Biological activity of soymilk fermented with Lactobacillus rhamnosus CRL 981

MARAZZA, J.; LEBLANC, JG.; SAVOY DE GIORI G.; GARRO M.,

Clermont-Ferrand

Congreso; 18ème Colloque du Club des Bactéries Lactiques; 2012

18ème Colloque du Club des Bactéries Lactiques

Interest in soybeans and soy-based products has grown significantly in the last decade due to their reported nutritional and health-promoting benefits. Researchers have credited phytochemicals in soybeans, especially isoflavones, for some of these beneficial health effects. Soy isoflavones are reported to play a role in the prevention of osteoporosis, cardiovascular disease, and several hormone dependent cancers. In soybean and soy derived products (non-fermented soy foods) isoflavones are predominantly found as glucosides. In order to exert a biological effect, isoflavone glucosides must be hydrolyzed by either intestinal mucosal or bacterial beta-glycosidase releasing the aglycones. Several studies have demonstrated that lactic acid bacteria with β-glucosidase activity are able to increase the aglycone content during soymilk fermentation. Previously we have shown that Lactobacillus (L.) rhamnosus CRL981 was able to proliferate in soymilk and produce a high beta-glucosidase activity achieving a complete hydrolysis of glucoside isoflavones after 12 h of fermentation.The objective of this study was to evaluate the biological activity of soymilk fermented with this lactic acid bacterium using a diabetes animal model. In order to induce diabetes, Balb/c mice were induced with an intraperitoneal injection of streptozotocin (STZ). The STZ induced animals then received unfermented soymilk or soymilk fermented with L. rhamnosus CRL981, others received a conventional diet (STZ positive control). A non STZ treated group of animals was also included (negative control).The administration of soymilk fermented with L. rhamnosus CRL981 was able to reduce the glucose levels of the diabetic mice by 40.2 % and of glycosylated hemoglobin by 23.6 % which could prevent cardiopathologies (micro and macro-vascular) associated to diabetes. This same fermented milk was also able to reduce the total cholesterol concentrations and triglycerides by 20.7 and 30.1 % respectively. Also, a decrease in LDL cholesterol was observed in the animals that received this soy product. The oxidative state of the STZ induced animals that received the L. rhamnosus CRL981 fermented soymilk, as shown by significant increases in catalase and superoxide dismutase activities (111.1 and 78.2 % respectively) was also improved.The results of this study clearly show that soymilk fermented with L. rhamnosus CRL981 was able to improve the health status of diabetic animals. This effect would be principally due to the capacity of this strain to increase the aglyconated isoflavones in soymilk due to is high beta-glycosidase activity.