Availability of potato protein concentrate as an alternative protein source to fish meal in greater amberjack (Seriola dumerili) diets

Potato protein concentrate (PPC) is a promising candidate as a fish meal (FM) substitute because it has high protein and essential amino acid content. In the present study, we replaced FM in greater amberjack diets with PPC to investigate the effect on growth and feed utilization. Four isonitrogenous, isolipidic and isocaloric experimental diets were prepared by substituting 0, 20, 40 and 60% of FM protein with PPC (Control, P20, P40 and P60 respectively). The in vitro protein digestibility of protein in PPC was 88.8%, relative to 100% protein in the FM. The in vitro protein digestibility of protein in the experimental diets also decreased with increasing PPC and was lowest at 84.2% in P60. After the 7‐week feeding trial, final body weight, weight gain and thermal growth coefficient tended to decrease with increasing PPC and were significantly lower in P60 than in the control (p < .05). Further, fish fed with diets P40 and P60 showed significantly lower feed conversion and protein efficiency ratios than the control group (p < .05). In conclusion, the results suggest that PPC can replace up to 20% of FM in the diet of greater amberjack without compromising the growth performance or feed efficiency.     

Inhibitory effects of heterocyclic amine-induced DNA adduct formation in mouse liver and lungs by beer

An evaluation of the in vivo antigenotoxic potential of beer components on heterocyclic amines including 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 3-amino-1-methyl-5H-pyrido[4.3-b]indole (Trp-P-2) was determined with particular focus on the target organs of tumorigenesis, and the protective mechanisms involved were investigated. Beer-solution, consisting of a freeze-dried and dissolved sample, given as drinking water, reduced the formation of MeIQx-DNA adducts in mouse liver and lungs. Beer-solution added in the diet as a mimic of food additives also significantly reduced the amount of DNA adducts present in the liver, lung, and kidney DNA of mice fed with MeIQx compared to control mice fed with MeIQx in the absence of beer-solution. The amount of adducts present in the liver of mice with single or continuous administration of Trp-P-2 was significantly reduced when beer-solution was given as part of the diet compared to control mice given Trp-P-2 without beer-solution. Protective effects were observed both with lager- and stout-type samples. In an effort to investigate the mechanisms responsible for the observed protective effects, the effects of beer-solution on metabolizing enzymes for heterocyclic amines were examined. Beer-solutions inhibited the metabolic activation of Trp-P-2 to Trp-P-2(NHOH), as demonstrated by HPLC analysis. Considering the overall suppression of the genotoxicity of MeIQx and Trp-P-2 by beer, we have shown that beer components can inhibit the metabolic activation of heterocyclic amines and subsequently suppress the observed genotoxicity. The results of this study show that beer components are protective against the genotoxic effects of heterocyclic amines on target organs associated with tumorigenesis in vivo.     

Inhibitory effects of (-)-epigallocatechin gallate on the mutation,DNA strand cleavage,and DNA adduct formation by heterocyclic amines

Green tea is known to be a potential chemopreventive agent against cancer. In this study, we investigated the inhibitory activities of tea extracts, and in particular the polyphenolic component (-)-epigallocatechin gallate (EGCG), against heterocyclic amine-induced genotoxicity. The tea extracts displayed inhibition of 2-hydroxyamino-6-methyldipyrido[1,2-a,3',2'-d]imidazole (Glu-P-1(NHOH))-induced mutagenicity. This inhibition can be accounted for by the presence of EGCG in the extracts. The mutagenic effect of Glu-P-1(NHOH), which induces single-strand cleavage in supercoiled circular DNA under neutral conditions, was inhibited by EGCG. Using the Drosophila repair test, a test for gross DNA damage, and DNA adduct detection by (32)P-postlabeling, we showed that EGCG prevented 2-amino-3,8-dimethylimidazo[4,5-f]quinoline-induced DNA damage and adduct formation in insect DNA. EGCG was found to accelerate the degradation of Glu-P-1(NHOH) in vitro. This observation suggested that the inhibition by EGCG is associated with an accelerated degradation of metabolically activated heterocyclic amines.