Detection of 2-amino-1-methyl-6-(4-hydroxyphenyl)imidazo[4,5-b]pyridine in broiled beef.

2-Amino-1-methyl-6-(4-hydroxyphenyl)imidazo[4,5-b]pyridine (4'-OH-PhIP) showed mutagenicity in Salmonella typhimurium TA98 in the presence of S9 mix, inducing 180 revertants per 100 micrograms. Since creatinine, tyrosine and glucose, which are present in meat, are expected to be involved in the formation of 4'-OH-PhIP, its presence in broiled beef was examined. 4'-OH-PhIP was detected in broiled beef by high-performance liquid chromatography and UV-spectrometry after extraction with 0.1 N HCl and purification by blue cotton treatment and ion exchange column chromatography. Its level was estimated to be 21.0 ng per g of broiled beef, which is comparable to that of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP).     

Liver cancer and precancerous changes in rats induced by the basic fraction of tryptophan pyrolysate

The basic fraction of a tryptophan pyrolysate (Trp-P-BF) was given orally to Wistar rats for about 2 years. In Experiment I, 5 male rats each were given 0.2, 0.4, 0.6 and 0.8% Trp-P-BF. Dose-dependent growth retardation was observed in these groups and neoplastic nodules were found in the liver of 1 rat given 0.2% Trp-P-BF and a hepatocellular carcinoma was found in 1 rat given 0.4% Trp-P-BF diet. In Experiment II, 25 rats of both sexes were fed 0.5% or 0.2% Trp-P-BF diet. Neoplastic nodules were induced in 2 of 22 males and 5 of 18 females given 0.2% Trp-P-BF diet. Mammary adenomas developed, but no neoplastic nodules were found in the liver of rats fed on 0.05% Trp-P-BF or control diet. Females were more sensitive to Trp-P-BF than males.     

Furan fatty acid as an anti-inflammatory component from the green-lipped mussel Perna canaliculus

A lipid extract of Perna canaliculus (New Zealand green-lipped mussel) has reportedly displayed anti-inflammatory effects in animal models and in human controlled studies. However, the anti-inflammatory lipid components have not been investigated in detail due to the instability of the lipid extract, which has made the identification of the distinct active components a formidable task. Considering the instability of the active component, we carefully fractionated a lipid extract of Perna canaliculus (Lyprinol) and detected furan fatty acids (F-acids). These naturally but rarely detected fatty acids show potent radical-scavenging ability and are essential constituents of plants and algae. Based on these data, it has been proposed that F-acids could be potential antioxidants, which may contribute to the protective properties of fish and fish oil diets against chronic inflammatory diseases. However, to date, in vivo data to support the hypothesis have not been obtained, presumably due to the limited availability of F-acids. To confirm the in vivo anti-inflammatory effect of F-acids in comparison with that of eicosapentaenoic acid (EPA), we developed a semisynthetic preparation and examined its anti-inflammatory activity in a rat model of adjuvant-induced arthritis. Indeed, the F-acid ethyl ester exhibited more potent anti-inflammatory activity than that of the EPA ethyl ester. We report on the in vivo activity of F-acids, confirming that the lipid extract of the green-lipped mussel includes an unstable fatty acid that is more effective than EPA.     

In vitro generation of insulin‐secreting cells from human pancreatic exocrine cells

Transplantation of surrogate β‐cells is a promising option for the treatment of insulin‐deficient diabetes mellitus in the future. Although pancreatic exocrine cells of rodents have been shown to transdifferentiate into insulin‐secreting cells, no studies are reported on human exocrine cells. Here, we report the generation of insulin‐secreting cells from exocrine cells of the human pancreas. When cultured in suspension with epidermal growth factor, human pancreatic exocrine cells readily formed spherical cell clusters. Expression of Pdx1 was induced in all 19 cases in which we successfully isolated exocrine cells, and insulin expression was induced in 11 cases. In addition, insulin secretion was evaluated in four cases, and the newly‐made cells were found to secrete insulin in response to various stimuli. Although further studies are required to improve both the quality and quantity of such insulin‐secreting cells, our data suggest that pancreatic exocrine cells represent a potential source of insulin‐secreting cells for treatment of type 1 diabetes. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00095.x, 2011)     

Adduct Formation at C-8 of Guanine on in vitro Reaction f the Ultimate Form of 2-Amino-l-methyl-6-phenylimidazo[4,5-b]pyridine with 2'-Deoxyguanosine and Its Phosphate Esters

We examined the reactivity of the N -hydroxyamino derivative of a carcinogenic heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5- b ]pyridine (PhIP), after its O -acetylation with four 2'-deoxyribonucleoside 3'-monophosphates. ³²P-Postlabeling analysis demonstrated that the levels of adducts with 2'-deoxyguanosine 3'-moiiophosphate were much higher than those with the other three nucleotides. ¹H-NMR, mass spectral and UV absorption spectral analyses of the major adducts formed by N -acetoxy-PhIP with 2'-deoxyguanosine and with its phosphate esters indicated that PhIP bound at the C-8 position of guanine, as previously demonstrated with other heterocyclic amines.     

The Steroidal Alkaloid Tomatidine and Tomatidine-Rich Tomato Leaf Extract Suppress the Human Gastric Cancer-Derived 85As2 Cells In Vitro and In Vivo via Modulation of Interferon-Stimulated Genes

The steroidal alkaloid tomatidine is an aglycone of α-tomatine, which is abundant in tomato leaves and has several biological activities. Tomatidine has been reported to inhibit the growth of cultured cancer cells in vitro, but its anti-cancer activity in vivo and inhibitory effect against gastric cancer cells remain unknown. We investigated the efficacy of tomatidine using human gastric cancer-derived 85As2 cells and its tumor-bearing mouse model and evaluated the effect of tomatidine-rich tomato leaf extract (TRTLE) obtained from tomato leaves. In the tumor-bearing mouse model, tumor growth was significantly inhibited by feeding a diet containing tomatidine and TRTLE for 3 weeks. Tomatidine and TRTLE also inhibited the proliferation of cultured 85As2 cells. Microarray data of gene expression analysis in mouse tumors revealed that the expression levels of mRNAs belonging to the type I interferon signaling pathway were altered in the mice fed the diet containing tomatidine and TRTLE. Moreover, the knockdown of one of the type I interferon-stimulated genes (ISGs), interferon α-inducible protein 27 (IFI27), inhibited the proliferation of cultured 85As2 cells. This study demonstrates that tomatidine and TRTLE inhibit the tumor growth in vivo and the proliferation of human gastric cancer-derived 85As2 cells in vitro, which could be due to the downregulation of ISG expression.