Paeoniflorin inhibits epithelial mesenchymal transformation and oxidative damage of lens epithelial cells in diabetic cataract via sirtuin 1 upregulation

Antioxidant effects of Paeoniflorin and relevant molecular mechanisms as related to a variety of diseases: A review

Paeoniflorin (PF), which is the main component of the Paeonia lactiflora Pall extract, is one of the traditional Chinese medicines. The pharmacological effects associated with PF include antioxidant, immunomodulatory, anti-inflammatory, anticancer, antidepressant-like and neuroprotective effects. Our previous studies had revealed that PF protected melanocytes and inhibited photodamage through the suppression of oxidative stress (OS). As OS plays a vital role in the progression of a variety of diseases, the capacity for PF to suppress OS may exert important effects upon them. However, no review exists on these antioxidant effects of PF as related to various diseases. Therefore, in this review we summarized studies involved with examining the antioxidant effects and molecular mechanisms of PF. Through its capacity to inhibit OS, PF has been shown to exert beneficial effects upon several systems including nervous, cardiac/vascular, digestive, and respiratory as well as specific diseases such as diabetes, autoimmune, pregnancy related, ocular, kidney, dermatology, along with suppression of distal flap necrosis, postoperative adhesions, and hearing loss. Such findings provide new insights and directions for future research directed at the development of PF as a natural antioxidant for the treatment of clinical diseases.

Genus Paeonia monoterpene glycosides: A systematic review on their pharmacological activities and molecular mechanisms

BACKGROUND

Genus Paeonia, which is the main source of Traditional Chinese Medicine (TCM) Paeoniae Radix Rubra (Chishao in Chinese), Paeoniae Radix Alba (Baishao in Chinese) and Moutan Cortex (Mudanpi in Chinese), is rich in active pharmaceutical ingredient such as monoterpenoid glycosides (MPGs). MPGs from Paeonia have extensive pharmacological effects, but the pharmacological effects and molecular mechanisms of MPGs has not been comprehensively reviewed.

PURPOSE

MPGs compounds are one of the main chemical components of the genus Paeonia, with a wide variety of compounds and strong pharmacological activities, and the structure of the mother nucleus-pinane skeleton is similar to that of a cage. The purpose of this review is to summarize the pharmacological activity and mechanism of action of MPGs from 2012 to 2023, providing reference direction for the development and utilization of Paeonia resources and preclinical research.

METHODS

Keywords and phrases are widely used in database searches, such as PubMed, Web of Science, Google Scholar and X-Mol to search for citations related to the new compounds, extensive pharmacological research and molecular mechanisms of MPGs compounds of genus Paeonia.

RESULTS

Modern research confirms that MPGs are the main compounds in Paeonia that exert pharmacological effects. MPGs with extensive pharmacological characteristics are mainly concentrated in two categories: paeoniflorin derivatives and albiflflorin derivatives among MPGs, which contains 32 compounds. Among them, 5 components including paeoniflorin, albiflorin, oxypaeoniflorin, 6'-O-galloylpaeoniflorin and paeoniflorigenone have been extensively studied, while the other 28 components have only been confirmed to have a certain degree of anti-inflammatory and anticomplementary effects. Studies of pharmacological effects are widely involved in nervous system, endocrine system, digestive system, immune system, etc., and some studies have identified clear mechanisms. MPGs exert pharmacological activity through multilateral mechanisms, including anti-inflammatory, antioxidant, inhibition of cell apoptosis, regulation of brain gut axis, regulation of gut microbiota and downregulation of mitochondrial apoptosis, etc. CONCLUSION: This systematic review delved into the pharmacological effects and related molecular mechanisms of MPGs. However, there are still some compounds in MPGs whose pharmacological effects and pharmacological mechanisms have not been clarified. In addition, extensive clinical randomized trials are needed to verify the efficacy and dosage of MPGs.

RASFF1A inhibits the epithelial-mesenchymal transition of lens epithelial cells induced by TGFβ through regulating HDAC6

To explore the role of Ras-association domain family 1 A (RASSF1A) in TGFβ2-induced changes of lens epithelial cells (LECs) behavior. The human LEC line SRA01/04 cells were treated with TGFβ2 in the presence or absence of RASSF1A and histone deacetylase 6 (HDAC6). qRT-PCR and western blot were performed to analysis mRNA and proteins expression. Cell proliferation was evaluated using MTT assay and colony formation assay. Transwell and scratch-wound healing assays were conducted to detected cell migration ability. RASSF1A was downregulated in TGFβ2-induced SRA01/04 cells. RASSF1A overexpression inhibited the cell viability, colony formation and migration abilities of SRA01/04 cells induced by TGFβ2. Overexpression of RASSF1A suppressed TGFβ2-induced EMT of SRA01/04 cells, which was manifested as inhibition of EMT-related proteins α-SMA, Vimentin, Snail and Fn expression. Moreover, RASSF1A down-regulated the expression of HDAC6. Importantly, HDAC6 reversed the effects of RASSF1A on SRA01/04 cells. These findings indicate that RASSF1A prevented TGFβ2-induced proliferation, migration, and EMT of LECs by regulating HDAC6 expression, suggesting that RASSF1A holds promise as a potential target for cataracts treatment.

Anti-inflammatory and pro-regenerative effects of a monoterpene glycoside on experimental periodontitis in a rat model of diabetes

OBJECTIVE

Paeoniflorin (Pae) is a monoterpene glycoside with immune-regulatory effects. Several studies have already demonstrated the impact of Pae on periodontitis, but its effect on diabetic periodontitis is unclear. In this study, our aim was to test the hypothesis that Pae had a strong anti-inflammatory effect that prevented bone loss in diabetic periodontitis.

METHODS

Thirty male Wistar albino rats were randomly divided into control (healthy, n = 10), periodontitis (PD) + diabetes (DM; n = 10), and PD + DM + Pae (n = 10) groups. Ligature-induced periodontitis was created by placing 4-0 silk ligatures around the lower first molars on both sides of the mandibulae. Experimental DM was created via an injection of 50 mg/kg and streptozotocin (STZ). Hyperglycemia was confirmed by the blood glucose levels of rats (>300 mg/dL). The bone mineral density (BMD), trabecular number, trabecular thickness, and bone loss were measured by micro-CT. The expression levels of IL-1β, IL-6, and TNF-α were measured in tissue homogenates by ELISA.

RESULTS

The PD + DM + Pae group had significantly less alveolar crest resorption when compared to the PD + DM group. There was also a significant difference between the PD + DM + Pae group compared to PD + DM group in trabecular thickness, BMD, and the number of trabeculae. Pae application led to a statistically significant decrease in IL-1β, IL-6, and TNF-α levels in diabetic periodontitis.

CONCLUSION

Systemic application of Pae suppressed inflammation caused by PD and DM, leading to reduced bone loss and enhanced bone quality.

Protein from Hylocereus polyrhizus protects MRC-5 cells against hydrogen peroxide (H2O2)-induced damage

The cytoprotective and potential molecular mechanisms of Hylocereus polyrhizus protein (RFPP) were investigated on the hydrogen peroxide (H2O2)-triggered damage in normal human embryonic lung (MRC-5) cells. An MTT assay was conducted to assess the MRC-5 cell viability after exposure to H2O2 or RFPP. Cell cycle distribution and apoptosis were explored via flow cytometry. The contents of related proteins were assessed via western blot. MRC-5 cells exhibited markedly decreased cellular viability after treatment with H2O2; however, treatment with RFPP suppressed this decrease. Additionally, RFPP interference dampened H2O2-triggered intracellular apoptosis levels and increased H2O2-triggered intracellular S phase. In these processes, the contents of phosphorylated (p)-AKT along with p-mTOR proteins were downregulated in 120 µM H2O2-treated cells compared with vehicle-treated cells. Nevertheless, in MRC-5 cells inoculated with RFPP, the levels expression of these proteins were reversed. To conclude, RFPP protected MRC-5 cells from H2O2-triggered damage via activation of the PI3K/AKT/mTOR cascade.

Nutraceutical Prevention of Diabetic Complications—Focus on Dicarbonyl and Oxidative Stress

Oxidative and dicarbonyl stress, driven by excess accumulation of glycolytic intermediates in cells that are highly permeable to glucose in the absence of effective insulin activity, appear to be the chief mediators of the complications of diabetes. The most pathogenically significant dicarbonyl stress reflects spontaneous dephosphorylation of glycolytic triose phosphates, giving rise to highly reactive methylglyoxal. This compound can be converted to harmless lactate by the sequential activity of glyoxalase I and II, employing glutathione as a catalyst. The transcription of glyoxalase I, rate-limiting for this process, is promoted by Nrf2, which can be activated by nutraceutical phase 2 inducers such as lipoic acid and sulforaphane. In cells exposed to hyperglycemia, glycine somehow up-regulates Nrf2 activity. Zinc can likewise promote glyoxalase I transcription, via activation of the metal-responsive transcription factor (MTF) that binds to the glyoxalase promoter. Induction of glyoxalase I and metallothionein may explain the protective impact of zinc in rodent models of diabetic complications. With respect to the contribution of oxidative stress to diabetic complications, promoters of mitophagy and mitochondrial biogenesis, UCP2 inducers, inhibitors of NAPDH oxidase, recouplers of eNOS, glutathione precursors, membrane oxidant scavengers, Nrf2 activators, and correction of diabetic thiamine deficiency should help to quell this.

Gastrodin protects retinal ganglion cells from ischemic injury by activating phosphatidylinositol 3-kinase/protein kinase B/nuclear factor erythroid 2-related factor 2 (PI3K/AKT/Nrf2) signaling pathway

Glaucoma is a progressive optic neuropathy and improper treatment may cause irreversible damage to visual function. Gastrodin is an effective active substance extracted from Gastrodia elata and possesses antioxidant as well as anti-inflammatory properties. However, the therapeutic potential of gastrodin for retinal ischemia/reperfusion (I/R) injury remains unclear. We adopted oxygen and glucose deprivation/reoxygenation (OGD/R) to induce R28 cells with the aim of simulating glaucomatous neurodegeneration. CCK-8 analysis and TUNEL were applied for examining cell proliferation and apoptosis . In addition, RT-qPCR and ELISA were performed to test the releases of inflammatory factors in cells . Related indicators of intracellular oxidative stress and ROS production were detected by corresponding kits. Moreover, western blot was applied to assay the expressions of PI3K/AKT/Nrf2 pathway-related proteins. OGD/R induction contributed to the decreased cell viability and reduced Bcl-2 protein expression, while the protein contents of Bax, Cyto-C, c-caspase 9 and c-PARP as well as ROS production were ascended. The co-treatment of hypoxia and gastrodin greatly improved R28 cell viability but effectively suppressed cell apoptosis, ROS level and the releases of OGD/R-induced inflammatory factors as well as oxidative stress. In addition, OGD/R stimulation reduced Nrf2, accompanied by a decrease in the phosphorylation levels of PI3K and AKT. Gastrodin significantly promoted the activation of PI3K/AKT/Nrf2 signaling pathway in R28 cells, which was then counteracted by PI3K/AKT inhibitors. In conclusion, the present study suggested that gastrodin has a protective effect on OGD/R-induced R28 cell injury, which is achieved through the activation of the PI3K/AKT/Nrf2 signaling pathway.

Diosmetin attenuates oxidative stress-induced damage to lens epithelial cells via the mitogen-activated protein kinase (MAPK) pathway

Cataract is a global ophthalmic disease that blinds the eye, and oxidative stress is one of its primary causes. Apoptosis of lens epithelial cells (LECs) is considered the major cytological basis of many cataracts except congenital cataracts. The purpose of this study was to investigate whether diosmetin could reduce oxidative stress-induced damage to LECs, and explore its regulatory pathway. Lens epithelial cell line SRA01/04 was used as the object of study. Using ultraviolet B (UVB) and hydrogen peroxide (H₂O₂) as sources of oxidative stress, the protective effects of diosmetin at different concentrations on cells were investigated, including inhibition of proliferation, apoptosis, and oxidative stress. Molecular docking was then used to predict the target proteins and validation was performed at the cellular and protein levels. The oxidative stress of SRA01/04 was induced by UVB and H₂O₂, and inhibition of proliferation and apoptosis were observed. Here, diosmetin has a dose-dependent cell-protecting effect. This effect is achieved by targeting the MEK2 protein and inhibiting the MAPK signaling. In conclusion, diosmetin reduces H₂O₂- and UVB-induced inhibition of SRA01/04 proliferation and apoptosis by reducing oxidative stress-induced activation of the MAPK pathway.