Maria Aparecida Costa

Degradação de ametrina em areia quartzosa com adição de solo rizosférico de cana-de-açúcar

Utilizando amostras de Areia Quartzosa esterilizada, nao esterilizada e com adicao de 10% de solo da rizosfera de cana-de-acucar cultivada em campo, na presenca e na ausencia do herbicida ametrina, a biodegradacao de 14C-ametrina foi avaliada juntamente com a quantidade de residuos extraiveis, nao-extraiveis e numero de microrganismos presentes. A taxa de desprendimento de 14CO2 aumentou em 3,5 vezes, com adicao de solo rizosferico de culturas previamente tratadas com o herbicida, em 1,7 vez, com a adicao de solo de rizosfera de culturas nao tratadas. A presenca de metabolitos detectada por cromatografia de camada delgada revela a maior degradacao nas amostras que tiveram a adicao de solo rizosferico. A microbiota presente na rizosfera ocasionou maior mineralizacao do herbicida ametrina.

Biodisponibilidade do beta-caroteno da folha desidratada de mandioca (Manihot esculenta Crantz)

The biological availability of b-carotene in cassava leaves (Manihot esculenta Crantz), was verified by means of an assay based on the hepatic depletion of vitamin A reserves model in rats. Rats depleted of hepatic vitamin A received dehydrated cassava leaves as b-carotene source for 25 days and were compared to groups that received diets with vitamin A, b-carotene and without vitamin A. The Zero group was formed of 8 animals that received a diet based on casein, lacking vitamin A, during 15 days. At the end of the experiment, all animals were killed and their livers, serum and feces were analyzed by high performance liquid chromatography (HPLC), and it was verified that the bioavailability of b-carotene of dehydrated cassava leaves was lower.

Alterações estruturais in vivo dos isômeros todo-trans, 9-cis e 13-cis do beta-caroteno

A biological assay was conducted in order to verify the possible structural interconversion of the 9-cis, 13-cis and all-trans b-carotene isomers. The different b-carotene isomers (either all-trans b-carotene, 9-cis b-carotene or 13-cis b-carotene) were administered for fifteen days to rats that had been previously depleted of liver carotenoids. It was possible to verify the in vivo re-isomerization of the isomers. The 9-cis b-carotene isomer can be converted into all-trans b-carotene, the latter re-isomerized into 9-cis b-carotene, and the 13-cis b-carotene modified into 9-cis b-carotene and all-trans b-carotene. From these results it can be concluded that the 13-cis isomer was more susceptible to isomerization than was the 9-cis b-carotene, because the latter could be isomerized into all-trans, but not into 13-cis b-carotene, while the 13-cis can be either modified to 9-cis or to all-trans b-carotene.