Effects of resveratrol and genistein on growth, nutrient utilization and fatty acid composition of rainbow trout.

The replacement of the finite and costly resource fish oil is an important task for aquaculture nutrition. A promising approach could be the use of plant bioactives that may have the potential to influence the metabolism and the synthesis of n-3 long chain polyunsaturated fatty acids, especially EPA (20:5n-3) and DHA (22:6n-3). In this study, the two phytochemicals resveratrol (RV) and genistein (G) were investigated for their effects on fish growth, nutrient utilization and body nutrient composition alongside their effects on whole body fatty acid (FA) composition. In a feeding trial lasting 8 weeks, rainbow trout (initial BW: 81.4±0.5 g) were held in a recirculating aquaculture system and fed six experimental diets with varying fish oil levels as plain variants or supplemented with 0.3% of dry matter (DM) of either RV or G. The six diets were as follows: diet F4 had 4% DM fish oil, diet F0 had 0% DM fish oil, diets F4+RV, F4+G, F0+RV and F0+G were equal to the diets F4 and F0, respectively, and supplemented with the phytochemicals RV and G. The feeding of the F0+RV diet resulted in reduced feed intake, growth rate and slightly reduced whole body lipid levels. At the same time, the amount of polyunsaturated FA and the n-3/n-6 ratio were significantly increased in whole body homogenates of rainbow trout fed diet F0+RV in comparison to the F0 control. The feeding of the F0+G diet led to reduced feed intake, slightly increased protein utilization but did not significantly affect the whole body FA composition. Overall, feeding the fish oil-free diet supplemented with the phytochemicals resulted in more pronounced effects on fish performance and FA composition than the single factors per se (dietary fish oil level or phytochemical). Present data indicate that G might not be of profitable use for trout nutrition. In terms of FA composition, RV could be a potentially useful complement for fish oil. However, the impairment of growth and performance parameters as observed in the present study discourages its use in trout diets.

Antioxidant properties of gallocatechin and prodelphinidins from pomegranate peel.

Gallocatechins and a range of prodelphinidins were purified by high performance liquid chromatography from pomegranate peel. Gallocatechin, gallocatechin-(4-8)-catechin, gallocatechin-(4-8)-gallocatechin and catechin-(4-8)-gallocatechin were all identified, purified and quantified by LC-DAD-MS and MS-MS. The antioxidant properties of these compounds were assessed using two methods: (i) inhibition of ascorbate/iron-induced peroxidation of phosphatidylcholine liposomes; and (ii) scavenging of the radical cation of 2,2-azinobis (3-ethyl-benzothiazoline-6-sulphonate, ABTS) relative to the water-soluble vitamin E analogue Trolox C (expressed as Trolox C equivalent antioxidant capacity, TEAC). The prodelphinidin dimers were potent antioxidants in the aqueous phase, being much more effective than the gallocatechin monomer. However, in the lipid phase, only one of the dimers (gallocatechin-(4-8)-catechin) was significantly more effective than the monomer in the inhibition of lipid peroxidation of phosphatidylcholine vesicles. This study represents the first report on the antioxidant properties of prodelphinidins.

Quantitative analysis of flavan-3-ols in Spanish foodstuffs and beverages.

An HPLC method, using detection after postcolumn derivatization with p-dimethylaminocynnamaldehyde (DMACA), was developed for the quantitative analysis of individual flavanols in food. This method was applied to flavanol determination in 56 different kinds of Spanish food products, including fruit, vegetables, legumes, beverages (cider, coffee, beer, tea, and wine), and chocolate. The determined compounds corresponded to the catechins and proanthocyanidin dimers and trimers usually present in food and, therefore, they were representative of the flavanols of low degree of polymerization consumed with the diet. The data generated could be used for calculation of the dietary intake of either individual or total flavanols, which would allow the further establishment of epidemiological correlations with the incidence of chronic diseases. Similar flavanol profiles were found in the different samples of a similar type of product, even though important variations could exist in the concentrations of total and individual flavanols among them. This was attributed to factors such as sample origin, stage of ripeness, post-harvesting conservation, and processing. Total flavanol contents varied from nondetectable in most of the vegetables to 184 mg/100 g found in a sample of broad bean. Substantial amounts were also found in some fruits, such as plum and apple, as well as in tea and red wine. Epicatechin was the most abundant flavanol, followed by catechin and procyanidin B2. In general, catechins were found in all the flavanol-containing products, but the presence of gallocatechins was only relevant in pomegranate, broad bean, lentil, grape, wine, beer, and tea, and most of the berries. Galloyled flavanols were only detected in strawberry, medlar, grape, and tea.