Bacillus sp. SAB E-41-derived extract shows antiaging properties via ctt1-mediated oxidative stress tolerance response in yeast Schizosaccharomyces pombe

Objective: To analyze potential activation of oxidative stress tolerance systems by SAB E-41 bacterial extract in promoting the life span of yeast Schizosaccharomyces pombe. Methods: In vitro analysis was done to assess antioxidant activity of SAB E-41 bacterial extract. Antiaging property of the particular extract was then assayed through spot test and chronological life span assays. Furthermore, sty1 mitogen-activated protein kinase, pap1 transcriptional factor of oxidative stress response and its downstream genes, ctt1 were evaluated via real time PCR. The protein level of ctt1 was then observed via Western Blot analysis. In addition, accumulation of reactive oxygen species and mitochondrial activity were conducted to understand the effect of SAB E-41 upon oxidative stress response systems in vivo. Results: The IC50 values of corresponding extract for antioxidant(DPPH; ABTS) and antiglycation were 402.40, 358.13 and 683.55 μg/mL, respectively. In addition, SAB E-41 extract(750 μg/mL) exhibited antiaging properties, which could be attributed to significant up-regulation of oxidative stress response genes, sty1, pap1 and ctt1. Interestingly, SAB E-41 extract could enhance stress tolerance phenotype of Schizosaccharomyces pombe against H2 O2-induced oxidative stress. These results were supported by increasing mitochondrial activity and reactive oxygen species intracellular levels. Conclusions: SAB E-41 extract could promote yeast life span likely via up-regulation of oxidative stress responses in yeast. Our results suggest that adaptive response via up-regulation of oxidative stress transcriptional factors, and its downstream gene, ctt1, as well as mitochondrial activity contributes in combating oxidative stress thus promoting yeast life span.

Nrf2-inducing and HMG-CoA reductase inhibitory activities of a polyphenol-rich fraction of Guazuma ulmifolia leaves

Objective: To fractionate and identify polyphenols from Guazuma ulmifolia Lam. leaves, and to explore their antioxidant, 5-hydroxy-3-methylglutaryl-coenzyme A(HMG-Co A) reductase inhibitory, and Nrf2 modulatory activities.Methods: The 1,1-diphenyl-2-picrylhydrazyl assay was used to evaluate the antioxidant activity of a polyphenolic fraction of the extract of Guazuma ulmifolia Lam. leaves. THP-1 gene reporter cell lines constructed with a transcriptional response element specific for Nrf2 and a minimal promoter for the firefly luciferase–green fluorescent protein transgene were used to determine the effect of the polyphenolic fraction on the Nrf2 signaling pathway. Furthermore, an assay of HMG-Co A reductase inhibitory activity was performed by using a commercial enzyme kit. Polyphenolic compounds were identified by liquid chromatographytandem mass spectrometry.Results: The polyphenolic fraction showed fairly strong antioxidant activity [IC50 =(14.90 ± 4.70) μg/m L] and inhibited HMG-Co A reductase activity by 69.10%, which was slightly lower than that by pravastatin(84.37%) and quercetin(84.25%). Additionally, the polyphenolic fraction activated the Nrf2 antioxidant signaling pathway at 500 μg/m L. Eleven subfractions resulting from the column chromatography separation of the polyphenolic fraction also showed relatively strong antioxidant activities(IC50: 17.46–217.14 μg/m L). The subfraction(F6) stimulated the Nrf2 signaling pathway and had HMG-Co A reductase inhibitory activity(65.43%). Moreover, the subfraction contained two main flavonoids: quercetin and quercimeritrin.Conclusions: The polyphenolic fraction of Guazuma ulmifolia could induce antioxidant genes via the Nrf2/antioxidant regulatory elements pathway, and is a promising candidate for an inhibitor of HMG-Co A reductase.