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The bioavailability of beta-carotene from cassava (Manihot esculenta Crantz) leaves was assayed in vitamin A deficient Wistar rats (Rattus norvegicus). Rats were separated into three groups and fed with a modified AIN-93G--vitamin A deficient--diet. Deficient rat received this diet without any additional vitamin A source. Controls received the diet with 7200 microg of synthetic beta-carotene (control), while experimentals (test) received 19.5 g of cassava leaves powder per kg of diet. The cassava leaves with beta-carotene promotes similar growth and tissue weight in rats to the synthetic beta-carotene. The relative bioavailability, estimated as the Retinol Accumulation Factor (RAF), was 16.5 and 27.5 for control and test groups, respectively, indicating that control and test rats should have an intake of 16.5 microg or 27.5 microg of beta-carotene from synthetic form or cassava leaves powder for each 1 microg of hepatic retinol stored, respectively. The cassava leaves beta-carotene bioavailability was lower than the synthetic beta-carotene probably because the beta-carotene from the leaf matrix may be bounded to protein complex or inside organelles, which impair carotenoid absorption. Our findings showed that beside the hepatic retinol recovery, cassava leaf beta-carotene could maintain rat growth and avoid vitamin A deficient symptoms.

One of the major dietary sources of vitamin A in the human diet is provitamin A carotenoids. However, the activity of these carotenoids as a vitamin A source is uncertain due to concerns about the bioavailability of the carotenoids from vegetables. This study evaluated the bioavailability of provitamin A carotenoids from native Brazilian dark-green vegetables. Vitamin A–depleted rats were fed a basal diet (AIN-93G) in which the synthetic vitamin A content was replaced by non conventional leaves. At the end of the 30 day-repletion period, 1 μg of retinol accumulated in the liver after the intake of 43.1, 95.3 or 178.9 μg β-carotene from Sonchus oleraceus (So) , Amaranthus viridis (Av) and Xanthosoma sagittifolium (Xs) leaves, respectively. The relative bioavailability of β-carotene from the leaves was 36 %, 16%, and 9% for So, Av, and Xs leaf, respectively. The results showed that the carotenoids from the three dark-green leaves were absorbed, converted to retinol, and stored in the liver of rats. Because they are pest-resistant and widely distributed vegetables, they may be an inexpensive alternative source of vitamin A to reduce vitamin A deficiency.

Schizolobium parahyba chymotrypsin inhibitor (SPCI) was completely purified as a single polypeptide chain with two disulfide bonds, by TCA precipitation and ion exchange chromatography. This purification method is faster and more efficient than that previously reported: SPCI is stable from pH 2 to 12 at 25 degrees C, and is highly specific for chymotrypsin at pH 7-12. It weakly inhibits elastase and has no significant inhibitory effect against trypsin and alpha-amylase. SPCI is a thermostable protein and resists thermolysin digestion up to 70 degrees C.

Non-governmental organizations (NGOs) in Brazil have used an alternative diet supplement known as multimixture (MM) composed of bran cereals, cassava leaf powder and eggshell powder. This study investigated the effectiveness of this MM supplement used concomitantly with other actions to improve children’s health. Thirty-one students enrolled in a rural school were examined for anthropometric and hematologic measures before and after the consumption of diet supplemented with MM. The results were compared with those from control group (n = 26) who consumed the same diet without MM. At the end of the study, the NGO intervention provided a beneficial effect on the nutritional status of children, since it improved their blood parameters and reduced the anemia independently of MM supplementation. The average height/age was significantly higher only in the group that received MM. The supplementation of the deficient diets with MM contributed significantly to the improvement of the children’s stature.

A mixture of bran cereals, cassava leaf and eggshell powder has been used as an alternative diet supplement to fight malnutrition in low-income communities in Brazil. Due to the high phytic acid content there are some concerns about the bioavailability of nutrients in this mixture (MM). This study investigated the effect of dietary concentrations of protein and NaCl on the bioavailability of MM calcium and phosphorus. Undernourished rats were given deficient diet supplemented with MM, with or without the addition of protein and NaCl. Calcium and phosphorus were found to be bioavailable, since rats fed MM supplemented diet showed higher femur calcium and phosphorus contents than did deficient rats (P

Laser Raman and Fourier transform infrared spectroscopies were applied in the investigation of conformational features of a chymotrypsin inhibitor (SPC), inactive on trypsin, isolated from Schizolobium parahyba, a Leguminosae of the Cesalpinoidae family, found in tropical and subtropical regions. As a serine protease inhibitor, its importance is related to the control of proteolytic activity, which in turn is involved in a wide range of critically important biotechnological issues, such as blood coagulation, tumour cell growth, and plant natural defences against predators. SPC is a 20 kDa molecular mass monomeric protein, with two disulfide bonds. Its complete aminoacid primary sequence has not yet been determined. We analysed protein backbone conformation for the lyophylized solid and for an evaporated film, through Raman scattering and FTIR, respectively. The presence of significant amounts of disordered structures and of non-negligible contributions from α -helical and β -sheet structures were reckoned in both cases. The geometries of the disulfide bonds were defined: a gauche - gauche - gauche geometry was verified for one of the two bridges and a transient gauche - gauche - trans / trans - gauche - trans geometry has been indicated for the second one.Two out of the three tyrosine residues were shown to be in external location in the solid protein, as well as the only tryptophan residue.