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In recent years considerable attention has been given to the use of natural substances as anticancer drugs. The natural antioxidant dipeptide L-carnosine belongs to this class of molecules because it has been proved to have a significant anticancer activity both in vitro and in vivo. Previous studies have shown that L-carnosine inhibits the proliferation of human colorectal carcinoma cells by affecting the ATP and Reactive Oxygen Species (ROS) production. In the present study we identified the Hypoxia-Inducible Factor 1α (HIF-1α) as a possible target of L-carnosine in HCT-116 cell line. HIF-1α protein is over-expressed in multiple types of human cancer and is the major cause of resistance to drugs and radiation in solid tumours. Of particular interest are experimental data supporting the concept that generation of ROS provides a redox signal for HIF-1α induction, and it is known that some antioxidants are able to suppress tumorigenesis by inhibiting HIF-1α. In the current study we found that L-carnosine reduces the HIF-1α protein level affecting its stability and decreases the HIF-1 transcriptional activity. In addition, we demonstrated that L-carnosine is involved in ubiquitin-proteasome system promoting HIF-1α degradation. Finally, we compared the antioxidant activity of L-carnosine with that of two synthetic anti-oxidant bis-diaminotriazoles (namely 1 and 2, respectively). Despite these three compounds have the same ability in reducing intracellular ROS, 1 and 2 are more potent scavengers and have no effect on HIF-1α expression and cancer cell proliferation. These findings suggest that an analysis of L-carnosine antioxidant pathway will clarify the mechanism underlying the anti-proliferative effects of this dipeptide on colon cancer cells. However, although the molecular mechanism by which L-carnosine down regulates or inhibits the HIF-1α activity has not been yet elucidated, this ability may be promising in treating hypoxia-related diseases. [ABSTRACT FROM AUTHOR]

Isoflavones exist in nature predominantly as glucosides such as daidzin or genistin and are rarely found in their corresponding aglycone forms daidzein and genistein. The metabolism and absorption of isoflavones ingested with food is well documented, but little is known about their use as topical photo-protective agents. The aim of this study was to investigate in a comparative analysis the photo-protective effects of isoflavones in both their aglycone and glucoside forms. In human skin fibroblasts irradiated with 60 mJ/cm2 ultraviolet B (UVB), we measured the expression levels of COX-2 and Gadd45, which are involved in inflammation and DNA repair, respectively. We also determined the cellular response to UVB-induced DNA damage using the comet assay. Our findings suggest that both the isoflavone glucosides at a specific concentration and combination with an aglycone mixture exerted an anti-inflammatory and photo-protective effect that prevented 41% and 71% of UVB-induced DNA damage, respectively. The advantages of using either isoflavone glucosides or an aglycone mixture in applications in the field of dermatology will depend on their properties and their different potential uses. [ABSTRACT FROM AUTHOR]

The anti-inflammatory effects and antioxidant activities of individual isoflavones are well established although little is known about the photoprotective effect of their combination. The aim of this study was to investigate the photoprotective effects of different concentrations of genistein and daidzein individually or combined. We measured the expression levels of the cyclo-oxygenase-2 (COX-2) and growth arrest and DNA-damage inducible (Gadd45) genes, which are involved in inflammation and DNA repair, respectively, in BJ-5ta human skin fibroblasts irradiated with 60mJ/cm2 UVB. We also determined the cellular response to UVBinduced DNA damage by Comet assay. We report that genistein and daidzein when administered combined, and at a specific concentration and ratio, exerted a synergistic photoprotective effect that was greater than the effect obtained with each isoflavone alone. The results reported herein suggest that low concentrations of genistein and daidzein combined may be good candidate ingredients for protective agents against UV-induced photodamage. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) plays an important role in the pathogenesis of celiac disease. We have examined the involvement of nuclear factor-κB (NF-κB), interferon regulatory factor-1 (IRF-1), and signal transducer and activator of transcription-1α (STAT-1α) on the synergistic induction of inducible nitric oxide synthase (iNOS) gene expression by gliadin (G) in association with interferon-γ (IFN-γ) in RAW 264.7 macrophages. We found that IFN-γ was efficient in enhancing the basal transcription of the iNOS promoter at 1, 6, and 24 h, whereas G had no effect. The G plus IFN-γ association caused an increase in iNOS promoter activity which was inhibited by pyrrolidine dithiocarbammate (PDTC) at 6 and 24 h as well as by genistein (Gen) and tyrphostine B42 (TB42) at 1 h, inhibitors of NF-κB, IRF-1, and STAT-1α activation, respectively. Similarly, the IFN-γ and G combination treatment led to a higher increase in iNOS mRNA levels at 1, 6, and 24 h compared with IFN-γ alone. Gen and TB42 inhibited iNOS mRNA levels at 1 h, whereas PDTC inhibited iNOS mRNA levels at 6 and 24 h. In addition, the synergistic induction of iNOS gene expression by G plus IFN-γ correlated with the induction of NF-κB, IRF-1, and STAT-1α/DNA binding activity and mRNA expression. In conclusion, our study, which provides evidence that the effect of G on iNOS gene transcription in IFN-γ-stimulated RAW 264.7 cells can be ascribed to all three transcription factors, may contribute to lead to new insights into the molecular mechanisms governing the inflammatory process in celiac disease. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) plays an important role in the pathogenesis of the histological changes seen in coeliac disease. We have investigated the effect of peptic-tryptic digest of gliadin (Pt-G) and gliadin (G) on inducible nitric oxide synthase (iNOS) protein expression in RAW 264.7 macrophages stimulated with interferon-γ (IFN-γ). Pt-G and G enhanced in a concentration and time-dependent manner NO production by IFN-γ-stimulated RAW 264.7 cells. The increase of iNOS protein expression was correlated with NF-κB/DNA binding activity and occurred at transcriptional level. Pyrrolidine dithiocarbamate and N-α-para-tosyl-L-lysine chloromethyl ketone, two known inhibitors of NF-κB activation, decreased significantly NO production and iNOS protein expression as well as NF-κB/DNA binding activity. Our results show that the effect of Pt-G and G on enhancement of iNOS protein expression in IFN-γ-treated RAW 264.7 cells is mainly mediated through NF-κB and suggest that blockage of NF-κB activation reduces enhancing effect of gluten on NO production in inflamed mucosa of coeliac patients. [ABSTRACT FROM AUTHOR]