Inhibition of advanced glycation end products formation by stilbene and phenanthrene derivatives from Prosthechea michuacana in vitro and in vivo / Inhibición de la formación de subproductos en la glicosilación avanzada por derivados de estilbeno y fenantreno de Prosthechea michuacana, in vitro e in vivo

In our previous study, we isolated from chloroform extract of the bulbs of orchid P. michuacana, three antioxidant compounds: two stilbene alpha-alpha´-dihydro, 3´,5´,2-trimethoxy-3-hydroxy-4-acetyl-4´-isopentenyl stilbene, 5-[2-(3-hydroxy-5-methoxyphenyl)ethyl]-2-methoxyphenol (gigantol) and one phenanthrene 4,6,7-trihydroxy-2-methoxy-8-(methylbut-2-enylphenanthren-1-1´-4´,6´,7´-trihydroxy-2´-methoxy-8´-(methylbut-2´-enyl)-phenanthrene. Following the study, we investigated the ability of isolated compounds to inhibit advanced glycation in vitro. Bovine serum albumin was glycated in the presence of glucose or methylglyoxal. Amadori-rich protein was prepared by dialyzing lysozyme that had been glycated by ribose. We also evaluated renal function by checking formation of advanced glycation and tail tendon collagen quality in streptozotocin-induced diabetic mice. Also determined the effect on LDL and hemoglobin. Compounds can efficiently inhibit the formation of AGEs by trapping reactive methylglyoxal and showed potent anti-Amadorin activity. Also exhibited a significant inhibitory activity on the glycated hemoglobin (GHb and HbA1c). Compounds showed a protective renal effect and reduction in mice tail tendon collagen. Also the tested compounds are potent agents for protecting LDL against oxidation and glycation. We concluded that compounds from P. michuacana are potent antiglycation agents, which can be of great value in the prevention of diabetic glycation-associated-pathogenesis.

En un estudio anterior, aislamos del extracto clorofórmico de los bulbos de la orquídea Prosthechea michuacana, tres compuestos antioxidantes: los estilbenos alfa-alfa´-dihidro, 3´,5´,2-trimethoxi-3-hidroxi-4-acetil-4´-isopentenil-stilbeno, 5-[2-(3-hydroxy-5-methoxyphenyl)ethyl]-2-methoxyphenol (gigantol) y el fenantreno 4,6,7-trihidroxi -2-methoxi-8-(metilbut-2-enilfenantren-1-1´-4´,6´,7´-trihidroxi-2´-metoxi-8´-(metilbut-2´-enil)-fenantreno. Continuando con el estudio, investigamos la capacidad de estos compuestos para inhibir la glicación avanzada in vitro. La seroalbúmina bovina se glicosiló en presencia de glucosa o metilglioxal. La reacción de Amadori se determinó con lisozima glicosilada previamente tratada con ribosa. También se evaluó la función renal mediante la formación de la glicación avanzada y la inhibición de AGEs en el ensayo sobre el colágeno del tendón de la cola en ratones con diabetes inducida con estreptozotocina. También determinamos el efecto de los compuestos aislados sobre LDL y hemoglobin. Los compuestos pueden inhibir eficazmente la formación de AGE atrapando el metilglioxal reactivo y muestran potente actividad anti Amadorin. También mostraron una actividad inhibitoria significativa en la formación de la hemoglobina glucosilada, GHB y HbA1c. Mostraron un efecto protector renal y una reducción en el colágeno glicosiladó del tendón de la cola. También estos compuestos son potentes agentes para la protección de LDL frente la oxidación y la glicación. En base a los resultados obtenidos se concluye que los compuestos aislados son potentes agentes antiglicación, que pueden ser de gran valor en la prevención de la patogénesis de la diabetes asociada a la glicación.

The Effect of Rice Germ Oil Supplement on Serum and Hepatic Lipid Levels of Streptozotocin-Induced Diabetic Mice

This study was carried out to investigate the effects of rice germ oil supplement on the lipid metabolism of insulin-dependent diabetic mice. Streptozotocin-induced diabetic mice were fed three kinds of experimental diets with 20% lipid, composed of 20% lard (L) : 10% lard and 10% rice germ oil (LRGO) ; and 20% rice germ oil (RBO), respectively, for 7 weeks. Diet intake, body weight, organ weight and lipid levels of serum, liver and feces were measured. There was no significant difference in diet intake, body weight and organ weight among the experimental groups. But the concentrations of serum triglyceride in the LRGO and RGO groups, and of serum total cholesterol in the RGO group, were significantly lower than those of the L group fed the 20% lard diet. The levels of hepatic total lipid of the RGO group, and of hepatic total cholesterol of the LRGO and RGO groups were significantly lower than those of the L group. The contents of total lipid and total cholesterol excreted in the feces of the LRGO and RGO groups were higher than those of the L group. These results suggest that rice germ oil can reduce the levels of total cholesterol concentrations in the serum or livers of insulin-dependent diabetic mice, and that the hypolipidemic effect of rice germ oil may be due to increasing fecal lipid excretion and decreasing lipid absorptivity.