EVALUATION OF ANTIRADICAL CAPACITY OF FERULOYL ESTERASE- PRODUCING Lactobacillus STRAINS AND MAINTENANCE OF ENZYMATIC ACTIVITY AFTER EXPOSURE TO GASTROINTESTINAL TRACT CONDITIONS

RUSSO, MATIAS IRINEO; ABEIJON MUKDSI, MARIA CLAUDIA; PEREZ CHAIA, ADRIANA; GAUFFIN CANO, MARIA PAOLA; MEDINA, ROXANA BEATRIZ

Tucumán

Congreso; XII Congreso Argentino de Microbiología General; 2017

Sociedad Argentina de Microbiología General (SAMIGE)

Feruloyl esterases (FE) are enzymes that catalyze the hydrolytic release of ferulic acid (FA), present in vegetable foods. FA is a phenolic acid with proven antioxidant properties. Lactobacillus fermentum CRL1446 (Lf), Lactobacillus johnsonii CRL1231 (Lj) and Lactobacillus acidophilus CRL1014 (La) are potential probiotic strains selected for their FE activity capable of releasing FA in vitro. The aim of the present work was to evaluate the antioxidant capacity of these FE-producing strains and the maintenance of FE activity after exposure to gastrointestinal tract (GIT) conditions. The antioxidant capacity was determined based on the antiradical activity against the synthetic radical DPPH (1, 1-diphenyl-2-picrylhydrazyl), which was evidenced by decrease of the absorbance at 517 nm. Supernatants and cell suspensions obtained from cultures in MRS and MRS medium supplemented with ethyl ferulate (EF) were incubated in presence of methanolic solution of DPPH (0.1 mM). After 30 minutes of incubation (darkness, room temperature), samples were centrifuged (6000 rpm, 10 min) and then the absorbance was measured at 517 nm. To evaluate the maintenance of FE activity after exposure to GIT conditions, cell suspensions were transferred to simulated gastric juices at pH 3 and 4. Samples were incubated at 37°C and harvested by centrifugation after 2h. Subsequently, cells were resuspended in simulated intestinal juice and further incubated 2h at 37°C. The samples were then centrifuged and the pellets were washed twice and resuspended in PBS pH 7. FE activity was determined using 1 mM methyl ferulate as substrate. Released FA was detected by HPLC. Supernatants showed radical capture percentages between 82-89%, being slightly higher in samples from MRS supplemented with EF, indicating that the presence of free FA as a product of hydrolysis of EF is partly responsible for the higher antioxidant capacity of these samples. With regard to cell suspensions, no significant differences were observed between the antiradical activity of cells grown in the absence and presence of EF. In both cases, the antiradical activity showed the following order: Lf> Lj> La. Among the three strains evaluated, Lf showed the highest maintenance of FE activity after GIT exposure (65 and 50% at pH 3 and 4, respectively). These in vitro results validate the use of L. fermentum CRL1446 as an oral probiotic with antioxidant properties that could be able to protect against oxidative stress.