Mina Lee

Anti-adipogenic activity of compounds isolated from Idesia polycarpa on 3T3-L1 cells

Recently, obesity is a complex multifactorial chronic disease increasing the risk for type 2 diabetes, coronary heart disease and hypertension, and has become a major worldwide health problem. In the course of screening natural products employing 3T3-L1 cells as an in vitro system, the methanol extract of Idesia polycarpa Maxim. Fruits (Flacourtiaceae) significantly inhibited adipocyte differentiation by measuring lipid contents using oil red O staining. One new compound, 6-(oxymethyl)-2-hydroxyphenyl-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (8), was isolated along with nine known compounds (1-7 and 9-10) from CHCl3 and n-BuOH fractions of the methanol extract of I. polycarpa fruits. Among them, idescarpin (1) with 1-hydroxy-6-oxo-2-cyclohexenecarboxylate moiety showed the most potent inhibitory activity on adipocyte differentiation with IC50 values of 23.2 μM. Idescarpin (1) dramatically suppressed the induction of C/EBPα expression, whereas it significantly increased the induction of PPARγ expression, supported by quantitative real time PCR and Western blot analysis. The down-regulation in mRNA levels of SREBP1c, SCD-1, and FAS by idescarpin (1) during adipocyte differentiation revealed that the inhibition of adipocyte differentiation was mediated by the regulation of lipogenesis. Taken together, we suggest that idescarpin (1) shows a great potential against obesity and diabetes though the anti-adipogenic activity and the up-regulation of PPARγ.

Neuroprotective biflavonoids of Chamaecyparis obtusa leaves against glutamate-induced oxidative stress in HT22 hippocampal cells

Four biflavonoids (1-4), five flavonoids glycosides (5-9), two catechins (10, 11), two lignans (12-13), neolignan glycoside (14) and phenylpropanoid glycoside (15) were isolated from the leaves of Chamaecyparis obtusa (Cupressaceae). Neuroprotective effects of the isolated compounds were evaluated employing HT22 mouse hippocampal cells, a model system to study glutamate-induced oxidative stress. The glutamate injured HT22 cells were protected significantly by amentoflavone (3), ginkgetin (4) and (-)-epitaxifolin 3-O-β-D-xylopyranoside (9). The reduced activities of antioxidant enzymes, superoxide dismutase (SOD), glutathione reductase (GR) in response to high concentration of glutamate were preserved by pre-treatment of 3, 4 or 9, while the activities of glutathione peroxidase (Gpx) and catalase (CAT) were little affected. The reduced content of GSH induced by glutamate was also recovered by 3, 4 or 9 in accommodation with the decrease in ROS production. In addition, the phosphorylation of ERK1/2 induced by glutamate insult was clearly prevented by 3, while little changed by 4. Taken together, amentoflavone (3), ginkgetin (4) and (-)-epitaxifolin 3-O-β-D-xylopyranoside (9) derived from C. obtusa could protect HT22 neuronal cells against glutamate-induced oxidative damage through preserving antioxidant enzymes activities and/or inhibiting ERK1/2 activation.

Anti-adipogenic diarylheptanoids from Alnus hirsuta f. sibirica on 3T3-L1 cells.

A new diarylheptanoid, (5S)-hydroxy-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-hepta-1E-en-3-one (1), was isolated along with seventeen known diarylheptanoids (2-18) from the methanol extract of Alnus hirsuta f. sibirica leaves using bioactivity-guided fractionation. Among the isolated compounds, compounds 1 and 2 and 4-12 reduced lipid accumulation dose-dependently in 3T3-L1 preadipocytes. Of the compounds active in the present assay system, the most potent compound 7, platyphyllonol-5-O-β-d-xylopyranoside, significantly suppressed the induction of peroxisome proliferator activated receptor γ (PPARγ and CCAAT/enhancer binding protein α (C/EBPα) protein expression, and inhibited adipocyte differentiation induced by troglitazone, a PPARγ agonist. It was demonstrated that compound 7 has anti-adipogenic activity mediated by the regulation of PPARγ dependent pathways.

Salicortin-Derivatives from Salix pseudo-lasiogyne Twigs Inhibit Adipogenesis in 3T3-L1 Cells via Modulation of C/EBPα and SREBP1c Dependent Pathway

Obesity is reported to be associated with excessive growth of adipocyte mass tissue as a result of increases in the number and size of adipocytes differentiated from preadipocytes. To search for anti-adipogenic phytochemicals, we screened for inhibitory activities of various plant sources on adipocyte differentiation in 3T3-L1 preadipocytes. Among the sources, a methanolic extract of Salix pseudo-lasiogyne twigs (Salicaceae) reduced lipid accumulation in a concentration-dependent manner. During our search for anti-adipogenic constituents from S. pseudo-lasiogyne, five salicortin derivatives isolated from an EtOAc fraction of this plant and bearing 1-hydroxy-6-oxo-2-cyclohexene-carboxylate moieties, namely 2′,6′-O-acetylsalicortin (1), 2′-O-acetylsalicortin (2), 3′-O-acetylsalicortin (3), 6′-O-acetylsalicortin (4), and salicortin (5), were found to significantly inhibit adipocyte differentiation in 3T3-L1 cells. In particular, 2′,6′-O-acetylsalicortin (1) had the most potent inhibitory activity on adipocyte differentiation, with an IC50 value of 11.6 μM, and it significantly down-regulated the expressions of CCAAT/enhancer binding protein α (C/EBPα) and sterol regulatory element binding protein 1 (SREBP1c). Furthermore, 2′,6′-O-acetylsalicortin (1) suppressed mRNA expression levels of C/EBPβ during the early stage of adipocyte differentiation and stearoyl coenzyme A desaturase 1 (SCD-1), acetyl-CoA carboxylase (ACC), and fatty acid synthase (FAS) expression, target genes of SREBP1c. In the present study, we demonstrate that the anti-adipogenesis mechanism of 2′,6′-O-acetylsalicortin (1) may be mediated via down-regulation of C/EBPα and SREBP1c dependent pathways. Through their anti-adipogenic activity, salicortin derivatives may be potential novel therapeutic agents against obesity.

Anti-adipogenic activity of a new cyclic diarylheptanoid isolated from Alnus japonica on 3T3-L1 cells via modulation of PPARγ, C/EBPα and SREBP1c signaling.

Total methanolic extract of Alnus japonica fruits exhibited significant anti-adipogenic activities in 3T3-L1 cells. A new cyclic diarylheptanoid (1) along with ten known compounds (2-11) were isolated by activity-guided fractionation. Compound 1, determined to be 4-hydroxy-alnus-3,5-dione, showed the most potent anti-adipogenic effect. Compound 1 significantly down-regulated expression of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), and sterol regulatory element binding protein 1 (SREBP1c) in 3T3-L1 cells, as determined by quantitative real-time PCR and Western blot analysis. Furthermore, compound 1 suppressed mRNA expression of C/EBPβ and C/EBPδ during the early stage of adipogenesis as well as stearoyl coenzyme A desaturase 1 (SCD-1) and fatty acid synthase (FAS), target genes of SREBP1c. Upon investigating the mechanism of natural products, we propose that cyclic diarylheptanoid (1), the most potent constituent of A. japonica, can be a potent therapeutic agent against obesity through anti-adipogenesis via down-regulation of PPARγ, C/EBPα, and SREBP1c signaling.

Antifibrotic constituents of Alnus firma on hepatic stellate cells

Suppression of hepatic stellate cell (HSC) growth and activation have been proposed as therapeutic strategies for the treatment and prevention of liver fibrosis. In the course of screening antifibrotic activity of natural products, the methanolic extract of Alnus firma barks (Betulaceae) showed inhibitory activity of cell proliferation on HSC-T6 cells. A new triterpenoid characterized as lup-20(29) en-2,28-diol-3-yl caffeate (13) was isolated with 12 known diarylheptanoids (1-12) from the barks of A. firma using bioactivity-guided fractionation. Among these compounds, 2 and 13 significantly inhibited the proliferation of HSCs in dose- and time-dependent manners at concentrations from 10 to 100 μM. Taken together, antifibrotic activities of A. firma and its active constituents might suggest the therapeutic potentials against liver fibrosis.

Antifibrotic Activity of Diarylheptanoids from Betula platyphylla toward HSC-T6 Cells

A chemical investigation of the n-butanol fraction of the inner bark of Betula platyphylla led to the isolation of seven diarylhepanoids, (-)-centrolobol (1), aceroside VII (2), aceroside VIII (3), (3R)-1,7-bis-(4-hydroxyphenyl)-3-heptanol-3-O-[2,6-bis-O-(β-D-apiofuranosyl)-β-D-glucopyranoside (4), 1,7-bis-(4-hydroxyphenyl)-5-hepten-3-one (5), platyphyllone (6) and platyphylloside (7). The antifibrotic effects of these isolates were evaluated with HSC-T6 cells by assessing cell proliferation. Among them, compounds 1, 2, 5 and 6 significantly inhibited the proliferation of HSCs in a dose-dependent manner at concentrations from 10 µM to 100 µM. Compound 5 in particular dramatically decreased the collagen content and increased the Caspase-3/7 activity. Taken together, the antifibrotic activity of B. platyphylla and its constituents might suggest therapeutic potential against liver fibrosis.

Standardization of Hippocastani Semen Extract

This study was carried out to establish standard analytical method of Hippocastani Semen extract. Each standard analytical methods were covered for exact and efficient analytical method. Consequently, analytical method of Deutsches Arzneibuch has been adopted for Hippocastani Semen extract. Analytical methods established in this study could be applied to a reasonable and unified quality control of Hippocastani Semen extract.