RESUMEN
In this research, our aim was to isolate and characterize the substance known as "meat factor," which is reported to enhance nonheme iron absorption. We used various analytical techniques, and the final step was a human study to measure the effect of a candidate compound on iron absorption. Lean beef was selected for study, as it is known to increase nonheme iron absorption. Cooked ground beef was homogenized and aliquots were taken through a simulated gastric and intestinal digestion. This was followed by purification using fast protein liquid chromatography. The fractions were collected and applied to a Caco-2 cell system designed to measure iron absorption using radioiron. Fractions with an enhancing effect were analyzed by mass spectrometry, nuclear magnetic resonance, and HPLC, and a proposed empirical formula was obtained for the substance in the most active fraction (C(8)H(20) NO(6)P). Tandem mass spectrometry was used to identify the compound as L-alpha-glycerophosphocholine (L-alpha) by comparing the spectra against authentic material. We added a commercially available food grade source of L-alpha to vegetarian lasagna, with and without 100 mg ascorbic acid (a known enhancer of nonheme iron absorption), at the same enhancer:iron molar ratio (2:1), and fed meals to 13 women of child-bearing age with low iron stores. The nonheme iron was labeled with stable isotopes of iron to provide a total dose per meal of 10 mg iron, and absorption was measured from erythrocyte incorporation. Nonheme iron absorption from lasagna was increased by the addition of either ascorbic acid (P = 0.010) or L-alpha (P = 0.023). We have identified L-alpha as a component of muscle tissue that enhances nonheme iron absorption, and this finding provides new opportunities for iron fortification of foods.
Asunto(s)
Glicerilfosforilcolina/análisis , Glicerilfosforilcolina/farmacología , Hierro/farmacocinética , Carne/análisis , Absorción , Adolescente , Adulto , Animales , Células CACO-2 , Bovinos , Cromatografía Líquida de Alta Presión , Estudios Cruzados , Femenino , Glicerilfosforilcolina/administración & dosificación , Humanos , Hierro/administración & dosificación , Hierro/metabolismo , Espectrometría de Masas , Persona de Mediana Edad , Espectrometría de Masas en TándemRESUMEN
We have generated transgenic maize plants expressing Aspergillus phytase either alone or in combination with the iron-binding protein ferritin. Our aim was to produce grains with increased amounts of bioavailable iron in the endosperm. Maize seeds expressing recombinant phytase showed enzymatic activities of up to 3 IU per gram of seed. In flour paste prepared from these seeds, up to 95% of the endogenous phytic acid was degraded, with a concomitant increase in the amount of available phosphate. In seeds expressing ferritin in addition to phytase, the total iron content was significantly increased. To evaluate the impact of the recombinant proteins on iron absorption in the human gut, we used an in vitro digestion/Caco-2 cell model. We found that phytase in the maize seeds was associated with increased cellular iron uptake, and that the rate of iron uptake correlated with the level of phytase expression regardless of the total iron content of the seeds. We also investigated iron bioavailability under more complex meal conditions by adding ascorbic acid, which promotes iron uptake, to all samples. This resulted in a further increase in iron absorption, but the effects of phytase and ascorbic acid were not additive. We conclude that the expression of recombinant ferritin and phytase could help to increase iron availability and enhance the absorption of iron, particularly in cereal-based diets that lack other nutritional components.
Asunto(s)
6-Fitasa/química , Aspergillus/enzimología , Ferritinas/química , Técnicas Genéticas , Glycine max/metabolismo , Hierro/farmacocinética , Proteínas de Plantas/química , Proteínas Recombinantes/química , Zea mays/enzimología , 6-Fitasa/metabolismo , Ácido Ascórbico/metabolismo , Aspergillus/genética , Células CACO-2 , ADN Complementario/metabolismo , Difusión , Ferritinas/farmacología , Genes de Plantas , Vectores Genéticos , Humanos , Immunoblotting , Hierro/metabolismo , Hierro/farmacología , Fosforilación , Plantas Modificadas Genéticamente , Proteínas Recombinantes/farmacología , Proteínas de Soja/química , Factores de Tiempo , Transgenes , Zea mays/genética , Zea mays/metabolismoRESUMEN
Certain cancer cells proliferate under conditions of oxidative stress (OS) and might therefore be selectively targeted by redox catalysts. Among these catalysts, compounds containing a chalcogen and a quinone redox centre are particularly well suited to respond to the presence of OS. These catalysts combine the specific electrochemical features of quinones and chalcogens. They exhibit high selectivity and efficiency against oxidatively stressed rat PC12, human Jurkat and human Daudi cells in cell culture, where their mode of action most likely involves the catalytic activation of existent and the generation of new reactive oxygen species. The high efficiency and selectivity shown by these catalysts makes them interesting for the development of anti-cancer drugs.
Asunto(s)
Calcógenos/química , Reductasas del Citocromo/química , Estrés Oxidativo , Quinonas/química , Animales , Catálisis , Línea Celular Tumoral , Calcógenos/farmacología , Electroquímica , Humanos , Células Jurkat , Modelos Moleculares , Estructura Molecular , Oxidación-Reducción/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Células PC12 , Quinonas/farmacología , Ratas , Especies Reactivas de Oxígeno/química , Especies Reactivas de Oxígeno/metabolismoRESUMEN
New asymmetric organotellurides exhibiting good antioxidant properties in vitro and in cell culture can be attached to human serum albumin.