Phosphatidylinositol 3 kinase/protein kinase B is responsible for the protection of paeoniflorin upon H₂O₂-induced neural progenitor cell injury

Herbal Medicine Extracts Improve Motor Function by Anti-Inflammatory Activity in hSOD1G93A Animal Model

Amyotrophic lateral sclerosis (ALS) is a multicomplex neurodegenerative disorder characterized by motor neuron death, muscle atrophy, and respiratory failure. Owing to its multicomplex mechanisms and multifactorial nature in the skeletal muscle and spinal cord (SC), no effective therapy has been developed. However, herbal medicines, known for their multitarget properties, have demonstrated promising efficacy with limited side effects in treating various diseases. Specifically, Paeonia lactiflora Pallas has been demonstrated to exhibit analgesic, antidepressant, anti-inflammatory, and neuroprotective effects. However, the pharmacological mechanisms underlying the beneficial effects of P. lactiflora in hSOD1G93A animal models remain unexplored. Therefore, this study was conducted to investigate the multitarget effects of P. lactiflora in hSOD1G93A transgenic mice, an ALS model. Footprint tests, western blot assays, and immunohistochemical analysis were used to assess the effect of P. lactiflora on the tibia anterior (TA), gastrocnemius (GC), and SC. The results revealed that P. lactiflora augmented motor function and decreased motor neuron loss in hSOD1G93A mice. Furthermore, P. lactiflora significantly lowered the expression of proteins associated with inflammation and oxidative stress in the skeletal muscle (TA and GC) and SC. P. lactiflora also regulated autophagy function by reducing the levels of key markers, such as P62/sequestosome 1 (SQSTM1), microtubule-associated proteins 1A/1B light chain 3B, and SMAD family member 2, in the muscle and SC. Overall, P. lactiflora treatment improved motor function, prevented motor neuron death, and exhibited anti-inflammatory and antioxidative effects in the skeletal muscle and SC of ALS mouse models. These results suggest that P. lactiflora could serve as a promising multitarget therapeutic agent for systemic and multipathological diseases.

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.

A review for the pharmacological effects of paeoniflorin in the nervous system

Paeoniflorin, a terpenoid glycoside compound extracted from Paeonia lactiflora Pall, shows preventive and therapeutic effects in various types of nervous system disorders. However, to date, no comprehensive knowledge on the pharmacological effects of paeoniflorin on the nervous system is available online. Clarification of this issue may be useful for the development of paeoniflorin as a new drug for the treatment of nervous system disorders. To this end, the authors summarize the pharmacological aspects of paeoniflorin and its possible mechanisms, such as restoration of mitochondrial function; inhibition of neuroinflammation, oxidative stress, and cellular apoptosis; activation of adenosine A1 receptor, cAMP response element-binding protein (CREB) and extracellular signal-regulated kinase 1/2 (ERK1/2); or enhancement of brain-derived neurotrophic factor and serotonin function, in the prevention of disorders such as cerebral ischemia, subarachnoid hemorrhage, vascular dementia, Alzheimer's disease, Parkinson's disease, depression, post-traumatic syndrome disorder, and epilepsy, by reviewing the previously published literature.

The Neuroprotective Effects of Paeoniflorin Against MPP+-induced Damage to Dopaminergic Neurons via the Akt/Nrf2/GPX4 Pathway

Paeoniflorin (PF), a water-soluble monoterpene glycoside extracted from the root of Paeonia lactiflora Pall, has been shown to exert neuroprotective effects against neurodegenerative diseases such as Parkinson's disease (PD). However, its underlying mechanisms remain unknown. Our results showed that at certain concentrations, PF alleviated 1-methyl-4-phenylpyridinium (MPP⁺)-induced morphological damage and inhibited neuronal ferroptosis. Moreover, our research indicated that the neuroprotective effect of PF could be partially blocked by ML385 (a nuclear factor erythroid-2-related factor 2 (Nrf2) inhibitor) and LY29400 (an Akt inhibitor). These findings suggest that PF protects against MPP⁺-induced neurotoxicity by preventing ferroptosis via activation of the Akt/Nrf2/Gpx4 pathway in vitro.

Adaptation to oxidative stress at cellular and tissue level

Several in vitro and in vivo investigations have already proved that cells and tissues, when pre-exposed to low oxidative stress by different stimuli such as chemical, physical agents and environmental factors, display more resistance against subsequent stronger ischaemic injuries, resulting in an adaptive response known as ischaemic preconditioning (IPC). The aim of this review is to report the most recent knowledge about the complex adaptive mechanisms, including signalling transduction pathways, antioxidant systems, apoptotic and inflammation pathways, underlying cell protection against oxidative damage. In addition, an update about in vivo adaptation strategies in response to ischaemic/reperfusion episodes and brain trauma is also given.

Paeoniflorin alleviates NG-nitro-L-arginine methyl ester (L-NAME)-induced gestational hypertension and upregulates silent information regulator 2 related enzyme 1 (SIRT1) to reduce H2O2-induced endothelial cell damage

Pregnancy-induced hypertension (PIH) is a leading cause of maternal mortality. Paeoniflorin has been reported to alleviate hypertension, thus relieving the injury of target organ. This study aimed to investigate the role of paeoniflorin in PIH development by regulating SIRT1 in rats. The mean arterial pressure (MAP), urine protein and histopathological damage of placenta in gestational hypertension rats were, respectively, detected by noninvasive tail-artery pressure measuring instrument, BCA method and H&E staining. The viability of human umbilical vein endothelial cells (HUVECs) treated with paeoniflorin or/and H₂O₂ was observed by CCK-8 assay. SIRT1 protein expression in HUVECs treated with paeoniflorin or/and H₂O₂ was analyzed by Western blot. Tunel assay, wound healing assay and tube formation assay were used to detect the apoptosis, migration and tube formation of HUVECs administrated with paeoniflorin or/and H₂O₂ or/and EX527 (SIRT1 inhibitor). As a result, MAP, urine protein and histopathological damage of placenta were enhanced in PIH rats, which were then alleviated by paeoniflorin. Paeoniflorin decreased the levels of sFlt-1, PlGF and VEGF in serum and placental tissues of gestational hypertension rats as well as the inflammatory response and oxidative stress. In addition, paeoniflorin promoted the expressions of SIRT1 and NO/eNOS and inhibited the production of iNOS in gestational hypertension rats to improve vascular endothelial cell injury. However, SIRT1 inhibition could suppress the protective effects of paeoniflorin on endothelial dysfunction of H₂O₂-induced HUVECs. In conclusion, paeoniflorin could improve gestational hypertension development by upregulating SIRT1.

Preparation and characterization of conductive nerve guide conduit filled with dual drug-loaded nanofibers

Peripheral nerve injury (PNI) has become one of the common clinical diseases. How to promote the regeneration and function recovery of the damaged peripheral nerve has been the focus of attention in the medical field. Evidence suggests that the longitudinal filling of oriented fibers in nerve guide conduit (NGC) is especially beneficial to the repair of long gap PNI. In this study, polypyrrole (PPy) nanospheres (PNSs) were prepared by the soft-templating method, and mixed with poly (lactic acid) (PLA) to prepare conductive PNSs/PLA NGC, and the optimal ratio of PNSs was 4.5%. PLA and vascular endothelial growth factor (VEGF) as shell, chitosan (CS) and paeoniflorin (PF) as core, oriented coaxial nanofibers were obtained and then filled into PNSs/PLA NGC. The composite NGC has excellent mechanical properties, electrical conductivity, hydrophilic properties, and degradation properties. Besides, the successive release of VEGF and PF can play a synergistic role in promoting nerve regeneration. In vitro experiments showed that the composite NGC was nontoxic and suitable for the adhesion and proliferation of nerve cells. In addition, PNSs combined with electrical stimulation (ES) can significantly promote the differentiation and proliferation of nerve cells, which is conducive to nerve regeneration. These positive results indicate that the composite NGC is a promising candidate in the repair of long gap PNI.

Paeoniflorin: A neuroprotective monoterpenoid glycoside with promising anti-depressive properties

BACKGROUND

Depression, as a prevalent and debilitating psychiatric disease, severely decreases the life quality of individuals and brings heavy burdens to the whole society. Currently, some antidepressants are applied in the treatment of severe depressive symptoms, while there are still some undesirable drawbacks. Paeoniflorin is a monoterpenoid glycoside that was firstly extracted from Paeonia lactiflora Pall, a traditional Chinese herb that is widely used in the Chinese herbal formulas for treating depression.

PURPOSE

This review summarized the previous pre-clinical studies of paeoniflorin in treating depression and further discussed the potential anti-depressive mechanisms for that paeoniflorin to be further explored and utilized in the treatment of depression clinically.

METHODS

Some electronic databases, e.g., PubMed and China National Knowledge Infrastructure, were searched from inception until April 2021.

RESULTS

This review summarized the effective anti-depressive properties of paeoniflorin, which is related to its functions in the upregulation of the levels of monoaminergic neurotransmitters, inhibition of the hypothalamic-pituitary-adrenal axis hyperfunction, promotion of neuroprotection, promotion of hippocampus neurogenesis, and upregulation of brain-derived neurotrophic factor level, inhibition of inflammatory reaction, downregulation of nitric oxide level, etc. CONCLUSION: This review focused on the pre-clinical studies of paeoniflorin in depression and summarized the recent development of the anti-depressive mechanisms of paeoniflorin, which approves the role of paeoniflorin plays in anti-depression. However, more high-quality pre-clinical and clinical studies are expected to be conducted in the future.

Paeoniflorin ameliorates neuropathic pain-induced depression-like behaviors in mice by inhibiting hippocampal neuroinflammation activated via TLR4/NF-κB pathway

Neuropathic pain (NP) that contributes to the comorbidity between pain and depression is a clinical dilemma. Neuroinflammatory responses are known to have potentially important roles in the initiation of NP and depressive mood. In this study, we aimed to investigate the effects of paeoniflorin (PF) on NP-induced depression-like behaviors by targeting the hippocampal neuroinflammation through the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway. We used a murine model of NP caused by unilateral sciatic nerve cuffing (Cuff). PF was injected intraperitoneally once a day for a total of 14 days. Pain and depression-like behavior changes were evaluated via behavioral tests. Pathological changes in the hippocampus of mice were observed by H&E staining. The levels of proinflammatory cytokines in the hippocampus were detected using ELISA. Activated microglia were measured by immunohistochemical staining. The TLR4/NF-κB signaling pathway-associated protein expression in the hippocampus was detected by western blotting. We found that the PF could significantly alleviate Cuff-induced hyperalgesia and depressive behaviors, lessen the pathological damage to the hippocampal cell, reduce proinflammatory cytokines levels, and inhibit microglial over-activation. Furthermore, PF downregulated the expression levels of TLR4/NF-κB signaling pathway-related proteins in the hippocampus. These results indicate that PF is an effective drug for improving the comorbidity between NP and depression.

Antidepressant Effect of Paeoniflorin Is Through Inhibiting Pyroptosis CASP-11/GSDMD Pathway

Nod-like receptor protein 3 (NLRP3)-associated neuroinflammation mediated by activated microglia is involved in the pathogenesis of depression. The role of the pore-forming protein gasdermin D (GSDMD), a newly identified pyroptosis executioner downstream of NLRP3 inflammasome mediating inflammatory programmed cell death, in depression has not been well defined. Here, we provide evidence that paeoniflorin (PF), a monoterpene glycoside compound derived from Paeonia lactiflora, ameliorated reserpine-induced mouse depression-like behaviors, characterized as increased mobility time in tail suspension test and forced swimming test, as well as the abnormal alteration of synaptic plasticity in the depressive hippocampus. The molecular docking simulation predicted that PF would interact with C-terminus of GSDMD. We further demonstrated that PF administration inhibited the enhanced expression of GSDMD which mainly distributed in microglia, along with the proteins involved in pyroptosis signaling transduction including caspase (CASP)-11, CASP-1, NLRP3, and interleukin (IL)-1β in the hippocampus of mice treated with reserpine. And also, PF prevented lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced pyroptosis in murine N9 microglia in vitro, evidenced by inhibiting the expression of CASP-11, NLRP3, CASP-1 cleavage, as well as IL-1β. Furthermore, VX-765, an effective and selective inhibitor for CASP-1 activation, reduced the expression of inflammasome and pyroptosis-associated proteins in over-activated N9 and also facilitated PF-mediated inhibition of pyroptosis synergistically. Collectively, the data indicated that PF exerted antidepressant effects, alleviating neuroinflammation through inhibiting CASP-11-dependent pyroptosis signaling transduction induced by over-activated microglia in the hippocampus of mice treated with reserpine. Thus, GSDMD-mediated pyroptosis in activated microglia is a previously unrecognized inflammatory mechanism of depression and represents a unique therapeutic opportunity for mitigating depression given PF administration.

Total glucosides of paeony: A review of its phytochemistry, role in autoimmune diseases, and mechanisms of action

ETHNOPHARMACOLOGICAL RELEVANCE

Paeoniae Radix Alba (PRA, called baishao in China), the root of Paeonia lactiflora Pall., has shown a rich medicinal value for more than 2000 years. PRA is used in local medicine and traditional medicine for autoimmune diseases associated with inflammation. At present, total glucosides of paeony (TGP), the main active ingredient of PRA, has been developed into a preparation for the treatment of autoimmune diseases, as TGP exhibits the effect of regulating immunity, anti-inflammatory, and analgesic effects.

AIM OF THE REVIEW

TGP was developed and applied to inflammation-related autoimmune diseases in modern clinical practice. Based on its application in traditional prescriptions, this article reviews PRA's botany and phytochemistry (including its extraction process and quality control), and discusses the clinical application and pharmacological research of TGP as an anti-inflammatory drug from the perspective of ethnopharmacology. Additionally, we review modern pharmacological and molecular-target research on TGP and discuss the mechanisms of TGP in treating autoimmune diseases. Through a systematic literature review, we also highlight the clinical efficacy of TGP in the treatment of immune diseases, and provide a reference for the continued scientific development and quality control of TGP so that its wider application and clinical value can be fully realized.

MATERIALS AND METHODS

Literature search was conducted through the Web of Science, Baidu Scholar, ScienceDirect, PubMed, CNKI, and WanFang DATA using the keywords "Total glucosides of paeony", "Paeonia lactiflora Pall. ", "Paeonia veitchii Lynch", "Paeoniae Radix Alba or white peony", "Paeoniae Radix Rubra or red peony", "Paeoniflorin", "Albiflorin", "Autoimmune diseases", and their combinations. In addition, information was collected from relevant textbooks, reviews, and documents.

RESULTS

Approximately 15 compounds have been identified in TGP, of which paeoniflorin and albiflorin are the most common constituents. In recent years, studies have found that TGP and its main chemical components are effective in the treatment of autoimmune diseases, such as rheumatoid arthritis, psoriasis, oral lichen planus, and Sjogren's syndrome. TGP has a variety of pharmacological effects related to PRA traditional effects, including anti-organ-damage, anti-inflammatory, analgesic, antioxidant, cardiovascular, and nervous-system protection. Previously published reports on TGP treatment of autoimmune diseases have shown that TGP regulates intracellular pathways, such as the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathways. However, there is no standardized preparation method for TGP, and there is insufficient quality control of formulations. Many related pharmacological studies have not tested TGP components, and the validity of such pharmacological results requires further verification.

CONCLUSIONS

Modern pharmacological research on TGP is based on the traditional usage of PRA, and its folk medicinal value in the treatment of autoimmune diseases has now been verified. In particular, TGP has been developed into a formulation used clinically for the treatment of autoimmune diseases. The combination of TGP capsules and chemicals to treat autoimmune diseases has the effect of increasing efficacy and reducing toxicity. Based on further research on its preparation, quality control, and mechanisms of action, TGP is expected to eventually play a greater role in the treatment of autoimmune diseases.

Paeoniflorin attenuates early brain injury through reducing oxidative stress and neuronal apoptosis after subarachnoid hemorrhage in rats

Paeoniflorin is a natural monoterpene glucoside from Paeoniae Radix with neuroprotective properties. However, it is still unclear whether paeoniflorin has neuroprotective effects on subarachnoid hemorrhage (SAH). This study explores the effect of paeoniflorin on early brain injury (EBI) using rat SAH model. We found that paeoniflorin significantly improves neurological deficits, attenuates brain water content and Evans blue extravasation at 72 h after SAH. Paeoniflorin attenuates the oxidative stress following SAH as evidenced by decrease of reactive oxygen species (ROS), malondialdehyde (MDA), 3-Nitrotyrosine, and 8-Hydroxy-2-deoxy guanosine (8-OHDG) level, increase of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase activity, and up-regulates the nuclear factor erythroid‑related factor 2 (Nrf2)/heme oxygenase‑1 (HO-1) pathway. Inhibition of microglia activation and neuro-inflammatory response both contributed to paeoniflorin's protective effects. Moreover, paeoniflorin treatment significantly reduces the ratio of Bax/Bcl-2, active caspase-3/ neuronal nuclei (NeuN) and TUNEL/DAPI positive cells at 72 h following SAH. Our results indicate that paeoniflorin may attenuate early brain injury after experimental SAH.

Pharmacokinetic Analysis of Huangqi Guizhi Wuwu Decoction on Blood and Brain Tissue in Rats with Normal and Cerebral Ischemia-Reperfusion Injury by Microdialysis with HPLC-MS/MS

Objective

The aim of our research was to analyze and compare the pharmacokinetics of paeoniflorin, calycosin, calycosin-7-o-β-d-6-glucoside, and 6-gingerol in the blood and brain tissue of normal and cerebral ischemia-reperfusion injury rats by HPLC-MS/MS method.

Methods

The blood and brain tissue samples of normal and middle cerebral artery occlusion (MCAO) rats were compared. The blood and brain tissue samples were collected by using microdialysis technique. The concentrations of paeoniflorin, calycosin, calycosin-7-o-β-d-6-glucoside, and 6-gingerol in blood and brain tissues were determined by the HPLC-MS/MS internal standard method.

Results

Compared with the normal group, the model group after the administration of the Huangqi Guizhi Wuwu Decoction showed that C_{max blood}, AUC_{0-t blood}, and AUC_{0-inf blood} of paeoniflorin were increased, CL_blood, t_{1/2 brain}, and V_brain of paeoniflorin were decreased; C_maxblood, AUC_0-tblood, AUC_0-infblood, and average residence time (MRT_brain) of calycosin-7-o-β-d-6-glucoside were decreased and the CL_blood and C_{max brain} of calycosin-7-o-β-d-6-glucoside were increased; C_{max blood} of calycosin was decreased, V_blood and V_brain of calycosin were increased; C_{max blood}, AUC_{0-t blood}, AUC_{0-inf blood}, and MRT_brain of 6-gingerol were decreased, CL_blood of 6-gingerol was increased.

Conclusion

This method is simple, rapid, and sensitive. It is suitable for the pharmacokinetic study of Huangqi Guizhi Wuwu Decoction in the blood and brain tissue of rats. Cerebral ischemia-reperfusion injury increased the content of paeoniflorin, calycosin, calycosin-7-o-β-d-6-glucoside, and 6-gingerol in the blood, affecting the clearance rate of paeoniflorin in the brain, the detention time of calycosin-7-o-β-d-6-glucoside and the 6-gingerol in the brain. In normal and cerebral ischemia-reperfusion rats, the content of paeoniflorin and 6-gingerol in the blood was higher than that in brain tissue, while the content of calycosin, calycosin-7-o-β-d-6-glucoside in the brain tissue was higher than that in blood, suggesting that calycosin and calycosin-7-o-β-d-6-glucoside have brain targeting properties.

Transcriptomics- and metabolomics-based integration analyses revealed the potential pharmacological effects and functional pattern of in vivo Radix Paeoniae Alba administration

Background

Radix Paeoniae Alba (RPA) and other natural medicines have remarkable curative effects and are widely used in traditional Chinese Medicine (TCM). However, due to their multi-component and multi-target characteristics, it is difficult to study the detailed pharmacological mechanisms for those natural medicines in vivo. Therefore, their real effects on organisms is still uncertain.

Methods

RPA was selected as research object, the present study was designed to study the complex mechanisms of RPA in vivo by integrating and interpreting the transcriptomic based RNA-seq and metabolomic based NMR spectrum after RPA administration in mice. A variety of dimension-reduction algorithms and classifier models were applied to the processing of high-throughput data.

Results

Among serum metabolites, the contents of PC and glucose were significantly increased, while the contents of various amino acids, lipids and their metabolites were significantly decreased in mice after RPA administration. Based on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, differential analysis showed that the liver was the site where RPA exerted a significant effect, which confirmed the rationality of “meridian tropism” in the theory in TCM. In addition, RPA played a role in lipid metabolism by regulating genes encoding enzymes of the glycerolipid metabolism pathway, such as 1-acyl-sn-glycerol-3-phosphate acyltransferase (Agpat), phosphatidate phosphatase (Lpin), phospholipid phosphatase (Plpp) and endothelial lipase (Lipg). We also found that RPA regulates several substance addiction pathways in the brain, such as the cocaine addiction pathway, and the related targets were predicted based on the sequencing data from pathological model in the GEO database. The overall effective pattern of RPA was intuitively presented with a multidimensional radar map through a self-designed model which found that liver and brain were mainly regulated by RPA compared with the traditional meridian tropism theory.

Conclusions

Overall this study expanded the potential application of RPA and provided possible targets and directions for further mechanism study, meanwhile, it also established a multi-dimensional evaluation model to represent the overall effective pattern of TCM for the first time. In the future, such study based on the high-throughput data sets can be used to interpret the theory of TCM and to provide a valuable research model and clinical medication reference for the TCM researchers and doctors.

Paeoniflorin Prevents Intestinal Barrier Disruption and Inhibits Lipopolysaccharide (LPS)-Induced Inflammation in Caco-2 Cell Monolayers

Inflammatory bowel disease (IBD) in humans is closely related to bacterial infection and the disruption of the intestinal barrier. Paeoniflorin (PF), a bioactive compound from Paeonia lactiflora Pallas plants, exerts a potential effect of anti-inflammatory reported in various researches. However, the effect of PF on intestinal barrier function and its related mechanisms has not been identified. Here, we investigate the PF potential anti-inflammatory effect on lipopolysaccharide (LPS)-stimulated human Caco-2 cell monolayers and explore its underlying key molecular mechanism. In this context, PF significantly increased TEER value, decreased intestinal epithelium FITC-dextran flux permeability, and restored the expressions of occludin, ZO-1, and claudin5 in LPS-induced Caco-2 cell. In vitro, treatment of PF significantly inhibited LPS-induced expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), and matrix metalloproteinase-9 (MMP-9). In addition, we found that PF suppressed nuclear factor kappa B (NF-κB) signaling via activating the Nrf2/HO-1 signaling pathways in ILPS-stimulated Caco-2 cells. Our findings indicate that PF has an inhibitory effect on endothelial injury. Our findings suggested that PF has an anti-inflammatory effect in ILPS-stimulated Caco-2 cells, which might be a potential therapeutic agent against IBD and intestinal inflammation.

A combined molecular biology and network pharmacology approach to investigate the multi-target mechanisms of Chaihu Shugan San on Alzheimer's disease

Chaihu Shugan San (CSS) is a well-known herbal formula used to nourish liver and blood, promote blood circulation and Qi flow in Traditional Chinese Medicine. Modern pharmacological studies and clinical uses showed that CSS could ameliorate cognitive dysfunction of Alzheimer's disease (AD). The present study aimed to elucidate the multi-target mechanisms of CSS on AD using network pharmacology analysis and verify its effect by biological experiments. Firstly, a total of 152 active compounds in CSS, 520 predicted biological targets and 160 AD-related targets were identified. Subsequently, the networks including herb-compound-target network, AD-target network, and CSS potential target-AD target network were constructed. 60 key targets highly responsible for the beneficial effect of CSS on AD were identified by central network topological analysis. They were significantly characterized as nuclear or cytoplasmic proteins with molecular function of protein binding. They were also enriched in various biological processes through PI3K-Akt signaling pathway, MAPK signaling pathway and HIF signaling pathway by GO function and KEGG pathway enrichment analysis. Pretreatment with CSS ameliorated Aβ-induced neural cell death and reduced the number of apoptotic cells in differentiated PC12 cells. Moreover, increased phosphorylation of Akt accompanied with decreased Bax expression was found after CSS pretreatment, suggesting that Akt signaling pathway was involved in the protective effect of CSS against neural cells death. The present study systematically revealed the multi-target mechanisms of CSS on AD using network pharmacology approach, as well as validated the protective effect of CSS against Aβ-induced neural cells death through Akt signaling pathway. It provided indications for further mechanistic studies and also for the development of CSS as a potential treatment for AD patients.

Paeoniflorin Inhibits Mesangial Cell Proliferation and Inflammatory Response in Rats With Mesangial Proliferative Glomerulonephritis Through PI3K/AKT/GSK-3β Pathway

Mesangial proliferative glomerulonephritis (MPGN) is the most common type of chronic kidney disease in China, characterized by mesangial cell proliferation and inflammatory response. Paeoniflorin, an effective composition extracted from Radix Paeoniae Alba, has been used for various kinds of kidney diseases. However, there are no studies reporting the effects of paeoniflorin on MPGN. The present study aims to investigate whether paeoniflorin plays a role in MPGN and confirm the underlying molecular mechanisms. Our results manifested that paeoniflorin strongly restrained 24 h urinary protein and promoted renal function and dyslipidemia in a MPGN rat model. Moreover, paeoniflorin attenuated mesangial cell proliferation and inflammation both in MPGN rats and human mesangial cells (HMCs) treated with lipopolysaccharide (LPS). In detail, paeoniflorin decreased the number of mesangial cells and expressions of proliferation marker Ki67 in MPGN rats. Paeoniflorin also inhibited HMC proliferation and blocked cell cycle progression. In addition, the contents of inflammatory factors and the expressions of macrophage marker iNOS were decreased after paeoniflorin treatment. Furthermore, we found that the protective effect of paeoniflorin was accompanied by a strong inhibition of the phosphatidylinositol 3-kinase (PI3K)/AKT/glycogen synthase kinase (GSK)-3β pathway. Paeoniflorin enhanced the inhibitory effect of PI3K inhibitor LY294002 and suppressed the activated effect of PI3K agonist insulin-like growth factor 1 (IGF-1) on PI3K/AKT/GSK-3β pathway. In conclusion, these results demonstrated that paeoniflorin ameliorates MPGN by inhibiting mesangial cell proliferation and inflammatory response through the PI3K/AKT/GSK-3β pathway.

Paeoniflorin protects spiral ganglion neurons from cisplatin-induced ototoxicity: Possible relation to PINK1/BAD pathway

The objective of this study was to elucidate whether paeoniflorin (PF) exerted an effect on cisplatin‐induced spiral ganglion neuron (SGN) damage, with special attention given to the role of PINK1/BAD pathway in this process. Middle cochlear turn culture and C57BL/6 mice were utilized to identify the character of PF in vitro and in vivo. We found that cisplatin treatment led to SGN damage, in which reactive oxygen species (ROS) generation increased, PINK1 expression decreased, BAD accumulation on mitochondria raised and mitochondrial apoptotic pathway activated. Conversely, we demonstrated that PF pre‐treatment obviously mitigated cisplatin‐induced SGN damage. Mechanistic studies showed that PF could reduce ROS levels, increase PINK1 expression, decrease the BAD accumulation on mitochondria and, thus, alleviate the activated mitochondrial apoptosis in SGNs caused by cisplatin. Overall, the findings from this work reveal the important role of PF and provide another strategy against cisplatin‐induced ototoxicity.

Paeoniflorin attenuated bupivacaine-induced neurotoxicity in SH-SY5Y cells via suppression of the p38 MAPK pathway

Bupivacain, a common local anesthetic, can cause neurotoxicity and permanent neurological disorders. Paeoniflorin has been widely reported as a potential neuroprotective agent in neural injury models. However, the roles and molecular basis of paeoniflorin in bupivacaine-induced neurotoxicity are still undefined. In the current study, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was performed to detect cell viability. Apoptotic rate was measured through double-staining of Annexin V-FITC and propidium iodide on a flow cytometer. Western blot assay was carried out to examine the protein levels of p38 mitogen-activated protein kinase (p38 MAPK), phosphorylated-p38 MAPK (p-p38 MAPK), Bcl-2, and Bax. caspase-3 activity was determined using a caspase-3 activity assay kit. We found that paeoniflorin dose-dependently attenuated bupivacaine-induced viability inhibition and apoptosis in SH-SY5Y cells. Moreover, paeoniflorin inhibited bupivacaine-induced activation of p38 MAPK pathway in SH-SY5Y cells. Paeoniflorin alone showed no significant effect on cell viability, apoptosis and p38 MAPK signaling in SH-SY5Y cells. Inhibition of p38 MAPK signaling by SB203580 or small interfering RNA targeting p38 (si-p38) abated bupivacaine-induced viability inhibition and apoptosis in SH-SY5Y cells. In conclusion, paeoniflorin alleviated bupivacaine-induced neurotoxicity in SH-SY5Y cells via suppression of the p38 MAPK pathway, highlighting the potential values of paeoniflorin in relieving bupivacaine-induced neurotoxicity.

Trametenolic acid B protects against cerebral ischemia and reperfusion injury through modulation of microRNA-10a and PI3K/Akt/mTOR signaling pathways

Trametenolic acid B (TAB) was a lanostane-type triterpenoid isolated from the trametes lactinea (Berk.) Pat. We have previously reported that extract from trametes lactinea (Berk.) Pat and TAB could efficiently improve learning and memory ability of the cerebral ischemia injury rats and suppress mitochondrial-mediated apoptosis in hydrogen peroxide damaged SH-SY5Y cells. However, the potential mechanisms have not been fully understood yet. The current study was to further investigate the protective effect of TAB on oxygen glucose deprivation/reoxygenation (OGD/R)-damaged SH-SY5Y cells and cerebral ischemia/reperfusion (I/R) injury rats, as well as its mechanisms involved. Cell experiments demonstrated that TAB (10, 20 and 40 μg/mL) protected OGD/R-induced SH-SY5Y cell injury by promoting cell proliferation and suppressing LDH leakage; Meanwhile, the results in vivo showed that TAB (20, 40 and 80 mg/kg) might significantly ameliorate the neurological deficit score, cerebral edema, neuronal cell loss and apoptosis, suppress cerebral infarction volume of the cerebral I/R injury rats. Further studies in vitro and in vivo indicated TAB could efficiently reduce OGD/R-damaged SH-SY5Y cell and cerebral I/R rat serum ROS, LDH and MDA levels, elevate SOD, GSH-Px and CAT activities, downregulate miR-10a mRNA and Bax, cytochrome C, cleaved-caspase-3 and cleaved-caspase-9 protein expressions, upregulate p-PIK3CA, p-Akt, p-mTOR, Bcl-2, pro-caspase-9 and pro-caspase-3 protein expressions and p-PIK3CA/PIK3CA, p-Akt/Akt, p-mTOR/mTOR ratios (P < 0.05 or P < 0.01, respectively). Our present study indicated that TAB possessed neuroprotective property against ODG/R and I/R injury by suppressing miR-10a expression, activating PI3K/Akt/mTOR signaling pathway, thereby reducing mitochondrial-mediated apoptosis, which provided a new insight for interpreting the underlying mechanisms of TAB' neuroprotective effect and a candidate agent to treat cerebral I/R injury.

Neuroprotection by Paeoniflorin against Nuclear Factor Kappa B-Induced Neuroinflammation on Spinal Cord Injury

Background

Acute spinal cord injury (SCI) is one of the most common and devastating causes of sensory or motor dysfunction. Nuclear factor-kappa B(NF-κB)-mediated neuroinflammatory responses, in addition to nitric oxide (NO), are key regulatory pathways in SCI. Paeoniflorin (PF), a major active component extracted from Paeonia roots, has been suggested to exert neuroprotective effects in the central nervous system. However, whether PF could improve the motor function after SCI in vivo is still unclear.

Method

Immunohistochemical analysis, western blot, real-time quantitative PCR, immunofluorescence staining, and histopathological and behavioral evaluation were used to explore the effects of paeoniflorin after SCI for 14 days.

Results

In this study, PF treatment significantly inhibited NF-κB activation and downregulated the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2(COX-2), and Nogo-A. Comparing behavioral and histological changes in SCI and PF treatment groups, we found that PF treatment improved motor function recovery, attenuated the histopathological damage, and increased neuronal survival in the SCI model. PF treatment also reduced expression levels of Bax and c-caspase-3 and increased the expression level of Bcl-2 and cell viabilities. Upregulation of TNF-α, IL-6, and IL-1β after injury was also prevented by PF.

Conclusion

These results suggest that the neuroprotective effects of PF are related to the inhibition of the NF-κB signaling pathway. And PF may be a therapeutic strategy in spinal cord injury.

Paeoniflorin Ameliorates Fructose-Induced Insulin Resistance and Hepatic Steatosis by Activating LKB1/AMPK and AKT Pathways

The present study aimed to evaluate the effects of paeoniflorin on insulin resistance and hepatic steatosis induced by fructose. Male Sprague-Dawley rats were fed 20% fructose drink for eight weeks. The insulin sensitivity, serum lipid profiles, and hepatic lipids contents were measured. The results showed that paeoniflorin significantly decreased serum insulin and glucagon levels, improved insulin sensitivity and serum lipids profiles, and alleviated hepatic steatosis in fructose-fed rats. Moreover, paeoniflorin enhanced the phosphorylation level of AMP-activated protein kinase (AMPK) and protein kinase B (PKB/AKT) and inhibited the phosphorylation of acetyl coenzyme A carboxylase (ACC)1 in liver. Paeoniflorin also increased the hepatic carnitine palmitoyltransferase (CPT)-1 mRNA and protein expression and decreased the mRNA expression of sterol regulatory element-binding protein (SREBP)1c, stearyl coenzyme A decarboxylase (SCD)-1 and fatty acid synthetase (FAS). Furthermore, we found that paeoniflorin significantly increased the heptatic protein expression of tumor suppressor serine/threonine kinase (LKB)1 but not Ca²⁺/CaM-dependent protein kinase kinase (CaMKK)β. These results suggest that the protective effects of paeoniflorin might be involved in the activation of LKB1/AMPK and insulin signaling, which resulted in the inhibition of lipogenesis, as well as the activation of β-oxidation and glycogenesis, thus ameliorated the insulin resistance and hepatic steatosis. The present study may provide evidence for the beneficial effects of paeoniflorin in the treatment of insulin resistance and non-alcoholic fatty liver.

Neuroprotective effect of paeoniflorin on okadaic acid-induced tau hyperphosphorylation via calpain/Akt/GSK-3β pathway in SH-SY5Y cells

Abnormal phosphorylation of tau, one of the most common symptoms of dementia, has become increasingly important in the study of the etiology and development of Alzheimer's disease. Paeoniflorin, the main bioactive component of herbaceous peony, is a monoterpene glycoside, which has been reported to exert beneficial effects on neurodegenerative disease. However, the effect of paeoniflorin on tauopathies remains ambiguous. SH-SY5Y cells were treated with okadaic acid (OA) for 8 h to induce tau phosphorylation and no cell death was observed. Optical microscopy results showed that paeoniflorin ameliorated okadaic acid induced morphological changes, including cell swelling and synapsis shortening. Western blotting data illustrated that paeoniflorin reversed okadaic acid induced tau hyperphosphorylation, which was enhanced by inhibiting the activities of calpain, Akt and GSK-3β. Transmission electron microscopy results showed that paeoniflorin alone can reduce the number of autophagosomes and stabilize the microtubule structure. In addition, calpastain and paeoniflorin enhance the effect of paeoniflorin on stabilizing microtubules. In addition, calpastain markedly enhanced the effect of paeoniflorin on reversing okadaic acid-lowered fluorescence intensity of both MAP-2 and β III-tubulin, two microtubule-associated proteins. This study shows that paeoniflorin protected SH-SY5Y cells against okadaic acid assault by interfering with the calpain/Akt/GSK-3β-related pathways, in which autophagy might be involved. Besides, paeoniflorin is found to relieve the stress response of the microtubule structure system caused by okadaic acid treatment. The results presented in this study suggest that paeoniflorin potentially plays an important role in tauopathies.

Paeoniflorin reduces neomycin-induced ototoxicity in hair cells by suppression of reactive oxygen species generation and extracellularly regulated kinase signalization

The present study was designed to investigate the effect of paeoniflorin (PF) on neomycin-induced ototoxicity in hair cells (HCs). Here, we took advantage of C57BL/6 mice and cochlear explants culture to determine the role of PF in vivo and in vitro. We demonstrated that neomycin exposure induced severe hearing loss and HC damage, which was mediated by activated mitochondrial apoptosis pathway, promoted extracellular signal-regulated kinase (ERK) signaling as well as enhanced reactive oxygen species (ROS) generation in HCs. Interestingly, we found that PF pretreatment significantly alleviated neomycin-induced hearing loss, attenuated HC injury and decreased HC apoptosis caused by neomycin. Mechanistic studies revealed that PF could decrease cellular ROS levels, suppress the activation of ERK signaling and, subsequently, mitigate the imbalance of mitochondrial apoptotic pathway, thus protecting HCs from neomycin-induced apoptosis. This study indicates that PF may serve as an antioxidative and anti-apoptotic agent to prevent hearing loss caused by neomycin.

Paeoniflorin exerts neuroprotective effects against glutamate‑induced PC12 cellular cytotoxicity by inhibiting apoptosis

Paeoniflorin (PF) is an active ingredient of Radix Paeoniae, which is known to exert neuroprotective effects. However, the mechanims behind the neuroprotective effects of PF are not yet fully understood. The apoptosis of neurons plays an important role in the cerebral ischemia-induced cascade response. This study aimed to investigate neuroprotective effects of PF against glutamate‑induced PC12 cellular cytotoxicity and to determine whether these effects are mediated via the inhibition of apoptosis in vitro and the activity of mitochondrial apoptosis-associated proteins in PC12 cells. Exposure of the PC12 cells to glutamate induced cell morphological changes, significantly decreased cell viability and induced apoptosis, with similar results being observed from the Hoechst 33342 staining and Annexin V/PI staining experiments. Glutamate also increased the lactate dehydrogenase release by the PC12 cells. However, treatment with PF prevented these effects. Furthermore, PF inhibited Bax and Bad expression and increased Bcl-2 and Bcl-xL expression; it also decreased the levels of downstream protein (caspase-3 and caspase-9). Collectively, our results indicate that PF protects PC12 cells against glutamate-induced neurotoxicity possibly through the inhibition of the expression of mitochondrial apoptosis-associated proteins.

Protective effects of paeoniflorin on TNBS-induced ulcerative colitis through inhibiting NF-kappaB pathway and apoptosis in mice

Paeoniflorin is traditionally used to treat inflammatory disorders. In our laboratory, we have scientifically validated the anti-inflammatory effect of paeoniflorin. In this study, it has been aimed to evaluate in vivo anti-inflammatory effect of paeoniflorin isolated from the dried peeled root of Paeonia lactiflora Pall. It was further intended to find out the probable mechanism of anti-inflammatory effect of paeoniflorin. The anti-inflammatory effect of paeoniflorin (15, 30 and 45mg/kg) was measured employing TNBS-induced ulcerative colitis model of acute inflammation. The TNBS injection resulted significant colitis formation when compared with un-injected mice. The anti-inflammatory effects of paeoniflorin for ulcerative colitis were assessed by body weight, colonic weight and length, macroscopic scores, and histopathological examinations. In addition, the colonic tissue levels of inflammation markers, including myeloperoxidase (MPO), IL-2, IL-6, IL-10, IL-12, IL-1β, TNF-α and IFN-γ were also determined to assess the effect of paeoniflorin. In addition, western blot demonstrated that paeoniflorin inhibited NF-kappaB signaling pathway and apoptosis in TNBS-induced ulcerative colitis tissues. In conclusion, all the findings of this study suggested that paeoniflorin has the anti-inflammatory effect in ulcerative colitis via inhibiting MAPK/NF-kappaB pathway and apoptosis in mice.

Paeoniflorin Attenuates Cerebral Ischemia-Induced Injury by Regulating Ca2+/CaMKII/CREB Signaling Pathway

Paeoniflorin (PF) is an active ingredient of Paeoniae Radix which possesses the neuroprotective effect. However, so far, the neuroprotective mechanism of PF has still not been fully uncovered. The Ca²⁺/Ca²⁺/calmodulin-dependent protein kinase II (CaMKII)/cAMP response element-binding (CREB) signaling pathway plays an important role in the intracellular signal transduction pathway involved in cell proliferation, cell survival, inflammation and metabolism. Herein, the neuroprotective roles of PF in the models of middle cerebral artery occlusion (MCAO) followed by reperfusion in rats and N-methyl-d-aspartic acid (NMDA)-induced excitotoxicity in primary hippocampal neurons were investigated. Moreover, we attempted to confirm the hypothesis that its protection effect is via the modulation of the Ca²⁺/CaMKI)/CREB signaling pathway. In this study, PF not only significantly decreased neurological deficit scores and infarct volume in vivo, but also improved neurons’ cell viability, and inhibited neurons’ apoptosis and intracellular Ca²⁺ concentration in vitro. Furthermore, PF significantly up-regulated p-CREB and p-CaMKII, and down-regulated calmodulin (CaM) in vivo and in vitro. The results indicate that the protective effect of PF on cerebral ischemia reperfusion injury is possible through regulating the Ca²⁺/CaMKII/CREB signaling pathway.

Investigation of the protective effect of Paeonia lactiflora on Semen Strychni-induced neurotoxicity based on monitoring nine potential neurotoxicity biomarkers in rat serum and brain tissue

Semen Strychni has been widely used as a traditional Chinese herb medicine, but its clinical use was limited for its potential neurotoxicity and nephrotoxicity. This study aimed to investigate S. Strychni-induced neurotoxicity and the neuro-protective effect of Paeonia lactiflora based on monitoring nine potential neurotoxicity biomarkers in rat serum and brain tissue. A sensitive liquid chromatography-tandem mass spectrometry method was developed and validated to monitor serotonin, tryptophan, dopamine, tyrosine and glutamate in serum and five brain regions (prefrontal cortex, hippocampus, striatum, cerebellum and hypothalamus). Analytes were separated on a CAPCELL CORE PC column (150 mm × 2 mm, 2.7 μm) with a gradient program of acetonitrile-water (0.2 % formic acid) and a total runtime of 7.5 min. In addition, enzyme-linked immunosorbent assay was conducted to determine four kinds of protein (tryptophan hydroxylase, tyrosine hydroxylase, endogenous brain-derived neurotrophic factor and nerve growth factor). Results demonstrated that the administration of S. Strychni could cause certain endogenous substances disorder. These analytes were found significantly changed (p < 0.05) in serum (except glutamate) and in certain tested brain regions in S. Strychni extract group. Pretreatment of P. lactiflora could significantly reverse the S. Strychni-induced neurotoxicity and normalize the levels of such endogenous substances. The study could be further used in predicting and monitoring neurotoxicity caused by other reasons, and it was expected to be useful for improving clinical use of S. Strychni through pretreatment with P. lactiflora.

Neuroprotective Effects of Theaflavins Against Oxidative Stress-Induced Apoptosis in PC12 Cells

Oxidative stress can induce neuronal apoptosis via the production of superoxide and hydroxyl radicals. This process is as a major pathogenic mechanism in neurodegenerative disorders. In this study, we aimed to clarify whether theaflavins protect PC12 cells from oxidative stress damage induced by H₂O₂. A cell model of PC12 cells undergoing oxidative stress was created by exposing cells to 200 μM H₂O₂ in the presence or absence of varying concentrations of theaflavins (5, 10, and 20 μM). Cell viability was monitored using the MTT assay and Hoechst 33258 staining, showing that 10 μM theaflavins enhanced cell survival following 200 μM H₂O₂ induced toxicity and increased cell viability by approximately 40 %. Additionally, we measured levels of intracellular reactive oxygen species (ROS) and antioxidant enzyme activity. This suggested that the neuroprotective effect of theaflavins against oxidative stress in PC12 cells is derived from suppression of oxidant enzyme activity. Furthermore, Western blot analyses indicated that theaflavins downregulated the ratio of pro-apoptosis/anti-apoptosis proteins Bax/Bcl-2. Theaflavins also downregulated the expression of caspase-3 compared with a H₂O₂-treated group that had not been treated with theaflavins. Interestingly, this is the first study to report that the four main components of theaflavins found in black tea can protect neural cells (PC12) from apoptosis induced by H₂O₂. These findings provide the foundations for a new field of using theaflavins or its source, black tea, in the treatment of neurodegenerative diseases caused by oxidative stress.

Paeoniflorin and Albiflorin Attenuate Neuropathic Pain via MAPK Pathway in Chronic Constriction Injury Rats

Neuropathic pain remains as the most frequent cause of suffering and disability around the world. The isomers paeoniflorin (PF) and albiflorin (AF) are major constituents extracted from the roots of Paeonia (P.) lactiflora Pall. Neuroprotective effect of PF has been demonstrated in animal models of neuropathologies. However, only a few studies are related to the biological activities of AF and no report has been published on analgesic properties of AF about neuropathic pain to date. The aim of this study was to compare the effects of AF and PF against CCI-induced neuropathic pain in rat and explore the underlying mechanism. We had found that both PF and AF could inhibit the activation of p38 mitogen-activated protein kinase (p38 MAPK) pathway in spinal microglia and subsequent upregulated proinflammatory cytokines (interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α)). AF further displayed remarkable effects on inhibiting the activation of astrocytes, suppressing the overelevated expression of phosphorylation of c-Jun N-terminal kinases (p-JNK) in astrocytes, and decreasing the content of chemokine CXCL1 in the spinal cord. These results suggest that both PF and AF are potential therapeutic agents for neuropathic pain, which merit further investigation.

Paeoniflorin protects Schwann cells against high glucose induced oxidative injury by activating Nrf2/ARE pathway and inhibiting apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Paeoniflorin (PF) is the principal bioactive component of Paeonia lactiflora Pall., which an included in Tang Luo Ning recipe, a traditional Chinese herbal medicine based on Huangqi Guizhi Wuwu decoction. PF is also widely used in Traditional Chinese Medicine for the treatment of blood-arthralgia disease including diabetic peripheral neuropathy (DPN), but its underlying molecular mechanism of neuroprotective effects is not yet well understood. Diabetic hyperglycemia induced oxidative stress in Schwann cells, an important component of the peripheral nervous system, has been proposed as a unifying mechanism for DPN. The objective of this study is to determine the effects of PF on Schwann cells oxidative stress and apoptosis induced by high glucose.

MATERIALS AND METHODS

RSC96 cells, a Schwann cell line, were treated with high glucose (150mM) and PF (1, 10 and 100μM). Subsequently, MTT assay was performed. The level of apoptosis was examined by flow cytometry and the oxidative stress was reflected by reactive oxygen species (ROS), malondialdehyde (MDA), glutathione S-transferases (GST) and glutathione peroxidase (GPX) levels. The mRNA expressions of Nuclear factor-E2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) were detected by qRT-PCR. The levels of Kelch-like ECH-associating protein 1 (Keap1), Nrf2, HO-1, γ-glutamylcysteine synthetase (γGCS), B-cell CLL/lymphoma 2 (Bcl-2), Bax and Caspase 3 were detected by High content analysis and/or Western blot.

RESULTS

The role of PF markedly suppressed high glucose induced Schwann cells oxidative stress by decreasing ROS and MDA levels and increasing GST and GPX activity. Western blot analysis showed that PF induced nuclear translocation of Nrf2. High content analysis showed that PF promoted Nrf2 dissociation from Keap1 and upregulating the Nrf2/ antioxidant response element (ARE) pathway. Furthermore, PF reduced Schwann cells apoptosis by increasing Bcl-2 and inhibiting Bax and Caspase-3 expressions.

CONCLUSIONS

PF in the management of Schwann cells oxidative stress induced by high glucose may be associated with activation of Nrf2/ARE pathway and Bcl-2-related apoptotic pathway.

The skin-depigmenting potential of Paeonia lactiflora root extract and paeoniflorin: in vitro evaluation using reconstructed pigmented human epidermis

OBJECTIVE

The roots of the herb Paeonia lactiflora ('White Peony') are used in association with other herbs in traditional clinical cosmetic practice in China as oral treatment for skin pigmentary disorders, such as brown or dark pigmentary spots. However, the skin-depigmenting potential of Paeonia lactiflora root extract and its main ingredient paeoniflorin has been scarcely investigated by topical application. The purpose of this study was to evaluate the efficacy of Paeonia lactiflora root extract and paeoniflorin as skin whitening agent in cosmetic application.

METHODS

Paeonia lactiflora root extract (containing 53.25% of paeoniflorin) and paeoniflorin (97% purity) were applied topically on reconstructed pigmented human epidermis model, a three-dimensional (3D) human skin equivalent, showing morphological and functional characteristics similar to those of in vivo human skin. Two specific methods were used for quantifying melanin inside the reconstructed pigmented epidermis: Fontana-Masson staining (2D quantification) and multiphoton microscopy (3D quantification).

RESULTS

Compared to vehicle (dimethyl sulfoxide DMSO), a significant decrease in 2D and 3D melanin content was observed after topical application on reconstructed pigmented epidermis of Paeonia lactiflora extract at 300 μg mL(-1) (-28% and -27%, respectively) and paeoniflorin at 120 μg mL(-1) /250 μM (-30% and -23%, respectively), which is in the same order of magnitude as the positive reference 4-n-butylresorcinol at 83 μg mL(-1) /500 μM (-26% and -40%, respectively).

CONCLUSION

These results demonstrate, for the first time, the depigmenting potential of paeoniflorin and thus the potential interest of using Paeonia lactiflora root extracts containing paeoniflorin in cosmetic or dermatological applications for reducing the severity of some hyperpigmented skin disorders.

Protective effects of paeoniflorin against FasL-induced apoptosis of intervertebral disc annulus fibrosus cells via Fas-FasL signalling pathway

In the present study, we demonstrate that the degeneration of intervertebral discs is caused by ageing and apoptosis of matrix cells. Apoptosis is as essential as the function of proteoglycan synthesis in assessing the possible degeneration of intervertebral discs; paeoniflorin (PF) induces cytoprotective effects on various types of cells. In this study, the function of PF in inhibiting Fas ligand (FasL)-induced apoptosis in annulus fibrosus cells was assessed, and the correlation between apoptosis and the Fas-FasL pathway was determined. Annulus fibrosus cells were derived from the intervertebral discs of 1-month-old Sprague Dawley rats; the cells were characterised by toluidine blue staining and subjected to apoptosis with FasL. PF was diluted to various concentrations and added to annulus fibrosus cells at various times. The impact of PF and FasL on cell apoptosis of annulus fibrosus cells was determined by flow cytometry. Western blot analysis was performed to determine the protein expression levels of Fas and caspase-3. The percentages of apoptotic annulus fibrosus cells as well as the expression levels of caspase-3 and Fas were significantly reduced following treatment with 208, 20.8 or 2.08 µM PF. PF inhibits the activation of the Fas-FasL signal pathway and decreases FasL-induced apoptosis of annulus fibrosus cells.

Activation of Type 4 Metabotropic Glutamate Receptor Attenuates Oxidative Stress-Induced Death of Neural Stem Cells with Inhibition of JNK and p38 MAPK Signaling

Promoting both endogenous and exogenous neural stem cells' (NSCs) survival in the hostile host environments is essential to cell replacement therapy for central nervous system (CNS) disorders. Type 4 metabotropic glutamate receptor (mGluR4), one of the members of mGluRs, has been shown to protect neurons from acute and chronic excitotoxic insults in various brain damages. The present study investigated the preventive effects of mGluR4 on NSC injury induced by oxidative stress. Under challenge with H2O2, loss of cell viability was observed in cultured rat NSCs, and treatment with selective mGluR4 agonist VU0155041 conferred protective effects against the loss of cellular viability in a concentration-dependent manner, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Pretreatment of VU0155041 (30 μM) also inhibited the excessive NSC death induced by H2O2, and group III mGluRs antagonist (RS)-a-methylserine-O-phosphate (MSOP) or gene-targeted knockdown abolished the protective action of mGluR4, indicated by propidium iodide-Hoechst and terminal deoxynucleotidyl transferase-mediated UTP nick end labeling (TUNEL) staining. Western blot assay demonstrated that mGluR4 activation reversed the decreased procaspase-8/9/3and the destructed Bcl-2/Bax expressing balance, and likewise, MSOP and mGluR4 knockdown abrogated the action of mGluR4 activity. Furthermore, inhibition of JNK and p38 mitogen-activated protein kinases (MAPKs) were observed after mGluR4 activation, and as paralleling control, JNK-specific inhibitor SP600125 and p38-specific inhibitor SB203580 significantly rescued the H2O2-mediated NSC apoptosis and cleavage of procaspase-3. We suggest that activation of mGluR4 prevents oxidative stress-induced NSC death and apoptotic-associated protein activities with involvement of inhibiting the JNK and p38 pathways in cell culture. Our findings may help to develop strategies for enhancing the resided and transplanted NSC survival after oxidative stress insult of CNS.

Paeoniflorin exerts a nephroprotective effect on concanavalin A-induced damage through inhibition of macrophage infiltration

BACKGROUND

It is well established that macrophage infiltration is involved in concanavalin A (conA)-induced liver injury. However, the role of macrophages in conA-induced renal injury remains unknown. The aims of this study were to investigate macrophage infiltration in conA-induced renal injury and determine whether paeoniflorin (PF) could inhibit macrophage infiltration into the kidney.

METHODS

BALB/C mice were pre-treated with or without PF 2 h (h) before conA injection. At 8 h after con A injection, all the mice were sacrificed; The liver and kidney histology were studied. The renal CD68 expression was detected by immunohistochemical and real-time PCR analysis. The level of expression of C-X-C chemokine receptor type 3 (CXCR3) was analyzed by western blot, immunohistochemical and real-time PCR. The pathophysiological involvement of CXCR3 in macrophage infiltration were investigated using dual-colour immunofluorescence microscopy.

RESULTS

PF administration significantly reduced the elevated serum levels of alanine transaminase (ALT), blood urea nitrogen (BUN), creatinine (Cr) and the severity of liver and renal damage compared with that in the conA-vehicle group. PF administration inhibited the increase in renal IL1β mRNA expression and concentration. Furthermore, immunohistochemical analysis showed that macrophages secreted CXCR3 in the kidneys of the conA-vehicle mice. Immunofluorescence microscopy demonstrated CXCR3 bound tightly to C-X-C motif ligand 11 (CXCL11) in the kidneys of the conA-vehicle mice and showed that PF treatment could suppress CXCR3/CXCL11 over-activation.

CONCLUSIONS

Macrophage infiltration was a notable pathological change in the kidneys of conA-treated mice. PF administration attenuated conA-induced renal damage, at least in part, by inhibiting the over-activated CXCR3/CXCL11 signal axis.

Paeoniflorin inhibits human gastric carcinoma cell proliferation through up-regulation of microRNA-124 and suppression of PI3K/Akt and STAT3 signaling

AIM: To examine the potential anti-tumor activity of paeoniflorin in the human gastric carcinoma cell line MGC-803.

METHODS: Cell viability and cytotoxic effects in MGC-803 cells were analyzed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay, respectively. Cell apoptosis of MGC-803 cells was measured using flow cytometry, DAPI staining assay and caspase-3 activity assay. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to measure the expression of microRNA-124 (miR-124) in response to paeoniflorin. The expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), phospho-Akt (p-Akt) and phospho-signal transducer and activator of transcription 3 (p-STAT3) were also measured by quantitative RT-PCR and Western blot analysis in normal, miR-124 and anti-miR-124 over-expressing MGC-803 cells, treated with paeoniflorin.

RESULTS: Paeoniflorin was found to inhibit MGC-803 cell viability in a dose-dependent manner. Paeoniflorin treatment was associated with the induction of apoptosis and caspase-3 activity in MGC-803 cells. Paeoniflorin treatment significantly increased miR-124 levels and inhibited the expression of PI3K, Akt, p-Akt and p-STAT3 in MGC-803 cells. Interestingly, the over-expression of miR-124 inhibits PI3K/Akt and phospho-STAT3 expressions in MGC-803 cells. PI3K agonist (IGF-1, 1 μg/10 μL) or over-expression of STAT3 reversed the effect of paeoniflorin on the proliferation of MGC-803 cells. Over-expression of anti-miR-124 in MGC-803 cells reversed paeoniflorin-induced up-regulation.

CONCLUSION: In summary, the in vitro data suggest that paeoniflorin is a potential novel therapeutic agent against gastric carcinoma, which inhibits cell viability and induces apoptosis through the up-regulation of miR-124 and suppression of PI3K/Akt and STAT3 signaling.