Jae Ho Choi

Immunostimulatory activity of aqueous extract isolated from Prunella vulgaris

Prunella vulgaris (P. vulgaris) has been used as a traditional medicine in the clinical treatment of herpetic keratitis and for its antioxidative and antimicrobial activities. In this study, we examined the immunostimulatory and antitumor activity of P. vulgaris in murine macrophage RAW 264.7 cells. Thus, we investigated the effects of an aqueous extract of P. vulgaris (PVAE) on macrophage function. We found that PVAE stimulated macrophage phagocytic activity, nitric oxide (NO) production and cytostatic activity. In addition, PVAE induced gene expression and production of macrophage-related cytokines such as TNF-alpha, IL-1beta and IL-6. Transient transfection revealed that NF-kappaB mediated the PVAE-induced increases in macrophage-related cytokine expression levels. Mitogen-activated protein kinases (MAP Kinase) were also significantly activated by the PVAE-induced NF-kappaB activation. Pretreatment with NF-kappaB inhibitor and MAP Kinase inhibitors inhibited the NO production and the phagocytic activity induced by PVAE. This demonstrates that PVAE stimulates macrophage activation via NF-kappaB transactivation and MAP kinase activation.

Protective effect of saponins derived from the roots of Platycodon grandiflorum against carbon tetrachloride induced hepatotoxicity in mice

The purpose of this study was to investigate the protective effects of the saponins isolated from the root of Platycodi Radix (Changkil saponins: CKS) on carbon tetrachloride (CCl(4))-induced hepatotoxicities in mice. Pretreatment with CKS prior to the administration of CCl(4) significantly prevented the increase in serum alanine aminotransferase and aspartate aminotransferase activities and hepatic lipid peroxidation formation. In addition, CKS prevented CCl(4)-induced apoptosis and necrosis, as indicated by a liver histopathologic study and DNA laddering. To determine whether Fas/Fas ligand (FasL) pathway involved in CCl(4)-induced acute liver injury, Fas and FasL proteins and caspase-3, -8 activities were tested by western blotting and ELISA. CKS markedly decreased CCl(4)-induced Fas/FasL protein expression levels and in turn attenuated CCl(4)-induced caspase-3, -8 activities in mouse livers. Additionally, CKS protected the CCl(4)-induced depletion of hepatic glutathione levels. The effect of CKS on CYP2E1, the major isozyme involved in CCl(4) bioactivation, was investigated. Treatment with CKS resulted in a significant decrease in the CYP2E1-dependent hydroxylation of aniline. In addition, CKS exhibited antioxidant effects on FeCl(2)-ascorbate induced lipid peroxidation in liver homogenates, and on superoxide radical scavenging activity. These findings suggest that the protective effects of CKS against CCl(4)-induced acute liver injury possibly involve mechanisms related to its ability to block CYP2El-mediated CCl(4) bioactivation and its free radical scavenging effects, and that is also protects against Fas/FasL pathway mediated apoptosis.

Protective effect of the Aralia continentalis root extract against carbon tetrachloride-induced hepatotoxicity in mice.

The root of Aralia continentalis Kitagawa has been used in traditional Korean medicine to relieve pain and to treat inflammation. The purpose of this study was to investigate the protective effects of the extract of A. continentalis roots (AC) against hepatotoxicity induced by carbon tetrachloride (CCl4) and the mechanism of its hepatoprotective effect. In mice, pretreatment with AC prior to the administration of CCl4 significantly prevented the increased serum enzymatic activity of ALT and AST as well as the formation of hepatic malondialdehyde. Histopathological evaluation of the livers also revealed that AC reduced the incidence of liver lesions induced by CCl4. In addition, pretreatment with AC significantly prevented both the depletion of reduced glutathione (GSH) content and the decrease in glutathione-S-transferase (GST) activity in the liver of CCl4-intoxicated mice. Hepatic GSH levels and GST activity were increased by treatment with AC alone. Heme oxygenase-1 (HO-1) is known to be induced by oxidative stress and to confer protection against oxidative tissue injuries. Interestingly, AC markedly upregulated hepatic HO-1 expression in CCl4-treated mice, which might provide anti-oxidative activity in the liver. These results indicate that AC plays a critical protective role in CCl4-induced acute liver injury by promoting anti-oxidative protein expression.

Saponins isolated from the root of Platycodon grandiflorum protect against acute ethanol-induced hepatotoxicity in mice

The protective effects of saponins isolated from the root of Platycodon grandiflorum (Changkil saponins: CKS) against alcoholic steatosis in liver injury induced by acute ethanol administration were investigated. Pretreatment with CKS prior to ethanol administration significantly prevented the increases in serum alanine aminotransferase activity, hepatic TNF-alpha level, hepatic lipid peroxidation and hepatic triglyceride level. CKS prevented ethanol-induced steatosis and necrosis, as indicated by liver histopathological studies. Additionally, CKS protected against ethanol-induced depletion of hepatic glutathione levels. CYP2E1 has been suggested as a major contributor to ethanol-induced oxidative stress and liver injury. The concurrent administration of CKS efficaciously abrogated the CYP2E1 induction and CYP2E1-dependents hydroxylation of aniline as compared to the individual treatment at higher doses. These findings suggest that CKS may prevent ethanol-induced acute liver injury, possibly through its ability to block CYP2El-mediated ethanol bioactivation and its free radical scavenging effects.

Inhibitory effect of Platycodi Radix on ovalbumin-induced airway inflammation in a murine model of asthma

Asthma is a chronic inflammatory disease of the airways characterized by an associated increase in airway responsiveness. In this study, we investigated the inhibitory effect of an aqueous extract from the root of Platycodi Radix (Changkil: CK) on airway inflammation in a murine model of asthma. Mice were sensitized and challenged by ovalbumin (OVA) inhalation to induce chronic airway inflammation and airway remodeling. CK markedly decreased the number of infiltrated inflammatory cells and the levels of Th1 and Th2 cytokines and chemokines compared with those in the OVA-induced group. In addition, CK reduced OVA-specific IgE levels in bronchoalveolar lavage (BAL) fluid. Based on lung histopathological studies, inflammatory cell infiltration and mucus hypersecretion were inhibited by CK administration compared to that in the OVA-induced group. Lung weight was reduced after CK administration. Also, increased generation of ROS in BAL fluid, as well as NF-kappaB nuclear translocation, by inhalation of OVA was diminished by CK. Moreover, CK reduced the OVA-induced upregulation of matrix metalloproteases activity. These findings indicate that oxidative stress may play a crucial role in the pathogenesis of bronchial asthma induced by OVA and that CK may be useful as an adjuvant therapy for the treatment of bronchial asthma.

Saponins derived from the roots of Platycodon grandiflorum inhibit HT-1080 cell invasion and MMPs activities: Regulation of NF-κB activation via ROS signal pathway

The chemopreventive effects of saponin derived from Platycodon grandiflorum (Changkil saponin; CKS) on tumor invasion and migration and the possible mechanisms involved in this protection were investigated in HT-1080 tumor cells. In this study, we found that CKS reduced 12-O-tetradecanoylphorbol-13-acetate (PMA)-enhanced Matrix metalloproteinases (MMP)-9 and MMP-2 activation in a dose-dependant manner and further inhibited HT-1080 cell invasion and migration. In addition, CKS suppressed PMA-enhanced expression of MMP-9 protein, mRNA and transcription activity levels through suppression of nuclear factor (NF)-kappaB activation without changing tissue inhibitor of metalloproteinase (TIMP)-1 level. CKS also reduced PMA-enhanced MMP-2 active forms through suppression of membrane-type 1 MMP (MT1-MMP) level, but did not alter MMP-2 and TIMP-2 levels. Moreover, reactive oxygen species (ROS) production induced by PMA was partly decreased in the presence of CKS and this suppression of ROS production may be related to diminish NF-kappaB activity. Therefore, our results suggested that the inhibitory effects of CKS on MMP-2 and MMP-9 activation, relation of tumor invasion and migration in vitro possibly involve mechanisms related to its ability to suppress PMA-enhanced NF-kappaB activation through ROS signaling pathway. Overall, CKS may be a valuable anti-invasive drug candidate for cancer therapy.

Protective effect of caffeic acid phenethyl ester against carbon tetrachloride-induced hepatotoxicity in mice

This study was designed to investigate the protective effects of the phenethyl ester of caffeic acid (CAPE) against carbon tetrachoride (CCl(4))-induced hepatotoxicities in mice. Pretreatment with CAPE prior to administration of CCl(4) significantly prevented the increases in serum alanine, aspartate aminotransferase and alkaline phosphatase activities, hepatic lipid peroxidation formation, and depletion of glutathione content. In addition, CAPE prevented CCl(4)-induced apoptosis and necrosis, as indicated by liver histopathology and DNA laddering studies. To determine whether the Fas/Fas ligand (FasL) pathway is involved in CCl(4)-induced acute liver injury, Fas and FasL proteins and caspase-3 and -8 activities were tested by western blotting and ELISA. CAPE markedly decreased CCl(4)-induced Fas/FasL protein expression levels and, in turn, attenuated CCl(4)-induced caspase-3 and -8 activities in mouse liver. Moreover, the effect of CAPE on CYP2E1, the major isozyme involved in CCl(4) bioactivation, was investigated. Treatment with CAPE significantly decreased the CYP2E1-dependent hydroxylation of aniline. In addition, CAPE attenuated the CCl(4)-mediated depletion of antioxidant enzyme (catalase, superoxide dismutase and glutathione-S-transferase) activities. These findings suggest that the protective effects of CAPE against CCl(4)-induced acute liver injury may involve its ability to block CYP2El-mediated CCl(4) bioactivation and to protect against Fas/FasL-mediated apoptosis.

Protective effects of saponins from the root of Platycodon grandiflorum against fatty liver in chronic ethanol feeding via the activation of AMP-dependent protein kinase.

Fatty liver and steatosis induced by alcohol is the earliest and most common response of the liver to alcohol and may be a precursor of more severe forms of liver injury. However, the mechanism of liver injury and deposition of fatty liver due to alcohol is complex. The protective effects of saponins from the root of Platycodon grandiflorum (Changkil saponins: CKS) against ethanol-induced liver injury in an enteral alcohol feeding model was investigated. Male Sprague-Dawley rats were given control diets or ethanol-containing diets enterally for 4 weeks. Treatment with CKS for 2 weeks significantly prevented the alcohol-induced increase in serum alanine aminotransferase and aspartate aminotransferase activities or decrease in serum albumin levels. Alcohol elevated the hepatic triglyceride content and induced cytochrome P450 2E1 (CYP2E1) expression. CKS treatment reduced CYP2E1 expression and hepatic triglyceride accumulation and prevented alcoholic liver steatosis. Chronic alcohol feeding decreased AMP-activated protein kinase-alpha (AMPKalpha) phosphorylation, which was restored by CKS treatment. Recovery of AMPKalpha phosphorylation by CKS was also followed by an increase in acetyl-CoA carboxylase phosphorylation. Our study suggests that CKS is a promising agent for preventing or treating human alcoholic fatty liver disease.

Protective effect of caffeic acid phenethyl ester on tert-butyl hydroperoxide-induced oxidative hepatotoxicity and DNA damage.

Increased oxidative stress and associated high levels of free radical generation have been described to occur during the pathogeneses of various diseases in animal models. In the present work, we investigated the protective effects of the phenethyl ester of caffeic acid (CAPE), an active component of honeybee propolis, on tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity in a cultured HepG2 cell line and in rat liver. CAPE was found to significantly reduce t-BHP-induced oxidative injury in HepG2 cells, as determined by cell cytotoxicity, and lipid peroxidation and reactive oxygen species (ROS) levels in a dose-dependent manner. Furthermore, CAPE protected HepG2 cells against t-BHP-induced oxidative DNA damage, as determined by the Comet assay. Consistently, CAPE reduced hydroxyl radical-induced 2-deoxy-d-ribose degradation by ferric ion-nitrilotriacetic acid and H2O2, and also removed the superoxide anion generated by a xanthine/xanthine oxidase system. Our in vivo study showed that pretreatment with CAPE prior to the administration of t-BHP significantly and dose-dependently prevented increases in the serum levels of hepatic enzyme markers (alanine aminotransferase and aspartate aminotransferase) and reduced lipid peroxidation in rat liver. Moreover, histopathological evaluation of livers consistently revealed that CAPE reduced liver lesion induction by t-BHP. Taken together, these results suggest that the protective effects of CAPE against t-BHP-induced hepatotoxicity may, at least in part, be due to its ability to scavenge ROS and protect DNA from oxidative stress-induced damage.

Suppression of phorbol-12-myristate-13-acetate-induced tumor cell invasion by bergamottin via the inhibition of protein kinase Cδ/p38 mitogen-activated protein kinase and JNK/nuclear factor-κB-dependent matrix metalloproteinase-9 expression

Matrix metalloproteinase (MMP) plays an important role in the invasion and metastasis of cancer cells. The inhibitory effects of bergamottin, a cytochrome P450 inhibitor from Citrus paradis (grapefruit), on tumor invasion and migration and the possible mechanisms involved in this inhibition were investigated in human fibrosarcoma HT-1080 cells. Bergamottin reduced phorbol-12-myristate-13-acetate (PMA)-induced activation of MMP-9 and MMP-2 and further inhibited cell invasion and migration. Bergamottin suppressed PMA-enhanced expression of MMP-9 protein, mRNA and transcription activity levels through suppression of nuclear factor-kappaB (NF-kappaB) activation without changing the tissue inhibitor of metalloproteinase 1 level. Bergamottin also reduced PMA-enhanced MMP-2 expression through suppression of membrane-type 1 MMP, but did not alter tissue inhibitor of metalloproteinase 2 levels. Bergamottin inhibited PMA-induced NF-kappaB nuclear translocation and IkappaBalpha degradation, which are upstream of PMA-induced MMP-9 expression and invasion. Furthermore, bergamottin strongly repressed the PMA-induced phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK), which are dependent on the protein kinase C-delta pathway. In conclusion, we demonstrated that the anti-invasive effects of bergamottin might occur through inhibition of protein kinase C-delta, p38 mitogen-activated protein kinase, and JNK phosphorylation and reduction of NF-kappaB activation, leading to downregulation of MMP-9 expression. These results suggest that the suppression of MMP expression contributes, at least in part, to the antitumor activity of bergamottin.