Shikonin (SKN), a highly liposoluble naphthoquinone pigment isolated from the roots of Lithospermum erythrorhizon, is known to exert antibacterial, wound-healing, anti-inflammatory, antithrombotic, and antitumor effects. The aim of this study was to examine SKN antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). The SKN was analyzed in combination with membrane-permeabilizing agents Tris and Triton X-100, ATPase inhibitors sodium azide and N,N′-dicyclohexylcarbodiimide, and S. aureus-derived peptidoglycan; the effects on MRSA viability were evaluated by the broth microdilution method, time-kill test, and transmission electron microscopy. Addition of membrane-permeabilizing agents or ATPase inhibitors together with a low dose of SKN potentiated SKN anti-MRSA activity, as evidenced by the reduction of MRSA cell density by 75% compared to that observed when SKN was used alone; in contrast, addition of peptidoglycan blocked the antibacterial activity of SKN. The results indicate that the anti-MRSA effect of SKN is associated with its affinity to peptidoglycan, the permeability of the cytoplasmic membrane, and the activity of ATP-binding cassette (ABC) transporters. This study revealed the potential of SKN as an effective natural antibiotic and of its possible use to substantially reduce the use of existing antibiotic may also be important for understanding the mechanism underlying the antibacterial activity of natural compounds.

BackgroundIn this study, we investigated the anti-obesity and anti-hyperlipidemic mechanisms of lambertianic acid (LA) isolated from Pinus koraiensis leaves and the ethanol extract of Pinus koraiensis leaves (EPK), both in vitro and in vivo.MethodsDifferentiated 3T3L-1 cells were treated with EPK (25 or 50 μg/mL) or LA (200 μM) and analyzed by western blotting or RT-PCR. In vitro, lipid accumulation of adipocytes was observed using Oil-Red-O staining and triglyceride analysis. The contribution of AMPK to anti-obesity activity was assessed by siRNA-mediated AMPK knockdown. After AMPK silencing, expression of AMPK was observed by western blotting. To confirm the in vitro activity, an animal study was conducted by administering a normal diet, HFD, and EPK for 6 weeks. Obesity-related physiological parameters and protein levels were measured.ResultsLA induced the expression of p-AMPK and inhibited PPARγ, C/EBP α, adiponectin, FAS, SREBP-1, and HMGCR expression. EPK containing LA significantly decreased lipid accumulation and triglyceride levels in the differentiated 3 T3-L1 cells. EPK treatment suppressed the expression of adipogenic transcription factors, FABP, GPDH, and cholesterol-synthesis-related factors in the differentiated 3 T3-L1 cells. EPK increased the expression of p-AMPK. The effects of EPK were reversed on inhibiting AMPK by using AMPK siRNA and compound C. In vivo analysis showed that body weight gain, serum triglyceride, total cholesterol, LDL cholesterol and AI value in the EPK treatment group were lower than those in the HFD control group. EPK induced the expression of p-AMPK and inhibited PPARγ in liver and adipose tissue.ConclusionsOverall, the results suggest that EPK containing LA exerts significant anti-obesity and cholesterol-lowering effects by activating AMPK.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-016-1031-2) contains supplementary material, which is available to authorized users.

Allomyrina dichotoma larva is a nutritional-worthy future food resource and it contributes to multiple pharmacological functions. However, its antidiabetic effect and molecular mechanisms are not yet fully understood. Therefore, we investigated the hypolipidemic effect of A. dichotoma larva extract (ADLE) in a high-fat diet (HFD)-induced C57BL/6J mice model. Glucose tolerance and insulin sensitivity in HFD-induced diabetic mice significantly improved after ADLE administration for six weeks. The levels of serum triglyceride (TG), aspartate aminotransferase (AST), alanine transferase (ALT) activity, and lipid accumulation were increased in the liver of HFD-fed mice, but the levels were significantly reduced by the ADLE treatment. Moreover, hepatic fibrosis and inflammatory gene expression in the liver from HFD-treated mice were ameliorated by the ADLE treatment. Dephosphorylation of AMP-activated protein kinase (AMPK) by palmitate was inhibited in the ADLE treated HepG2 cells, and subsequently reduced expression of lipogenic genes, such as SREPBP-1c, ACC, and FAS were observed. The reduced expression of lipogenic genes and an increased phosphorylation of AMPK was also observed in the liver from diabetic mice treated with ADLE. In conclusion, ADLE ameliorates hyperlipidemia through inhibition of hepatic lipogenesis via activating the AMPK signaling pathway. These findings suggest that ADLE and its constituent bioactive compounds are valuable to prevent or treat hepatic insulin resistance in type 2 diabetes.

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Fomes fomentarius, an edible mushroom, is known to have anti-cancer, anti-inflammatory, and anti-diabetes effects. However, the underlying anti-cancer mechanism of F. fomentarius is unknown. To determine the molecular mechanism of the anti-cancer effects of F. fomentarius, various methods were used including fluorescence-activated cell sorting, Western blotting, migration, and crystal violet assays. F. fomentarius ethanol extract (FFE) decreased cell viability in six cancer cell lines (MDA-MB-231, MCF-7, A549, H460, DU145, and PC-3). FFE decreased the migration of MDA-MB-231 cells without causing cell toxicity. Furthermore, FFE attenuated the expression of matrix metalloproteinase-9 and phosphorylation of Akt as well as increased E-cadherin in MDA-MB-231 cells. FFE arrested the S and G2/M populations by inhibiting the expression of cell cycle regulatory proteins such as cyclin-dependent kinase 2, cyclin A/E, and S-phase kinase-associated protein 2. FFE increased the sub-G1 population and expression of cleaved caspase-9, -3, and cleaved poly adenosine diphosphate (ADP-ribose) polymerase at 72 h and suppressed B-cell lymphoma 2. Interestingly, FFE and AKT inhibitors showed similar effects in MDA-MB-231 cells. Additionally, FFE contained betulin which inhibited p-AKT in MDA-MB-231 cells. Our findings demonstrate that FFE inhibits cell motility and growth and induces apoptosis by inhibiting the phsphoinositide 3- kinase /AKT pathway and caspase activation.

Chromatography technology was employed to clarify the mechanism of interaction between multi-wall carbon nanotubes (MWCNT) and proteins. A column (16×100 mm) was packed with purified MWCNT, and various proteins were eluted with phosphate buffered saline (PBS) with and without gradient systems. It was found that albumin in bovine serum was eluted immediately from the column without any adsorption to MWCNT. Conversely, the non-albumin proteins, including a protein of 85 kDa molecular mass and a group of proteins with molecular masses higher than 115 kDa, exhibited considerably high affinity towards MWCNT. A sample of pure bovine serum albumin was also eluted immediately from the column, while lysozyme did not elute as a peak with PBS, but eluted with 0.6 M NaCl. Fundamentally, carbon nanotubes are devoid of any electrical charge. Therefore, other forces including the hydrogen bonds, hydrophilic interactions, and van der Waals forces were most probably responsible for the differential elution behaviors. In conclusion, this chromatographic method provided a simple and direct analysis of the interactions between carbon nanotubes and the various proteins.

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Background: Dental caries and periodontal disease are bacterial infectious disease, mainly caused by plaque, a bacterial colony deposited on the tooth surface and gum tissue. Dental plaque disclosants easily stain the dental plaque, making them effective for scaling and tooth brushing education. As the erythrosine typically contained in dental plaque disclosants is highly cytotoxic, a low toxicity additive is needed. In this study, we aimed to examine the natural pigments with negligible cytotoxicity but can effectively stain the dental plaques for use in dental plaque disclosants. Methods: The pigmentation of eight types of natural pigments was tested on bovine tongue and teeth, as well as on head and neck tissue sections of experimental ICR mice. The cytotoxicity of gingival epithelial cells was measured via MTT assay. Pigmentation was performed on the bovine tongue and tooth surface. Pigmentation in the oral environment was observed in four mandibular incisors. A 2 Tone was used as a control. Results: Of the eight types of natural pigments, purple and blue pigments were effective in coloring dental plaques on the enamel surface as well as in the head and neck tissue sections. Additionally, purple and blue pigments were visible on the surface of the bovine tongue. Red, pink, orange, green, purple, and yellow pigments showed strong cytotoxicity, whereas brown and blue pigments had relatively low cytotoxicity. Blue pigment was effective in staining the dental plaque of four mandibular incisors. Conclusion: We suggest that the blue pigment derived from Gardenia jasminoides Ellis (Rubiaceae), which is effective for coloring dental plaques and has low cytotoxicity, is useful as a naturally derived dental disclosant.