Regulating activities of α-amylase and α-glucosidase through the use of specific inhibitors is a main strategy for controlling type 2 diabetes. Smilax aristolochiifolia root decoctions are traditionally used in Mexico as hypoglycemic and for weight loss, but the active principles and mechanisms underlying such putative metabolic effects are yet unknown. Here, we isolated the major bioactive compounds from a hydroethanolic extract of S. aristolochiifolia root by fast centrifugal partition chromatography and evaluated their effects against pancreatic α-amylase and yeast α-glucosidase. A chlorogenic acid-rich fraction (CAF) inhibited α-amylase activity with an IC50 value of 59.28 μg/mL in an uncompetitive manner and α-glucosidase activity with an IC50 value of 9.27 μg/mL in a noncompetitive mode. Also, an astilbin-rich fraction (ABF) inhibited α-glucosidase activity with an IC50 value of 12.30 μg/mL, in a noncompetitive manner. CAF inhibition α-amylase was as active as acarbose while both CAF and ABF were 50-fold more potent inhibitors of α-glucosidase than acarbose. The molecular docking results of chlorogenic acid and astilbin with α-amylase and α-glucosidase enzymes correlated with the inhibition mechanisms suggested by enzymatic assays. Our results prove that S. aristolochiifolia roots contain chlorogenic acid and astilbin, which inhibit carbohydrates-hydrolyzing enzymes, suggesting a new mechanism for the hypoglycemic effect reported for this plant.

Recibido: 28 de noviembre de 2012 Aceptado: 17 de enero de 2013 RESUMEN Los desechos que se tienen de la obtención de jugos son principalmente cáscara y bagazo, sin embargo son una buena fuente de compuestos fenólicos, mayoritariamente de flavonoides. El objetivo de este trabajo fue extraer y cuantificar el contenido fenólico de la cáscara de lima, así como su actividad antioxidante. Esto se determinó evaluando el mejor sistema de extracción de compuestos fenólicos y flavonoides, teniendo como variables: tipo de solvente (metanol, acetona y hexano) y tamaño de partícula (tamiz 20 (T1) y 50 (T2)). La determinación de la actividad antioxidante se realizó mediante dos métodos ABTS •+ y DPPH•, comparando la efectividad entre ellos. El mejor modelo de extracción de los compuestos fenólicos y flavonoides fue utilizando metanol como solvente y un tamaño de partícula pequeño (300 μm). El valor más alto de actividad antioxidante (91,69 %) se obtuvo con el método ABTS •+ , en los extractos con metanol y acetona, sin diferencias entre los tamices utilizados. La cáscara de lima tiene 8,79 mg EAG/g ms y 14,325 mg quercetina/g ms. La utilización de cáscara de lima representa una alternativa para el aprovechamiento de biocompuestos, que son considerados como sustitutos de los antioxidantes sintéticos existentes. Palabras clave: flavonoides, cáscara de lima, actividad antioxidante.

The aim of this study was to assess the ability of the biotransformation of hesperidin from lime peel by Aspergillus saitoi in solid fermentation. The decrease of hesperidin by High-Performance Liquid Chromatography (HPLC) was monitored during 8 days of fermentation. The radical scavenging activity of DPPH · and ABTS ·+ increased to 5.8 and 11 times, respectively, after 6 days of fermentation compared with unfermented lime peel. Similarly, the phenolic content of the extract of fermented lime peel was 8.66 times higher than unfermented lime peel, while flavonoids increased 5.14 times. After 6 days of fermentation, A. saitoi biotransformed hesperidin from lime peels and increased its antioxidant activity. These results provide important information concerning the potential of the solid fermentation in the citrus industry waste through the biotransformation of flavonoids, which provides an effective solution for modifying the flavonoid structure and improving their initial bioactivity.