Hee Yang

Caffeinated coffee, decaffeinated coffee, and the phenolic phytochemical chlorogenic acid up-regulate NQO1 expression and prevent H2O2-induced apoptosis in primary cortical neurons

Neurodegenerative disorders are strongly associated with oxidative stress, which is induced by reactive oxygen species including hydrogen peroxide (H₂O₂). Epidemiological studies have suggested that coffee may be neuroprotective, but the molecular mechanisms underlying this effect have not been clarified. In this study, we investigated the protective effects of caffeinated coffee, decaffeinated coffee, and the phenolic phytochemical chlorogenic acid (5-O-caffeoylquinic acid), which is present in both caffeinated and decaffeinated coffee, against oxidative neuronal death. H₂O₂-induced apoptotic nuclear condensation in neuronal cells was strongly inhibited by pretreatment with caffeinated coffee, decaffeinated coffee, or chlorogenic acid. Pretreatment with caffeinated coffee, decaffeinated coffee, or chlorogenic acid inhibited the H₂O₂-induced down-regulation of anti-apoptotic proteins Bcl-2 and Bcl-X(L) while blocking H₂O₂-induced pro-apoptotic cleavage of caspase-3 and pro-poly(ADP-ribose) polymerase. We also found that caffeinated coffee, decaffeinated coffee, and chlorogenic acid induced the expression of NADPH:quinine oxidoreductase 1 (NQO1) in neuronal cells, suggesting that these substances protect neurons from H₂O₂-induced apoptosis by up-regulation of this antioxidant enzyme. The neuroprotective efficacy of caffeinated coffee was similar to that of decaffeinated coffee, indicating that active compounds present in both caffeinated and decaffeinated coffee, such as chlorogenic acid, may drive the effects.

7,8,4′-Trihydroxyisoflavone Attenuates DNCB-Induced Atopic Dermatitis-Like Symptoms in NC/Nga Mice

Atopic dermatitis (AD) is characterized by chronic highly pruritic and relapsing inflammatory skin lesions. Despite its growing prevalence, therapeutic treatments remain limited. Natural immune modulators from herbal extracts or derivatives may be useful for treating AD symptoms. This study examined the effect of 7,8,4′-trihydroxyisoflavone (7,8,4′-THIF), a metabolite of soy isoflavone daidzin, on AD-like symptoms. Repeated epicutaneous application of 2,4-dinitrochlorobenzene (DNCB) was performed on the ear and dorsal skin of NC/Nga mice to induce AD-like symptoms and skin lesions, and 7,8,4′-THIF (200 and 400 nmol) or tacrolimus (100 µg) was applied topically for 3 weeks to assess their anti-pruritic effects. We found that 7,8,4′-THIF alleviated DNCB-induced AD-like symptoms as quantified by skin lesion, dermatitis score, ear thickness, and scratching behavior. Histopathological analysis demonstrated that 7,8,4′-THIF decreased DNCB-induced eosinophil and mast cell infiltration into skin lesions. We also found that 7,8,4′-THIF significantly alleviated DNCB-induced loss of water through the epidermal layer. In addition to reducing the DNCB-induced increase in serum IgE, 7,8,4′-THIF also lowered skin lesion levels of the chemokine thymus and activation regulated chemokine; Th2 cytokines interleukin (IL)-4, IL-5, and IL-13; and Th1 cytokines IL-12 and interferon-γ. These results suggest that 7,8,4′-THIF might be a potential therapeutic candidate for the treatment of atopic dermatitis.

Flt3 is a target of coumestrol in protecting against UVB-induced skin photoaging

While skin aging is a naturally occurring process by senescence, exposure to ultraviolet (UV) radiation accelerates wrinkle formation and sagging of skin. UV induces skin aging by degrading collagen via activating matrix metalloproteinases (MMPs). In this study, we show that coumestrol, a metabolite of the soybean isoflavone daidzein, has a preventive effect on skin photoaging in three-dimensional human skin equivalent model. Coumestrol inhibited UVB-induced MMP-1 expression and activity. Whole human kinase profiling assay identified FLT3 kinase as a novel target protein of coumestrol in UVB-induced signaling pathway in skin. Coumestrol suppresses FLT3 kinase activity, and subsequently, Ras/MEK/ERK and Akt/p70 ribosomal S6 kinase pathway. This suppresses AP-1 activity and in turn, diminishes MMP-1 gene transcription. Using X-ray crystallography, the binding of coumestrol to FLT3 was defined and implied ATP-competitive inhibition. Residues Lys644 and Phe830 showed local changes to accommodate coumestrol in the ATP-binding pocket. 4-APIA, a pharmacological inhibitor of FLT3, inhibited MMP-1 expression and induced signal transduction changes similar to coumestrol. Taken together, coumestrol inhibits UVB-induced MMP-1 expression by suppressing FLT3 kinase activity. These findings suggest that coumestrol is a novel dietary compound with potential application in preventing and improving UVB-associated skin aging.

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.

Sulforaphane epigenetically enhances neuronal BDNF expression and TrkB signaling pathways.

SCOPE Brain-derived neurotrophic factor (BDNF) is a neurotrophin that supports the survival of existing neurons and encourages the growth and differentiation of new neurons and synapses. We investigated the effect of sulforaphane, a hydrolysis product of glucoraphanin present in Brassica vegetables, on neuronal BDNF expression and its synaptic signaling pathways. METHODS AND RESULTS Mouse primary cortical neurons and a triple-transgenic mouse model of Alzheimers disease (3 × Tg-AD) were used to study the effect of sulforaphane. Sulforaphane enhanced neuronal BDNF expression and increased levels of neuronal and synaptic molecules such as MAP2, synaptophysin, and PSD-95 in primary cortical neurons and 3 × Tg-AD mice. Sulforaphane elevated levels of synaptic TrkB signaling pathway components, including CREB, CaMKII, ERK, and Akt in both primary cortical neurons and 3 × Tg-AD mice. Sulforaphane increased global acetylation of histone 3 (H3) and H4, inhibited HDAC activity, and decreased the level of HDAC2 in primary cortical neurons. Chromatin immunoprecipitation analysis revealed that sulforaphane increased acetylated H3 and H4 at BDNF promoters, suggesting that sulforaphane regulates BDNF expression via HDAC inhibition. CONCLUSION These findings suggest that sulforaphane has the potential to prevent neuronal disorders such as Alzheimers disease by epigenetically enhancing neuronal BDNF expression and its TrkB signaling pathways.

Bakuchiol suppresses proliferation of skin cancer cells by directly targeting Hck, Blk, and p38 MAP kinase

Bakuchiol is a meroterpene present in the medicinal plant Psoralea corylifolia, which has been traditionally used in China, India, Japan and Korea for the treatment of premature ejaculation, knee pain, alopecia spermatorrhea, enuresis, backache, pollakiuria, vitiligo, callus, and psoriasis. Here, we report the chemopreventive properties of bakuchiol, which acts by inhibiting epidermal growth factor (EGF)-induced neoplastic cell transformation. Bakuchiol also decreased viability and inhibited anchorage-independent growth of A431 human epithelial carcinoma cells. Bakuchiol reduced A431 xenograft tumor growth in an in vivo mouse model. Using kinase profiling, we identified Hck, Blk and p38 mitogen activated protein kinase (MAPK) as targets of bakuchiol, which directly bound to each kinase in an ATP-competitive manner. Bakuchiol also inhibited EGF-induced signaling pathways downstream of Hck, Blk and p38 MAPK, including the MEK/ERKs, p38 MAPK/MSK1 and AKT/p70S6K pathways. This report is the first mechanistic study identifying molecular targets for the anticancer activity of bakuchiol and our findings indicate that bakuchiol exhibits potent anticancer activity by targeting Hck, Blk and p38 MAPK.

Gingerenone A Attenuates Monocyte-Endothelial Adhesion via Suppression of I Kappa B Kinase Phosphorylation: GINGERENONE A ATTENUATES MONOCYTE -ENDOTHELIAL ADHESION

During the early stages of atherosclerosis, monocytes bind and migrate into the endothelial layer, promoting inflammation within the aorta. In order to prevent the development of atherosclerosis, it is critical to inhibit such inflammation. The therapeutic effects of ginger have been investigated in several models of cardiovascular disease. However, although a number of previous studies have focused on specific compounds, the mechanisms of action responsible remain unclear. Here, we investigated five major compounds present in ginger, and observed that gingerenone A exhibited the strongest inhibitory effects against tumor necrosis factor (TNF)‐α and lipopolysaccharide (LPS) induced monocyte‐endothelial adhesion. Furthermore, gingerenone A significantly suppressed the expression of TNF‐α and LPS‐induced vascular cell adhesion molecule‐1 (VCAM‐1) and chemokine (C‐C motif) ligand 2 (CCL2), key mediators of the interaction between monocytes, and endothelial cells. Transactivation of nuclear factor‐κB (NF‐κB), which is a key transcription factor of VCAM‐1 and CCL2, was induced by TNF‐α and LPS, and inhibited by treatment of gingerenone A. Gingerenone A also inhibited the phosphorylation of NF‐κB inhibitor (IκB) α and IκB Kinase. Taken together, these results demonstrate that gingerenone A attenuates TNF‐α and LPS‐induced monocyte adhesion and the expression of adhesion factors in endothelial cells via the suppression of NF‐κB signaling. J. Cell. Biochem. 119: 260–268, 2018.

Hirsutenone Directly Targets PI3K and ERK to Inhibit Adipogenesis in 3T3-L1 Preadipocytes

Adipogenesis is a key driver of the expansion of adipose tissue mass that causes obesity. Hirsutenone (HST) is an active botanical diarylheptanoid present in Alnus species. In this study, we evaluated the effects of HST on adipogenesis, its mechanisms of action and the molecular targets involved. Using Oil Red O staining, we observed that HST dose‐dependently suppresses lipid accumulation during adipogenesis in 3T3‐L1 preadipocytes, concomitant with a decrease in peroxisome proliferator‐activated receptor‐γ (PPARγ), CCAAT/enhancer‐binding protein α (C/EBPα) and fatty acid synthase (FAS) protein expression. This inhibitory effect was largely limited to the early stage of adipogenesis, which includes mitotic clonal expansion (MCE), as evidenced by delayed cell cycle entry of preadipocytes from G1 to S phase. Furthermore, the regulation of MCE was accompanied by suppression of phosphatidylinositol 3‐kinase (PI3K) and extracellular‐regulated kinase (ERK) activity. HST was also shown to bind directly to PI3K and ERK1 in a non‐ATP competitive manner. Our results suggest that HST attenuates adipogenesis by directly targeting PI3K and ERK during MCE in 3T3‐L1 preadipocytes, underscoring the potential therapeutic application of HST in preventing obesity. J. Cell. Biochem. 116: 1361–1370, 2015.

The Ginsenoside Derivative 20(S)‐Protopanaxadiol Inhibits Solar Ultraviolet Light‐Induced Matrix Metalloproteinase‐1 Expression

Ginsenosides are major pharmacologically active compounds present in ginseng (Panax ginseng). Among the ginsenosides, 20‐O‐β‐D‐glucopyranosyl‐20(S)‐protopanaxadiol (GPPD) and ginsenoside Rb1 (Rb1) have previously been reported to exhibit anti‐wrinkle effects. In this study, 20(S)‐protopanaxadiol (20(S)‐PPD), an aglycone derivative of the Rb1 metabolite was investigated for its anti‐wrinkle benefit and compared to GPPD and Rb1. The anti‐wrinkle effect of 20(S)‐PPD during solar UV light was investigated using a human skin equivalent model and human keratinocytes. 20(S)‐PPD attenuated solar UV‐induced matrix metalloproteinase (MMP)‐1 expression to a greater extent than GPPD and Rb1. 20(S)‐PPD treatment modulated MMP‐1 mRNA expression and the transcriptional activity of activator protein (AP)‐1, a major transcription factor of MMP‐1. Two upstream signaling pathways for AP‐1, the MEK1/2‐ERK1/2‐p90RSK and MEK3/6‐p38 pathways, were also suppressed. Taken together, these findings highlight the potential of 20(S)‐PPD for further development as a preventative agent for sunlight‐induced skin wrinkle. J. Cell. Biochem. 118: 3756–3764, 2017.

Molecular cloning and anti-invasive activity of cathepsin L propeptide-like protein from Calotropis procera R. Br. against cancer cells

Abstract Cathepsin L of cancer cells has been shown to play an important role in degradation of extracellular matrix for metastasis. In order to reduce cell invasion, cathepsin L propeptide-like proteins which are classified as the I29 family in the MEROPS peptidase database were characterized from Calotropis procera R. Br., rich in cysteine protease. Of 19 candidates, the cloned and expressed recombinant SnuCalCp03-propeptide (rSnuCalCp03-propeptide) showed a low nanomolar Ki value of 2.3 ± 0.2 nM against cathepsin L. A significant inhibition of tumor cell invasion was observed with H1975, HT29, MDA-BM-231, PANC1, and PC3 with a 76, 67, 67, 63, and 79% reduction, respectively, in invasion observed in the presence of 400 nM of the rSnuCalCp03-propeptide. In addition, thermal and pH study showed rSnuCalCp03-propeptide consisting of secondary structures was stable at a broad range of temperatures (30–70 °C) and pH (2–10, except for 5 which is close to the isoelectric point of 5.2).