Hemato-biochemical parameters in rats fed Lupinus angustifolius L. (sweet lupin) seed protein and fiber fractions

The effects of Lupinus angustifolius L. (sweet lupin), cv. Unicrop seed meal and five of its fractions on different parameters of blood, plasma/serum and liver were studied in two experiments. Groups of four growing rats were pair-fed for 10 days on diets that contained the same amounts of energy and protein and were supplemented with amino acids and minerals to target requirements for growing rats. In addition to the lactalbumin (LACT) and raw lupin seed meal, which was fully supplemented (LMFS), five fractions were tested: four protein fractions (aqueous fractions that were soluble [LPAD] and insoluble [LPADI] after dialysis at pH 7.0, and phosphate-citrate buffer extracted ones that were soluble [BUSOL] and insoluble [BUDI] after dialysis at pH 7.0) and dialyzed residue (LMR) containing the material from the meal insoluble in water and buffer. The cellular components and parameters of blood plasma and serum were subjected to detailed studies. Cellular elements were, in fact, little affected by the seed meal and its fractions when compared with those obtained from the control. Significant changes, however, were found in plasma urea (p<0.05), albumin (p<0.05), alkaline phosphatase (p<0.05), total cholesterol (p<0.01) triglycerides, and liver lipid and cholesterol. A significant lowering effect on total plasma cholesterol was observed in growing rats fed the seed meal and its fractions compared with that value obtained from the lactalbumin control. The buffer-dialyzed insoluble (BUDI) fraction, which resembled γ-conglutin and was found to be in an almost pure form, lowered total plasma cholesterol by 34% compared with that value for the lactalbumin fed group. Liver lipid and cholesterol were also found to be decreased in rats fed L. angustifolius seed meal and its fractions. The observed hypocholesterolemic effects were greater than any values previously reported for such a short feeding period. The underlying mechanism(s) of the cholesterol lowering effects is not clear. However, the disproportionate value for arginine: lysine and/or cystine: methionine in the proteins may be a modulating factor(s). In addition, other biochemical changes were dependent on the involvement of general N metabolism and/or parenchymatous degeneration of the liver tissues by some unknown modulating factor.