[Action of soluble carbohydrates from avocado (Persea gratissima Gaertner) fruit on utilization of calcium in the rat].

Abstract

Ethanolic extract containing soluble sugars was prepared from avocados (variety americana) coming from Madagascar. In this extract, thin layer and paper chromatography showed the presence of a ketoheptose, the mannoheptulose, in amount of 0.1 g/ml extract or 1.1 g/100 g fresh pulp. Physiological experiments were performed with avocado extract and comparatively with a sample of commercial mannoheptulose. Six-month-old rats were given by stomach tube 10 mM CaCl2 solution (+ 45Ca) containing a carbohydrate. Depending on the group, the carbohydrate was 20 and 100 mM glucose (control), D-mannoheptulose 200, 100, 50 and 25 mM, avocado extract concentrated or diluted 1/2, 1/4, 1/8, 1/16. Blood samples were taken at different times after the administration and plasma radioactivity was measured. Rats were sacrificed at 24 hours; femur and axis radioactivity was used as a measure of calcium absorption. Both mannoheptulose and avocado extract were potent on calcium absorption. This absorption increased progressively with sugar concentration, in mannoheptulose and avocado groups. The interpretation of these results was discussed and also their application to the Nutrition in tropical and subtropical countries.