17 Dachang Wu Ming Zhong Sun Cuili Zhang Yi Xin Journal of Animal and Plant Sciences JAPS 20142014/12/01 24 6 1766-1771 1018-7081 NA <p>This study was designed to analyse the antioxidant capacity of lactic acid bacteria (LAB) in order to&nbsp;<a id="OLE_LINK55" name="OLE_LINK55"></a><a id="OLE_LINK54" name="OLE_LINK54"></a>provide characteristic parameters and theoretical basis for its further utilization as a natural antioxidant. Further experiment was carried out to study its protection mechanism through oxidative stress Caco-2 cell model in vitro. For this purpose, antioxidative activity of cells and different cellular fractions&nbsp;<em>of&nbsp;<a id="OLE_LINK19" name="OLE_LINK19"></a><a id="OLE_LINK18" name="OLE_LINK18"></a>Lactobacillus delbrueckii</em>&nbsp;(ATCC7830) was evaluated by scavenging capacity of superoxide anion free radicals (SAFR)，reducing power and total antioxidant capacity assay. Low dose of H2O2 (100&mu;mol/L) was used to establish oxidative damaged model on Caco-2 cells, the bacteria&rsquo;s protecting effect on the damaged cells was further researched. The results showed that extracellular secretions of&nbsp;<em>Lactobacillus delbrueckii&nbsp;</em>has the strongest antioxidant activity, following by cells, and cells can clear superoxide radicals. The ability to scavenge SAFR of this LAB was (42.4&plusmn;0.32) % (cell lysates, the highest), the reducing power was (3.01&plusmn;0.20, cell extracellular secretions, the highest), and the total antioxidant ability was (4.32&plusmn;0.36, cell extracellular secretions, the highest). The above antioxidative character made this LAB possible to protect Caco-2 cells being damaged by low dose of H2O2. Further analysis showed that the total antioxidant capacity (T-AOC) of culture supernatant and lysate were significantly increased compared with the negative control group and the oxidative stress group (<em>p</em>&lt;0.01). Also increased the anti-superoxide anion (O2-) free radicals (<em>p</em>&lt;0.01) level. All the results indicate that<a id="OLE_LINK25" name="OLE_LINK25"></a><a id="OLE_LINK24" name="OLE_LINK24"></a>&nbsp;different fractions from lactic acid bacteria have various capabilities on reducing power, scavenging superoxide anion free radicals ability and total antioxidant capacity. Extracellular secretions have the most obvious antioxidant character.&nbsp;<em>Lactobacillus delbrueckii</em> could protect Caco-2 cells under oxidative stress by increasing its antioxidative function in vitro.</p> Antioxdiative, Lactobacillus, oxidative stress, Caco-2 cell, in vitro Pakistan Agricultural Scientists Forum https://thejaps.org.pk/AbstractView.aspx?mid=2014-JAPS-253