Table 1.
Lactic acid bacteria used in this study.
Fig 1.
DPPH and HRS activities of the CFSs (mean ± SD, n = 3).
MRS broth control sample without Lactobacillus. The letters a, b, c, d, and e indicate statistically significant difference at p < 0.05 within each row comparison between the DPPH radical scavenging groups. The letters a’, b’, c’, d’, and e’ indicate statistically significant difference at p < 0.05 within each row comparison between the HRS groups. Bars with no common letters are significantly different (p < 0.05).
Fig 2.
RP values of the CFSs (mean ± SD, n = 3).
MRS control sample without lactobacilli. RP values are expressed as μM of cysteine. Different letters indicate statistically significant differences at p < 0.05. Bars with no common letters are significantly different (p < 0.05).
Fig 3.
ILAP of the CFSs (mean ± SD, n = 3).
MRS control sample without lactobacilli. Different letters mean statistically significant differences at p < 0.05. Bars with no common letters are significantly different (p < 0.05).
Table 2.
Correlations among the four chemical antioxidant activity assays.
Fig 4.
Cytotoxicity of the CFSs on human hepatocellular carcinoma HepG2 cells.
Negative control was untreated cells (mean ± SD, n = 3).
Fig 5.
AAs of the CFSs evaluated by the CAA method.
(A) Peroxyl radical-induced oxidation of DCFH to DCF in HepG2 cells, and inhibition of oxidation by CFS and MRS (mean ± SD, n = 3). (B) CAA units of CFS and MRS broth. CAA unit was calculated as the difference in the area under the curve between the tested samples and control wells. Data represent the mean ± SD values that were obtained from six wells in each group. Different letters mean statistically significant differences at p < 0.05.
Fig 6.
DPPH radical scavenging, HRS, RP, and ILAP values vs. CAA indexes for the different CFSs and MRS broth.
(A) CAA values vs DPPH radical scavenging and ILAP indexes for CFSs and MRS broth. (B) CAA values vs HRS and RP indexes for CFSs and MRS broth. (○) represents DPPH radical scavenging values; (●) represents HRS values; (☐) represents RP values; and (■) represents ILAP values. * and ** mean statistically significant difference at p < 0.05 and p < 0.01, respectively. Abbreviations: HRS, hydroxyl radical scavenging; RP, reducing power; ILAP, inhibition of linoleic acid peroxidation; CFSs, cell-free supernatants; CAA, cellular antioxidant activity; rDPPH, correlation between the CAA and DPPH radical scavenging activity assay; rILAP, correlation between the CAA and ILAP assay; rHRS, correlation between the CAA and HRS assay; and rRP, correlation between the CAA and RP assay.