-induced hepatic lipogenesis in human HepG2 cells through activation of the liver kinase B1 and silent information regulator T1/AMPK-dependent pathway.

SCOPE Increasing evidence indicates that polyphenols may protect against metabolic disease through activating AMP-activated protein kinase (AMPK). The aims of our study were to provide new data on the molecular mechanism(s) underlying the role of the phenolic compound, 3-caffeoyl, 4-dihydrocaffeoylquinic acid (CDCQ) from Salicornia herbacea, in the prevention of high glucose-induced lipogenesis in human HepG2 cells. METHODS AND RESULTS Nile red staining assays were used to demonstrate lipid accumulation in the cells. Expression of sterol regulatory element-binding protein-1c (SREBP-1c) and fatty acid synthase (FAS) gene at the levels of promoter activity, mRNA, and protein was demonstrated using transient transfection assays, quantitative RT-PCR, and Western blot analyses, respectively. We found that CDCQ suppressed high glucose-induced lipid accumulation in HepG2 cells. CDCQ strongly inhibited high glucose-induced FAS expression by modulating SREBP-1c activation. Moreover, the use of both a specific inhibitor and liver kinase B1 (LKB1)-siRNA transfected HepG2 cells showed that CDCQ activated AMPK via silent information regulator T1 (SIRT1) or LKB1 in HepG2 cells. CONCLUSION These results indicate that CDCQ prevented lipid accumulation by blocking the expression of SREBP-1c and FAS through LKB1/SIRT1 and AMPK activation in HepG2 cells, suggesting that CDCQ plays a potential role in the prevention of lipogenesis by AMPK activation.

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.

Inhibitory effect of 3-caffeoyl-4-dicaffeoylquinic acid from Salicornia herbacea against phorbol ester-induced cyclooxygenase-2 expression in macrophages.

Salicornia herbacea (S. herbacea), an annual herb that grows in the salt marshes of the Korean peninsula, has been used as a folk medicine to treat a variety of diseases such as constipation, obesity, diabetes, and cancer. However, the effect of S. herbacea on inflammation is unclear. In the present study, we investigated the effects of a novel chlorogenic acid, 3-caffeoyl-4-dicaffeoylquinic acid (CDCQ), isolated from S. herbacea, on cyclooxygenase-2 (COX-2) expression in murine macrophage RAW 264.7 cells. Phorbol 12-myristate 13-acetate (PMA) induces COX-2 expression and production of prostaglandin E(2) (PGE(2)). PMA-induced COX-2 protein, gene expression and PGE(2) production were significantly inhibited by CDCQ in a dose-dependent manner. Transfection of hCOX-2, as well as of deletion and mutation promoter constructs, revealed that the CCAAT/enhancer-binding protein (C/EBP) and activator protein-1 (AP-1) predominantly contributed to the effects of CDCQ. In addition, electrophoretic mobility shift assays and transfection results showed that CDCQ directly inhibited PMA-induced C/EBP and AP-1 transcription and binding activity. CDCQ also remarkably reduced PMA-induced C/EBPbeta and c-jun protein expression. Furthermore, CDCQ significantly inhibited PMA-induced activation of the mitogen-activated protein kinases (MAP kinases), JNK and p38. These findings demonstrate that CDCQ effectively attenuates COX-2 production, and enhance our understanding of the anti-inflammatory properties of CDCQ.

Hypouricemic Effects of Anthocyanin Extracts of Purple Sweet Potato on Potassium Oxonate-induced Hyperuricemia in Mice

Gout is a clinical syndrome in which tissue damage is induced by a chronic metabolic disorder associated with increased concentrations of uric acid in the blood. The study investigated the hypouricemic effects of anthocyanin extracts from purple sweet potato (APSP), and allopurinol, on serum uric acid levels in hyperuricemic mice. It was found that administration of a single oral dose of 100 mg/kg APSP to such animals reduced the serum uric acid concentration to 4.10 ± 0.04 mg/dL, compared with a concentration of 10.25 ± 0.63 mg/dL in the hyperuricemic control group. Copyright

A New Fibrinolytic Enzyme (55 kDa) from Allium tuberosum: Purification, Characterization, and Comparison

Chives have been used both as food and as medicine. Previously, two fibrinolytic enzymes, ATFE-I (90 kDa) and ATFE-II (55 kDa), were identified in chives (Allium tuberosum), a perennial herb. In the present work, ATFE-II was purified by ion-exchange chromatography followed by gel filtration. In addition, the enzyme properties of ATFE-I and ATFE-II were compared. The molecular mass and isoelectric point (pI value) of ATFE-II were 55 kDa and pI 4.0, respectively, as revealed using one- or two-dimensional fibrin zymography. ATFE-II was optimally active at pH 7.0 and 45°C. ATFE-II degraded the Aα-chain of human fibrinogen but did not hydrolyze the Bβ-chain or the γ-chain, indicating that the enzyme is an α-fibrinogenase. The proteolytic activity of ATFE-II was completely inhibited by 1 mM leupeptin, indicating that the enzyme belongs to the cysteine protease class. ATFE-II was also inhibited by 1 mM Fe²(+). ATFE-II exhibited high specificity for MeO-Suc-Arg-Pro-Tyr-p-nitroaniline (S-2586), a synthetic chromogenic substrate of chymotrypsin. Thus proteolytic enzymes from A. tuberosum may be useful as thrombolytic agents.

Silver-stained fibrin zymography: separation of proteases and activity detection using a single substrate-containing gel

A new zymogram method, silver-stained fibrin zymography, for separation of protease bands and activity detection using a single substrate gel, was developed. The method takes advantage of the nanoscale sensitivity of both zymography and silver staining. After SDS-PAGE in a gel containing fibrin, the gel was incubated in enzyme reaction buffer and the zymogram was silver-stained. Bands with protease activity were stained with silver in clear areas where the protein substrate had been degraded. The molecular sizes of proteases were accurately determined. Furthermore, proteases of high molecular weight were clearly and sharply resolved.

Quercetin Glucoside Profiling of Fresh Onion ( Allium cepa) and Aged Black Onion Using HPLC-ESI/MS/MS

Quercetin is a major flavonoid present in onions, which acts as an antioxidant. Quercetin exists both as a free compound and conjugated with carbohydrates, primarily as glucosides in onion. Aged black onion was made through a 30 day aging process in which the onions were kept in an environment of 60℃ and high humidity (90% RH). Quercetin and quercetin glucosides were assayed in onion bulbs before and after the aging process, using high performance liquid chromatography-electrospray ion trap mass spectrometry (HPLC-ESI/MS/MS). Quercetin mono- and diglucosides were identified in fresh onion bulbs, whereas quercetin aglycone was the only form present in aged black onion bulbs. These findings indicate that the quercetin mono- and di-glucosides present in fresh onions undergo complete deglycosylation during the aging process. Such profiling will provide a rapid method that can be used to assess changes in the two major quercetin glycosides during the aging process of onion bulbs.