RESUMEN
Calotropis procera (Aiton) W.T.Aiton,Apocynaceae, popularly known as "algodão-de-seda", is a wild African bush, rich in bioactive substances that determine the medicinal potential of this species. Diabetes mellitus is a disease that affects about 10% of the population. This study aimed to evaluate the antihyperglycaemic activity of the hydroalcoholic extract of the leaves of C. procera of occurrence in coast of Pernambuco, Brazil. The hydroalcholic extract of the leaves of C. procera (300 and 600 mg/kg/day), vehicle, insulin (6U, s.c.) or metformin (500 mg/ kg/day) were administered orally to streptozotocin-induced diabetic rats (n = 7/group) for four weeks. Changes in body weight, food and water intake, biochemical markers, fasting glucose levels and oral glucose tolerance test were evaluated. The results showed that the C. procera dried extract (300 and 600 mg/kg) reduced significantly the level of blood glucose throughout the evaluation period and improved metabolic status of the animals and ameliorate the oral tolerance glucose test. The phytochemical screening revealed and quantified the presence of phenolic compounds and flavonoids in a percentage of 29.1 and 2.9%, respectively. Thus, we conclude that the extract of the leaves of C. procera has antihyperglycemic activity.
RESUMEN
The effects of the contents and chemical composition of the foliar epicuticular waxes of species from the caatinga (Aspidosperma pyrifolium, Capparis yco, Maytenus rigida and Ziziphus joazeiro) and cerrado (Aristolochia esperanzae, Didymopanax vinosum, Strychnos pseudoquina and Tocoyena formosa) were evaluated as to the resistance to water loss by means of an experimental device constructed for this purpose. In general, the waxes of the caatinga species investigated were more efficient against water loss than cerrado species. Increase of the thickness of the waxy deposits from 40 to 90m g.cm-2 had no significant effect on the resistance to water loss. The chemistry of the wax constituents was shown to be an important factor to determine the degree of resistance to evaporation. n-Alkanes and alcoholic triterpenes were the most efficient barriers, while hentriacontan-16-one (a ketone) and ursolic acid (an acid triterpene) revealed lowefficiency. The higher efficiency of the waxes of the leaves from caatinga species (mainly those of C. yco and Z. joazeiro) is probably accounted for the predominance of n-alkanes in their composition. The lower efficiency of the waxes of A. pyrifolium (caatinga), T. formosa and A. esperanzae (both species from the cerrado) is probably a consequence of the predominance of triterpenoids in the waxes of the two former species and hentriacontan-16-one in the latter