Oxidative stress is the main pathogenesis of diabetic microangiopathy, which can cause microvascular endothelial cell damage and destroy vascular barrier. In this study, it is found that carnosol protects human microvascular endothelial cells (HMVEC) through antioxidative mechanisms. First, we measured the antioxidant activity of carnosol. We showed that carnosol pretreatment suppressed tert-butyl hydroperoxide (t-BHP)-induced cell viability, affected the production of lactate dehydrogenase (LDH) as well as reactive oxygen species (ROS), and increased the produce of nitric oxide (NO). Additionally, carnosol promotes the protein expression of vascular endothelial cadherin (VE-cadherin) to keep the integrity of intercellular junctions, which indicated that it protected microvascular barrier in oxidative stress. Meanwhile, we investigated that carnosol can interrupt Nrf2-Keap1 protein−protein interaction and stimulated antioxidant-responsive element (ARE)-driven luciferase activity in vitro. Mechanistically, we showed that carnosol promotes the expression of heme oxygenase 1(HO-1) and nuclear factor-erythroid 2 related factor 2(Nrf2). It can also promote the expression of endothelial nitric oxide synthase (eNOS). Collectively, our data support the notion that carnosol is a protective agent in HMVECs and has the potential for therapeutic use in the treatments of microvascular endothelial cell injury.

The potential protective effects of Curcuma Radix on diabetic retinopathy were investigated through network pharmacology, molecular docking, and cellular experiments. Network pharmacology results identified four primary active ingredients and twenty key target molecules; Protein-protein interaction network analysis revealed that the core targets regulated by Curcuma Radix in DR include AKT2, RAF1, IL6, IRS1 and IGF1R. KEGG enrichment analysis indicated that Curcuma Radix may improve DR through the HIF-1 signaling pathway, FOXO signaling pathway, and VEGF signaling pathway. Molecular docking results indicated that curcumin, demethoxycurcumin, bisdemethoxycurcumin, and naringenin exhibited favorable docking activities with the core targets AKT2, RAF1, MAPK14, IL6, IRS1 and IGF1R.The ARPE-19 cell experiment results indicated that the four active ingredients could enhance cell viability and mitigate oxidative damage. They exhibited significant gene expression regulation effects on AKT2, RAF1, MAPK14, IL6, IRS1 and IGF1R, which were consistent with the molecular docking outcomes.Through the HUVEC endothelial cell model, the protective effects of the two compounds on the cellular barrier were validated. Demethoxycurcumin and bisdemethoxycurcumin demonstrated protective effects on endothelial cells by modulating ICAM-1 and VCAM-1 to improve barrier damage.This study preliminarily revealed, through network pharmacology and experimental validation that four active components in Curcuma Radix modulated high-glucose-induced ARPE-19 cell models by regulating the gene expression of AKT2, RAF1, MAPK14, IL6, IRS1 and IGF1R. Two of these components also mitigated thrombin-induced endothelial cell barrier damage in the HUVEC cell model by regulating VCAM-1 and ICAM-1 expression, thereby providing protection against DR. This study provides a theoretical foundation for investigating the pharmacological basis and mechanisms underlying these effects.