Emodin and rhein in Cassia tora ameliorates activity of mitochondrial enzymes involved in oxidative phosphorylation in the retina of diabetic mice

Eun Ko,Taewon Han,Moonsung Choi,Sooim Shin,Min Young Um

doi:10.1186/s13765-021-00609-2

Abstract

Cassia tora is an annual herb, which has pharmacological effects such as antioxidant, hypolipidemic, and antidiabetic effects. Accordingly, its effect on diabetes has been well-studied. However, it is unclear whether it has an effect on mitochondrial dysfunction associated with diabetes. In this study, the effects of emodin and rhein in C. tora seed ethanolic extract (ER/CSEE) on retinal mitochondrial function were examined in high-fat diet (HFD)-fed mice. HFD-fed mice exhibited decreased mitochondrial function followed by compensatory increase in the expression levels of mitochondrial enzymes. However, ER/CSEE treatment for 12 weeks ameliorated the activity of retinal mitochondrial complexes and reduced the expression level of enzymes involved in oxidative phosphorylation, except that of complex II and citrate synthase in citric acid cycle. This suggests that repairing capacity of enzymes in electron transport chain and citric acid cycle of mitochondria are different in response to the metabolic state. Therefore, it concluded that emodin and rhein play a pharmacological role in fat metabolism by influencing activities of enzymes in citric acid cycle linked with beta-oxidation in retina.

Highlights

Type 2 diabetes (T2D) is the most threatening metabolic disease, affecting more than 10% population worldwide [1]
To identify the function of emodin and rhein in C. tora on diabetic eyes, we investigated their effect on mitochondrial function in the eyes of mice with diabetes
Our previous research shows that blood index and expression level of mitochondrial enzymes, the inclusion of ER/C. tora seed ethanolic extract (CSEE) with high-fat diet (HFD) diet prevented the deleterious effects of HFD diet

Summary

Introduction

Type 2 diabetes (T2D) is the most threatening metabolic disease, affecting more than 10% population worldwide [1]. Cassia tora is well known in East Asia as an alternative medicine to treat diabetes and retinal dysfunction. In a previous study, when the butanol-extracted fraction of C. tora seeds was administrated to streptozotocin-induced diabetic rats, the diabetes was ameliorated by the reduction of postprandial blood glucose and insulin secretion [12]. The effect of C. tora seeds on mitochondrial dysfunction associated with T2D are poorly examined. We assessed the efficacy of emodin and rhein in C. tora seeds ethanolic extract (ER/CSEE) on the retinal health of mice with diabetes induced by a high-fat diet (HFD). We examined the effect of ER/CSEE treatment on the mitochondrial function of the retina by measuring the activity of enzymes involved in OXPHOS thereby identify the linkage between the C. tora and functional improvement of mitochondria

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Results

Conclusion