IN VITRO ANTI-RADICAL ACTIVITY OF BIFIDOBACTERIUM BIFIDUM AND LACTOBACILLUS REUTERI CELL-FREE EXTRACTS

Probiotic microorganisms are known to be able to exhibit antioxidant activity. Most of beneficial probiotics effects are due to the action of their derivatives (structural components and metabolites). The aim of the work was to investigate the antiradical activity of cell-free extracts containing bacterial derivatives of Bifidobacterium bifidum 1 and Lactobacillus reuteri DSM 17938 probiotic strains, by their hydroxyl radical scavenging activity in the model system of their generation. Cell-free extracts were obtained from disintegrators and cultures of probiotic bacteria cultured in the disintegrators of their own cells. A metabiotic HYLAK FORTE was chosen as the reference drug. At a concentration 20% vol. in the incubation medium the hydroxyl radical scavenging by L. reuteri cell-free extracts was at a level of 75–90 %, and the hydroxyl radical scavenging by B. bifidum cell-free extracts was at a level of 50–60%. The metabiotic provided the same level of the hydroxyl radical scavenging activity when its content in the incubation medium was lower in 1.5 – 2.5 times. Extracts obtained from disintegrators showed a more pronounced antiradical activity than extracts from probiotic cultures. Based on the weight of the dry residue, concentrations for 50% hydroxyl radical scavenging (ІС50) by extracts and metabiotic were calculated. According to this indicator, L. reuteri extract obtained from disintegrate was the most effective (IC50 = 1.57 mg/ml). Other investigated derivative-containing products were arranged in decreasing order of antiradical activity as follows: B. bifidum extract from disintegrate (IC50 = 1, 64 mg/ml) > B. bifidum extract from culture (IC50 = 1, 75 mg/ml) > L. reuteri extract from culture (IC50 = 1, 86 mg/ml) > HYLAK FORTE (IC50 = 11, 03 mg/ml). Thus, all the studied extracts showed antiradical activity with respect to the most reactive hydroxyl radical. The obtained results encourage further study of the antioxidant properties of L. reuteri and B. bifidum cell-free extracts in order to elucidate the mechanisms of their biological activity and justify the appropriateness of their therapeutic use.