CONICET | Buscador de Institutos y Recursos Humanos

The search natural alternatives that improve human health is a subject of great interest nowadays. It is accepted that food proteins may act as precursors of biologically active peptides with different physiological effects, such as antihypertensive and antioxidant activities. Antihypertensive activity is mediated by inhibition of angiotensin-converting enzyme (ACE) and antioxidant, by the uptake of free radicals and active oxygen species. Oenococcus oeni X2L isolated from argentinean wine produces and releases an exoprotease that acts on nitrogenous macromolecular fraction (NMF) of red wines. The aim of the present work was to study the ACE-inhibitory (I-ACE) and antioxidant activities of NMF of red wine treated with the O. oeni exoprotease. Also, the potentiation by phenolic compounds was evaluated. O. oeni was grown in grape juice basal medium pH 4.8. Cell from exponential growth phase was starved by resuspension in citrate buffer for 2h at 20 °C and the supernatant was used as O. oeni protease source. NMF or the same fraction clarified with active charcoal to eliminate phenolic compounds (CNMF), were treated with O. oeni exoprotease during 60 min at 30°C. I-ACE activity percentage of each sample was measured by Cushman and Cheung method and total antioxidant capacity was evaluated by two methods, ferric reducing/antioxidant power (FRAP) and DPPH radical scavenging activity. Amino acid and peptide concentrations of samples were measured by Doi method. The NMF and CNMF showed an I-ACE activity percentage of 50.53 and 37.5 % and after treatment of both fractions with O. oeni supernatant the values increased to 65.8 and 54.3%, respectively. The ferric reducing power of NMF and CNMF without exoprotease treatment were 882.0 and 91.25 µM/l FeSO4, respectively. This activity was higher after the enzyme action (1,481 and 415 µM/l FeSO4 to NMF and CNMF, respectively). Also, DPPH radical scavenging activity showed that the greatest activity was found with NMF (87.12%) and CNMF (73.2%) after the exoprotease treatment. The higher I-ACE and antioxidant activities observed in NMF and CNMF treated with O. oeni exoprotease could be related to a significant increase in the peptide concentrations observed in trials performed with bacteria supernatant. Differences in biological activity between the two macromolecular fractions would be correlated to the lowest concentration of phenolic compounds remaining after clarification (784.8 and 245.4 mEq GAE/l to NMF and CNMF, respectively). Therefore, the phenolic compounds were involved to improving the activities studied.