A purified extract from prickly pear cactus (Opuntia fuliginosa) controls experimentally induced diabetes in rats.

The hypoglycemic activity of a purified extract from prickly pear cactus (Opuntia fuliginosa) was evaluated on STZ-induced diabetic rats. Blood glucose and glycated hemoglobin levels were reduced to normal values by a combined treatment of insulin and Opuntia extract. When insulin was withdrawn from the combined treatment, the prickly pear extract alone maintained normoglycemic state in the diabetic rats. The blood glucose response to administered glucose also showed that the rats receiving the combination treatment of insulin and Opuntia extract for 7 weeks followed by Opuntia extract alone were capable of rapidly returning blood glucose to the levels of the nondiabetic rats. Although the mechanism of action is unknown, the magnitude of the glucose control by the small amount of Opuntia extract required (1 mg/kg body weight per day) preclude a predominant role for dietary fiber. These very encouraging results for diabetes control by the purified extract of this Opuntia cactus make the need for clinical studies in humans evident.

[Elimination of toxic compounds, biological evaluation and partial characterization of the protein from jojoba meal (Simmondsia chinensis [Link] Schneider]. / Eliminación de compuestos tóxicos, evaluación biológica y caracterización parcial de la proteína de pasta de jojoba (Simmondsia chinensis [Link] Schneider).

The purpose of this study was to establish a new methodology to remove the toxic compounds present in jojoba meal and flour. Also, to perform the biological evaluation of the detoxified products and to chemically characterize the protein fractions. Jojoba meal and seed without testa were deffated with hexane and detoxified with a 7:3 isopropanol-water mixture which removed 86% of total phenolic compounds and 100% of simmondsins originally present, the resulting products had reduced bitterness and caused no deaths on experimental animals. NPR values obtained for diets containing such products were significantly different from those obtained with the casein control (p less than 0.05). Total protein was made up of three different fractions: the water-soluble fraction was the most abundant (61.8%), followed by the salt-soluble (23.6%), and the alkaline soluble fraction (14.6%). The nitrogen solubility curves showed that the isoelectric point for the water-soluble and salt-soluble fractions was pH 3.0, while that of the alkaline fraction fell in the range of 4.5-5.0. All fractions had a maximum solubility at pH 7.0. The methodology reported here, offers a viable solution to eliminate toxic compounds from jojoba meal or seeds, and upgrades the potential use of products such as animal feed or raw material for the production of protein isolates.

[Isolation and partial characterization of phenoloxidase from apples (Malus domestica, var. Anna)]. / Aislamiento y caracterización parcial de la enzima fenoloxidasa de manzana (Malus domestica, var. Anna).

This study pursued the isolation and partial characterization of the enzyme polyphenoloxidase from apple (Malus domestica Anna variety), grown in the Hermosillo Coast (State of Sonora, Mexico). The effects of pH and temperature as well as its specificity towards substrates, and its behavior under conditions of hydrophobic chromatography, were studied. The enzyme was isolated from a residual powder obtained from ripe apples homogenized with cold acetone. The extract thus prepared was used to characterize the enzyme, and it showed an optimum pH of 5.36 and an optimum temperature of 35 degrees C. The substrate specificity proved to decrease from 4-methyl catechol, chlorogenic acid, catechol, and caffeic acid, to 3,4-dihydroxiphenyl alanine (DOPA). The enzyme resulted to be more thermostable (temperature range: 35 degrees C to 60 degrees C) than the rest of oxidases of plant origin. When the extract was eluted under conditions of hydrophobic chromatography separation, it appeared as a single peak resulting in a 300 fold purification. The phenolase activity characteristics found in the present study were similar to those observed in other apples from temperate climates; however, this particular polyphenoloxidase is more thermostable under natural conditions. This explains why apples of the Anna variety, at the high harvesting temperature, show a very fast formation of brown spots even when there is a minor damage. The content of compounds with phenolic group was high (1.16 g/100 g fresh weight). Further increase of the velocity of fruit enzymatic browning was due to this reason.