Department of Molecular and Developmental Biology, Institute of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan.
Master's Program in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba 305-8575, Japan.
Int J Mol Sci. 2024 Oct 3;25(19):10648. doi: 10.3390/ijms251910648.
In recent years, the health benefits of lactic acid bacteria have garnered attention, but their antioxidant activity remains relatively underexplored. We have been analyzing the antioxidant activities of various dietary phytochemicals by assessing their ability to mitigate oxidative stressor-induced toxicity in zebrafish larvae through pretreatment. In this study, the antioxidant activities of 24 strains of heat-killed lactic acid bacteria from various origins were examined using this zebrafish assay system. The results revealed that all 24 strains possessed antioxidant activity that reduces hydrogen peroxide toxicity. Further detailed analysis using the H61 strain, which exhibited the strongest activity, showed that no direct antioxidant activity was observed in the assay system, suggesting that the detected antioxidant activity was entirely indirect. Moreover, it was found that pretreatment of zebrafish larvae with the H61 strain for more than 6 h was required to exert its antioxidant activity. This duration was similar to that required by dietary antioxidants that activate the Keap1-Nrf2 pathway, suggesting potential involvement of this pathway. However, analysis using Nrf2-knockout zebrafish revealed that the antioxidant activity of strain H61 is independent of Nrf2, indicating that it represents a novel indirect antioxidant activity that does not involve the Keap1-Nrf2 pathway. To further characterize this activity, the ability to mitigate the toxicity of oxidative stressors other than hydrogen peroxide was examined. The results indicated that while the toxicity of -butyl hydroperoxide was reduced, unlike with the Keap1-Nrf2 pathway, it was not effective in counteracting the toxicity of paraquat or arsenite, which generate superoxide radicals. In conclusion, we have identified a novel indirect antioxidant activity in lactic acid bacteria.
近年来，乳酸菌的健康益处引起了人们的关注，但它们的抗氧化活性仍相对未得到充分探索。我们一直在通过预处理评估各种膳食植物化学物质减轻斑马鱼幼虫氧化应激诱导毒性的能力来分析它们的抗氧化活性。在这项研究中，我们使用这种斑马鱼测定系统来检查来自不同来源的 24 株热灭活乳酸菌的抗氧化活性。结果表明，所有 24 株菌株都具有减轻过氧化氢毒性的抗氧化活性。使用表现出最强活性的 H61 菌株进行的进一步详细分析表明，在测定系统中未观察到直接的抗氧化活性，表明检测到的抗氧化活性完全是间接的。此外，发现需要用 H61 菌株预处理斑马鱼幼虫超过 6 小时才能发挥其抗氧化活性。这个时间与激活 Keap1-Nrf2 通路的膳食抗氧化剂所需的时间相似，表明可能涉及该通路。然而，使用 Nrf2 敲除斑马鱼的分析表明，菌株 H61 的抗氧化活性不依赖于 Nrf2，表明它代表一种不涉及 Keap1-Nrf2 通路的新型间接抗氧化活性。为了进一步表征这种活性，我们检查了减轻除过氧化氢以外的氧化应激剂毒性的能力。结果表明，虽然降低了 -丁基过氧化物的毒性，但与 Keap1-Nrf2 通路不同，它不能有效抵抗超氧化物自由基生成的百草枯或亚砷酸盐的毒性。总之，我们已经确定了乳酸菌中一种新的间接抗氧化活性。
