Anti-oxidative and anti-inflammatory effects of cinnamaldehyde on protecting high glucose-induced damage in cultured dorsal root ganglion neurons of rats

Mechanistic insights into the anti-oxidative and anti-inflammatory functions of covalent-reactive cinnamyl compounds within Cinnamomum cassia

BACKGROUND

Cinnamomum cassia Presl (Lauraceae) is widely used as a medicinal plant in the folk medicine and pharmaceutic industry, for its promising anti-inflammatory, anti-oxidative, and anti-bacterial function. However, the major bioactive components were still in debate, and their underlying molecular mechanism was not yet fully understood.

PURPOSE

This study aimed to identify the bioactive ingredients of C. cassia and investigate the molecular mechanism using in vitro and in silico methods.

METHODS

UPLC-QTOF/MS/MS analysis was used to characterize the chemical constituents of alcoholic extract from C. cassia. Reduced glutathione was employed to deplete covalent active cinnamyl compounds. Subsequently, the anti-inflammatory and antioxidant effects of covalent reactive and non-covalent reactive ingredients from C. cassia extract were compared. Their molecular mechanisms were investigated using untargeted metabolomics, in vitro assays, surface plasmon resonance (SPR), and molecular modeling.

RESULTS

Chemical analysis and in vitro assays confirmed the covalent reactive cinnamyl compounds, such as cinnamaldehyde and 2-methoxycinnamaldehyde, exhibited anti-inflammatory and anti-oxidative activity on LPS-stimulated macrophages. Untargeted metabolomics revealed that cinnamaldehyde, one of the covalent reactive cinnamyl compounds, primarily affected amino acid metabolism, and glucose metabolism, promoted glutathione synthesis within LPS-stimulated macrophages, and affected the metabolic profile of M1 macrophages. Consistent with these findings, cinnamaldehyde significantly increased glutathione synthesis and induced glutathione efflux from murine macrophages. In contrast to the literature data, we observed that cinnamaldehyde did not cause GSH depletion, nor elevate the expression of glutamate-cysteine ligase (GCL) in proinflammatory macrophages at low concentrations. The SPR experiment and molecular modeling demonstrated that GCLC was the potential target of cinnamaldehyde.

CONCLUSIONS

Our study not only demonstrated the reactive cinnamyl species as the principal antioxidative component of C. cassia but also unveiled a novel molecular mechanism whereby covalent reactive compounds exert their antioxidative effects through covalent modification of GCLC at its active center.

Cinnamaldehyde attenuates TNF-α induced skeletal muscle loss in C2C12 myotubes via regulation of protein synthesis, proteolysis, oxidative stress and inflammation

Inflammation is the primary driver of skeletal muscle wasting, with oxidative stress serving as both a major consequence and a contributor to its deleterious effects. In this regard, regulation of both can efficiently prevent atrophy and thus will increase the rate of survival [1]. With this idea, we hypothesize that preincubation of Cinnamaldehyde (CNA), a known compound with anti-oxidative and anti-inflammatory properties, may be able to prevent skeletal muscle loss. To examine the same, C2C12 post-differentiated myotubes were treated with 25 ng/ml Tumor necrosis factor-alpha (TNF-α) in the presence or absence of 50 μM CNA. The data showed that TNF-α mediated myotube thinning and a lower fusion index were prevented by CNA supplementation 4 h before TNF-α treatment. Moreover, a lower level of ROS and thus maintained antioxidant defense system further underlines the antioxidative function of CNA in atrophic conditions. CNA preincubation also inhibited an increase in the level of inflammatory cytokines and thus led to a lower level of inflammation even in the presence of TNF-α. With decreased oxidative stress and inflammation by CNA, it was able to maintain the intracellular level of injury markers (CK, LDH) and SDH activity of mitochondria. In addition, CNA modulates all five proteolytic systems [cathepsin-L, UPS (atrogin-1), calpain, LC3, beclin] simultaneously with an upregulation of Akt/mTOR pathway, in turn, preserves the muscle-specific proteins (MHCf) from degradation by TNF-α. Altogether, our study exhibits attenuation of muscle loss and provides insight into the possible mechanism of action of CNA in curbing TNF-α induced muscle loss, specifically its effect on proteolysis and protein synthesis.

Cinnamaldehyde Alleviates Bone Loss by Targeting Oxidative Stress and Mitochondrial Damage via the Nrf2/HO-1 Pathway in BMSCs and Ovariectomized Mice

Osteoporosis (OP) is typically brought on by disruption of bone homeostasis. Excessive oxidative stress and mitochondrial dysfunction are believed to be the primary mechanisms underlying this disorder. Therefore, in order to restore bone homeostasis effectively, targeted treatment of oxidative stress and mitochondrial dysfunction is necessary. Cinnamaldehyde (CIN), a small molecule that acts as an agonist for the nuclear factor erythroid 2-related factor (Nrf2), has been found to possess antiapoptotic, anti-inflammatory, and antioxidant properties. We found that CIN, while rescuing apoptosis, can also reduce the accumulation of reactive oxygen species (ROS) to improve mitochondrial dysfunction and thus restore the osteogenic differentiation potential of BMSCs disrupted by hydrogen peroxide (H2O2) exposure. The role of CIN was preliminarily considered to be a consequence of Nrf2/HO-1 axis activation. The ovariectomized mice model further demonstrated that CIN treatment ameliorated oxidative stress in vivo, partially reversing OVX-induced bone loss. This improvement was seen in the trabecular microarchitecture and bone biochemical indices. However, when ML385 was concurrently injected with CIN, the positive effects of CIN were largely blocked. In conclusion, this study sheds light on the intrinsic mechanisms by which CIN regulates BMSCs and highlights the potential therapeutic applications of these findings in the treatment of osteoporosis.

A systematic review on anti-diabetic plant essential oil compounds: Dietary sources, effects, molecular mechanisms, and safety

Type 2 diabetes mellitus (T2DM) is a multifaceted metabolic syndrome defined through the dysfunction of pancreatic β-cells driven by a confluence of genetic and environmental elements. Insulin resistance, mediated by interleukins and other inflammatory elements, is one of the key factors contributing to the progression of T2DM. Many essential oils derived from dietary plants are beneficial against various chronic diseases. We reviewed the anti-diabetic properties of dietary plant-derived essential oil compounds, with a focus on their molecular mechanisms by modulating specific signaling pathways and other critical inflammatory mediators involved in insulin resistance. High-quality literature published in the last 12 years, from 2010 to 2022, was collected from the Scopus, Web of Science, PubMed, and Embase databases using the search terms "dietary plants," "essential oils," "anti-diabetic," "insulin resistance," "antihyperglycemic," "T2DM," "anti-diabetic essential oils," and anti-diabetic mechanism." According to the results, the essential oil compounds, including cinnamaldehyde, carvacrol, zingerone, sclareol, zerumbone, myrtenol, thujone, geraniol, citral, eugenol, thymoquinone, thymol, citronellol, α-terpineol, and linalool have been demonstrated to contain strong anti-diabetic effects via modulating various signal transduction pathways linked to glucose metabolism. Additionally, in diabetes-related animal models, they can also considerably reduce the expression of TNF-α, IL-1β, IL-4, IL-6, iNOS, and COX-2. The main signaling molecules regulated by these compounds include AMPK, GLUT4, Caspase-3, PPARγ, PPARα, NF-κB, p-IκBα, MyD88, MCP-1, SREBP-1c, AGEs, RAGE, VEGF, Nrf2/HO-1, and SIRT-1. They can also significantly inhibit the generation of TBARS and MDA, reduce oxidative stress, increase insulin levels, adiponectin, and glycoprotein enzymes, boost antioxidant enzymes like SOD, CAT, and GPx, as well as reduce glutathione and vital glycolytic enzymes. Besides, they can significantly lower the levels of liver enzymes and lipid profile markers. Moreover, most essential oil compounds are generally safe based on animal studies. In conclusion, dietary plant-derived essential oil compounds have potential anti-diabetic effects by influencing different signaling pathways and molecular targets linked to glucose metabolism, and should be safe and beneficial against diabetes and related complications.

Treatment Management of Diabetic Wounds Utilizing Herbalism: An Overview

BACKGROUND AND OBJECTIVES

Diabetes Mellitus, commonly known as DM, is a metabolic disorder which is characterized by high blood glucose level, i.e., chronic hyperglycemia. If it is not managed properly, DM can lead to many severe complexities with time and can cause significant damage to the kidneys, heart, eyes, nerves and blood vessels. Diabetic foot ulcers (DFU) are one of those major complexities which affect around 15-25% of the population diagnosed with diabetes. Due to diabetic conditions, the body's natural healing process slows down leading to longer duration for healing of wounds only when taken care of properly. Herbal therapies are one of the approaches for the management and care of diabetic foot ulcer, which utilizes the concept of synergism for better treatment options. With the recent advancement in the field of nanotechnology and natural drug therapy, a lot of opportunities can be seen in combining both technologies and moving towards a more advanced drug delivery system to overcome the limitations of polyherbal formulations.

METHODS

During the writing of this document, the data was derived from existing original research papers gathered from a variety of sources such as PubMed, ScienceDirect, Google Scholar.

CONCLUSION

Hence, this review includes evidence about the current practices and future possibilities of nano-herbal formulation in treatment and management of diabetic wounds.

Cinnamic aldehyde, an anti-inflammatory component in Du-Huo-Ji-Sheng-Tang, ameliorates arthritis in II collagenase and monosodium iodoacetate induced osteoarthritis rat models

Background and aim

Du-Huo-Ji-Sheng-Tang (DHJST) is a Chinese herbal formula used for arthralgia and arthritis treatment clinically. This study aims to evaluate the joint-protecting efficacy of DHJST and to identify the active constituents as the evaluation marker.

Experimental procedure

DHJST can be categorized into three recipes: Blood-tonifying-herbs Si-Wu-Tang (SWT), Wind-dampness-dispelling-herbs (WDH) and Qi-tonifying-herbs (TH). All formulas were used to explore the joint-protecting efficacies.

Results and conclusion

s: Firstly, DHJST could decrease the arthritis progression in the monosodium-iodoacetate-induced rat and cure arthritis in the type II collagenase-induced rat. Further, in lipopolysaccharide-stimulated RAW 264.7 cells, DHJST, TH and Cinnamomum cassia (CC), an ingredient in TH, were the most potent nitric oxide (NO) and prostaglandin E₂ (PGE₂) inhibitors. The major components, cinnamic aldehyde, showed the strongest NO and PGE₂ inhibition. Up-regulated inducible NO synthase (iNOS) and cyclooxygenase-2 were inhibited by DHJST, TH, CC, and cinnamic aldehyde. In interleukin-1β-stimulated primary chondrocytes, upregulated iNOS was inhibited by DHJST, TH, Cinnamomum cassia, and cinnamic aldehyde. Upregulated matrix metalloprotease-13 was only inhibited by DHJST and TH and Eucommia ulmoides (EU) extract. Results suggest that DHJST presented joint-protective and cure arthritis effects. TH presented equal joint-protective effects as DHJST. The major anti-inflammatory ingredient in TH was Cinnamomum cassia in TH. And cinnamic aldehyde was the potent anti-inflammatory active compound in Cinnamomum cassia. Therefore, this study may facilitate the modern use of DHJST with TH as a simplified version but equally effective anti-osteoarthritic agents with cinnamic aldehyde as a quality control marker of DHJST and TH in osteoarthritis prevention or treatment.

The potential for traditional Chinese therapy in treating sleep disorders caused by COVID-19 through the cholinergic anti-inflammatory pathway

Since the outbreak of Coronavirus disease (COVID-19) in 2019, it has spread rapidly across the globe. Sleep disorders caused by COVID-19 have become a major concern for COVID-19 patients and recovered patients. So far, there’s no effective therapy on this. Traditional Chinese therapy (TCT) has a great effect on sleep disorders, with rare side effects and no obvious withdrawal symptoms. The cholinergic anti-inflammatory pathway, a neuroregulatory pathway in the central nervous system that uses cholinergic neurons and neurotransmitters to suppress inflammatory responses, has been reported to be associated with sleep disorders and psychiatric symptoms. Many studies have shown that TCT activates the cholinergic anti-inflammatory pathway (CAP), inhibits inflammation, and relieves associated symptoms. Therefore, we believe that TCT may be a potential therapeutic strategy to alleviate sleep disorders induced by COVID-19 through CAP. In this review, we analyzed the relationship between cytokine storm induced by Coronavirus and sleep disorders, explained the influence of CAP on sleep disorders, discussed the TCT’s effect on CAP, and summarized the treatment effect of TCT on sleep disorders. Based on these practical researches and theoretical basis, we propose potential strategies to effectively improve the sleep disorders caused by COVID-19.

Rolipram and pentoxifylline combination ameliorates experimental diabetic neuropathy through inhibition of oxidative stress and inflammatory pathways in the dorsal root ganglion neurons

Diabetic neuropathy (DN) is the most challenging microvascular complication of diabetes and there is no suitable treatment for it, so the development of new agents to relieve DN is urgently needed. Since oxidative stress and inflammation play an essential role in the development of DN, clearance of these factors are good strategies for the treatment of this disease. According to key role of cyclic adenosine monophosphate (cAMP) in the regulation of oxidative stress and inflammatory pathways, it seems that phosphodiesterase inhibitors (PDEIs) can be as novel drug targets for improving DN through enhancement of cAMP level. The aim of this study was to evaluate the effects of rolipram, a selective PDE4 inhibitor, and pentoxifylline, a general PDE inhibitor on experimental model of DN and also to determine the possible mechanisms involved in the effectiveness of these agents. We investigated the effects of rolipram (1 mg/kg) and pentoxifylline (100 mg/kg) and also combination of rolipram (0.5 mg/kg) and pentoxifylline (50 mg/kg), orally for five weeks in rats that became diabetic by STZ (55 mg/kg, i.p.). After treatments, motor function was evaluated by open-field test, then rats were anesthetized and dorsal root ganglion (DRG) neurons isolated. Next, oxidative stress biomarkers and inflammatory factors were assessed by biochemical and ELISA methods, and RT-PCR analysis in DRG neurons. Rolipram and/or pentoxifylline treatment significantly attenuated DN - induced motor function deficiency by modulating distance moved and velocity. Rolipram and/or pentoxifylline treatment dramatically increased the cAMP level, as well as suppressed DN - induced oxidative stress which was associated with decrease in LPO and ROS and increase in TAC, total thiol, CAT and SOD in DRG neurons. On the other hand, the level of inflammatory factors (TNF-α, NF-kB and COX2) significantly decreased following rolipram and/or pentoxifylline administration. The maximum effectiveness was with rolipram and/or pentoxifylline combination on mentioned factors. These findings provide novel experimental evidence for further clinical investigations on rolipram and pentoxifylline combination for the treatment of DN.

Protective Effects of Cinnamaldehyde on the Oxidative Stress, Inflammatory Response, and Apoptosis in the Hepatocytes of Salmonella Gallinarum-Challenged Young Chicks

The development of novel therapeutics to treat multidrug-resistant pathogenic infections like Salmonella gallinarum is the need of the hour. Salmonella infection causes typhoid fever, jaundice, and Salmonella hepatitis resulting in severe liver injury. Natural compounds have been proved beneficial for the treatment of these bacterial infections. The beneficial roles of cinnamaldehyde due to its antibacterial, anti-inflammatory, and antioxidative properties have been determined by many researchers. However, alleviation of liver damage caused by S. gallinarum infection to young chicks by cinnamaldehyde remains largely unknown. Therefore, this study was performed to identify the effects of cinnamaldehyde on ameliorating liver damage in young chicks. Young chicks were intraperitoneally infected with S. gallinarum and treated with cinnamaldehyde orally. Liver and serum parameters were investigated by qRT-PCR, ELISA kits, biochemistry kits, flow cytometry, JC-1 dye experiment, and transcriptome analysis. We found that ROS, cytochrome c, mitochondrial membrane potential (Ψm), caspase-3 activity, ATP production, hepatic CFU, ALT, and AST, which were initially increased by Salmonella infection, significantly ( $P<0.05$ ) decreased by cinnamaldehyde treatment at 1, 3, and 5 days postinfection (DPI). In addition, S. gallinarum infection significantly increased proinflammatory gene expression (IL-1β, IL-6, IL-12, NF-κB, TNF-α, and MyD-88) and decreased the expression of anti-inflammatory genes (IL-8, IL-10, and iNOS); however, cinnamaldehyde reverted these effects at 1, 3, and 5 DPI. Transcriptome analysis showed that S. gallinarum modulates certain genes of the AMPK-mTOR pathway for its survival and replication, and these pathway modulations were reversed by cinnamaldehyde treatment. We concluded that cinnamaldehyde ameliorates inflammation and apoptosis by suppressing NF-Kβ/caspase-3 pathway and reverts the metabolic changes caused by S. gallinarum infection via modulating the AMPK-mTOR pathway. Furthermore, cinnamaldehyde has antibacterial, anti-inflammatory, antioxidative, and antiapoptotic properties against S. gallinarum-challenged young chicks and can be a candidate novel drug to treat salmonellosis in poultry production.

Jinmaitong Alleviates Diabetic Neuropathic Pain Through Modulation of NLRP3 Inflammasome and Gasdermin D in Dorsal Root Ganglia of Diabetic Rats

Jinmaitong (JMT) is a compound prescription of traditional Chinese medicine that has been used to treat diabetic neuropathic pain (DNP) for many years. Here, we investigated the effects of JMT on the activation of NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome and pyroptosis in Dorsal root ganglia (DRG) of diabetic rats. Streptozotocin (STZ)-induced diabetic rats were gavaged with JMT (0.88 g/kg/d) or alpha-lipoic acid (ALA, positive control, 0.48 mmol/kg/d) for 12 weeks. Distilled water was administered as a vehicle control to both diabetic and non-affected control rats. Blood glucose levels and body weights were measured. Behavioral changes were tested with mechanical withdrawal threshold (MWT) and tail-flick latency (TFL) tests. Morphological injury associated with DRG was observed with hematoxylin and eosin (H&E) and Nissl’s staining. mRNA and protein levels of NLRP3 inflammasome components (NLRP3, ASC, caspase-1), downstream IL-1β and gasdermin D (GSDMD) were evaluated by immunohistochemistry, quantitative real time-PCR and western blot. The results showed that JMT had no effect on blood glucose levels and body weights, but significantly improved MWT and TFL behavior in diabetic rats, and attenuated morphological damage in the DRG tissues. Importantly, JMT decreased the mRNA and protein levels of components of NLRP3 inflammasome, including NLRP3, ASC and caspase-1. JMT also down-regulated the expression of IL-1β and GSDMD in the DRG of DNP rats. In addition, ALA treatment did not perform better than JMT. In conclusion, JMT effectively relieved DNP by decreasing NLRP3 inflammasome activation and pyroptosis, providing new evidence supporting JMT as an alternative treatment for DNP.

Neuroprotective Effect of Cinnamaldehyde on Secondary Brain Injury After Traumatic Brain Injury in a Rat Model

OBJECTIVE

The aim of this study was to investigate the possible neuroprotective effects of cinnamaldehyde (CA) on secondary brain injury after traumatic brain injury (TBI) in a rat model.

METHODS

Rats were randomly divided into 4 groups: control (n = 9), TBI (n = 9), vehicle (0.1% Tween 80; n = 8), and CA (100 mg/kg) (n = 9). TBI was induced by the weight-drop model. In brain tissues, myeloperoxidase activity and the levels of luminol-enhanced and lucigenin-enhanced chemiluminescence were measured. Interleukin 1β, interleukin 6, tumor necrosis factor α, tumor growth factor β, caspase-3, and cleaved caspase-3 were evaluated with an enzyme-linked immunosorbent assay method. Brain injury was histopathologically graded after hematoxylin-eosin staining. Y-maze and novel object recognition tests were performed before TBI and within 24 hours of TBI.

RESULTS

Higher myeloperoxidase activity levels in the TBI group (P < 0.001) were suppressed in the CA group (P < 0.05). Luminol-enhanced and lucigenin-enhanced chemiluminescence, which were increased in the TBI group (P < 0.001, for both), were decreased in the group that received CA treatment (P < 0.001 for both). Compared with the increased histologic damage scores in the cerebral cortex and dentate gyrus of the TBI group (P < 0.001), scores of the CA group were lower (P < 0.001). Decreased number of entries and spontaneous alternation percentage in the Y-maze test of the TBI group (P < 0.05 and P < 0.01, respectively) were not evident in the CA group.

CONCLUSIONS

CA has shown neuroprotective effects by limiting neutrophil recruitment, suppressing reactive oxygen species and reducing histologic damage and acute hippocampal dysfunction.

Network pharmacology-based research uncovers cold resistance and thermogenesis mechanism of Cinnamomum cassia

BACKGROUND

Cinnamomum cassia (L.) J.Presl (Cinnamon) was known as a kind of hot herb, improved circulation and warmed the body. However, the active components and mechanisms of dispelling cold remain unknown.

METHODS

The effects of several Chinses herbs on thermogenesis were evaluated on body temperature and activation of brown adipose tissue. After confirming the effect, the components of cinnamon were identified using HPLC-Q-TOF/MS and screened with databases. The targets of components were obtained with TCMSP, SymMap, Swiss and STITCH databases. Thermogenesis genes were predicted with DisGeNET and GeneCards databases. The protein-protein interaction network was constructed with Cytoscape 3.7.1 software. GO enrichment analysis was accomplished with STRING databases. KEGG pathway analysis was established with Omicshare tools. The top 20 targets for four compounds were obtained according to the number of edges of PPI network. In addition, the network results were verified with experimental research for the effects of extracts and major compounds.

RESULTS

Cinnamon extract significantly upregulated the body temperature during cold exposure.121 components were identified in HPLC-Q-TOF/MS. Among them, 60 compounds were included in the databases. 116 targets were obtained for the compounds, and 41 genes were related to thermogenesis. The network results revealed that 27 active ingredients and 39 target genes. Through the KEGG analysis, the top 3 pathways were PPAR signaling pathway, AMPK signaling pathway, thermogenesis pathway. The thermogenic protein PPARγ, UCP1 and PGC1-α was included in the critical targets of four major compounds. The three major compounds increased the lipid consumption and activated the brown adipocyte. They also upregulated the expression of UCP1, PGC1-α and pHSL, especially 2-methoxycinnamaldehyde was confirmed the effect for the first time. Furthermore, cinnamaldehyde and cinnamon extract activated the expression of TRPA1 on DRG cells.

CONCLUSION

The mechanisms of cinnamon on cold resistance were investigated with network pharmacology and experiment validation. This work provided research direction to support the traditional applications of thermogenesis.

Jinmaitong ameliorates diabetes-induced peripheral neuropathy in rats through Wnt/β-catenin signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Jinmaitong (JMT) is a prescription of Traditional Chinese Medicine, which is composed of ten herbal drugs and two animal drugs. It has long been used for the treatment of diabetic peripheral neuropathy (DPN).

AIM OF STUDY

Wnt/β-catenin pathway is considered as an essential and direct driver of myelinogenesis. This study aims to evaluate the protective effect of JMT against DPN dynamically during a 16-weeks' treatment, and to investigate the underlying mechanism in which the Wnt/β-catenin pathway is involved.

MATERIALS AND METHODS

Diabetic model was induced by single intraperitoneal injection of Streptozotocin (STZ) using male Sprague-Dawley rats. The model rats were divided into five groups and administrated with JMT at three doses (0.437, 0.875, and 1.75 g/kg per day), neurotropin (positive drug, 2.67 NU/kg per day), and placebo (deionized water), respectively, for continuous 8 weeks (n = 9-10), 12 weeks (n = 8-10), or 16 weeks (n = 7-9). Meanwhile, rats in control group were administrated with placebo (n = 10 for 8 weeks, n = 9 for 12 and 16 weeks, respectively). Blood glucose and body weight were monitored every four weeks. Mechanical allodynia was assessed using mechanical withdrawal threshold (MWT) test. The morphological change of sciatic nerves were observed by transmission electron microscope (TEM) and hematoxylin and eosin (HE) stain. The mRNA and protein levels of targeted genes were evaluated by quantitative real time-PCR and western bolt, respectively. Myelin protein zero (MPZ) and mediators involved in Wnt/β-catenin pathway, such as β-catenin, glycogen synthase kinase 3β (GSK-3β), and WNT inhibitory factor-1 (WIF-1), were compared among different groups after treatment of 8, 12, and 16 weeks, respectively.

RESULTS

The mechanical allodynia and peripheral nerve morphology were degenerated in DPN rats over time, and notably improved after JMT-treatment of 12 and 16 weeks. The decreased MPZ level in DPN rats were also significantly amended by JMT. More importantly, we found that the suppressed Wnt/β-catenin pathway in sciatic nerves of DPN rats was overtly up-regulated by JMT in a time-dependent manner. Among the three doses, JMT at the middle dose showed the best effect.

CONCLUSIONS

JMT effectively ameliorated diabetic-induced peripheral neuropathy, which was mediated by the activation of Wnt/β-catenin signaling pathway. This study provided new perspective to understand the neuroprotective mechanism of JMT.

Natural Cinnamaldehyde and Its Derivatives Ameliorate Neuroinflammatory Pathways in Neurodegenerative Diseases

Neurodegenerative diseases are devastating and incurable disorders characterized by neuronal dysfunction. The major focus of experimental and clinical studies are conducted on the effects of natural products and their active components on neurodegenerative diseases. This review will discuss an herbal constituent known as cinnamaldehyde (CA) with the neuroprotective potential to treat neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD). Accumulating evidence supports the notion that CA displays neuroprotective effects in AD and PD animal models by modulating neuroinflammation, suppressing oxidative stress, and improving the synaptic connection. CA exerts these effects through its action on multiple signaling pathways, including TLR4/NF-κB, NLRP3, ERK1/2-MEK, NO, and Nrf2 pathways. To summarize, CA and its derivatives have been shown to improve pathological changes in AD and PD animal models, which may provide a new therapeutic option for neurodegenerative interventions. To this end, further experimental and clinical studies are required to prove the neuroprotective effects of CA and its derivatives.

Involvement of Neural Transient Receptor Potential Channels in Peripheral Inflammation

Transient receptor potential (TRP) channels are a superfamily of non-selective cation channels that act as polymodal sensors in many tissues throughout mammalian organisms. In the context of ion channels, they are unique for their broad diversity of activation mechanisms and their cation selectivity. TRP channels are involved in a diverse range of physiological processes including chemical sensing, nociception, and mediating cytokine release. They also play an important role in the regulation of inflammation through sensory function and the release of neuropeptides. In this review, we discuss the functional contribution of a subset of TRP channels (TRPV1, TRPV4, TRPM3, TRPM8, and TRPA1) that are involved in the body’s immune responses, particularly in relation to inflammation. We focus on these five TRP channels because, in addition to being expressed in many somatic cell types, these channels are also expressed on peripheral ganglia and nerves that innervate visceral organs and tissues throughout the body. Activation of these neural TRP channels enables crosstalk between neurons, immune cells, and epithelial cells to regulate a wide range of inflammatory actions. TRP channels act either through direct effects on cation levels or through indirect modulation of intracellular pathways to trigger pro- or anti-inflammatory mechanisms, depending on the inflammatory disease context. The expression of TRP channels on both neural and immune cells has made them an attractive drug target in diseases involving inflammation. Future work in this domain will likely yield important new pathways and therapies for the treatment of a broad range of disorders including colitis, dermatitis, sepsis, asthma, and pain.

Topical co-administration of Teucrium polium hydroethanolic extract and Aloe vera gel triggered wound healing by accelerating cell proliferation in diabetic mouse model

Diabetic wounds are major issues in patients with diabetes. Medicinal plants of Teucrium polium and Aloe vera have antioxidant and anti-inflammatory properties that may be profitable for diabetic patients. This study was conducted to evaluate the effect of co-administration of ointments prepared from Teucrium polium hydroethanolic extract (TPEO) and Aloe vera gel (AVGO) on excisional wound healing in a diabetic mouse model. Following the induction of diabetes and circular excisional wound (7 mm), the mice were divided into six groups, namely (Ⅰ) control mice treated with mupirocin (as a standard drug), (Ⅱ and Ⅲ) the mice treated with 5 and 10 % TPEO, (Ⅳ and Ⅴ) the mice treated with 5 and 10 % AVGO, and (Ⅵ) the mice treated with a combination of 5% TPEO and 5% AVGO (TPEO+AVGO). To investigate the wound area, we further evaluated the wound area ratio, histological analysis and the serum levels of tissue antioxidant capacity (TAC) and malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β), immunohistochemistry staining for vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF-1), glucose transporter-1(GLUT-1) and collagen type 1 and mRNA expression levels for VEGF, IGF-1, GLUT-1 and fibroblast growth factor-2 (FGF-2). The results showed that administration of the ointments, especially in combination form, shortened the inflammatory phase and reduced the levels of tissue MDA, TNF-α and IL-1β compared to mupirocin group (P < 0.05). Moreover, fibroblasts proliferation, collagen deposition, VEGF, IGF-1, GLUT-1-positive cells and level of TAC, and expressions of VEGF, IGF-1, GLUT-1 and FGF-2 were significantly (P < 0.05) increased in TPEO and AVGO, and especially in the mice treated with the mixed form. Therefore, topical co-administration of TPEO + AVGO accelerated open diabetic wound healing through shortening the inflammatory phase and increasing cell proliferation and collagen deposition.

Topical application of Cinnamomum hydroethanolic extract improves wound healing by enhancing re-epithelialization and keratin biosynthesis in streptozotocin-induced diabetic mice

Context: Cinnamomum verum J. Presl. (Lauraceae) has a high number of polyphenols with insulin-like activity, increases glucose utilization in animal muscle, and might be beneficial for diabetic patients.Objective: This study evaluated the effectiveness of an ointment prepared from Cinnamomum verum hydroethanolic extract on wound healing in diabetic mice.Materials and methods: A total of 54 male BALB/c mice were divided into three groups: (1) diabetic non-treated group mice that were treated with soft yellow paraffin, (2 and 3) mice that were treated with 5 and 10% C. verum. Two circular full-thickness excisional wounds were created in each mouse, and the trial lasted for 16 d following induction of the wound. Further evaluation was made on the wound contraction ratio, histopathology parameters and mRNA levels of cyclin D1, insulin-like growth factor 1 (IGF-1), glucose transporter-1 (GLUT-1), total antioxidant capacity, and malondialdehyde of granulation tissue contents. HPLC apparatus was utilized to identify the compounds.Results: The HPLC data for cinnamon hydroethanolic extract identified cinnamaldehyde (11.26%) and 2-hydroxyl cinnamaldehyde (6.7%) as the major components. A significant increase was observed in wound contraction ratio, fibroblast proliferation, collagen deposition, re-epithelialization and keratin biosynthesis in the C. verum-treated groups in comparison to the diabetic non-treated group (p < 0.05). The expression level of cyclin D1, IGF1, GLUT 1 and antioxidant capacity increased in the C. verum-treated groups in comparison to the diabetic non-treated group (p < 0.05).Conclusions: Topical administration of C. verum accelerated wound healing and can possibly be employed in treating the wounds of diabetic patients.

The effects of Cinnamaldehyde on early brain injury and cerebral vasospasm following experimental subarachnoid hemorrhage in rabbits

The neuroprotective and vasodilatory effects of cinnamaldehyde have been widely studied and documented. On the basis of these findings, we hypothesized that cinnamaldehyde exhibits therapeutic effects on subarachnoid hemorrhage-induced early brain injury and cerebral vasospasm. Thirty-two adult male New Zealand white rabbits were randomly divided into four groups of eight rabbits: control, subarachnoid hemorrhage, subarachnoid hemorrhage + vehicle, and subarachnoid hemorrhage + cinnamaldehyde. An intraperitoneal dose of 50 mg/kg cinnamaldehyde was administered 5 min following an intracisternal blood injection, followed by three further daily injections at identical doses. The animals were sacrificed 72 h after subarachnoid hemorrhage was induced. The cross-sectional areas and arterial wall thicknesses of the basilar artery were measured and hippocampal degeneration scores were evaluated. Treatment with cinnamaldehyde was effective in providing neuroprotection and attenuating cerebral vasospasm after subarachnoid hemorrhage in rabbits. It effectively increased the cross-sectional areas of the basilar artery and reduced the arterial wall thickness; in addition, hippocampal degeneration scores were lower in the cinnamaldehyde group. The findings of this study showed, for the first time to our knowledge, that cinnamaldehyde exhibits neuroprotective activity against subarachnoid hemorrhage-induced early brain injury and that it can prevent vasospasm. Potential mechanisms underlying the neuroprotection and vasodilation were discussed. Cinnamaldehyde could play a role in subarachnoid hemorrhage treatment.

CGRP Reduces Apoptosis of DRG Cells Induced by High-Glucose Oxidative Stress Injury through PI3K/AKT Induction of Heme Oxygenase-1 and Nrf-2 Expression

Dorsal root ganglion (DRG) neurons, which are sensitive to oxidative stress due to their anatomical and structural characteristics, play a complex role in the initiation and progression of diabetic bladder neuropathy. We investigated the hypothesis that the antioxidant and antiapoptotic effects of CGRP may be partly related to the expression of Nrf2 and HO-1, via the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, thus reducing apoptosis and oxidative stress responses. This study shows that CGRP activates the PI3K/AKT pathway, thereby inducing increased expression of Nrf2 and HO-1 and resulting in the decrease of reactive oxygen species and malondialdehyde levels and reduced neuronal apoptosis. These effects were suppressed by LY294002, an inhibitor of the PI3K/AKT pathway. Therefore, regulation of Nrf2 and HO-1 expression by the PI3K/AKT pathway plays an important role in the regulation of the antioxidant and antiapoptotic responses in DRG cells in a high-glucose culture model.

Cytotoxicity and Pro-/Anti-inflammatory Properties of Cinnamates, Acrylates and Methacrylates Against RAW264.7 Cells

BACKGROUND/AIM

Periodontitis is a chronic inflammatory disease linked to various systemic age-related conditions. It is known that α,β-unsaturated carbonyl compounds such as dietary cinnamates (β-phenyl acrylates) and related (meth)acrylates can have various positive and negative health effects, including cytotoxicity, allergic activity, pro-and anti-inflammatory activity, and anticancer activity. To clarify the anti-inflammatory properties of α,β-unsaturated carbonyl compounds without a phenolic group in the context of periodontal tissue inflammation and alveolar bone loss, we investigated the cytotoxicity and up-regulatory/down-regulatory effect of three trans-cinnamates (trans-cinnamic acid, methyl cinnamate, trans-cinnamaldehyde), two acrylates (ethyl acrylate, 2-hydroxyethyl acrylate), and three methacrylates (methyl methacrylate, 2-hydroxyethyl methacrylate, and triethyleneglycol dimethacrylate) using RAW264.7 cells.

MATERIALS AND METHODS

Cytotoxicity was determined using a cell counting kit (CCK-8) and mRNA expression was determined using real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Pro-inflammatory and anti-inflammatory properties were assessed in terms of expression of mRNAs for cyclo-oxygenase-2 (Cox2), nitric oxide synthase 2 (Nos2), tumor necrosis factor-alpha (Tnfa) and heme oxygenase 1 (Ho1).

RESULTS

The most cytotoxic compound was 2-hydroxyethyl acrylate, followed by ethyl acrylate and cinnamaldehyde (50% lethal cytotoxic concentration, LC₅₀=0.2-0.5 mM). Cox2 mRNA expression was up-regulated by cinnamaldehyde and 2-hydroxyethyl acrylate, particularly by the former. In contrast, the up-regulatory effect on Nos2 mRNA expression was in the order: cinnamaldehyde >> ethyl acrylate ≈ triethyleneglycol dimethacrylate >> methyl methacrylate ≈ methyl cinnamate. On the other hand, cinnamic acid and 2-hydroxyethyl methacrylate had no effect on gene expression. The two acrylates, but not cinnamates and methacrylates, up-regulated the expression of Ho1 mRNA at a non-cytotoxic concentration of 0.1 mM. Expression of Cox2, Nos2 and Tnfa mRNAs induced by Porphyromonas gingivalis lipopolysaccharide was greatly suppressed by cinnamaldehyde, methyl cinnamate and the two acrylates at 0.1 mM (p<0.05), and slightly, but significantly suppressed by cinnamic acid and methacrylates at 0.1-1 mM (p<0.05).

CONCLUSION

Cinnamaldehyde and acrylates exhibited both anti-inflammatory and pro-inflammatory properties, possibly due to their marked ability to act as Michael reaction acceptors, as estimated from the beta-carbon ¹³C-nuclear magnetic resonance spectra. Methyl cinnamate exhibited potent anti-inflammatory activity with less cytotoxicity and pro-inflammatory activity, suggesting that this compound may be useful for treatment of periodontal disease and related systemic diseases.

Cinnamaldehyde regulates H2 O 2 -induced skeletal muscle atrophy by ameliorating the proteolytic and antioxidant defense systems

Skeletal muscle atrophy/wasting is associated with impaired protein metabolism in diverse physiological and pathophysiological conditions. Elevated levels of reactive oxygen species (ROS), disturbed redox status, and weakened antioxidant defense system are the major contributing factors toward atrophy. Regulation of protein metabolism by controlling ROS levels and its associated catabolic pathways may help in treating atrophy and related clinical conditions. Although cinnamaldehyde (CNA) enjoys the established status of antioxidant and its role in ROS management is reported, impact of CNA on skeletal muscle atrophy and related pathways is still unexplored. In the current study, the impact of CNA on C2C12 myotubes and the possible protection of cultured cells from H ₂ O ₂ -induced atrophy is examined. Myotubes were treated with H ₂ O ₂ in the presence and absence of CNA and the changes in the antioxidative, proteolytic systems, and mitochondrial functions were scored. Morphological analysis showed significant protective effects of CNA on length, diameter, and nuclei fusion index of myotubes. The evaluation of biochemical markers of atrophy; creatine kinase, lactate dehydrogenase, succinate dehydrogenase along with the study of muscle-specific structural protein (i.e., myosin heavy chain-fast [MHCf] type) showed significant protection of proteins by CNA. CNA pretreatment not only checked the activation of proteolytic systems (ubiquitin-proteasome E3-ligases [MuRF1/Atrogin1]), autophagy [Beclin1/LC3B], cathepsin L, calpain, caspase), but also prevented any alteration in the activities of antioxidative defense enzymes (catalase, glutathione- S-transferase, glutathione-peroxidase, superoxide dismutase, glutathione reductase). The results suggest that CNA protects myotubes from H ₂ O ₂ -induced atrophy by inhibiting/resisting the amendments in proteolytic systems and maintains cellular redox-balance.

Strategies and Research Progress of Chinese Medicine in Prevention and Treatment of Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) seriously affects the quality of life in patients with type 2 diabetes mellitus. This paper reviews the role of Chinese medicine in the main treatment goal of DPN, including protecting pancreatic β-cells, in the use of antioxidation therapy to delay disease progression, and in the endpoint of neural repair and regeneration. We propose that protecting the body from injury caused by high glucose and oxidative stress, and promoting repair and regeneration of nerves should be the research direction for the prevention and treatment of DPN.

Cinnamaldehyde exerts vasculoprotective effects in hypercholestrolemic rabbits

The effects of cinnamaldehyde (CIN), a commonly consumed food flavor, against high-cholesterol diet (HCD)-induced vascular damage in rabbits were evaluated. Male New Zealand rabbits (n = 24) were allocated to four groups at random: control, fed with standard rabbit chow; CIN, fed with standard diet and administered CIN; HCD, fed with 1% cholesterol-enriched diet; and HCD-CIN, fed with HCD and treated with CIN. CIN was orally given at a dose of (10 mg/kg/day) concomitantly with each diet type from day 1 until the termination of the experimental protocol (4 weeks). HCD elicited significant elevations in serum levels of total cholesterol (TC), triglycerides (TGs), and high- and low-density lipoprotein cholesterol (HDL-C and LDL-C, respectively) compared with control rabbits. Moreover, aortic levels of nitric oxide metabolites (NOx) and antioxidant enzyme activities were significantly lower, while aortic levels of malondialdehyde (MDA) and myeloperoxidase (MPO) activity were significantly higher, in HCD-fed rabbits relative to control animals. CIN administration mitigated or completely reversed HCD-induced metabolic alterations, vascular oxidative stress, and inflammation. Moreover, CIN ameliorated HCD-induced vascular functional and structural irregularities. Aortic rings from HCD-CIN group showed improved relaxation to acetylcholine compared to aortas from HCD group. Moreover, CIN decreased atherosclerotic lipid deposition and intima/media (I/M) ratio of HCD aortas. CIN-mediated effects might be related to its ability to attenuate the elevated aortic mRNA expression of cholesteryl ester transfer protein (CETP) and MPO in HCD group. Interestingly, the vasculoprotective effects of CIN treatment in the current study do not seem to be mediated via Nrf2-dependent mechanisms. In conclusion, CIN may mitigate the development of atherosclerosis in hypercholestrolemic rabbits via cholesterol-lowering, antiinflammatory and antioxidant activities.

Jiao-Tai-Wan Improves Cognitive Dysfunctions through Cholinergic Pathway in Scopolamine-Treated Mice

Cognitive dysfunction is characterized as the gradual loss of learning ability and cognitive function, as well as memory impairment. Jiao-tai-wan (JTW), a Chinese medicine prescription including Coptis chinensis and cinnamon, is mainly used for the treatment of insomnia, while the effect of JTW in improving cognitive function has not been reported. In this study, we employed a scopolamine- (SCOP-) treated learning and memory deficit model to explore whether JTW could alleviate cognitive dysfunction. In behavioral experiments, Morris water maze, Y-maze, fearing condition test, and novel object discrimination test were conducted. Results showed that oral administration of JTW (2.1 g/kg, 4.2 g/kg, and 8.4 g/kg) can effectively promote the ability of spatial recognition, learning and memory, and the memory ability of fresh things of SCOP-treated mice. In addition, the activity of acetylcholinesterase (AChE) was effectively decreased; the activity of choline acetyltransferase (ChAT) and concentration of acetylcholine (Ach) were improved after JTW treatment in both hippocampus and cortex of SCOP-treated mice. JTW effectively ameliorated oxidative stress because of decreased the levels of malondialdehyde (MDA) and reactive oxygen species (ROS) and increased the activities of superoxide dismutase (SOD) and catalase (CAT) in hippocampus and cortex. Furthermore, JTW promotes the expressions of neurotrophic factors including postsynaptic density protein 95 (PSD95) and synaptophysin (SYN) and brain-derived neurotrophic factor (BDNF) in both hippocampus and cortex. Nissl's staining shows that the neuroprotective effect of JTW was very effective. To sum up, JTW might be a promising candidate for the treatment of cognitive dysfunction.

Preconditioning of adipose tissue-derived mesenchymal stem cells with deferoxamine increases the production of pro-angiogenic, neuroprotective and anti-inflammatory factors: Potential application in the treatment of diabetic neuropathy

Diabetic neuropathy (DN) is one of the most frequent and troublesome complications of diabetes mellitus. Evidence from diabetic animal models and diabetic patients suggests that reduced availability of neuroprotective and pro-angiogenic factors in the nerves in combination with a chronic pro-inflammatory microenvironment and high level of oxidative stress, contribute to the pathogenesis of DN. Mesenchymal stem cells (MSCs) are of great interest as therapeutic agents for regenerative purposes, since they can secrete a broad range of cytoprotective and anti-inflammatory factors. Therefore, the use of the MSC secretome may represent a promising approach for DN treatment. Recent data indicate that the paracrine potential of MSCs could be boosted by preconditioning these cells with an environmental or pharmacological stimulus, enhancing their therapeutic efficacy. In the present study, we observed that the preconditioning of human adipose tissue-derived MSCs (AD-MSCs) with 150μM or 400μM of the iron chelator deferoxamine (DFX) for 48 hours, increased the abundance of the hypoxia inducible factor 1 alpha (HIF-1α) in a concentration dependent manner, without affecting MSC morphology and survival. Activation of HIF-1α led to the up-regulation of the mRNA levels of pro-angiogenic factors like vascular endothelial growth factor alpha and angiopoietin 1. Furthermore this preconditioning increased the expression of potent neuroprotective factors, including nerve growth factor, glial cell-derived neurotrophic factor and neurotrophin-3, and cytokines with anti-inflammatory activity like IL4 and IL5. Additionally, we observed that these molecules, which could also be used as therapeutics, were also increased in the secretome of MSCs preconditioned with DFX compared to the secretome obtained from non-preconditioned cells. Moreover, DFX preconditioning significantly increased the total antioxidant capacity of the MSC secretome and they showed neuroprotective effects when evaluated in an in vitro model of DN. Altogether, our findings suggest that DFX preconditioning of AD-MSCs improves their therapeutic potential and should be considered as a potential strategy for the generation of new alternatives for DN treatment.

Cinnamaldehyde Ameliorates Cadmium-Inhibited Root Elongation in Tobacco Seedlings via Decreasing Endogenous Hydrogen Sulfide Production

Cinnamaldehyde (CA) is natural plant-derived compound that has been highly appreciated for its medicinal properties. However, little information is known about the regulation of plant intrinsic physiology by CA. To address these gaps, physiological, histochemical, and biochemical approaches were applied to investigate CA-facilitated cadmium (Cd) tolerance in the roots of tobacco (Nicotiana tabacum) seedlings. Treatment with CdCl₂ at 20 μM for 72 h resulted in the significant decrease in root elongation by 40.39% as compared to control. CA alleviated Cd-inhibited root elongation in dose- and time-dependent manners. The addition of CA at 20 μM induced significant increase in root elongation by 42.58% as compared to Cd treatment alone. CA abolished Cd-induced ROS (reactive oxygen species) accumulation, lipid peroxidation, loss of membrane integrity, cell death, and free Cd2+ accumulation in roots. CA blocked the Cd-induced increase in the endogenous H₂S level through the down-regulation of d-cysteine desulfhydrase (DCD) expression. H₂S scavenger hypotaurine (HT) or potent H₂S-biosynthetic inhibitor dl-propargylglicine (PAG) were able mimic the action of CA on the blockade of Cd-induced H₂S accumulation, cell death, and growth inhibition. Enhancement of the endogenous H₂S level with NaHS (H₂S donor) abrogated all the beneficial capabilities of CA, HT, and PAG. Collectively, these results suggest that CA has great potential to confer plant tolerance against Cd stress, which is closely associated with its capability to inhibit Cd-induced H₂S production. This study not only provides evidences for the regulation of plant physiology by CA but also sheds new light on the cross-talk between CA and H₂S in physiological modulations.