Aucubin alleviates doxorubicin-induced cardiotoxicity through crosstalk between NRF2 and HIPK2 mediating autophagy and apoptosis

BACKGROUND

Doxorubicin (DOX) is widely used for the treatment of a variety of cancers. However, its clinical application is limited by dose-dependent cardiotoxicity. Recent findings demonstrated that autophagy inhibition and apoptosis of cardiomyocytes induced by oxidative stress dominate the pathophysiology of DOX-induced cardiotoxicity (DIC), however, there are no potential molecules targeting on these.

PURPOSE

This study aimed to explore whether aucubin (AU) acting on inimitable crosstalk between NRF2 and HIPK2 mediated the autophagy, oxidative stress, and apoptosis in DIC, and provide a new and alternative strategy for the treatment of DIC.

METHODS AND RESULTS

We first demonstrated the protection of AU on cardiac structure and function in DIC mice manifested by increased EF and FS values, decreased serum CK-MB and LDH contents and well-aligned cardiac tissue in HE staining. Furthermore, AU alleviated DOX-induced myocardial oxidative stress, mitochondrial damage, apoptosis, and autophagy flux dysregulation in mice, as measured by decreased ROS, 8-OHdG, and TUNEL-positive cells in myocardial tissue, increased SOD and decreased MDA in serum, aligned mitochondria with reduced vacuoles, and increased autophagosomes. In vitro, AU alleviated DOX-induced oxidative stress, autophagy inhibition, and apoptosis by promoting NRF2 and HIPK2 expression. We also identified crosstalk between NRF2 and HIPK2 in DIC as documented by overexpression of NRF2 or HIPK2 reversed cellular oxidative stress, autophagy blocking, and apoptosis aggravated by HIPK2 or NRF2 siRNA, respectively. Simultaneously, AU promoted the expression and nuclear localization of NRF2 protein, which was reversed by HIPK2 siRNA, and AU raised the expression of HIPK2 protein as well, which was reversed by NRF2 siRNA. Crucially, AU did not affect the antitumor activity of DOX against MCF-7 and HepG2 cells, which made up for the shortcomings of previous anti-DIC drugs.

CONCLUSION

These collective results innovatively documented that AU regulated the unique crosstalk between NRF2 and HIPK2 to coordinate oxidative stress, autophagy, and apoptosis against DIC without compromising the anti-tumor effect of DOX in vitro.

Aucubin produces anti-osteoporotic effects under mechanical stretch stress and orthodontic tooth movement

Aucubin (AU), an iridoid glycoside extracted from Eucommia ulmoides, exerts anti-osteoporotic effects by promoting osteogenesis, as reported in previous studies. Here, we investigated the effects of AU under mechanical stretch stress. MC3T3-E1 cells were treated with dexamethasone (DEX) in vitro and subjected to mechanical stretch stress to establish an osteoporotic orthodontic force cell model. AU treatment increased the mRNA and protein expressions of BMP2, OPN, RUNX2, COL-1 and other osteogenic differentiation factors in MC3T3-E1 cells. Furthermore, we established an in vivo orthodontic tooth movement (OTM) model of osteoporosis. Serum parameter detection of ALP concentration, radiography of the femur, hematoxylin-eosin (HE) staining, and micro-CT of the maxilla confirmed that AU could partially reverse the damage induced by DEX. Immunohistochemical (IHC) analysis showed that AU increased the expression of COL-1, OCN, and OPN on the tension side of the periodontium. In conclusion, AU treatment promotes osteogenic differentiation under mechanical stretch stress and positively affects bone remodeling during OTM in DEX-induced osteoporosis.

Neuroprotective effects of Aucubin against cerebral ischemia-reperfusion injury

AIMS

To study the role of Aucubin (AU) in cerebral ischemia-reperfusion injury and investigate the potential mechanisms.

METHODS

For the in vitro experiment, primary microglia were cultured and stimulated by Lipopolysaccharides (LPS) and treated with AU. Male C57/BL6J mice were used and middle cerebral artery occlusion (MCAO) model was performed to induce cerebral ischemia-reperfusion injury. For the short-term effects, mice administrated with AU (40 mg/kg) for 3 days after MCAO were evaluated for the infarct volume and neurological deficits. The neuroinflammatory factors and microglia activation were determined by Real-time PCR, western blot and immunofluorescence staining. For the long-term effects, MCAO mice were injected daily with AU (5 mg/kg or 10 mg/kg) for 28 days. Behavior tests were used to assess the neurological deficits of MCAO mice, and white matter integrity was determined by myelin basic protein (MBP) staining and black-gold staining.

RESULTS

AU suppressed LPS-induced activation of microglia and pro-inflammatory cytokines release, and downregulated the NF-κB and MAPK pathways in primary microglia. In addition, AU attenuated ischemic injury and inhibited the neuro-inflammatory response in MCAO mice. Moreover, AU induced prolonged improvements in sensorimotor function and memory function following MCAO, and preserved white matter integrity in the long-term experiments.

CONCLUSIONS

AU protected against ischemic injury, which might be correlated with the downregulation of NF-κB and MAPK signaling pathways. Furthermore, AU alleviated cognitive impairment after stroke and restored white matter integrity. Our data indicated that AU might be a potential compound for the treatment of stroke and post-stroke cognitive impairment.

Aucubin provides protection against cerebral ischaemia-reperfusion injury by suppressing neuronal apoptosis, oxidative stress, and inflammation through the modulation of the AKT-GSK-3β-Nrf2 signal cascade

Aucubin (AU) is a naturally occurring iridoid glycoside known to possess a wide range of pharmacological properties and exhibit a notable protective effect against various pathological conditions. Studies have shown that AU has neuroprotective properties in different neurological diseases. However, its potential protective effects against cerebral ischemia-reperfusion (CIR) injury have not been thoroughly investigated. This study aimed to investigate the impact of AU on CIR injury and explore the underlying mechanism. Cultured neurons treated with AU showed a significant reduction in apoptosis, oxidative stress, and inflammation caused by oxygen-glucose deprivation and reoxygenation (OGD/R). In a rat model of CIR, treatment with AU resulted in a significant decrease in cerebral infarct size and neurological deficits. AU treatment also reversed the increased apoptosis, oxidative stress, and inflammation in the brains of CIR rats. Furthermore, AU was found to enhance the activation of nuclear factor-erythroid 2-related factor 2 (Nrf2), accompanied by increased phosphorylation of serine/threonine-protein kinase AKT and glycogen synthase kinase-3 beta (GSK-3β). The activation of Nrf2 induced by AU was reversed when the AKT-GSK-3β cascade was blocked. Additionally, the neuroprotective effect of AU was significantly reduced when Nrf2 was pharmacologically suppressed. In conclusion, these findings suggest that AU exerts a neuroprotective effect on CIR injury, and this effect is mediated by the activation of Nrf2 through the AKT-GSK-3β axis. This work highlights the potential of AU as a drug candidate for the treatment of CIR injury.

Attenuated memory impairment and neuroinflammation in Alzheimer's disease by aucubin via the inhibition of ERK-FOS axis

Alzheimer's disease (AD) is a degenerative illness accompanied by cognitive and memory loss. In addition to the widely accepted, convincing amyloid cascade hypothesis, the activation of glial cells and neuroinflammation, especially the microglia-mediated neuroinflammation, has an essential role in the development and progression of AD. Therefore, the anti-inflammatory treatment is becoming a promising therapeutic strategy. Aucubin (Au) is a natural product derived from many plants with anti-inflammatory and antioxidant activities. Up to now, no research has been conducted to investigate the anti-inflammatory effects of Au and its neuroprotective quality on AD and the potential molecular mechanisms of its medical roles. In our study, the results of network pharmacology revealed the potential therapeutic effect of Au on AD. The results of studies in vivo showed that Au improved the behaviors, counteracted cognitive and memory deficits, and ameliorated AD-like pathological features of the mouse brain, e.g., the deposition of Aβ plaques, neuronal damage, and inflammatory responses induced by glial cell overactivation, in APP/PS1 mice. The transcriptome sequencing further confirmed that the pathological symptoms of AD could be reversed by inhibiting the ERK/FOS axis to alleviate the inflammatory response. The in vitro experiments revealed that Au suppressed the BV2 cell activation, inhibited the phosphorylation of ERK1/2 and the expression of c-FOS, and reduced the LPS-induced inflammatory mediator production by BV2 cells and primary astrocytes. Our study suggested that Au exerted its neuroprotective effects by inhibiting the inflammatory responses, which could be a promising treatment of AD.

Traditional Chinese Medicine formula Bu-Shen-Huo-Xue-Fang (BSHXF) protects nucleus pulposus cells against the inflammatory and oxidative stress-induced degenerative changes

Degeneration of the intervertebral disc is primarily caused by the loss of nucleus pulposus cells (NPCs) and extracellular matrix (ECM) (IDD). Bu-Shen-Huo-Xue-Fang (BSHXF), a traditional Chinese medicine decoction, has been used to treat IDD in clinical; nevertheless, the active components and underlying molecular mechanisms remain unknown. BSHXF improved IL-1β and H2O2 stimulation-induced injuries on NPCs by promoting cell viability, increasing ECM deposition, inhibiting cell senescence, and decreasing the levels of inflammatory factors. The active ingredients in BSHXF were identified by LC-MS/MS analysis; three active ingredients from the principal drugs, Aucubin, Tanshinol, and Tanshinone II A promoted NPC viability; and Aucubin and Tanshinol promoted NPC viability more. Aucubin and Tanshinol, respectively, improved H2O2 stimulation-induced injuries on NPCs by promoting cell viability, increasing ECM deposition, inhibiting cell senescence, and decreasing the levels of inflammatory factors. The activator of NF-κB and Wnt signaling pathways attenuated Aucubin and Tanshinol's protective effects by promoting ECM degradation and NPC senescence. Aucubin, Tanshinol, and Tanshinone II A were identified as the most potent compounds in BSHXF protection against degenerative changes in NPCs. The NF-κB and Wnt signaling pathways might be involved in the protective effects of Aucubin and Tanshinol against H2O2-induced degenerative changes.

Aucubin inhibits hepatic stellate cell activation through stimulating Nrf2/Smad7 axis

AIM

Liver fibrosis may develop into end-stage liver disease if left unprevented. The study is attempting to identify a compound to ameliorate liver fibrosis progression with high efficiency and low toxicity, as well as to analyze its potential molecular mechanism.

METHODS

The drug screening was performed using human hepatic stellate cell line LX-2 for identifying the compound as collagen I inhibitor. Primary Human hepatic stellate cells and LX-2 cell line were used to detect the antifibrotic function activity and molecular mechanism analysis in vitro. The CCl4-induced mouse experimental model was used to measure the amelioration in liver fibrosis.

RESULTS

This study identified Aucubin, a natural compound, as a candidate for anti-liver fibrosis. Besides, Aucubin could inhibit the collagen I and α-SMA expressions in LX-2 cells and primary human hepatic stellate cells, as well as the cell proliferation. In terms of mechanism, Aucubin could upregulate Smad7 in hepatic stellate cells in a dose-dependent manner and block TGF-β signaling. We also found that Nrf2 might be a direct target for the action of Aucubin, whose activation was necessary for Smad7 upregulation. In an in-vivo mouse model, Aucubin efficiency ameliorated the progression of CCl4-induced liver fibrosis, and reduced the hepatic levels of collagen deposition, transaminase and inflammatory cytokines.

CONCLUSION

Capable of inhibiting the activation of hepatic stellate cells in vitro and in vivo, Aucubin may be a potential therapeutic candidate for liver fibrosis, which is dependent on the suppression of TGF-β signaling through stimulating Nrf2/Smad7 axis.

Aucubin improves chronic unpredictable mild stress-induced depressive behavior in mice via the GR/NF-κB/NLRP3 axis

Eucommia ulmoides Oliv (EUO) is a traditional therapeutic drug that tonifies the liver and kidney and may improve depression. However, the mechanism of action of the main component, aucubin (AU), is unknown. To study the therapeutic effect of AU, we constructed a chronic unpredictable mild stress (CUMS) depression model in mice. Depression-like behaviors, pathological damage, hormonal changes, inflammation, intranuclear expression of glucocorticoidreceptor (GR), and hippocampal protein expression were assessed. Immunofluorescence staining of the hippocampus showed that CUMS decreased neuronal regeneration, and axons were observed to be reduced and broken. Intracellular GR expression decreased in the hippocampus and hypothalamus, and serum levels of stress hormones increased. Furthermore, molecular changes indicative of pyroptosis were observed. AU administration reversed these changes and significantly improved the depression-like behavior induced by CUMS. Our results suggested that AU improves depression by promoting the intranuclear expression of GR and inhibiting nuclear factor-kappa B-mediated inflammatory activation-driven cell pyroptosis.

Dual effect of aucubin on promoting VEGFR2 mediated angiogenesis and reducing RANKL-induced bone resorption

BACKGROUND

Angiogenesis is regarded as a critical role in bone repair and regeneration, involving in pathological bone disorders such as osteoporosis. Aucubin, an iridoid glycoside primarily derived from Eucommia ulmoides, is reported to inhibit osteoclast activity, enhance bone formation and promote angiogenesis in osteoporosis models. Our study is to further investigate the anti-osteoporosis effect of aucubin in transgenic medaka, and the pro-angiogenic effect of aucubin and its mechanism of action both in vivo and in vitro.

METHODS

The anti-osteoporosis effect of aucubin was confirmed by using RANKL-stimulated bone resorption transgenic medaka. The pro-angiogenic effect of aucubin in vivo was investigated using vascular endothelial growth factor (VEGF) tyrosine kinase inhibitor II (VRI)-induced vascular insufficient transgenic zebrafish model. Furthermore, endothelial cell proliferation, migration, tube formation and the mechanisms were evaluated to identify the pro-angiogenic effect of aucubin in normal and su5416-injured human umbilical vein endothelial cells (HUVECs).

RESULTS

Aucubin decreased the resorption of the mineralized bone matrix and centra degradation in heat-shocked transgenic col10α1:nlGFP/rankl:HSE:CFP medaka. Moreover, aucubin reversed VRI-induced vascular insufficiency in zebrafish through regulating flt1, kdr, kdrl, vegfaa, ang-1, ang-2, tie1 and tie2 mRNA expressions in Tg(fli1a:EGFP)y1 or AB wild type zebrafish. Aucubin promoted cell proliferation by upregulating p-mTOR, p-Src, p-MEK, p-Erk1/2, p-Akt and p-FAK in HUVECs. Furthermore, aucubin exhibited a pro-angiogenic effect on su5416-injured HUVECs by promoting their proliferation, migration, and tube formation through regulating the phosphorylation of VEGFR2, MEK, ERK and the ratio of Bcl2-Bax.

CONCLUSION

Aucubin could reduce bone resorption in RANKL-induced osteoporosis medaka by live imaging. Meanwhile, aucubin exhibited a protective effect in VRI-induced vascular insufficient zebrafish by regulating VEGF-VEGFR and Ang-Tie signaling pathways. Additionally, aucubin promoted the proliferation, migration and tube formation of HUVECs probably by mediating VEGFR2/MEK/ERK, Akt/mTOR and Src/FAK signalling pathways. This study further indicated the dual effect of aucubin on angiogenesis and osteogenesis which may be beneficial to its treatment of osteoporosis.

Mixed elicitation with salicylic acid and hydrogen peroxide modulates the phenolic and iridoid pathways in Castilleja tenuiflora plants

MAIN CONCLUSION

SA and H₂O₂, in single and mixed elicitation stimulate specialized metabolism and activate oxidative stress in C. tenuiflora plants. Single elicitation with salicylic acid (SA at 75 µM) and, hydrogen peroxide (at 150 µM), and mixed elicitation (75 µM SA + 150 µM H₂O₂) were evaluated on specialized metabolism in Castilleja tenuiflora Benth. plants. Total phenolic content (TPC), phenylalanine ammonia-lyase (PAL) activity, antioxidant enzymes and specialized metabolite profiles, as well as the expression levels of eight genes involved in phenolic (Cte-TyrDC, Cte-GOT2, Cte-ADD, Cte-AO3, Cte-PAL1, Cte-CHS1) and terpene pathways (Cte-DXS1 and Cte-G10H) and their correlation with major metabolite (verbascoside and aucubin) concentrations were investigated. TPC content (three-fold) and PAL activity (11.5-fold) increased with mixed elicitation, as well as catalase and peroxidase activity (11.3-fold and 10.8-fold, respectively), compared to single elicitation. Phenylethanoid accumulation was greatest under mixed elicitation, followed by SA and H₂O₂. Lignan accumulation was differential, depending on the plant part and the elicitor. Flavonoids only appeared after mixed elicitation. The high concentration of verbascoside under mixed elicitation was related to a high gene expression. Single elicitation induced iridoid accumulation in specific parts (H₂O₂ in aerial parts and SA in roots), whereas under mixed elicitation, it accumulated in both parts. A high concentration of aucubin in the aerial part was related to a high expression level of genes of the terpene pathway Cte-DXS1 and Cte-G10H, and in the root with Cte-G10H, while Cte-DXS1 was downregulated in this tissue in all treatments. Mixed elicitation with SA and H₂O₂ represents an interesting tool to increase the production of specialized metabolites in plants.

Aucubin enhances the antitumor activity of cisplatin through the inhibition of PD-L1 expression in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a leading cause of cancer-associated mortality in the world. However, the anticancer effects of aucubin against HCC have yet to be reported. Cisplatin often decreased CD8⁺ tumor-infiltrating lymphocytes in the tumor microenvironment through increasing programmed death-ligand 1 (PD-L1) expression, which seriously affected the prognostic effect of cisplatin in the treatment of patients with HCC. Therefore, it is necessary to identify a novel therapeutic avenue to increase the sensitivity of cisplatin against HCC.

PURPOSE

This study aims to evaluate the anti-tumor effect of aucubin on HCC, and also to reveal the synergistic effects and mechanism of aucubin and cisplatin against HCC.

STUDY DESIGN AND METHODS

An H22 xenograft mouse model was established for the in vivo experiments. Cancer cell proliferation was detected by MTT assay. RT-qPCR was performed to analyze CD274 mRNA expression in vitro. Western blotting was employed to determine the expression levels of the PD-L1, p-Akt, Akt, p-β-catenin, and β-catenin in vitro. Immunofluorescence was carried out to examine β-catenin nuclear accumulation in HCC cells. Immunohistochemistry was used to detect tumoral PD-L1 and CD8α expression in xenograft mouse model.

RESULTS

Aucubin inhibits tumor growth in a xenograft HCC mouse model, but did not affect HCC cell viability in vitro. Aucubin treatment significantly inhibited PD-L1 expression through inactivating Akt/β-catenin signaling pathway in HCC cells. Overexpression of PD-L1 dramatically reversed aucubin-mediated tumoral CD8⁺ T cell infiltration and alleviated the antitumor activity of aucubin in xenograft mouse model. Moreover, Cisplatin could induce the expression of PD-L1 through the activation of the Akt/β-catenin signaling pathway in HCC cells, which can be blocked by aucubin in vitro. In xenograft mouse model, cisplatin treatment induced PD-L1 expression and alleviated the infiltration of CD8⁺ T lymphocytes in the tumor microenvironment. Aucubin not only abrogated cisplatin-induced PD-L1 expression but also enhanced the antitumor efficacy of cisplatin in a mouse xenograft model of HCC.

CONCLUSION

Aucubin exerts antitumor activity against HCC and also enhances the antitumor activity of cisplatin by suppressing the Akt/β-catenin/PD-L1 axis.

Aucubin protects mouse cochlear hair cells from cisplatin-induced ototoxicity via activation of the PI3K/AKT/STAT3 pathway

Cisplatin is commonly used to treat cancers and is associated with a significant risk of irreversible sensorineural hearing loss. However, no effective preventive strategies are available for cisplatin-induced HL. Therefore, significant efforts have been made to discover new drugs protecting cochlear hair cells from cisplatin-induced damage. We found that a new phytochemical, aucubin, attenuated cisplatin-induced apoptosis, the production of reactive oxygen species, and mitochondrial dysfunction in House Ear Institute Organ of Corti 1 cells and cochlear hair cells. Moreover, aucubin attenuated cisplatin-induced sensorineural hearing loss and hair cells loss in vivo. Furthermore, RNA sequencing analysis revealed that the otoprotective effects of aucubin were mainly mediated by increased STAT3 phosphorylation via the PI3K/AKT pathway. Inhibition of the STAT3 signaling pathway with the inhibitor S3I-201 or siRNA disrupted the protective effects of aucubin on cisplatin-induced apoptosis. In conclusion, we identified an otoprotective effect of aucubin. Therefore, aucubin could be used to prevent cisplatin-induced ototoxicity.

Aucubin supplementation alleviate diabetes induced-disruption of blood-testis barrier and testicular damage via stabilizing cell junction integrity

Disruption of blood-testis barrier (BTB) was a crucial pathological feature of diabetes induced-testicular injury at early phase. Aucubin (AU), a main active component in Eucommiae Cortex, has drawn attention for its benefits against male reproductive system disease. The current study was aimed at investigating the protective role of AU and exploring the underlying mechanism in diabetic model. A murine model of type 2 diabetes mellitus (T2DM) was induced by high-fat diet (HFD) combined with streptozocin (STZ). Testicular weight index and morphology, sperm quality, integrity of BTB and protein levels were analyzed. The underlying mechanism of the protective effect of AU was further explored in Sertoli cells (SCs) cultured with high glucose (HG). Our results showed AU inhibited testicular structural destruction, restored disruption of BTB and improved abnormal spermatogenic function in diabetic mice. Consistent with in vivo results, HG induced decreased transcellular resistance and increased permeability in SCs monolayers, while AU exposure reverses this trend. Meanwhile, reduced expression of Zonula occludin-1(ZO-1) and Connexin43(Cx43) in testicular tissue diabetic mice and HG-induced SCs was prominently reversed via AU treatment. Mechanistic studies suggested a high affinity interaction between AU and c-Src protein was identified based on molecular docking, and the activation of c-Src was significantly inhibited in AU treatment. Furthermore, AU significantly increased the expression of Cx43 and ZO-1 proteins HG-induced SCs, which can be further enhanced in gene-silenced c-Src cells to some extent. Our results suggested that AU ameliorated disruption of BTB and spermatogenesis dysfunction in diabetic mice via inactivating c-Src to stabilize cell junction integrity.

Aucubin promoted neuron functional recovery by suppressing inflammation and neuronal apoptosis in a spinal cord injury model

BACKGROUND

Spinal cord injury (SCI) can cause severe motor impairment. Post-SCI treatment has focused primarily on secondary injury, with neuroinflammation and neuronal apoptosis as the primary therapeutic targets. Aucubin (Au), a Chinese herbal medicine, exerts anti-inflammatory and neuroprotective effects. The therapeutic effects of Aucubin in SCI have not been reported.

METHODS

In this study, we carried out an in vivo SCI model and a series of in vitro experiments to explore the therapeutic effect of Aucubin. Western Blotting and immunofluorescence were used to study the effect of Aucubin on microglial polarization and neuronal apoptosis and its underlying mechanism.

RESULTS

We found that Aucubin can promote axonal regeneration by reducing neuroinflammation and neuronal apoptosis, which is beneficial to motor recovery after spinal cord injury in rats. Our further in vitro experiments showed that Aucubin can activate the toll-like receptor 4 (TLR4)/myeloid differentiation protein-88 (MyD88)/IκBα/nuclear factor kappa B (NF-κB) signaling pathway to reduce neuroinflammation and reverse mitochondrial dysfunction to reduce neuronal apoptosis.

CONCLUSIONS

In summary, these results suggest that Aucubin may ameliorate secondary injury after SCI by reducing neuroinflammation and neuronal apoptosis. Therefore, Au may be a promising post-SCI therapeutic drug.

Aucubin ameliorates liver fibrosis and hepatic stellate cells activation in diabetic mice via inhibiting ER stress-mediated IRE1α/TXNIP/NLRP3 inflammasome through NOX4/ROS pathway

Type 2 diabetes (T2DM) is closely associated with hepatic injury, which could promote/exacerbate hepatic inflammation, steatosis, and accelerate liver fibrosis progression. Aucubin (AU), as an active ingredient isolated from Eucommia ulmoides, exists a nutritional value in hepatoprotective effect and diabetic complications. However, whether it possesses more outstanding features on improving liver injury in diabetic conditions and the underlying mechanism is unclear. Our research investigated the treatment of AU on liver fibrosis and potential mechanisms on high-fat diet/streptozotocin-induced diabetic mice and high glucose (HG)&TGF-β1-induced LX-2 cells. Results showed that AU restored hepatic function without affecting blood sugar levels in diabetic mice. Meanwhile, the enhanced levels of total cholesterol, triglycerides, and LDL-c were reversed in hepatic tissue after AU treatment. Histomorphology assays including H&E, Masson, PAS, Oil red and Sirius red staining showed that AU treatment reduced liver swelling, steatosis and fibrosis. Mechanistic studies showed that AU alleviated NLRP3 inflammasome activation and inflammatory responses via inhibiting ER stress-mediated IRE1α/TXNIP signaling pathway, which could postpone the development of T2DM induced hepatic fibrosis. In addition, the ROS generation and the up-regulated expression of NADHP oxidase 4 (NOX4) in the liver tissue were suppressed by AU treatment. Moreover, in vitro model, NOX4 activation was prominently enhanced and AU treatment blocked HG&TGF-β1-induced NOX4 derived superoxide generation and thereby ameliorating hepatic stellate cell activation, which can be abrogated in the overexpression of NOX4 LX-2 cells. In addition, inhibition effects on ER stress-mediated IRE1α/TXNIP/NLRP3 inflammasome by AU treatment also were abolished in the overexpression of NOX4 LX-2 cells. Meanwhile, molecular docking results indicated that AU and NOX4 protein have a higher affinity. Taken together, AU might be a potential nutraceutical or therapeutic drug to ameliorate hepatic impairment and fibrosis in T2DM.

Aucubin as a natural potential anti-acute hepatitis candidate: Inhibitory potency and hepatoprotective mechanism

BACKGROUND

Hepatic inflammation can substantially impact the development of acute hepatitis. It is a pressing need to identify and exploit novel therapeutic targets as well as effective drug therapies against acute hepatitis. Aucubin (AU) is one of the main active components extracted from the leaves of Eucommia ulmoides and possesses significant anti-inflammatory and antioxidant activities. However, the protective effect and mechanism of AU on acute hepatitis have not been reported yet.

PURPOSE

This study aims to investigate the protective effect of AU on LPS-induced acute hepatitis and the mechanism of action.

METHODS

The limma package was used to analyze differentially expressed genes (DEGs) between LPS-induced acute hepatitis and normal groups based on Gene Expression Omnibus (GEO) microarray data. Network pharmacology predicted targets for AU therapy against acute hepatitis, and Gene Ontology (GO) enrichment analysis of the biological processes involved in these targets. The key pathways were analyzed by protein-protein interaction, KEGG (Kyoto Encyclopedia of Genes and Genomes), and GSEA (Gene Set Enrichment Analysis) enrichment. The important interaction targets between AU and key pathways were evaluated by molecular simulation. The in silico predicted mechanism was verified based on in vitro and in vivo experiments.

RESULTS

A total of 116 intersection targets between AU prediction targets and differentially expressed genes were identified. They were functionally involved in the imbalance of "inflammation-anti-inflammation" and "oxidation-antioxidation" systems in the process of LPS-induced cases. In vitro experiments revealed that AU reduced inflammation in LPS-induced HepG2 cells by reducing the inflammatory cytokines TNF-α, IL-6, as well as iNOS enzyme activity levels. In addition, LPS-induced oxidative stress can be alleviated by AU via adjusting the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), Malone dialdehyde (MDA) and reactive oxygen species (ROS). Protein-protein interaction and GSEA results showed that AU might exert anti-inflammatory effects mainly through the STAT3/NF-κB signal pathway. Molecular dynamics simulation as well as in vivo tests further demonstrated AU restrained nuclear transfer of NF-κB (P65), probably through reducing phosphorylation of STAT3. In addition, AU appears to reduce oxidative stress by upregulating NRF2/HO-1.

CONCLUSION

We explored potential targets and signal pathways of AU in inhibiting acute hepatitis. AU exerted anti-inflammatory and antioxidant activities and may be a useful candidate drug for the treatment of acute hepatitis.

Potentials of using dietary plant secondary metabolites to mitigate nitrous oxide emissions from excreta of cattle: Impacts, mechanisms and perspectives

Nitrous oxide (N₂O) is a potent greenhouse gas as well as the key component depleting the ozone sphere of the earth. Cattle have high feed and water intakes and excrete large amounts of urine and feces. N₂O can be produced from cattle excreta during storage and use as fertilizer. Mitigating the N₂O emissions from cattle excreta during production is important for protecting the environment and the sustainable development of the cattle industry. Feeding cattle with low-protein diets increases N utilization rates, decreases N excretion and consequently reduces N₂O emissions. However, this approach cannot be applied in the long term because of its negative impact on animal performance. Recent studies showed that dietary inclusion of some plant secondary metabolites such as tannins, anthocyanins, glucosinolates and aucubin could manipulate the N excretion and the urinary components and consequently regulate N₂O emissions from cattle excreta. This review summarized the recent developments in the effects of dietary tannins, anthocyanins and glucosinolates on the metabolism of cattle and the N₂O emissions from cattle excreta and concluded that dietary inclusion of tannins or anthocyanins could considerably reduce N₂O emissions from cattle excreta.

Beneficial effects of Aucubin on restoration of rabbits with cartilage defect

Osteochondral grafts are suitable materials for repair of articular cartilage defect and plastic and reconstructive surgery. In our study, osteochondral allografts from rabbits were preserved in vitro for 28 days, and chondrocyte death, degradation of collagen and proteoglycan, morphological alterations, and inflammatory reaction were observed in the grafts. Supplementing of Aucubin with 10 or 20 μM in the preservation solution inhibited chondrocyte death, matrix degradation, pathological alterations and inflammation in allografts preserved in vitro, compared with that preserved in standard preservation solution. In addition, after transplantation of 20 μM Aucubin-treated allografts, the osteochondral repair and regeneration of rabbits with knee joint defect were accelerated. In conclusion, Aucubin was beneficial for maintaining chondrocyte viability and normal morphology, and inhibiting inflammatory occurrence in rabbit osteochondral grafts preserved in vitro, and facilitated osteochondral repair and regeneration of rabbits with knee defect. These findings might provide novel insights for preservation of grafts for clinical articular cartilage repair and plastic surgery.

Neuroprotective effects of aucubin on hydrogen peroxide-induced toxicity in human neuroblastoma SH-SY5Y cells via the Nrf2/HO-1 pathway

BACKGROUND

When redox balance is lost in the brain, oxidative stress can cause serious damage that leads to neuronal loss, in congruence with neurodegenerative diseases. Aucubin (AU) is an iridoid glycoside and that is one of the active constituents of Eucommia ulmoides, has many pharmacological effects such as anti-inflammation, anti-liver fibrosis, and anti-atherosclerosis.

PURPOSE

The present study aimed to evaluate the inhibitory effects of AU on cell oxidative stress against hydrogen peroxide (H₂O₂)-induced injury in SH-SY5Y cells in vitro.

METHODS

SH-SY5Y cells were simultaneously treated with AU and H₂O₂ for 24 h. Cell viability was measured by CCK-8. Additionally, mitochondrial membrane depolarization, reactive oxygen species (ROS) generation, and cell apoptosis were measured by flow cytometry.

RESULTS

The results showed that AU can significantly increase the H₂O₂-induced cell viability and the mitochondrial membrane potential, decrease the ROS generation, malondialdehyde (MDA), and increase glutathione (GSH) contents and the superoxide dismutase (SOD) activity. We also found that H₂O₂ stimulated the production of nitric oxide (NO), which could be reduced by treatment with AU through inhibiting the inducible nitric oxide synthase (iNOS) protein expression. In H₂O₂-induced SH-SY5Y cells, the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) content and cell apoptosis were significantly reduced by AU treatment through nuclear factor E2-related factor 2/hemo oxygenase-1 (Nrf2/HO-1) activation, inhibiting the expression of p-NF-κB/NF-κB and down-regulating MAPK and Bcl-2/Bax pathways.

CONCLUSION

These results indicate that AU can reduce inflammation and oxidative stress through the NF-κB, Nrf2/HO-1, and MAPK pathways.

Aucubin ameliorates the LPS-induced inflammatory response in bovine endometrial epithelial cells by inhibiting NF-κB and activating the Keap1/Nrf2 signalling pathway

Cows are susceptible to pathogenic bacterial infection after pregnancy, leading to inflammation of the endometrium. Aucubin (AU) has been proven to exhibit highly effective anti-inflammatory activity, but its ability to protect against endometritis in dairy cows remains unclear. Therefore, the goal of the present study was to evaluate the protective effect of AU on the LPS-induced inflammatory response of bovine endometrial epithelial cells (BEECs). After pre-treating BEECs with AU (10, 20 and 50 μM) for 6 hr, the cells were stimulated with LPS for 3 hr. Subsequently, BEECs apoptosis was analysed by flow cytometry, the expression of pro-inflammatory cytokine mRNA was detected by qRT-PCR, and changes in NF-κB and Keap1/Nrf2 signalling were analysed by western blotting and immunofluorescence analyses. The results showed that AU can reduce TNF-α, IL-1β, IL-6, COX-2 and iNOS mRNA expression in BEECs and reduce cell apoptosis. Furthermore, AU significantly reduced the level of NF-κB p65 and IκB phosphorylation and inhibited the nuclear translocation of NF-κB p65. AU also activated the Keap1/Nrf2 pathway, promoting the nuclear transfer of Nrf2 and increasing Keap1, Nrf2, HO-1 and NQO1 mRNA and protein levels. Taken together, these results indicate that AU ameliorates the LPS-induced inflammatory response by inhibiting NF-κB and activating the Keap1/Nrf2 signalling pathway, which has a protective effect on BEECs.

Aucubin inhibited lipid accumulation and oxidative stress via Nrf2/HO-1 and AMPK signalling pathways

Aucubin (AU) is the main active ingredient of Aucuba japonica which has showed many positive effects such as anti‐inflammation and liver protection. Non‐alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. In this research, we explored the effects of AU on the tyloxapol‐induced NAFLD in mice and apolipoprotein C‐III (apoC‐III) induced‐3T3L1 cells. Tyloxapol (300 mg/kg) was injected to C57BL/6 mice with aucubin. The differentiated 3T3‐L1 cells were treated with or without aucubin after stimulation of apoC‐III (100 μg/mL). In results, aucubin inhibited hyperlipidaemia, oxidative stress and inflammation by influencing the content of total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), very low density lipoprotein (VLDL), myeloperoxidase (MPO), superoxide dismutase (SOD), tumour necrosis factor receptor‐α (TNF‐α), interleukin‐1β (IL‐1β), and IL‐6 in blood. AU activated NF‐E2‐related factor 2 (Nrf2), peroxisome proliferator‐activated receptor α (PPARα), PPARγ and hemeoxygenase‐1 (HO‐1) and promoted the phosphorylation of adenosine 5′‐monophosphate‐activated protein kinase (AMPKα), AMPKβ, acetyl‐CoA carboxylase (ACC) and protein kinase B (AKT). In conclusion, AU performed the function of hypolipidaemic by its obvious anti‐inflammation and antioxidant activity, which may become a kind of new drug targeting at NAFLD.

The therapeutic effect of aucubin-supplemented hyaluronic acid on interleukin-1beta-stimulated human articular chondrocytes

BACKGROUND

Injection of exogenous hyaluronic acid (HA) into the joint capsule improves symptoms of early stage osteoarthritis (OA). However, reactive oxygen species degrade HA into small oligosaccharides that can elicit pro-inflammatory responses. Likewise, disturbance of the antioxidant enzyme system and generation of oxidative stress by pro-inflammatory cytokines worsen knee OA. Accordingly, we proposed the use of aucubin, an antioxidant and anti-inflammatory compound, as a versatile adjuvant to HA for treating OA.

METHODS

Primary human chondrocytes were cultured in media supplemented with aucubin in a series of concentrations (0, 0.01, 0.1, 1, and 10 μg/ml) to study dose-dependent toxicity. We then evaluated the therapeutic effects of HA (100 μg/ml) supplemented with aucubin (10 μg/ml) on interleukin-1 beta (IL-1β, 10 ng/ml)-stimulated chondrocytes.

RESULTS

The use of aucubin did not change cell viability or alter lactate dehydrogenase release to normal chondrocytes. Although the proliferation and sulfated glycosaminoglycan production were not affected, aucubin partially restored the hypertrophic transformation of chondrocytes. Relative to treatment with HA or aucubin alone, real-time PCR revealed that aucubin-supplemented HA down-regulated the mRNA levels of tumor necrosis factor-alpha (TNF-α), corrected collagen type 1 and aggrecan, and up-regulated tissue inhibitor of metalloproteinase 1. Moreover, ELISA testing also showed a reduced TNF-α production. Although superoxide dismutases activity was still distributed, aucubin restored total antioxidant capacity of IL-1β-stimulated chondrocytes. Western blotting further showed that aucubin inhibited cyclooxygenase-2 and regulated the nuclear factor (erythroid-derived 2)-like 2 pathway.

CONCLUSION

Aucubin can enhance the anti-catabolic and anti-inflammatory effects of HA on OA chondrocytes.

Aucubin protects against lipopolysaccharide-induced acute pulmonary injury through regulating Nrf2 and AMPK pathways

Aucubin (Ai), a natural compound isolated from plants, including Aucuba japonica and Eucommia ulmoides, shows significant anti-inflammatory and anti-oxidative bioactivities. Here, we attempted to explore the protect effects of Ai on LPS-induced acute lung injury (ALI). Our results indicated that Ai increased the survival rate and ameliorated pathogenic processes in lipopolysaccharide (LPS)-induced mice. However, nuclear factor erythroid 2-related factor 2 (Nrf2) deletion may impede protective effect of Ai. Additionally, Ai reduced oxidative stress by down-regulating malondialdehyde (MDA) and O₂· activity, and enhancing Nrf2-targeted signals, including heme oxygenase-1 (HO-1) and quinone oxidoreductase-1 (NQO-1). Also, Ai inhibited pro-inflammatory cytokines and phosphorylated-nuclear factor-κB (NF-κB) expression in LPS-administrated mice. However, these protective effects of Ai were suppressed in Nrf2-knockout mice. Importantly, Nrf2-deficiency showed no effects on phosphorylated AMP-activated protein kinase (p-AMPK) expression in mice treated with LPS and Ai. Similarly, in LPS-induced macrophages, Ai reduced reactive oxygen species (ROS) generation, elevated NQO-1 and HO-1 expression. LPS-stimulated pro-inflammatory cytokines and p-NF-κB were reversed by Ai. Of note, we found that Ai-induced Nrf2 activation was dependent on AMPK activation. Suppression of AMPK levels may inhibit Nrf2 activation, finally leading to up regulation of inflammatory response and oxidative stress. Thus, our findings indicated the crosstalk between Nrf2 and AMPK signaling pathways, and the interaction was essential for the anti-oxidant and anti-inflammatory effects of Ai in LPS-induced macrophages, which might be beneficial for finding new treatments against ALI.

Involvement of bone morphogenetic protein-related pathways in the effect of aucubin on the promotion of osteoblast differentiation in MG63 cells

Aucubin, an iridoid glycoside found in several plants, such as Eucommia ulmoide and Rehmannia, has various pharmacological effects. Bone formation is a complex process in which osteoblast differentiation plays an important role. This study aimed to investigate the promotion effects of aucubin on osteoblast differentiation in MG63 cells, a human osteoblast-like cell line. Aucubin not only improved osteoblast differentiation, as shown by enhanced ALP (alkaline phosphatase) concentration and mineralization in cells, but increased the expression of various cytokines, including collagen I, osteocalcin, osteopontin, integrin β1, and Osterix. Aucubin strongly enhanced the levels of BMP2 (bone morphogenetic proteins-2) in MG63 cells, which play a central role during osteoblast differentiation. Further data show that aucubin exposure after 1 day, 7 days, and 14 days enhanced the expression of Smad1, 5, and 8, and the phosphoresced levels of MAPKs (mitogen-activated protein kinases) family Erk (extracellular signal-regulated kinases), JNK (c-Jun-NH2-terminal kinases), P38, and Akt (serine/threonine protein kinase)/mTOR (mammalian target of rapamycin)/p70s6k in MG63 cells. This study shows the improved effects of aucubin on osteoblast differentiation in MG63 cells, related to the signaling of BMP2-mediated Smads (drosophila mothers against decapentaplegic proteins), MAPKs, and Akt/mTOR/p70S6K. This study indicates the potential of aucubin for osteoporosis treatment.

Effect of aucubin on neural precursor cell survival during neuronal differentiation

PURPOSE OF THE STUDY

Aucubin (ACB) is an iridoid glycoside with various biological activities. Previously, it is reported that ACB reduces cell survival and proliferation in many human tumors, whereas it facilitates cell survival and neuroprotection in damaged neuronal cells and disease models. However, its effects on cell survival in the non-proliferating or differentiated neurons are not known.

MATERIALS AND METHODS

We examined whether ACB facilitated cell survival in differentiating neural precursor cells, HiB5, compared with the proliferating HiB5 cells at various concentrations.

RESULTS

The cell viabilities were evaluated by measuring MTT values, cell numbers, amounts of neurotransmittersD1 and protein amounts of neuronal markers. Here, we showed that ACB promotes cell survival in differentiated neurons (10-200 μg/mL), but reduces it in proliferating NPCs (200-400 μg/mL). Protein amounts of neurofilament proteins, NF-H, NF-M, PSD-95 in post-synaptic density, GAP-43 in growing neurites and NeuN in differentiated neurons were upregulated by addition of ACB, indicating that cell survival increased in differentiated neurons, shown by immunoblot analysis. Especially, when PDGF was added into N2 media to facilitate neuronal differentiation of HiB5 cells, the viability of differentiated HiB5 cells was significantly elevated following the increase of ACB concentration. Furthermore, ACB promoted cell survival of specific neuron types, such as GABAergic neurons and glutamatergic neurons. When differentiated neurons were immunostained with markers for specific neurons, neuronal subtypes producing GABA and GAD 65/67 were immunostained more than subtypes producing glutamate and vGluT1.

CONCLUSION

These results indicate that ACB improves neuronal cell survival in differentiated cells, suggesting it may be a therapeutic compound for neurodegenerative disorders.

Aucubin promotes angiogenesis via estrogen receptor beta in a mouse model of hindlimb ischemia

Aucubin (AU) is an iridoid glycoside that has been shown to display estrogenic properties and has various pharmacological effects. Herein, we described the angiogenic properties of AU. In the study, hindlimb ischemia was induced by ligation of femoral artery on the right leg of ovariectomized mice. AU treatment significantly accelerated perfusion recovery and reduced tissue injury in mice muscle. Quantification of CD31-positive vessels in hindlimb muscles provided evidences that AU promoted angiogenesis in peripheral ischemia. In addition, results from quantitative PCR and western blot suggested AU induced angiogenesis via vascular endothelial cell growth factor (VEGF)/Akt/endothelial nitric oxide synthase (eNOS) signaling pathway. More interestingly, AU's angiogenic effects could be completely abolished in estrogen receptor beta (ERβ) knockout mice. In conclusion, the underlying mechanisms were elucidated that AU produced pro-angiogenic effects through ERβ-mediated VEGF signaling pathways. These results expand knowledge about the beneficial effects of AU in angiogenesis and blood flow recovery. It might provide insight into the ERβ regulating neovascularisation in hindlimb ischemia and identify AU as a potent new compound used for the treatment of peripheral vascular disease.

The Protective Effect of Aucubin from Eucommia ulmoides Against Status Epilepticus by Inducing Autophagy and Inhibiting Necroptosis

Eucommia ulmoides Oliv. is a famous traditional Chinese medicine which exhibits anti-oxidative stress ability and neuro-protective effects. Aucubin is the predominant component of Eucommia ulmoides Oliv. Our present study is intended to investigate aucubin's potential protective effects on neurons against epilepsy in the hippocampus by establishing the lithium-pilocarpine induced status epilepticus (SE) rat model in vivo. Aucubin (at a low dose and a high dose of 5[Formula: see text]mg/kg and 10[Formula: see text]mg/kg, respectively) was administered through gavage for two weeks before lithium-pilocarpine injection. Rats were sacrificed at 4, 24 and 72[Formula: see text]h after SE induction. Pretreatment with both low-dose and high-dose aucubin significantly reduced the number of death neurons ([Formula: see text]) and increased the number of surviving neurons ([Formula: see text]) in DG, Hilus, CA1 and CA3 hippocampal regions post SE. Meanwhile, it significantly inhibited necroptosis proteins (MLKL and RIP-1) ([Formula: see text] or [Formula: see text]) and enhanced autophagy protein (Beclin-1 and LC3BII/LC3BI) prevalence in the hippocampus ([Formula: see text] or [Formula: see text]). In conclusion, aucubin appeared to ameliorate damages in lithium-pilocarpine induced SE in hippocampus, reduce the number of apoptotic neurons, and increased the number of survival neurons by inducing autophagy and inhibiting necroptosis. These original findings might provide an important basis for the further investigation of the therapeutic role of aucubin in treatment or prevention of epilepsy-related neuronal damages.

Aucubin and its hydrolytic derivative attenuate activation of hepatic stellate cells via modulation of TGF-β stimulation

Eucommia ulmoides is an important traditional Chinese medicine and has been used as a tonic with a long history. Aucubin is an active component extracted from Eucommia ulmoides, which has liver-protection effects. However the mechanisms are still unclear. To investigate the inhibitory effects and the underlying mechanisms of aucubin on TGF-β1-induced activation of hepatic stellate cells and ECM deposition, Human hepatic stellate cells (LX-2 cells) were incubated with TGF-β1 to evaluate the anti-fibrotic effect of aucubin. Western blot was used to investigate the expression of α-SMA, Col I, Col III, MMP-2 and TIMP-1. ROS production was monitored using DCFH-DA probe, and NOX4 expression was detected by Real-time PCR. Results indicated that TGF-β1 stimulated the activation and ECM deposition of LX-2 cells. Compared with the control group, aucubin and aucubigenin both reduced the protein expression of α-SMA, Col I, Col III and MMP-2 in LX-2 cells. Aucubin and aucubigenin also suppressed the generation of ROS and down-regulated the NOX4 mRNA expression. Taken together, aucubin and aucubigenin both inhibit the activation and ECM deposition of LX-2 cells activated by TGF-β1. Aucubin and aucubigenin are potential therapeutic candidate drugs for liver fibrosis.

Protective effects of aucubin on osteoarthritic chondrocyte model induced by hydrogen peroxide and mechanical stimulus

Background

During the onset of osteoarthritis (OA), certain biochemical events have been shown to accelerate cartilage degradation, including the dysregulation of cartilage ECM anabolism, abnormal generation of reactive oxygen species (ROS) and overproduction of proteolytic enzymes and inflammatory cytokines. The potency of aucubin in protecting cellular components against oxidative stress, inflammation and apoptosis effects are well documented, which makes it a potential candidate for OA treatment. In this study, we aimed to evaluate the protective benefits of aucubin against OA using H₂O₂ and compression induced OA-like chondrocyte models.

Methods

The effects of aucubin were studied in porcine chondrocytes after 1 mM H₂O₂ stimulation for 30 min or sustained compression for 24 h. Effects of aucubin on cell proliferation and cytotoxicity of chondrocytes were measured with WST-1 and LDH assays. ROS production was evaluated by the Total ROS/Superoxide Detection Kit. Caspase-3 activity was evaluated by the CaspACE assay system. The levels of apoptosis were evaluated by the Annexin V-FITC apoptosis detection kit. OA-related gene expression was measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Total DNA quantification was evaluated by the DNeasy Blood and Tissue kit. Sulfated-glycosaminoglycans (sGAGs) production and content were evaluated by DMMB assay and Alcian blue staining.

Results

The results showed that the ROS scavenge effects of aucubin appeared after 1 h of pretreatment. Aucubin could reduce the caspase-3 activity induced by H₂O₂, and reduced the apoptosis cell population in flowcytometry. In RT-qPCR results, aucubin could maintain ACAN and COL2A1 gene expressions, and prevent IL6 and MMP13 gene up-regulation induced by H₂O₂ and compression stimulations. In the DMMB assay and Alcian blue staining, aucubin could maintain the sGAG content and protect chondrocytes against compressive stress, but not oxidative stress from H₂O₂.

Conclusions

These results indicated that aucubin has protective effects in an osteoarthritic chondrocyte model induced by H₂O₂ and mechanical stimulus.

Prophylactic administration of an extract from Plantaginis Semen and its major component aucubin inhibits mechanical allodynia caused by paclitaxel in mice

The chemotherapeutic agent paclitaxel (PTX) causes peripheral neuropathy as a major dose-limiting side effect, and this peripheral neuropathy is difficult to control. Our previous report showed that prophylactic repetitive administration of goshajinkigan (牛車腎氣丸 niú chē shèn qì wán), but not hachimijiogan (八味地黃丸 bā wèi dì huáng wán), which lacks two of the constituents of goshajinkigan, inhibited PTX-induced mechanical allodynia in mice. Thus, the herbal medicines Plantaginis Semen (車前子 chē qián zǐ) or Achyranthis Radix (牛膝 niú xī) may contribute to the inhibitory action of goshajinkigan on the exacerbation of PTX-induced mechanical allodynia [Andoh et al, J. Tradit. Complement. Med. 2014; 4: 293–297]. Therefore, in this study, we examined whether an extract of Plantaginis Semen (EPS) or Achyranthis Radix (EAR) would relieve PTX-induced mechanical allodynia in mice. A single intraperitoneal injection of PTX caused mechanical allodynia, which peaked on day 14 after injection. Repetitive oral administration of EPS, but not EAR, starting from the day after PTX injection significantly inhibited the exacerbation of PTX-induced mechanical allodynia. Repetitive intraperitoneal injection of aucubin, one of the main components of EPS, starting from the day after PTX injection also significantly reduced PTX-induced mechanical allodynia. However, repetitive intraperitoneal injection of geniposide acid (a precursor of aucubin) or catalpol (a metabolite of aucubin) did not prevent the exacerbation of mechanical allodynia. These results suggest that prophylactic administration of EPS is effective for preventing the exacerbation of PTX-induced allodynia. Aucubin may contribute to the inhibitory action of EPS on the exacerbation of PTX-induced allodynia.

Impact of the dual defence system of Plantago lanceolata (Plantaginaceae) on performance, nutrient utilisation and feeding choice behaviour of Amata mogadorensis larvae (Lepidoptera, Erebidae)

Iridoid glycosides are plant defence compounds with potentially detrimental effects on non-adapted herbivores. Some plant species possess β-glucosidases that hydrolyse iridoid glycosides and thereby release protein-denaturing aglycones. To test the hypothesis that iridoid glycosides and plant β-glucosidases form a dual defence system, we used Plantago lanceolata and a polyphagous caterpillar species. To analyse the impact of leaf-age dependent differences in iridoid glycoside concentrations and β-glucosidase activities on insect performance, old or young leaves were freeze-dried and incorporated into artificial diets or were provided freshly to the larvae. We determined larval consumption rates and the amounts of assimilated nitrogen. Furthermore, we quantified β-glucosidase activities in artificial diets and fresh leaves and the amount of iridoid glycosides that larvae feeding on fresh leaves ingested and excreted. Compared to fresh leaves, caterpillars grew faster on artificial diets, on which larval weight gain correlated positively to the absorbed amount of nitrogen. When feeding fresh young leaves, larvae even lost weight and excreted only minute proportions of the ingested iridoid glycosides intact with the faeces, indicating that the hydrolysis of these compounds might have interfered with nitrogen assimilation and impaired larval growth. To disentangle physiological effects from deterrent effects of iridoid glycosides, we performed dual choice feeding assays. Young leaves, their methanolic extracts and pure catalpol reduced larval feeding in comparison to the respective controls, while aucubin had no effect on larval consumption. We conclude that the dual defence system of P. lanceolata consisting of iridoid glycosides and β-glucosidases interferes with the nutrient utilisation via the hydrolysis of iridoid glycosides and also mediates larval feeding behaviour in a concentration- and substance-specific manner.

UPLC-MS/MS determination and gender-related pharmacokinetic study of five active ingredients in rat plasma after oral administration of Eucommia cortex extract

ETHNOPHARMACOLOGICAL RELEVANCE

Eucommiae cortex (EC), the bark of Eucommia ulmoides Oliv., has been traditionally used to treat many diseases in China for more than 2000 years. The pharmacological effects are primarily attributed to the presence of lignans, iridoids and phenolics, which are main active ingredients in EC.

AIM OF THE STUDY

First, to investigate the active ingredients that can be absorbed into the rat plasma according to which ingredients exhibit significant correlation of drug concentration-time curve. Second, to establish an efficient ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method for simultaneous determination of ingredients absorbed in rat plasma. Finally, to investigate gender effect on the pharmacokinetics of the ingredients absorbed in male and female rats plasma after oral administration with EC extract.

MATERIALS AND METHODS

18 ingredients from EC were detected by UPLC-MS/MS, 9 out of 18 ingredients were absorbed into rat plasma. And 5 ingredients exhibit significant correlation of drug concentration-time curve. They were pinoresinol di-O-β-d-glucopyranoside (PDG), geniposide (GE), geniposidic acid (GA), aucubin (AN) and chlorogenic acid (CA). The analytes were extracted from rat plasma via a simple protein precipitation procedure and osalmid was used as the internal standard. Chromatographic separation was achieved on a Waters ACQUITY HSS T3 column (2.1mm×100mm, 1.8μm) using a gradient elution program with acetonitrile and 0.1% formic acid water as the mobile phase, with a flow rate of 0.3mLmin(-1). The detection was performed on a triple-quadrupole tandem mass spectrometer by multiple reactions monitoring (MRM) mode in a positive ion mode via electrospray ionization (ESI). The transition monitored were /z 683.00[M+H](+)→235.10 for PDG, / z 389.00[M+H](+)→208.80 for GE, m/z 375.00[M+H](+)→194.79 for GA, m/z 364.00[M+NH4](+)→148.81 for AN, m/z 355.10[M+H](+)→162.84 for CA and m/z 230.03[M+H](+)→120.77 for internal standard.

RESULTS

The developed method showed good linearity over a wide concentration range, the lower limits of quantification and higher accuracy and precision for determination of the 5 analytes. Then the method was applied to study the pharmacokinetics in rats, and the results indicated that there were significant differences in pharmacokinetic parameters of the analytes between the male and female rats, and absorptions of these analytes in male group were all significantly higher than those in female group.

CONCLUSION

This study established an efficient, sensitive and selective UPLC-MS/MS method for simultaneous determination of the five ingredients in rat plasma, and it could be successfully applied to the comparative pharmacokinetic studies in male and female rats after oral administration with EC extract.

The Effects of Plantago major on the Activation of the Neutrophil Respiratory Burst

Plantago major is a common plant that grows worldwide in temperate zones and is found in fields, lawns, and on the roadsides. Its leaves and seeds have been used in almost all parts of the world for centuries as a wound healer, analgesic, antioxidant, and antibiotic, as well as an immune system modulator, antiviral, antifungal, and anti-inflammatory agent. Baicalein and aucubin are the two most biologically active components of P. major, and both have been shown to have antioxidant, anti-inflammatory, and anticancer properties. Neutrophils have a pivotal role in wound healing and inflammation. Their principal mechanism of host defense is the killing of pathogens via the production of reactive oxygen species (ROS). The aim of the present study was to determine the in vitro effects of P. major extract, baicalein, and aucubin on human neutrophil respiratory burst activity. The cytotoxicity of the agents was assessed by lactate dehydrogenase (LDH) assays. A standard luminol-dependent chemiluminescence (CL) assay was utilized to monitor the respiratory burst of the neutrophils after exposure to P. major extract and its two active ingredients, baicalein and aucubin. Three replicates per group were included in each of the three runs of the experiments and analysis of variance (ANOVA) was used for statistical analysis. P. major and baicalein were not toxic to the cells at any of the concentrations examined. Aucubin was toxic to the cells only at the highest concentration tested (P = 0.0081). However, genistein was toxic to the cells at all of the concentrations examined except for the lowest concentration of 16.9 μg/ml (P = 0.985). P. major (−0.10 ± 0.11), aucubin (0.06 ± 0.16), baicalein (−0.10 ± 0.11), and genistein (−0.18 ± 0.07) all significantly (P < 0.0001) inhibited ROS production from the neutrophils. P. major extract inhibited neutrophil ROS production, as did aucubin and baicalein. Therefore, these components should be investigated further with relation to the regulation of destructive ROS production in conditions such as periodontal disease.