Caffeic Acid Phenethyl Ester, a Major Component of Propolis, Suppresses High Fat Diet-Induced Obesity through Inhibiting Adipogenesis at the Mitotic Clonal Expansion Stage

In the present study, we aimed to investigate the antiobesity effect of CAPE in vivo, and the mechanism by which CAPE regulates body weight in vitro. To confirm the antiobesity effect of CAPE in vivo, mice were fed with a high fat diet (HFD) with different concentrations of CAPE for 5 weeks. CAPE significantly reduced body weight gain and epididymal fat mass in obese mice fed a HFD. In accordance with in vivo results, Oil red O staining results showed that CAPE significantly suppressed MDI-induced adipogenesis of 3T3-L1 preadipocytes. FACS analysis results showed that CAPE delayed MDI-stimulated cell cycle progression, thereby contributing to inhibit mitotic clonal expansion (MCE), which is a prerequisite step for adipogenesis. Also, CAPE regulated the expression of cyclin D1 and the phosphorylation of ERK and Akt, which are upstream of cyclin D1. These results suggest that CAPE exerts an antiobesity effect in vivo, presumably through inhibiting adipogenesis at an early stage of adipogenesis

TCA contributes to the inhibitory effect of BPLE on UVB-induced MMP-1 expression in HaCaT cells.

<p><i>A</i> and <i>C</i>, Protein expression was analyzed by Western blotting (MMP-1), Zymography (MMP-2), and ELISA (MMP-1 contents). Cells were treated with BPLE/PLE (A) or TCA/DAA (C) at the indicated concentration for 1 h before being exposed to 0.01 J/cm² of UVB, and media was harvested 48 h later. <i>B</i> and <i>D</i>, Cell viability of HaCaT cells in the presence or absence of BPLE, PLE (B) or TCA, DAA (D). Cell viability was measured using MTT assay. Each experiment was performed in triplicate. The data are presented as the mean ±S.D. of MMP-1 protein content and cell viability. Means with different letters (a-c) within a graph were significantly different from each other at <i>p</i> < 0.05.</p

BPLE and TCA decrease collagen degradation and MMP-1 expression in a human skin equivalent model <i>A</i>, A schematic diagram of the 3D human skin cell culture system.

<p>The experimental procedure was described in the Materials and Methods. <i>B and C</i>, BPLE and TCA inhibit UVB-induced MMP-1 protein expression levels and collagen degradation. The serial sections, from the human skin equivalent, were mounted onto silane-coated slides and subjected to Masson’s trichrome staining (B and D) or to immunohistochemical staining using anti-MMP-1 antibody (C and E). MMP-1 appears brown. Relative density was measured using the ImageJ program. Means with different letters (a-d) within a graph were significantly different from each other at <i>p</i> < 0.05.</p

BPLE and TCA inhibit UVB-induced binding affinity of AP-1 residues in HaCaT cells.

<p><i>A</i>, <i>B</i>, <i>and C</i>, DNA binding activity of phospho-c-jun (A), c-Fos (B) and Fra-1 (C). Cells were treated with BPLE and TCA at the indicated concentrations for 1 h before being exposed to 0.01 J/cm² of UVB and nuclear extract was collected 4 h later. DNA binding activity was measured by TransAM AP-1 DNA-binding ELISA kit. Means with different letters (a-d) within a graph were significantly different from each other at <i>p</i> < 0.05. <i>D</i>, Phosphorylated and total protein levels of c-Jun were measured by Western blot assay. Relative band intensity is expressed as fold of control and indicated on top of each band.</p

Brown Pine Leaf Extract and Its Active Component <i>Trans</i>-Communic Acid Inhibit UVB-Induced MMP-1 Expression by Targeting PI3K

<div><p>Japanese red pine (<i>Pinus densiflora</i>) is widely present in China, Japan, and Korea. Its green pine leaves have traditionally been used as a food as well as a coloring agent. After being shed, pine leaves change their color from green to brown within two years, and although the brown pine leaves are abundantly available, their value has not been closely assessed. In this study, we investigated the potential anti-photoaging properties of brown pine leaves for skin. Brown pine leaf extract (BPLE) inhibited UVB-induced matrix metalloproteinase-1 (MMP-1) expression to a greater extent than pine leaf extract (PLE) in human keratinocytes and a human skin equivalent model. HPLC analysis revealed that the quantity of <i>trans</i>-communic acid (TCA) and dehydroabietic acid (DAA) significantly increases when the pine leaf color changes from green to brown. BPLE and TCA elicited reductions in UVB-induced MMP-1 mRNA expression and activator protein-1 (AP-1) transactivation by reducing DNA binding activity of phospho-c-Jun, c-fos and Fra-1. BPLE and TCA also inhibited UVB-induced Akt phosphorylation, but not mitogen activated protein kinase (MAPK), known regulators of AP-1 transactivation. We additionally found that BPLE and TCA inhibited phosphoinositide 3-kinase (PI3K), the upstream kinase of Akt, in vitro. In summary, both BPLE and its active component TCA exhibit protective effects against UVB-induced skin aging. Taken together, these findings underline the potential for BPLE and TCA to be utilized as anti-wrinkling agents and cosmetic ingredients, as they suppress UVB-induced MMP-1 expression.</p></div

BPLE and TCA inhibit UVB-induced Akt phosphorylation but not Mitogen-activated kinase (MAPK) signaling pathway in HaCaT cells.

<p><i>A-D</i>, Cells were treated with BPLE (A, C) and TCA (B, D) at the indicated concentration for 1 h before exposed to 0.01 J/cm² of UVB and collected after 30 min. Phosphorylated and total protein levels were analyzed by Western blot assay. Relative band intensity is expressed as fold of control and indicated on top of each band.</p