Julio Sanhueza

Flavonoids as stabilizers of fish oil: An alternative to synthetic antioxidants

The antioxidant activities against fish oil oxidation of six commercially available flavonoids and of five flavonoids purified from two Chilean native plants were compared to those ofdl-α-tocopherol and of two synthetic antioxidants, butylated hydroxytoluene and butylated hydroxyanisole. Among the commercial flavonoids, catechin, morin and quercetin showed a higher activity when fish oil oxidation (either spontaneous or Fe2+-induced) was assessed from the formation of peroxides or thiobarbituric acid-reactive substances. Among the native flavonoids, the 5,3′,4′-trihydroxy-7-methoxy flavanone (designated as Pt-2) showed the highest antioxidant activity. Mixtures of quercetin or of Pt-2 withdl-α-tocopherol produced better inhibitory effects when compared to that of each substance assayed by itself. Also, when Pt-2 and quercetin were assayed in combination (0.3 g/kg oil and 0.7 g/kg oil, respectively), a synergistic antioxidant effect was observed. Results indicate that several flavonoids could be used as natural antioxidants as a means to replace those synthetic antioxidants, the use of which has been questioned.

TISSUE ACCRETION AND MILK CONTENT OF DOCOSAHEXAENOIC ACID IN FEMALE RATS AFTER SUPPLEMENTATION WITH DIFFERENT DOCOSAHEXAENOIC ACID SOURCES

Background: Docosahexaenoic acid (DHA) is highly concentrated in the mammalian nervous and visual system. The fatty acid, which is required by the fetus and the newborn, is supplied by the mother from their tissue reservoirs. It has been suggested that mother’s supplementation with DHA during pregnancy and even before pregnancy. Different sources of DHA are available for supplementation such as: single-cell algae triglycerides (TG), egg’s yolk phospholipids (PL), DHA ethyl esther (EE), and sn-2 DHA monoacylglyceride (MG). We evaluated comparatively the effectiveness of these different DHA sources to produce tissue DHA accretion and to increase milk DHA content. Methods: Female Wistar rats fed a diet which provided no DHA, were daily supplemented by 40 days before mating (BM) and during the pregnancy with either TG, PL, EE, or MG to an amount which provided 8 mg/kg b.w. of DHA. Samples of blood plasma, erythrocytes, hepatic and adipose tissue were obtained from rats at the BM condition and after the delivery (AD), and milk samples were also obtained from the gastric content of the pups nursed by the rats at day 3, 11 and 20 of suckling. Samples were processed to assess DHA and arachidonic acid (AA) content by gas-chromatography. Results: TG, PL, EE, and MG supplementation produced a similar intestinal absorption of DHA as estimated from the plasma DHA at the BM condition. However, PL and MG supplementation produced a higher accretion of DHA into erythrocytes, hepatic, and adipose tissue than TG and EE supplementation at the BM condition. AA content was not modified by the different supplementing oils. A reduction of the DHA content of plasma, erythrocytes, hepatic and adipose tissue at the AD condition was observed, and a reduction of AA for the hepatic and adipose tissues was also observed, suggesting the importance of these tissues as DHA and AA reservoirs. Milk secretion from PL and MG supplemented rats showed a higher DHA content than secretion from TG- and EE-supplemented rats. Conclusions: We conclude that PL and MG supplementation provides higher tissue DHA accretion and higher milk DHA content than TG and EE supplementation. However, we were not able to visualize the comparative advantages derived from PL vs. MG supplementation.

Supplementation of Female Rats with α-Linolenic Acid or Docosahexaenoic Acid Leads to the Same Omega-6/Omega-3 LC-PUFA Accretion in Mother Tissues and in Fetal and Newborn Brains

Background: Maternal omega-3 fatty acid supplementation has been suggested to provide docosahexaenoic acid (DHA) for the normal brain development during gestation. DHA can be given as such (preformed) or through the omega-3 precursor alpha-linolenic acid (LNA) which is transformed into DHA by elongation and desaturation reactions. Western diet provides low amounts of LNA and DHA; therefore, supplementation with these omega-3 fatty acids has been suggested for pregnant women. However, the bioequivalence of LNA ingestion to DHA supplementation has not been established. Methods: Recently weaning female Wistar rats were fed a diet containing a small amount of LNA and no DHA. The animals were daily supplemented 40 days before mating, during pregnancy, and until delivery with 60 mg/kg of LNA or 6 mg/kg of DHA dissolved in coconut oil. Fatty acids were given as ethyl ester derivatives. Controls received coconut oil. The fatty acid composition of blood plasma, erythrocytes, liver, visceral adipose tissue, and brain segments (frontal cortex, hippocampus, and cerebellum) was analyzed. Brain segments obtained from 16- and 19-day-old fetuses and from 2- and 21-day-old rats were also analyzed for fatty acid composition. Results: Supplementation with LNA and DHA induced a similar accretion of DHA in plasma, erythrocytes, liver, and brain segments of the mothers. The adipose tissue showed a higher DHA accretion after DHA-supplementation. The DHA accretion in frontal cortex, hippocampus, and cerebellum obtained from the fetuses and the newborn rats was similar when the mothers were supplemented with LNA and DHA. Our results show that under our experimental conditions a similar accretion of DHA in the different tissues of the mothers and in the brain segments of fetuses and newborn rats is obtained after LNA and DHA supplementation. Conclusion: LNA and DHA, at the amounts given in this study, show a similar bioequivalence for DHA accretion in different tissues of the mother and in brain segments of fetuses and newborn rats.

Effect of the degree of hydrogenation of dietary fish oil on the trans fatty acid content and enzymatic activity of rat hepatic microsomes.

The degree of fat hydrogenation and the trans fatty acid content of the diet affect the fatty acid composition of membranes, and the amount and the activity of some membrane enzymes. We describe the effects of four isocaloric diets containing either sunflower oil (SO, 0% trans), fish oil (FO, 0.5% trans), partially hydrogenated fish oil (PHFO, 30% trans), or highly hydrogenated fish oil (HHFO, 3.6% trans) as fat sources on the lipid composition and the trans fatty acid content of rat hepatic microsomes. We also describe the effect of these diets on the cytochrome P-450 content and on the aminopyrine N-demethylase, aniline hydroxylase, and UDP-glucuronyl transferase microsomal activities. Cytochrome P-450 content was dependent on the degree of unsaturation of the diet, being higher for the FO-containing diet and lower for the HHFO diet. Aminopyrine N-demethylase activity also correlated with the degree of unsaturation of the diet as did the cytochrome P-450 content did (FO>SO>PHFO>HHFO). Aniline hydroxylase activity appeared to be independent of the degree of unsaturation of the dietary fat, but correlated with the trans fatty acid content of the diet, which was also reflected in the trans content of the microsomal membranes. UDP-glucuronyl transferase activity was higher for the FO-containing diet than for the SO diet, showing intermediate values after the PHFO and HHFO diets.

Effect of Supplementation with Docosahexaenoic Acid Ethyl Ester and sn-2 Docosahexaenyl Monoacylglyceride on Plasma and Erythrocyte Fatty Acids in Rats

Background/Aims: Docosahexaenoic acid (C22:6, DHA) is an omega-3 fatty acid required for the normal development of the mammalian nervous and visual system. DHA is provided by the mother during pregnancy and lactating period. Mother’s DHA supplementation during pregnancy, and even before pregnancy, has been suggested. DHA can be provided by marine oils, egg’s yolk phospholipids, single cell algae oils, the pure fatty acid, or by the ethyl ester derivative (DHA-EE). Another way to provide DHA can be by sn-2 docosahexaenyl monoacylglyceride (DHA-MG), obtained by the treatment of fish oil with stereospecific lipases. sn-2 Fatty acid monoacylglycerides can be more easily absorbed at the intestine than other fatty acid derivatives. Methods: Female rats fed with a synthetic, which provided essentially no DHA, received a 40-day supplementation of either DHA-EE or DHA-MG. Plasma and erythrocyte fatty acid composition were assessed by gas chromatography at day 0 and 40 of supplementation. Results: DHA-EE increased plasma and erythrocyte DHA by 15 and 11.9%, respectively, with no modification of arachidonic acid (AA) content. DHA-MG supplementation increased plasma and erythrocyte DHA by 24 and 23.8%, respectively, but reduced AA by 5.5 and 3%, respectively. Conclusions: We conclude that in the rat, DHA-MG supplementation allows a higher plasma and erythrocyte DHA content than DHA-EE with minor modification of AA content.

Inhibitory action of conventional food-grade natural antioxidants and of natural antioxidants of new development on the thermal-induced oxidation of cholesterol

Cholesterol is a molecule with an unsaturated bond; therefore, like polyunsaturated fatty acids, it is prone to oxidation. Cholesterol oxidation products (COPs) are found in many common foods and have been shown to be atherogenic, cytotoxic, mutagenic and possibly carcinogenic. Therefore, efforts to prevent or to avoid COPs formation during manufacture and/or processing of foods are of high priority. The effect of natural antioxidants on COPs formation has not been extensively studied. We assayed the effect of some widely applied natural antioxidants, such as tocopherol homologs (α-T, γ-T, and δ-T) and rosemary extract, and of some natural products of newly developed as antioxidants, such as the flavonoids quercetin, catechin, morin, and rutin, and also of an alkaloid-derived product, boldine, to inhibit cholesterol oxidation of soybean oil, added of cholesterol, induced in the Rancimat test conditions (150°C and air bubbling). Formation of six different COPs at the induction period and at the 100 μS conductivity value was monitored by gas chromatography. Under the experimental conditions γ-T, quercetin, and rosemary extract prove effective to inhibit both soybean oil oxidation and COP formation. α-T, catechin, and morin are less efficient to prevent COP formation. δ-T, rutin and boldine are devoid of protective action against COP formation. γ-T, quercetin and rosemary extract may inhibit COP formation from the nucleus and from the lateral chain of the cholesterol molecule.

ACIDO DOCOSAHEXAENOICO (DHA), DESARROLLO CEREBRAL, MEMORIA Y APRENDIZAJE: LA IMPORTANCIA DE LA SUPLEMENTACIÓN PERINATAL

El acido docosahexaenoico (DHA) es un acido graso omega-3 de cadena larga derivado del acido alfa-linolenico. El DHA, junto con el acido araquidonico, es el acido graso poliinsaturado que se encuentran en mayor concentracion en el tejido nervioso. Se ha propuesto que el DHA tiene un importante rol en la formacion y en la funcion del sistema nervioso, particularmente en el cerebro. Su mecanismo de accion aun no esta totalmente dilucidado pero se propone que actuaria a nivel de las membranas celulares regulando sus funciones metabolicas y tambien a nivel de la expresion de genes relacionados con la funcion cerebral. Se ha correlacionado el contenido cerebral de DHA con la capacidad de aprendizaje y con el nivel de inteligencia de los recien nacidos y lactantes. Numerosos ensayos en animales de experimentacion y en ninos han demostrado la necesidad del acido graso durante el desarrollo cerebral. El DHA, formado a partir de su precursor, proveniente de la dieta, o desde las reservas tisulares, es aportado por la madre al feto durante el periodo gestacional y a traves de la leche durante la lactancia. Se ha sugerido la necesidad de suplementar a la madre con DHA durante el periodo gestacional, e incluso antes de este, para asegurar el adecuado aporte del acido graso para el normal desarrollo del cerebro fetal. La suplementacion se puede realizar a traves de aceites con alto contenido de DHA, a partir de fosfolipidos, en la forma de etil esteres de DHA, o como monogliceridos que contienen DHA como unico acido graso. En este trabajo se discute el rol del DHA en el desarrollo del sistema nervioso y en la funcionalidad del cerebro, y las evidencias que lo relacionan con una mayor capacidad de aprendizaje de las crias provenientes de madres previamente suplementadas con DHA. Ademas, se discute cual podria ser la mejor forma de suplementar con DHA la nutricion de la madre y del recien nacido a partir de los productos disponible para la suplementacion.

Effect of Dietary Hydrogenated Fish Oil on the Plasma Lipoprotein Profile and on the Fatty Acid Composition of Different Tissues of the Rat

Dietary fatty acids are actively incorporated into membrane lipids, and fat intake can modify the composition and the biochemical activity of cellular membranes and the pattern of plasma lipoproteins. Industrial hydrogenation of polyunsaturated oils leads to the formation of isomeric trans fatty acids which are incorporated into cellular membranes when they are present in the diet. The trans fatty acid amount present in hydrogenated oils depends on the degree of hydrogenation, being high for partially hydrogenated oils and low for highly hydrogenated oils. Hydrogenated fish oil is widely used in some countries for the production of margarine and industrial fats. This study compares the fatty acid composition of plasma, erythrocytes, subcutaneous adipose tissue, and hepatic microsomal membranes and the plasma lipoprotein profile after feeding rats with a synthetic diet containing either fish oil, partially hydrogenated fish oil, or highly hydrogenated fish oil. It is observed that the tissue content of monounsaturated fatty acids increases and that the content of polyunsaturated fatty acids decreases after an increase of the degree of hydrogenation of the dietary fat. Tissues from animals fed partially hydrogenated fish oil show significant amounts of trans fatty acids only. The plasma triacylglyceride composition and the lipoprotein profile are also altered by the degree of hydrogenation of the dietary fat. Triacylglycerides decrease after highly hydrogenated fat feeding only. Total cholesterol and low-density lipoprotein cholesterol are significantly increased after partially hydrogenated fat feeding. Although no direct evidence is presented, this effect may be attributable to the high content of trans isomers of this dietary fat which nutritionally may behave as saturated fatty acids.

Effect of the Degree of Hydrogenation of Fish Oil on the Enzymatic Activity and on the Fatty Acid Composition of Hepatic Microsomes from Young and Aged Rats

By modifying the degree of hydrogenation of dietary fat, it is possible to modify the fatty acid composition and the biochemical activity of cellular tissues. The age can be another variable influencing these modifications. The effect of isocaloric diets containing oils with different degrees of hydrogenation: fish oil (FO, 0.3% trans), partially hydrogenated fish oil (PHFO, 29% trans), or highly hydrogenated fish oil (HHFO, 2.3% trans), in the fatty acid composition (cis and trans isomers) of hepatic microsomes from young (70-day-old) and aged (18-month-old) rats, in the microsomal cytochrome P-450 (C-450) content, and in the aminopyrine N-demethylase (AND), aniline hydroxylase (AH), NADPH cytochrome P-450 reductase (NCR), UDP-glucuronyl transferase (UGT), and GSH-S transferase (GST) enzymatic activities were studied. Fatty acid composition and n–6/n–3 ratio of microsomal membranes was modified to a higher extent in young rats. C-450 content and AND activity were reduced when the degree of hydrogenation of dietary fat was increased in the young and the aged rats. AH activity was higher after the PHFO diet in the young rats only. NCR activity was reduced in the young animals when the hydrogenation of the fat was increased. However, in aged rats the enzyme exhibited a higher activity after the PHFO and HHFO diet. UGT and GST activities where not affected by the level of hydrogenation of the dietary fat in both the young and the aged rats. However, UGT activity was higher in the young rats, while GST activity was higher in the aged animals. We conclude that hydrogenation of dietary fat can modify the fatty acid composition of hepatic microsomes, young animals being more sensitive to these changes than aged animals. These effects were also reflected in the amount and/or the activity of some molecular components of the hepatic microsomal mixed-function oxidase enzyme system. Microsomal trans fatty acid composition is not affecting the activity of the enzymes, the age of the animals being the most important factor

Alimentos funcionales, nutraceúticos y foshu: ¿vamos hacia un nuevo concepto de alimentación?

The increase of economic development and life expectancy of humans has aroused concerns about the health and nutrition in important groups of the population. These modifications have stimulated the development of functional foods (FF), nutraceuticals (NT) and FOSHU (Food with Specific Health Uses) in many countries around the world, mainly in those of greater development. FF are foods to which one or more healthy component has been added without changing its characteristics. The definition of FF is now incorporated into the food normative of many countries. NT is a more complex concept, because it is not referred to a food but to components of a food that can be ingested in amounts greater than those frequently consumed. NT are not pharmaceuticals since they have no therapeutic action although they may have preventive properties. FOSHU is a concept of foods with exclusive medical actions developed in Japan. This review discusses the signifi cance of these new food concepts establishing their origins, potentialities, differences and future projections of these types of foods or food components.