Abstract:

Objective: The antioxidant activity of Lactobacillus plantarum NDC75017 isolated from traditional yoghurt was
investigated in different systems. Methods: Free radical-scavenging ability, total antioxidant capacity (T-AOC), glutathione
peroxidase (GSH-Px) activity, total superoxide dismutase (T-SOD) activity, reducing power, and metal ion chelating
capability were determined in the intact cells, cell-free extract, extracellular secretion, and inactive cells. Results: The
strain had resistance to hydrogen peroxide, the cell-free extract indicated the strongest superoxide anion and DPPH radical
scavenging capacity, and the extracellular secretion showed the best hydroxyl radical scavenging capacity. Both the latter
two samples exhibited the most potent T-AOC (P ＜ 0.05), showing a significant difference from two other samples. The
extracellular secretion displayed the highest GSH-Px and T-SOD enzyme activities, significantly higher than those of the cell
free extract and inactive cell groups (P ＜ 0.05). All these four samples possessed reducing power and metal ion chelating
capability, more effective for Fe2+ than Cu2+. Conclusion: Lactobacillus plantarum NDC75017 has good antioxidant activity
as a metal ion chelator, electron provider, and radical stabilizer for inhibiting oxidation.

Key words: Lactobacillus plantarum NDC75017, antioxidant activity, action mechanism