Propriedades imunestimulatorias e antitumoral de concentrados proteicos de soro de leite bovino, de caseina e de um isolado proteico de soja. / Antitumoral and imunostimulating properties of bovine milk whey proteics concentrates, of casein and a soy protein isolated.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The objective of the present work was the investigation of immunomodulation and anticancer properties presented by bovine milk proteins with special attention to the whey proteins, in the form of whey protein concentrate (WPC). For such a task, adequate methodology was established for the production of concentrates of caseins and whey proteins, which permitted maximum preservation of their structural and functional properties. The protein concentrates produced were characterized for percentual components composition and their amino acid profiles. For the obtention of sodium caseinate (NaC) and of acid whey protein concentrate (aWPC) precipitation of casein at the isoeletric pH (pH 4.6, 20°C) was used. The acidic whey was concentrated by ultrafiltration/diafiltration and liophilization to obtain the WPC. The caseinate was obtained by neutralization of the isoeletric casein clot with sodium hydroxide solution, then dehydrated in spray dryer. Coagulated casein (CoC) and the "sweet" whey were obtained by treating defatted and pasteurized milk (72°C , 20 sec) with commercial preparation of coagulum (Há-La, Chr Hansen Brasil) containing chymosin, for approximately 45 min at 34°C. Coagulum and ?sweet? whey were separated by filtration. The coagulum was washed several times with water, homogenized (hammer mill and colloidal mill), neutralized and the suspension was spray dried. The whey was concentrated by ultrafiltration, submitted to diafiltration, freeze-dried and lyophilized. Whey protein concentrates (WPC) containing 80-85% protein was obtained with minimum denaturation of the most labile proteins. Protein denaturation was monitored by solubility tests in aqueous solutions at pH 4.6. Immunomodulating activity of the WPC was monitored by the plaque forming cells method (PFC), according to modification of Cunningham and Szenberg (1968) procedure. Isogenic male mice of the A/J line (6-8 weeks of age) were used in the tests. The test measures humoral or primary immune response by the spleen cells. The technique was standardized and the PFC counting was done in spleen cells suspension five days after immunization when the immune response was at maximum. PFC tests were performed for each lot of WPC produced. The immunomodulating and anticancer properties of WPC and WPI (IM) from cows milk were studied in comparison with casein and soy protein isolate, commercial preparations. One hundred and thirty two A/J female mice were used in the experiments, 33 for each treatment. They were maintained in isolators and fed diets containing 20% to protein and 15% lipids (corn oil, lard and cocoa fat), modified according to AIN-76 (1977), during 32 weeks. The following protein sources were utilized: whey protein concentrate (WPC), ImmunocalTM (IM), commercial casein (CC) and soy protein isolate (SPI). After 4 weeks on the diets the animals were subcutaneously injected with azoxymethane (5mg/kg bw) for 6 consecutive weeks, for colon cancer induction. The animals were sacrificed at 3 different time intervals, when spleen immune response (PFC), liver glutathione concentration, monitoring of carcinogenesis (aberrant crypt foci, ACF), quantification and histological analysis of colon tumors were evaluated. No statistical differences were found in body weight gain among treatments. A strong positive correlation was found between liver glutathione concentration and antibody producing cells in the spleen (PFC), r=0.998, r=0.995, after 4 weeks and 32 weeks, respectively, ther beginning the experiment. The largest number of tumors was found in the animals fed the SPI diet (18.20 ± 5.46), compared to CC (14.33 ± 3.43) and the groups fed WPC and IM, respectively 9.33 ± 2.96 and 8.56 ± 3.09. No statistical difference was found between WPC and IM and both were superior and statistically different from CC and SPI. It suggested that whatever the mechanisms may be, the milk protein, in special the whey proteins protected the intestinal tissue against specific carcinogen for colon cancer in mice.

ASSUNTO(S)

soro do leite celulas camundongos milk whey mice cells

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