Bong-Hee Kim

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.

Evaluation of the total oxidant scavenging capacity of saponins isolated from Platycodon grandiflorum.

The antioxidant activity of saponins isolated from Platycodon grandiflorum (PG; Balloon flower) was determined using the total oxidant-scavenging capacity (TOSC) assay. Platycodigenin, polygalacic acid, platycodin D, platycoside E and deapioplatycoside E were isolated and their structures were characterised based on their physical and spectral properties and by comparison of these results with similar data in the literature. Platycodin D showed the greatest TOSC value against peroxyl radicals, followed (in decreasing order) by polygalacic acid, platycodigenin, deapioplatycosides E and platycoside E. Although the TOSC value of the saponins against peroxyl radicals was less than that of glutathione (GSH) and Trolox used as positive controls. However, TOSC value of platycodigenin, deapioplatycoside E, platycodin D or platycoside E against peroxynitrite was 2.35-, 1.27-, 1.02- or 0.75-fold of GSH, respectively, while polygalacic acid exhibited no scavenging capacity of peroxynitrites. These results suggest importance of the presence of hydroxyl group at carbon 24 in platycodigenin in peroxynitrite scavenging. As the number of attached sugar residues in the saponin glycosides is increased, the scavenging capacity of peroxyl radical, but not peroxynitrite was significantly decreased. These results showed that PG saponins have potent antioxidant activities, which is different according to the structure of aglycones and the number of attached sugar residues.

Pseudoruegeria lutimaris sp. nov., isolated from a tidal flat sediment, and emended description of the genus Pseudoruegeria

A Gram-negative-staining, non-motile and rod-shaped bacterial strain, HD-43(T), was isolated from a tidal flat sediment collected from Hwang-do, an island of Korea. Strain HD-43(T) grew optimally at pH 7.0-8.0, at 30 degrees C and in the presence of 2 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain HD-43(T) clustered with Pseudoruegeria aquimaris SW-255(T). It exhibited 96.6 % 16S rRNA gene sequence similarity and 79.4 % gyrB sequence similarity with P. aquimaris SW-255(T). Strain HD-43(T) contained Q-10 as the predominant ubiquinone and C(18 : 1)omega7c as the major fatty acid. The major polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, an unidentified aminolipid, an unidentified glycolipid and an unidentified lipid. The DNA G+C content was 73.5 mol%. The mean DNA-DNA relatedness between strain HD-43(T) and P. aquimaris SW-255(T) was 5 %. Differential phenotypic properties demonstrated that strain HD-43(T) is clearly distinguishable from P. aquimaris. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain HD-43(T) is considered to represent a novel species of the genus Pseudoruegeria, for which the name Pseudoruegeria lutimaris sp. nov. is proposed. The type strain is HD-43(T) (=KCTC 22690(T) =CCUG 57754(T)).

Planomicrobium flavidum sp. nov., isolated from a marine solar saltern, and transfer of Planococcus stackebrandtii Mayilraj et al. 2005 to the genus Planomicrobium as Planomicrobium stackebrandtii comb. nov.

A Gram-positive to Gram-variable, motile and coccoid- or short rod-shaped bacterial strain, ISL-41(T), was subjected to a polyphasic study to investigate its exact taxonomic position. Strain ISL-41(T) grew optimally at pH 7.0-8.0 and 30 degrees C. It contained MK-8 and MK-7 as the predominant menaquinones and anteiso-C(15 : 0), iso-C(16 : 0), anteiso-C(17 : 0) and C(16 : 1)omega7c alcohol as the major fatty acids. The DNA G+C content was 45.9 mol%. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain ISL-41(T) belonged to the genus Planomicrobium. The levels of similarity between the 16S rRNA gene sequence of strain ISL-41(T) and those of the type strains of recognized Planomicrobium species and Planococcus stackebrandtii were 97.4-98.6 %. Mean DNA-DNA relatedness values between strain ISL-41(T) and the type strains of Planomicrobium species and Planococcus stackebrandtii were 13-25 %. Differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, showed that strain ISL-41(T) could be differentiated from recognized Planomicrobium species and Planococcus stackebrandtii. On the basis of the phenotypic, phylogenetic and genetic data, strain ISL-41(T) is considered to represent a novel species within the genus Planomicrobium, for which the name Planomicrobium flavidum sp. nov. is proposed. The type strain is ISL-41(T) (=KCTC 13261(T)=CCUG 56756(T)). It is also proposed that Planococcus stackebrandtii be transferred to the genus Planomicrobium as Planomicrobium stackebrandtii comb. nov. (type strain K22-03(T)=MTCC 6226(T)=DSM 16419(T)=JCM 12481(T)).

Hepatic expression of cytochrome P450 in type 2 diabetic Goto-Kakizaki rats.

Although hepatic expression of cytochrome P450 (CYP) changes markedly in diabetes, the role of ketone bodies in the regulation of CYP in diabetes is controversial. The present study was performed to determine the expression and activity of CYP in non-obese type II diabetic Goto-Kakizaki (GK) rats with normal levels of ketone bodies. In the present study, basal serum glucose levels increased 1.95-fold in GK rats, but acetoacetate and β-hydroxybutyrate levels were not significantly different. Hepatic expression of CYP reductase and CYP3A2 was up-regulated in the GK rats, and consequently, activities of CYP reductase and midazolam 4-hydroxylase, mainly catalyzed by CYP3A2, increased. In contrast, hepatic expression of CYP1A2 and CYP3A1 was down-regulated and the activities of 7-ethoxyresorufin-O-deethylase and 7-methoxyresorufin-O-demethylase, mainly catalyzed by CYP1A, also decreased in GK rats. Hepatic levels of microsomal protein and total CYP and hepatic expression of cytochrome b(5), CYP1B1, CYP2B1 and CYP2C11 were not significantly different between the GK rats and normal Wistar rats. Moreover, the expression and activity of CYP2E1, reported to be up-regulated in diabetes with hyperketonemia, were not significantly different between GK rats and control rats, suggesting that elevation of ketone bodies plays a critical role in the up-regulation of hepatic CYP2E1 in diabetic rats. Our results showed that the expression of hepatic CYP is regulated in an isoform-specific manner. The present results also show that the GK rat is a useful animal model for the pathophysiological study of non-obese type II diabetes with normal ketone body levels.

1'-Acetoxychavicol acetate isolated from Alpinia galanga ameliorates ovalbumin-induced asthma in mice.

The World Health Organization reports that 235 million people are currently affected by asthma. This disease is associated with an imbalance of Th1 and Th2 cells, which results in the upregulation of cytokines that promote chronic inflammation of the respiratory system. The inflammatory response causes airway obstruction and can ultimately result in death. In this study we evaluated the effect of 1′-acetoxychavicol acetate (ACA) isolated from Alpinia galanga rhizomes in a mouse model of ovalbumin (OVA)-induced asthma. To generate the mouse model, BALB/c mice were sensitized by intraperitoneal injection of OVA and then challenged with OVA inhalation for 5 days. Mice in the vehicle control group were sensitized with OVA but not challenged with OVA. Treatment groups received dexamethasone, 25 mg/kg/day ACA, or 50 mg/kg/day ACA for 5 days. Asthma-related inflammation was assessed by bronchoalveolar lavage fluid cell counts and histopathological and immunohistochemical analysis of lung tissues. Our results showed that ACA reduced the infiltration of white blood cells (especially eosinophils) and the level of IgE in the lungs of mice challenged with OVA and suppressed histopathological changes such as airway remodeling, goblet-cell hyperplasia, eosinophil infiltration, and glycoprotein secretion. In addition, ACA inhibited expression of the Th2 cytokines interleukin (IL)-4 and IL-13, and Th1 cytokines IL-12α and interferon-γ. Because asthmatic reactions are mediated by diverse immune and inflammatory pathways, ACA shows promise as an antiasthmatic drug candidate.

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.

Hepatic metabolism of sulfur amino acids in db/db mice

To determine the effect of type-2 diabetes and obesity on the hepatic metabolism of sulfur amino acids, hepatic sulfur amino acid metabolism was determined in db/db mice. Hepatic methionine was markedly decreased in db/db mice, although the hepatic activity of betaine homocysteine methyltransferase was increased. The decrease in hepatic methionine was reflected by decreased sulfur-containing methionine metabolites, including S-adenosylmethionine, homocysteine, cysteine, and hypotaurine in liver and plasma. In contrast, S-adenosylhomocysteine, putrescine, and spermidine were increased in db/db mice. The hepatic level and activity of methionine adenosyltransferase I/III, an S-adenosylmethionine synthesizing enzyme, were significantly increased. These results suggest that increased polyamine synthesis, in conjunction with decreased hepatic methionine levels, is partly responsible for the reduction in hepatic S-adenosylmethionine. Decreased homocysteine in liver and plasma may be attributable to the decrease in hepatic methionine and upregulation of hepatic betaine homocysteine methyltransferase. Glutathione in liver and plasma did not change despite decreased γ-glutamylcysteine ligase activity. The decreased hepatic hypotaurine may be attributable to the downregulation of cysteine dioxygenase. The major finding of this study is that db/db mice exhibited decreases in hepatic methionine and its sulfurcontaining metabolites.

Expression of hepatic and ovarian cytochrome P450 during estrous cycle in rats

It is known that gender differences in drug metabolism are largely attributed to changes in sex and growth hormones. Serum concentrations of estradiol, progesterone, prolactin, follicle-stimulating hormone, and luteinizing hormone change markedly during the human menstrual cycle and the rat estrous cycle. However, little information is available regarding the effects of the human menstrual cycle or the rat estrous cycle on expression and activity of cytochrome P450 (CYP) isoforms. The present study was carried out to determine the expression and activity of CYP-dependent drug-metabolizing enzymes in the liver and ovary during the estrous cycle. The expression and activity of microsomal CYP isoforms (CYP1A1, CYP1A2, CYP1B1, CYP2B1, CYP2C11, CYP2C12, CYP2E1, CYP3A1, CYP3A2, and CYP4A), cytochrome b5 and NADPH-dependent CYP reductase in the liver and ovary were measured in female rats in diestrus and proestrus. Our results indicated that hepatic and ovarian expression and activity of CYP isoforms, cytochrome b5, and NADPH-dependent CYP reductase were not different between diestrus and proestrus, although serum estradiol concentration and uterus weight were markedly increased in the proestrus phase. These results suggest that the cytochrome P450-dependent system is not sensitive to changes in the estrous cycle, and further studies are warranted to determine the effects of the estrous cycle on in vivo metabolism of xenobiotics.

Preparation and evaluation of solid lipid nanoparticles with JSH18 for skin-whitening efficacy

A new molecule having the structure of 6-methyl-3-phenethyl-3,4-dihydro-1H-quinazoline-2-thione (JSH18) was synthesized and it was possibly presupposed to show depigmentation through the inhibition of tyrosinase which is involved in the formation of melanin. Therefore, we are going to develop JSH18 as an inhibitor of melanin synthesis with topical formulations to show its optimal efficiency for skin whitening. Solid lipid nanoparticles (SLNs) play an important role as drug delivery systems for intravenous, peroral, parenteral, or ocular administration and for topical delivery. The particle size of prepared SLNs of JSH18 was variable from 59.8–919.6 nm. When the optimal SLNs cream (PU3) including 4 uM of JSH18 was applied to the backs of hairless rats for four days after the backs were irradiated by UV ray for seven days and the skin color was checked by reflectance spectrophotometer, the rat skin applied with PU3 cream quickly recovered to normal compared to SLNs cream without JSH18. Taken together, this study suggests topical formulations such as creams including SLNs with JSH18 might be an appropriate carrier for skin-whitening agents.