As cellular senescence, reactive oxygen species (ROS) accumulate excessively, causing cellular damage. Flavonoids derived from natural products are known for their antioxidant effects and their ability to delay cellular senescence. Previous studies have attempted to mitigate cellular senescence using flavonoids from natural sources. However, the detailed mechanisms and regulatory targets of some flavonoids exhibiting antioxidant effects have not been fully elucidated. Therefore, we screened a library of flavonoids for antioxidant properties. Isoschaftoside, a glycosidic flavonoid, significantly reduced ROS levels in senescent cells. It was found that mitochondrial function was restored, and dependence on glycolysis was reduced in senescent cells treated with isoschaftoside. Additionally, we identified that isoschaftoside suppresses ROS by reducing the expression of RAC2 and LINC00294 in senescent cells. Taken together, this study establishes a novel mechanism for ROS inhibition and the regulation of cellular senescence by isoschaftoside. Our findings contribute important insights to antioxidant and anti-senescence research.

Background: Reactive oxygen species (ROS) generated by mitochondrial dysfunction damage cellular organelles and contribute to skin aging. Therefore, strategies to reduce mitochondrial ROS production are considered important for alleviating skin aging, but no effective methods have been identified. Methods: In this study, we evaluated substances utilized as cosmetic ingredients and discovered Camellia sinensis (C. sinensis) as a substance that reduces mitochondrial ROS levels. Results: C. sinensis extracts were found to act as senolytics that selectively kill senescent fibroblasts containing dysfunctional mitochondria. In addition, C. sinensis extracts facilitated efficient electron transport in the mitochondrial electron transport chain (ETC) by increasing the efficiency of oxidative phosphorylation (OXPHOS), thereby reducing mitochondrial ROS production, a byproduct of the inefficient ETC. This novel mechanism of C. sinensis extracts led to the restoration of skin aging and the skin barrier. Furthermore, epigallocatechin gallate (EGCG) was identified as an active ingredient that plays a key role in C. sinensis extract-mediated skin aging recovery. Indeed, similar to C. sinensis extracts, EGCG reduced ROS and improved skin aging in an artificial skin model. Conclusions: Our data uncovered a novel mechanism by which C. sinensis extract reverses skin aging by reducing mitochondrial ROS production via selective senescent cell death/increased OXPHOS efficiency. Our results suggest that C. sinensis extract or EGCG may be used as a therapeutic agent to reverse skin aging in clinical and cosmetic applications.

Reactive oxygen species (ROS)-mediated damage to macromolecules and cellular organelles is one of the major causes of senescence. Therapeutic strategies that lower ROS levels have been proposed as important treatments for senescence, but effective mechanisms for reducing ROS levels have not been discovered. Here, we aimed to find a combination that has a synergistic effect on ROS reduction using senomorphics known to reduce ROS. Combination treatment with BRAF inhibitor SB590885 and p38 MAPK inhibitor SB203580 showed a synergistic effect on ROS reduction compared to treatment with either drug alone. The synergistic effect of ROS reduction through this combination led to a synergistic effect that restored mitochondrial function and ameliorated senescence-associated phenotypes. To elucidate the underlying mechanism by which the synergistic effect of the two drugs reverses senescence, we performed RNA sequencing and identified metallothionein 2A (MT2A) as a key gene. MT2A was upregulated in response to combination therapy, and overexpression of MT2A led to a decrease in ROS and subsequent recovery of senescence-associated phenotypes, similar to the effects of combination therapy. Taken together, we found a drug combination that showed synergistic effects on ROS reduction, which contributed to the recovery of senescence-associated phenotypes through MT2A gene regulation. This study opens up a new avenue in aging research by demonstrating that combination therapy with existing senomorphics can enhance the ability to reverse senescence and that similar reversal effects can be achieved through gene regulation regulated by combination therapy.

One of the major causes of senescence is oxidative stress caused by ROS, which is mainly generated from dysfunctional mitochondria. Strategies to limit mitochondrial ROS production are considered important for reversing senescence, but effective approaches to reduce them have not yet been developed. In this study, we screened the secondary metabolites that plants produce under oxidative stress and discovered sauchinone as a potential candidate. Sauchinone induced mitochondrial function recovery, enabling efficient electron transport within the electron transport chain (ETC). This led to a decrease in ROS production, a byproduct of inefficient electron transport. The reduction in ROS by sauchinone rejuvenated senescence-associated phenotypes. To understand the underlying mechanism by which sauchinone rejuvenates senescence, we carried out RNA sequencing and found VAMP8 as a key gene. VAMP8 was downregulated by sauchinone. Knockdown of VAMP8 decreased mitochondrial ROS levels and subsequently rejuvenated mitochondrial function, which was similar to the effect of sauchinone. Taken together, these studies revealed a novel mechanism by which sauchinone reduces mitochondrial ROS production by regulating mitochondrial function and VAMP8 expression. Our results open a new avenue for aging research to control senescence by regulating mitochondrial ROS production.

Background: Reactive oxygen species (ROS) generated due to mitochondrial dysfunction are one of the primary causes of the initiation and progression of senescence. Although reducing mitochondrial ROS production is known as an effective strategy for the treatment of aging, effective components that reduce mitochondrial ROS production or effective treatments that utilize them have not yet been developed. Methods: Screening of plant-generated secondary metabolites to overcome ROS-mediated stress found that ε-viniferin, a dimer of resveratrol, effectively reduces mitochondrial ROS production. Results: ε-viniferin induced efficient electron transport and reduced mitochondrial ROS, a consequence of inefficient electron transport. In addition, ε-viniferin acted as a senolytic that selectively eliminates senescent fibroblasts, thereby restoring mitochondrial function and senescence-associated phenotypes. RNA sequencing analysis revealed that regulator of G protein signaling 16 (RGS16) was an important gene for ε-viniferin-mediated senescence rejuvenation. Upregulation of RGS16 showed similar effects as ε-viniferin in reducing mitochondrial ROS production and restoring mitochondrial function. Conclusions: This study discovered a novel mechanism by which ε-viniferin rejuvenates senescence by lowering ROS production in mitochondria. The novel mechanism will serve as a basis for developing therapeutics that regulate mitochondrial ROS production to treat aging.

Genotoxins cause significant damage to the genetic material of aquatic organisms, requiring rapid and accurate assessment. Fish-derived cells sensitive to genotoxins have proven to be a useful tool for measuring genotoxicity, but the long treatment times required for measurement limit their application in situations requiring rapid testing. Previous studies have shown that fish cells can be kept unstarved for up to 6 h using media containing 1% FBS. In this study, the 1% FBS/6 h parameter was used for genotoxicity assessment. Therefore, genotoxicity assessment was performed after only 6 h of genotoxin treatment in a medium containing 1% FBS. The new genotoxicity assessment method provided faster and more accurate genotoxicity data for climbazole and metolachlor than the existing assessment system using the 15% FBS/96 h parameter. Furthermore, these advantages of the new platform enabled the determination of the genotoxicity of various genotoxins, such as dibenz[a,h]anthracene and ethoprophos. In summary, we have developed a genotoxicity assessment that can generate genotoxicity data rapidly and accurately. This new platform will serve as a foundation for rapid genotoxicity assessment of many genotoxins.