St. John’s Wort (SJW) has been used as an estrogen agonist in the systems affected by menopause. Also, hypericin, a bioactive compound of SJW, has been used as a photosensitizer in photodynamic therapy. In the present study, we investigate the anti-proliferative and pro-apoptotic effects of SJW to demonstrate the chemo-preventive effect in human breast cancer cells. MCF-7 cells were cultured with DMSO or various concentrations of SJW ethanol extract (SJWE). Cell viability, proliferation, apoptosis, the expression of proteins involved in cell growth and apoptosis, and caspase-3/7 activity were examined. SJWE dose-dependently suppressed cell growth and induced apoptosis of MCF-7 cells. Mechanistically, SJWE enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and decreased the expression of p-mammalian target of rapamycin (p-mTOR) and p-eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). Also, SJWE inhibited the phosphorylation of protein kinase B (Akt) and showed increases in the expression of pro-apoptotic proteins Bax and Bad with decreases in the expression of anti-apoptotic proteins including B-cell lymphoma 2 (Bcl-2), B-cell lymphoma-extra large (Bcl-xL), and p-Bcl-2-associated death promoter (p-Bad). SJWE at 50 μg/mL showed markedly enhanced caspase-7 activation. Taken together, our results provide evidence that SJWE shows anti-proliferative and pro-apoptotic effects via inhibition of AMPK/mTOR and activation of a mitochondrial pathway. Therefore, SJWE can be used as a chemo-preventive agent without photo-activation.

Obesity is the main risk factor for metabolic syndromes and there has been an upsurge in demand for effective therapeutic strategies. This study investigated the effect of red pepper seed water extract (RPS) on the process of differentiation in 3T3-L1 adipocytes. RPS treatment significantly suppressed cellular lipid accumulation and reduced the expression of adipocytes-associated proteins, peroxisome proliferator-activated receptor-[Formula: see text] (PPAR-[Formula: see text]), CCAAT/enhancer-binding proteins [Formula: see text] (C/EBP [Formula: see text]), sterol regulatory element binding protein-1c (SREBP-1c), as well as fatty acid synthase (FAS), and fatty acid binding protein 4 (FABP4). The inhibitory effect of RPS on differentiation was mainly through the modulation of the C/EBP [Formula: see text] and C/EBP [Formula: see text] expression at the early phase of differentiation. Moreover, at the early phase of differentiation, RPS markedly increased the phosphorylation of AMP-activated protein kinase (AMPK). Such enhancing effect of RPS was abolished in the presence of compound C. Our results suggest that activation of AMPK at early stage of adipogenesis is involved in the anti-adipogenesis effect of RPS.

BACKGROUND/OBJECTIVESThe anti-diabetic activity of pear through inhibition of α-glucosidase has been demonstrated. However, little has been reported about the effect of pear on insulin signaling pathway in obesity. The aims of this study are to establish pear pomace 50% ethanol extract (PPE)-induced improvement of insulin sensitivity and characterize its action mechanism in 3T3-L1 cells and high-fat diet (HFD)-fed C57BL/6 mice.MATERIALS/METHODSLipid accumulation, monocyte chemoattractant protein-1 (MCP-1) secretion and glucose uptake were measure in 3T3-L1 cells. Mice were fed HFD (60% kcal from fat) and orally ingested PPE once daily for 8 weeks and body weight, homeostasis model assessment of insulin resistance (HOMA-IR), and serum lipids were measured. The expression of proteins involved in insulin signaling pathway was evaluated by western blot assay in 3T3-L1 cells and adipose tissue of mice.RESULTSIn 3T3-L1 cells, without affecting cell viability and lipid accumulation, PPE inhibited MCP-1 secretion, improved glucose uptake, and increased protein expression of phosphorylated insulin receptor substrate 1 [p-IRS-1, (Tyr632)], p-Akt, and glucose transporter type 4 (GLUT4). Additionally, in HFD-fed mice, PPE reduced body weight, HOMA-IR, and serum lipids including triglyceride and LDL-cholesterol. Furthermore, in adipose tissue, PPE up-regulated GLUT4 expression and expression ratio of p-IRS-1 (Tyr632)/IRS, whereas, down-regulated p-IRS-1 (Ser307)/IRS.CONCLUSIONSOur results collectively show that PPE improves glucose uptake in 3T3-L1 cells and insulin sensitivity in mice fed a HFD through stimulation of the insulin signaling pathway. Furthermore, PPE-induced improvement of insulin sensitivity was not accompanied with lipid accumulation.

In this study, the protective effect of red pepper seed water extract (RPS) against the obesity in high fat diet (HFD)-fed mice was investigated (HFD control group, and HFD group treated with 100 or 200 mg/kg body weight of RPS for 13 weeks). The application of RPS partially reversed the HFD-induced increases in body weight and adipose tissue weight. The patterns of the adipose tissue weights were parallel to the patterns of fat area, as measured in DXA procedure. In the adipose tissue, RPS suppressed the expression of adipogenic transcription factors and adipose marker genes. AMP-activated protein kinase activation was observed in the adipose tissue by RPS treatment. In addition, RPS improved high homeostasis model assessment of insulin resistance and hyperlipidemia in HFD fed mice. These findings suggest that RPS can be used as a potential therapeutic substance for reducing body fat and obesity related diseases.

BACKGROUND/OBJECTIVESReducing the number of adipocytes by inducing apoptosis of mature adipocytes as well as suppressing differentiation of preadipocytes plays an important role in preventing obesity. This study examines the anti-adipogenic and pro-apoptotic effect of red pepper seed water extract (RPS) prepared at 4℃ (RPS4) in 3T3-L1 cells.MATERIALS/METHODSEffect of RPS4 or its fractions on lipid accumulation was determined in 3T3-L1 cells using oil red O (ORO) staining. The expressions of AMP-activated protein kinase (AMPK) and adipogenic associated proteins [peroxisome proliferator-activated receptor-γ (PPAR-γ), CCAAT/enhancer-binding proteins α (C/EBP α), sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC)] were measured in 3T3-L1 cells treated with RPS4. Apoptosis and the expression of Akt and Bcl-2 family proteins [B-cell lymphoma 2 (Bcl-2), Bcl-2-associated death promoter (Bad), Bcl-2 like protein 4 (Bax), Bal-2 homologous antagonist/killer (Bak)] were measured in mature 3T3-L1 cells treated with RPS4.RESULTSTreatment of RPS4 (0–75 µg/mL) or its fractions (0–50 µg/mL) for 24 h did not have an apparent cytotoxicity on pre and mature 3T3-L1 cells. RPS4 significantly suppressed differentiation and cellular lipid accumulation by increasing the phosphorylation of AMPK and reducing the expression of PPAR-γ, C/EBP α, SREBP-1c, FAS, and ACC. In addition, all fractions except ethyl acetate fraction significantly suppressed cellular lipid accumulation. RPS4 induced the apoptosis of mature adipocytes by hypophosphorylating Akt, increasing the expression of the pro-apoptotic proteins, Bak, Bax, and Bad, and reducing the expression of the anti-apoptotic proteins, Bcl-2 and p-Bad.CONCLUSIONSThese finding suggest that RPS4 can reduce the numbers as well as the size of adipocytes and might useful for preventing and treating obesity.