Catalpol alleviates hypoxia ischemia-induced brain damage by inhibiting ferroptosis through the PI3K/NRF2/system Xc-/GPX4 axis in neonatal rats

Hypoxic-ischemic encephalopathy (HIE) is a brain damage caused by perinatal hypoxia and blood flow reduction. Severe HIE leads to death. Available treatments remain limited. Oxidative stress and nerve damage are major factors in brain injury caused by HIE. Catalpol, an iridoid glucoside found in the root of Rehmannia glutinosa, has antioxidant and neuroprotective effects. This study examined the neuroprotective effects of catalpol using a neonatal rat HIE model and found that catalpol might protect the brain through inhibiting neuronal ferroptosis and ameliorating oxidative stress. Behavior tests suggested that catalpol treatment improved functions of motor, learning, and memory abilities after hypoxic-ischemic injury. Catalpol treatment inhibited changes to several ferroptosis-related proteins, including p-PI3K, p-AKT, NRF2, GPX4, SLC7A11, SLC3A2, GCLC, and GSS in HIE neonatal rats. Catalpol also prevented changes to several ferroptosis-related proteins in PC12 cells after oxygen-glucose deprivation. The ferroptosis inducer erastin reversed the protective effects of catalpol both in vitro and in vivo. We concluded that catalpol protects against hypoxic-ischemic brain damage (HIBD) by inhibiting ferroptosis through the PI3K/NRF2/system Xc-/GPX4 axis.

Regulatory mechanisms of Gentiopicroside on human diseases: a brief review

Gentiopicroside (GPS), a single compound isolated from Gentiana lutea L. and the crucial representative of secoiridoid constituent, has been permitted for centuries in traditional Chinese medicine. GPS and its metabolites have been increasingly used in the search for clinical management with therapeutic properties and fewer side effects. The objective of this review was to provide a comprehensive overview of the involvement of molecular pathways in the therapeutic effects of GPS on human diseases and chronic conditions. This study presents a meticulously conducted comprehensive search of the PubMed and Google Scholar databases (from 1983 to 2023), aimed at identifying articles relating to regulatory mechanisms of GPS on human diseases and the pharmacokinetics of GPS. The inclusion criteria were meticulously and precisely defined to encompass original research papers that explicitly focused on elucidating the regulatory mechanisms of GPS in various human diseases through in vitro and animal studies. Notably, these studies were mandated to integrate specific genetic markers or pathways as essential components of their research inquiries. The evaluated pharmacokinetic parameters included maximum plasma concentration (Cmax), time to reach maximum plasma concentration (Tmax), area under the curve (AUC), clearance, and plasma half-life (t1/2). Subsequently, through a rigorous screening process of titles and abstracts, studies conducted in vitro or on animals, as well as those reporting pharmacokinetic data related to drugs other than GPS or language barriers, were systematically excluded. Drawing from the data and studies pertaining to this review, we conducted a thorough and informative analysis of the pharmacological characteristics and biological functions of GPS. These encompassed a wide range of effects, including hepatoprotective, anti-inflammatory, antifibrotic, antioxidant, analgesic, antitumor, and immunomodulatory properties. The analysis provided a comprehensive and insightful understanding of GPS's pharmacological profile and its diverse activities. Enhancing theoretical and experimental methodologies could prove advantageous in expanding the clinical applications of GPS. This could involve optimizing the bioavailability and pharmacokinetics of GPS, uncovering additional biomarkers and potential biotransformation pathways, and investigating its combined effects with standard-of-care medications.

Anti-inflammatory effect and mechanism of catalpol in various inflammatory diseases

Catalpol is a kind of iridoid glucoside, widely found in a variety of plants, mostly extracted from the rhizome of the traditional medicinal herb rehmanniae. It has various biological activities such as anti-inflammatory, antioxidant, and antitumor. The anti-inflammatory effects of catalpol have been demonstrated in a variety of diseases, such as neurological diseases, atherosclerosis, renal diseases, respiratory diseases, digestive diseases, bone and joint diseases, eye diseases, and periodontitis. The purpose of this review is to summarize the existing literature on the anti-inflammatory effects of catalpol in a variety of inflammatory diseases over the last decade and to focus on the anti-inflammatory mechanisms of catalpol.

Catalpol Alleviates Isoflurane-Induced Hippocampal Learning and Memory Dysfunction and Neuropathological Changes in Aged Mice

INTRODUCTION

Isoflurane-associated perioperative neurocognitive disorders (PNDs) is a common complication that occurs commonly in elderly patients characterized by deterioration of hippocampus-dependent cognitive function. Mounting evidence has shown that hippocampal impairment and inflammatory processes are implicated in the pathogenesis of PNDs. Catalpol has been suggested to play a role in the modulation of neuroprotection and neurotransmission. Therefore, we surmised that catalpol may play a similar role during isoflurane-induced PNDs.

METHODS

In our current study, aged mice were exposed to isoflurane to develop a mouse model of PNDs and preconditioned with catalpol for 2 weeks before modeling. Three weeks after isoflurane exposure, behavioral, histological, biochemical, electrophysiological, and immunofluorescent assays were performed.

RESULTS

Our results showed that catalpol preadministration significantly alleviated cognitive impairment in the Morris water maze, novel object recognition, and Y-maze behavioral tests. Neuropathological analyses showed that catalpol preadministration reduced the loss of neurons and synapses; in line with this, it is revealed that hippocampal synaptic plasticity was restored. Mechanistically, catalpol preadministration suppressed the activation of microglia and decreased the expression of NLRP3 inflammasome.

CONCLUSION

Our results indicate that catalpol preadministration could effectively alleviate cognitive impairment and neuropathological damage in isoflurane-exposed aged mice with its neuroprotective effects via modulation of the NLRP3 inflammatory pathway. Furthermore, the NLRP3 inflammatory pathway was revealed to be involved in these effects.

Oleuropein Protects Human Retinal Pigment Epithelium Cells from IL-1β-Induced Inflammation by Blocking MAPK/NF-κB Signaling Pathways

Proinflammatory mediators such as interleukin (IL)-1β cause retinal pigment epithelium (RPE) inflammation, which is related to visual deterioration, including age-related macular degeneration and diabetic retinopathy. Oleuropein is a polyphenol compound that shows potent anti-inflammatory, antioxidant, and anti-cancer activities, but its effects on IL-1β-induced inflammation have not been examined in the adult RPE cell line ARPE-19. Here, we assessed the ability of oleuropein to attenuate this inflammation in ARPE-19 cells. IL-1β induced secretion of the inflammatory cytokines IL-6, monocyte chemoattractant protein-1 (MCP)-1, and soluble intercellular adhesion molecule (sICAM)-1. As measured by enzyme-linked immunosorbent assay, oleuropein significantly inhibited levels of all three proteins and led to decreased monocyte adhesiveness to ARPE-19 cells. To clarify the underlying anti-inflammatory mechanisms, we used western blots to evaluate the effect of oleuropein on inactivation of the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. The results showed that oleuropein significantly decreased levels of the inflammatory mediator cyclooxygenase-2 and increased anti-inflammatory protein HO-1 expression. We next examined if the anti-inflammatory activity of oleuropein arises via inactivated NF-κB. We found that suppressing phosphorylation of the JNK1/2 and p38 MAPK signaling pathways inhibited IL-6, MCP-1, and sICAM-1 secretion, implicating these pathways and NF-κB suppression in the effects of oleuropein. These results indicate that oleuropein shows potential for the prevention and treatment of inflammatory diseases of the retina.

Oleuropein Protects Against Cerebral Ischemia Injury in Rats: Molecular Docking, Biochemical and Histological Findings

This study was designed to evaluate the underlying protective mechanisms of oleuropein involved in alleviating brain damage in a rat model of ischemic stroke. Male Wistar rats were divided into four groups; Control, stroke (MCAO), MCAO + clopidogrel (Clop) and MCAO + oleuropein (Ole). Results showed that the MCAO group evidenced significant brain edema (+ 9%) as well as increases of plasma cardiac markers such as lactate deshydrogenase (LDH), creatine kinase (CK-MB), fibrinogen and Trop-T by 11 %, 43%, 168 and 590%, respectively, as compared to the control group. Moreover, infarcted rats exhibited remarkable elevated levels of angiotensin converting enzyme (ACE), both in plasma and brain tissue, with astrocyte swelling and necrotic neurons in the infarct zone, hyponatremia, and increased rate of thiobarbituric acid-reactive substances (TBARS) by 89% associated with decreases in the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (Cat) by 51%, 44 and 42%, respectively, compared to normal control rats. However, MCAO rats treated with oleuropein underwent mitigation of cerebral edema, correction of hyponatremia, remarkable decrease of plasma fibrinogen and cardiac dysfunctional enzymes, inhibition of ACE activity and improvement of oxidative stress status in brain tissue. Furthermore, in silico analysis showed considerable inhibitions of ACE, protein disulfide isomerase (PDI) and TGF-β1, an indicative of potent anti-embolic properties. Overall, oleuropein offers a neuroprotective effect against ischemic stroke through its antioxidative and antithrombotic activities.

Catalpol enhanced physical exercise-mediated brain functional improvement in post-traumatic stress disorder model via promoting adult hippocampal neurogenesis

Post-traumatic stress disorder (PTSD) is a serious psychiatric disorder characterized by hyper-response to environmental cues as well as the associated depressive and cognitive dysfunctions. According to the key roles of hippocampus for cognitive and emotional regulation, improving hippocampal functions, particularly hippocampal neural plasticity, is the necessary pathway to attenuate the core symptoms of PTSD. The effects of the alternative therapies such as exercise and natural compounds to reduce PTSD symptoms and promote adult hippocampal neurogenesis have been widely demonstrated. However, what is the effect of combining the exercise with traditional Chinese medical compounds remains unknown. In current study, we evaluated the effects of catalpol, which showed the pro-neurogenic effects in previous report, in regulating exercise-mediated PTSD therapeutic effects. With behavioral tests, we found that catalpol treatment promoted the effects of exercise to reduce the response of mice to dangerous cues, and simultaneously enhanced the antidepressant and cognitive protection effects. Moreover, by immunofluorescence we identified that catalpol promoted exercise-mediated hippocampal neurogenesis by enhancing the neural differentiation and mature neuronal survive. We further found that the promote effects of catalpol to exercise-induced environmental hyper-response, antidepressant effects and cognitive protective effects were all compromised by blocking neurogenesis with temozolomide (TMZ). This result indicates that hippocampal neurogenesis is prerequisite for catalpol to promote exercise-mediated brain functional improvement in PTSD model. In conclusion, our research identified the new function of natural compounds catalpol to promote the exercise-mediated brain functional changes in PTSD model, which depend on its effect promoting adult hippocampal neurogenesis.

Catalpol counteracts the pathology in a mouse model of Duchenne muscular dystrophy by inhibiting the TGF-β1/TAK1 signaling pathway

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease caused by a mutation in the gene encoding the dystrophin protein. Catalpol is an iridoid glycoside found in Chinese herbs with anti-inflammatory, anti-oxidant, anti-apoptotic, and hypoglycemic activities that can protect against muscle wasting. In the present study we investigated the effects of catalpol on DMD. Aged Dystrophin-deficient (mdx) mice (12 months old) were treated with catalpol (100, 200 mg·kg-1·d-1, ig) for 6 weeks. At the end of the experiment, the mice were sacrificed, and gastrocnemius (GAS), tibialis anterior (TA), extensor digitorum longus (EDL), soleus (SOL) muscles were collected. We found that catalpol administration dose-dependently increased stride length and decreased stride width in Gait test. Wire grip test showed that the time of wire grip and grip strength were increased. We found that catalpol administration dose-dependently alleviated skeletal muscle damage, evidenced by reduced plasma CK and LDH activity as well as increased the weight of skeletal muscles. Catalpol administration had no effect on dystrophin expression, but exerted anti-inflammatory effects. Furthermore, catalpol administration dose-dependently decreased tibialis anterior (TA) muscle fibrosis, and inhibited the expression of TGF-β1, TAK1 and α-SMA. In primary myoblasts from mdx mice, knockdown of TAK1 abolished the inhibitory effects of catalpol on the expression levels of TGF-β1 and α-SMA. In conclusion, catalpol can restore skeletal muscle strength and alleviate skeletal muscle damage in aged mdx mice, thus may provide a novel therapy for DMD. Catalpol attenuates muscle fibrosis by inhibiting the TGF-β1/TAK1 signaling pathway.

Therapeutic potential of catalpol and geniposide in Alzheimer's and Parkinson's diseases: A snapshot of their underlying mechanisms

Rehmannia glutinosa, the fresh or dried root of Rehmannia glutinosa (Gaertn.) Libosch. ex Fisch. & Mey., and Gardenia, the fruit of Gardenia jasminoides Ellis from Rubiaceae, both are famous traditional Chinese medicines that have been traditionally used in China. Catalpol and geniposide, as two kinds of iridoid glycosides with high activities, are the main bioactive components in Rehmannia glutinosa and Gardenia jasminoides Ellis, respectively. Over the past few decades, catalpol and geniposide have been widely studied for their therapeutic effects. The preclinical experiments demonstrated that they possessed significant neuroprotective activities against Alzheimer's disease, Parkinson's disease, stroke, and depression, etc. In this paper, the pharmacological effects and mechanisms of catalpol and geniposide on Alzheimer's disease and Parkinson's disease from 2005 to now were systematically summarized and comprehensively analyzed. At the same time, the pharmacokinetic characteristics of the analyzed compounds were also described, hoping to provide some enlightenment for the design, research, and development of iridoid glycosides.

Chloroquine enhances catalpol's ability to promote apoptosis by inhibiting catalpol's autophagy-promoting effect on gastric cancer

PURPOSE

Gastric cancer, which is derived from gastric mucosal epithelial cells, is a representative solid tumour, and more than 1 million cases are diagnosed worldwide each year. However, treatment methods and therapeutics for gastric cancer are limited, and further research is needed to develop novel strategies.

METHODS

In this experiment, we studied the effect of catalpol from the extract of Dihuang from traditional Chinese medicine on gastric cancer cells.

RESULTS

The results showed that catalpol led to a dose-dependent reduction in gastric cancer cell proliferation. When the promotion of autophagy by catalpol was inhibited, the proapoptotic effects of catalpol on gastric cancer cells were enhanced. Bax, an apoptosis-related marker, was upregulated in catalpol-treated cells, and its expression was increased in the group treated with catalpol in combination with an inhibitor compared to the group treated with catalpol alone. Opposite results were obtained with BCL-2 inhibition. Flow cytometry showed that apoptosis rates were higher in cells treated with a combination of autophagy inhibitors. Accumulation of reactive oxygen species (ROS) in gastric cancer cells showed the group treated with the combination of catalpol and an inhibitor enhanced ROS production. Transwell assays showed that catalpol plus autophagy inhibitors exerted a stronger inhibitory effect on the migration ability of AGS cells than catalpol alone.

CONCLUSIONS

In summary, the above results indicate that inhibition of catalpol-induced autophagy could better promote the apoptosis of gastric cancer cells.

Protective effects of catalpol and rhein in murine experimental autoimmune encephalomyelitis via regulation of T helper (Th) 1, Th2, Th17, and regulatory T cell responses

OBJECTIVE

To examine the effects of catalpol and rhein on pro- and anti-inflammatory responses in C57BL/6 mice with experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis.

METHODS

Female C57BL/6 mice were randomly divided into four groups (n = 30): (a) normal saline control, (b) EAE control, (c) EAE + prednisone acetate (PA, 6 mg/kg), and (d) EAE + catalpol (40 mg/kg) and rhein (5 mg/kg). EAE was induced by injection of myelin oligodendrocyte glycoprotein 35-55 plus pertussis toxin. Treatments were orally administered daily for 40 d. Disease progression and neurological function were assessed using a semi-quantitative scale of tail and limb paralysis. Brains and spinal cords were collected on Days 6, 20, and 40 and assessed for histopathological changes by hematoxylin and eosin staining. Production of interleukin (IL)-2, IL-4, IL-10, and IL-17A protein was measured by enzyme-linked immunosorbent assay. Expression of the T helper (Th)1-, Th2-, Th17-, and regulatory T cell (Treg)-specific transcription factors T-bet, GATA3, ROR-γt, and Foxp3, respectively, were analyzed by quantitative reverse-transcription polymerase chain reaction and western blot analysis.

RESULTS

Combination treatment with catalpol and rhein significantly alleviated the clinical disability and neurological dysfunction of mice with EAE. Catalpol and rhein treatment also reduced the infiltration of pro-inflammatory T cells into pathological lesions; significantly increased the expression of the anti-inflammatory factors GATA3, Foxp3, IL-4, and IL-10; and significantly decreased the expression of the pro-inflammatory factors T-bet, ROR-γt, IL-2, and IL-17A.

CONCLUSION

Catalpol and rhein reduced the neurological disabilities of mice with EAE, at least in part by rebalancing the pro- and anti-inflammatory environment in the brains and spinal cords.

Catalpol ameliorates LPS-induced endometritis by inhibiting inflammation and TLR4/NF-κB signaling

Catalpol is the main active ingredient of an extract from Radix rehmanniae, which in a previous study showed a protective effect against various types of tissue injury. However, a protective effect of catalpol on uterine inflammation has not been reported. In this study, to investigate the protective mechanism of catalpol on lipopolysaccharide (LPS)-induced bovine endometrial epithelial cells (bEECs) and mouse endometritis, in vitro and in vivo inflammation models were established. The Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway and its downstream inflammatory factors were detected by enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), western blot (WB), and immunofluorescence techniques. The results from ELISA and qRT-PCR showed that catalpol dose-dependently reduced the expression of pro-inflammatory cytokines such as tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and IL-6, and chemokines such as C-X-C motif chemokine ligand 8 (CXCL8) and CXCL5, both in bEECs and in uterine tissue. From the experimental results of WB, qRT-PCR, and immunofluorescence, the expression of TLR4 and the phosphorylation of NF-κB p65 were markedly inhibited by catalpol compared with the LPS group. The inflammatory damage to the mouse uterus caused by LPS was greatly reduced and was accompanied by a decline in myeloperoxidase (MPO) activity. The results of this study suggest that catalpol can exert an anti-inflammatory impact on LPS-induced bEECs and mouse endometritis by inhibiting inflammation and activation of the TLR4/NF-κB signaling pathway.

Anticancer activity of globularifolin against human adenoid cystic carcinoma cells is due to ROS-mediated apoptotic cell death and modulation of the JAK/STAT signalling pathway

PURPOSE

Adenoid cystic carcinoma is a rare and under-researched disease. There is hardly any chemotherapy available for it, hence the urgent need to develop novel and efficient chemotherapy. Therefore, we examined the anticancer effects of globularifolin, an acylated iridoid glucoside, against salivary adenoid cystic carcinoma (SACC-83) cell line and normal human salivary gland (HSG) cell line.

METHODS

Cell counting and colony formation assays were used to determine cell viability. Acridin orange (AO)/ethidium bromide (EB) staining and comet assay were used for the detection of apoptosis. Reactive oxygen species (ROS) determination and cell cycle analysis were performed by flow cytometry. Transwell assay was used to monitor cell migration and Western blot analysis was used to determine protein expression.

RESULTS

Globularifolin inhibited the growth of SACC-83 cell line and exhibited an IC50 of 10 µM. Nonetheless, the cytotoxic effects of globularifolin were comparatively negligible against normal HGS cells with an IC50 of 80 µM. The investigation of the mechanism of action revealed that the anticancer effects of globularifolin against the SACC-83 cells was due to the induction of apoptotic cell death as indicated by AO/EB staining. Globularifolin treatment also resulted in enhancement of the Bax, Caspase 3 and 9 expression and decline of the Bcl-2 expression. Globularifolin also blocked the SACC-83 cells at the G0/G1 phase of the cell cycle. Moreover, cell invasion assay revealed that globularifolin inhibited the migration of the SACC-83 cells concentration-dependently, which was also coupled with the downregulation of metalloproteinase (MMP) 2 and 9. JAK/STAT is an important pathway involved in the proliferation and tumorigenesis of cancer cells and this research found that globularifolin could inhibit this pathway.

CONCLUSION

We conclude that globularifolin may prove essential in the development of systemic therapy for adenoid cystic carcinoma.

Gentiopicroside abrogates lipopolysaccharide-induced depressive-like behavior in mice through tryptophan-degrading pathway

Targeting neuroinflammatory disturbances has been acknowledged as a potential strategy for treatment of depressive disorder in humans. Over-activation of tryptophan-degrading pathway by pro-inflammatory cytokines resulted in N-methyl-d-aspartate (NMDA)-mediated excitotoxicity, which is implicated in pathophysiology of depression. Gentiopicroside (Gent) has powerful anti-inflammatory property and exhibits promising antidepressant effect in an animal model of pain/depression dyad by down-regulating GluN2B-containing NMDA receptors. Therefore, the present study aimed to investigate the ability of Gent to abolish depressive-like behavior induced by lipopolysaccharide (LPS) in mice. Acute administration of LPS (0.5 mg/kg, i.p.) increased immobility time in both forced swimming test (FST) and tail suspension test (TST) without affecting spontaneous locomotor activity, indicative of depressive-like behavior. Gent (50 mg/kg, i.p.) administered once a day for three consecutive days prevented the development of depressive-like behavior induced by LPS. The antidepressant-like effect was paralleled with restoration of LPS-induced alterations in brain inflammatory mediators (i.e. IL-1β and TNF-α). In addition, Gent prevented over-activation of indoleamine 2,3-double oxygen enzyme (IDO) and recovered GluN2B subunit expression in the PFC challenged by LPS. In conclusion, our results suggested that Gent pretreatment provided protection against LPS-induced depressive-like behavior and the effect appeared to be demonstrated, at least partially, by blocking various steps of tryptophan-degrading pathway.

The Molecular Targets of Swertiamarin and its Derivatives Confer Anti- Diabetic and Anti-Hyperlipidemic Effects

The herbal plant extract of Enicostemma littorale is widely used to medicate and treat type II Diabetes. This extract in medicine has shown its value in reducing blood glucose & lipid levels, and improving the kidney functioning, lipid profile, controlling blood pressure and heart rate. The well characterized chemical components such as iridoid and secoiridoid glycosides are present in aqueous and ethanolic extracts of the plant. Swertiamarin, a secoiridoid glycoside, is identified as the lead compound that confers anti-hyperglycemic & anti-hyperlipidemic effects. The swertiamarin binds with one or more molecular targets to alter their expression and/or activity. The in silico, in vivo and in vitro studies have been carried out to uncover the underlying molecular mechanism of action of swertiamarin and its derivatives for showing the better anti-diabetic & anti-hyperlipidemic activities. In brief, the present review focuses on unraveling the information about molecular targets of swertiamarin. Our review will open new avenues to develop therapeutic approaches and drugs to treat diabetes and other inflammatory diseases.

Lyophilized Powder of Catalpol and Puerarin Protected Cerebral Vessels from Ischemia by Its Anti-apoptosis on Endothelial Cells

Catalpol and puerarin are two monomers of Rehmannia glutinosa and Lobed Kudzuvine Root, which are two herbs commonly used together in ancient prescriptions of traditional Chinese medicine for cerebral ischemia. Our previous study shows that the lyophilized powder of the two monomers improved the outcome of cerebral ischemia excellently in rodents. However, if it protects vessels from ischemia is unknown. The present research studied the protection of lyophilized powder of catalpol and puerarin (CP) on endothelial cells and the relative mechanism in vivo and in vitro. Middle cerebral artery occlusion (MCAO) rats were used to study the improvement of CP on neurological deficiency, regional cerebral blood flow (rCBF), and infarct volume. The morphology of vessels and the apoptosis of brain vascular endothelial cells (BVECs) were observed and detected by immunohistochemistry approaches. To study how CP protected primary BVECs (pBVECs) from ischemic penumbra, oxygen glucose deprivation (OGD)-damaged pBVECs were cultured in the condition of insufficient nutrition and low oxygen which recapitulate the low perfusion of ischemic penumbra. Using the cell model, the mechanism by which CP protected pBVECs was studied by shRNA and pathway inhibitors. CP at the dose of 65.4 mg/kg increased regional cerebral blood flow (rCBF), reduced infarct volume, protected vessel integrity and inhibited endothelial cell apoptosis in vivo. But it only improved rCBF, vessel integrity and BVECs apoptosis at the dose of 32.7 mg/kg. In vitro, the protection of CP on pBVECs was proved to be ERK/HIF-1a- and PI3K/AKT/mTOR/HIF-1a-dependent. This study indicates a possibility of CP being a new drug for cerebral ischemia. Besides, this research provides an alternative cell model for penumbra ECs study.

Amelioration of Diabetic Mouse Nephropathy by Catalpol Correlates with Down-Regulation of Grb10 Expression and Activation of Insulin-Like Growth Factor 1 / Insulin-Like Growth Factor 1 Receptor Signaling

Growth factor receptor-bound protein 10 (Grb10) is an adaptor protein that can negatively regulate the insulin-like growth factor 1 receptor (IGF-1R). The IGF1-1R pathway is critical for cell growth and apoptosis and has been implicated in kidney diseases; however, it is still unknown whether Grb10 expression is up-regulated and plays a role in diabetic nephropathy. Catalpol, a major active ingredient of a traditional Chinese medicine, Rehmannia, has been reported to possess anti-inflammatory and anti-aging activities and then used to treat diabetes. Herein, we aimed to assess the therapeutic effect of catalpol on a mouse model diabetic nephropathy and the potential role of Grb10 in the pathogenesis of this diabetes-associated complication. Our results showed that catalpol treatment improved diabetes-associated impaired renal functions and ameliorated pathological changes in kidneys of diabetic mice. We also found that Grb10 expression was significantly elevated in kidneys of diabetic mice as compared with that in non-diabetic mice, while treatment with catalpol significantly abrogated the elevated Grb10 expression in diabetic kidneys. On the contrary, IGF-1 mRNA levels and IGF-1R phosphorylation were significantly higher in kidneys of catalpol-treated diabetic mice than those in non-treated diabetic mice. Our results suggest that elevated Grb10 expression may play an important role in the pathogenesis of diabetic nephropathy through suppressing IGF-1/IGF-1R signaling pathway, which might be a potential molecular target of catalpol for the treatment of this diabetic complication.

Geniposidic acid protected against ANIT-induced hepatotoxity and acute intrahepatic cholestasis, due to Fxr-mediated regulation of Bsep and Mrp2

ETHNOPHARMACOLOGICAL RELEVANCE

Geniposidic acid (GPA) is the main constituent of Gardenia jasminoides Ellis (Rubiaceae), which has long been used to treat inflammation, jaundice and hepatic disorders. The cholagogic effect of Gardenia jasminoides Ellis (Rubiaceae) and GPA have been widely reported, but the underlying occurrence mechanism remains unclear.

AIM OF THE STUDY

This investigation was designed to evaluate the hepatoprotection effect and potential mechanisms of GPA derived from Gardenia jasminoides Ellis (Rubiaceae) on fighting against α-naphthylisothiocyanate (ANIT) caused liver injury with acute intrahepatic cholestasis.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats were intragastrically (i.g.) administered with the GPA (100, 50 and 25mg/kg B.W. every 24h) for seven consecutive days, and then they were treated with ANIT (i.g. 65mg/kg once in the 5th day) which induced liver injury with acute intrahepatic cholestasis. Serum and bile biochemical analysis, bile flow rate and liver histopathology were measured to evaluate the protective effect of GPA fight against ANIT treatment. The protein and mRNA expression levels of farnesoid X receptor (Fxr), bile-salt export pump (Bsep), multidrug resistance associated protein2 (Mrp2), were evaluated to study the effect of liver protection about GPA against ANIT induced hepatotoxicity and underlying mechanisms.

RESULTS

Some abnormalities were observed on ANIT treated rats including weight loss, reduced food intake and hair turned yellow. Obtained results demonstrated that at dose 100 and 50mg/kg B.W. (P<0.01) and 25mg/kg B.W. (P<0.05) of GPA pretreated dramatically prevented ANIT induced decreased in bile flow rate. Compared with ANIT treated group, the results of bile biochemical parameters about total bile acid (TBA) was increased by GPA at groups with any dose (P<0.01), glutathione (GSH) was increased significantly at high dose (P<0.01) and medium dose (P<0.05), total bilirubin (TB) was increased at high and medium dose (P<0.05), direct bilirubin (DB) was only increased at high dose (P<0.01). Serum levels of glutamic-Oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), γ-glutamyltranspeptidase (γ-GT), TB, DB and TBA in comparison with ANIT treated group (P<0.01) were reduced by GPA (between 100 and 50mg/kg B.W.) pretreatment. Histopathology of the liver tissue showed that pathological damages and hepatic portal area filled with bile were relieved after GPA pretreatment compared with ANIT treated group. The protein and mRNA expression of Fxr, Bsep and Mrp2 were decreased in ANIT treated group. On the contrary, the protein and mRNA of Fxr, Bsep and Mrp2 were up regulated significantly pretreatment by GPA at dose of high and medium groups. On protein level of Bsep and Mrp2 the result shown no statistical difference in GPA (25mg/kg B.W.), but it was not same shown in mRNA level.

CONCLUSION

The results of this investigation have demonstrated that the GPA exerts a dose dependent hepatoprotection effect on ANIT induced liver damage with acute intrahepatic cholestasis in rats, which may due to Fxr mediated regulation of bile transporters like Bsep and Mrp2.

Gentiopicroside prevents interleukin-1 beta induced inflammation response in rat articular chondrocyte

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, Gentiana macrophylla Pall have been prescribed for the treatment of pain and inflammatory conditions. In addition, it is a common Tibetan medicinal herb used for the treatment of tonsillitis, urticaria, and rheumatoid arthritis (RA), while the flowers of G. macrophylla Pall have been traditionally treated as an anti-inflammatory agent to clear heat in Mongolian medicine. The secoiridoid glycosides and their derivatives are the primary active components of G. macrophylla and have been demonstrated to be effective as anti-inflammatory agents.

MATERIALS AND METHODS

Solvent extraction and D101 macroporous resin columns were employed to concentratethe gentiopicroside. Gentiopicroside cytotoxicity was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; the toxicity of gentiopicroside in chondrocytes was reconfirmed using Hoechst staining. Western blotting, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry were utilized to explore the protective effects and mechanisms of gentiopicroside prevents interleukin-1 beta induced inflammation response in rat articular chondrocyte.

RESULTS

The MTT assay demonstrated that 50, 500, and 1,500 μg/mL of gentiopicroside exhibited no significant toxicity to chondrocytes (P>0.05) after 24h. Using immunohistochemistry, ELISA, RT-PCR, Western blot method to explore the protective effect and mechanism of gentiopicroside on chondrocytes induced by IL-1β. The results showed some pathways of IL-1β signal transduction were inhibited by gentiopicroside in rat chondrocytes: p38, ERK and JNK. Meanwhile, gentiopicroside showed inhibition in the IL-1β-induced release of MMPs while increasing Collagen type II expression.

CONCLUSIONS

The current study demonstrated that gentiopicroside exhibited a potent protective effect on IL-1β induced inflammation response in rat articular chondrocyte. Thus, gentiopicroside could be a potential therapeutic strategy for treatment of OA.

Immunohistochemistry, histopathology, and biomarker studies of swertiamarin, a secoiridoid glycoside, prevents and protects streptozotocin-induced β-cell damage in Wistar rat pancreas

BACKGROUND

Diabetes mellitus is globally the major cause for metabolic syndrome in STZ-induced diabetic rats, leading to mortality. Treatment of diabetes by oral hypoglycemic agents causes adverse side effects and thus treatment with natural herbal drugs like swertiamarin is promising. Swertiamarin, an active compound isolated from Enicostemma littorale possesses antidiabetic activity and enhances β cell regeneration which causes reversal of diabetes.

OBJECTIVES

The present study aims at the following: (1) to evaluate antidiabetic, anti-hyperlipidaemic, activity of swertiamarin in Streptozotocin- induced diabetic rats using biomarkers. (2) To assess histopathological alterations in Pancreas, Liver, Kidney, and Heart of swertiamarin-treated STZ-induced diabetic rats and confirm cytoprotective activity of swertiamarin by Immunohistochemistry and morphometric investigations.

METHODS

Diabetes was induced intraperitoneally in male Wistar rats by Streptozotocin (STZ 50 mg/kg). After STZ-induction, hyperglycemic rats were treated with doses of swertiamarin orally (15, 25, 50 mg/kg) each for 28 days. Glibenclamide (2.5 mg/kg), a sulphonyl urea, was used as a standard drug. The glycemic control was measured by the biochemical parameter assays. Histopathology analysis of organs and immunohistochemistry of islets were carried out.

RESULTS

Our study results showed that oral administration of swertiamarin at a dosage of 15, 25, 50 mg/kg bw for 28 days resulted in a significant (p < 0.01) decrease in fasting blood glucose, HbA1c, TC, TG, LDL, and increased the levels of hemoglobin, plasma insulin, TP, body weight, and HDL levels significantly (p < 0.01) when compared to STZ-induced diabetic rats, as confirmed by immunohistochemical studies. The effect of swertiamarin on Carbohydrate-metabolizing enzymes was investigated and found to have normal therapeutic activity. Histopathological studies of Pancreas of swertiamarin-treated diabetic rats showed regeneration of islets when compared to STZ-induced diabetic rats, as confirmed by immunohistochemical studies.

CONCLUSION

Our research results clearly substantiate that swertiamarin possesses antihyperglycemic, antihyperlipidemic, cytoprotective, and immune reactivity and also a broad spectrum potential of treating diabetes and other complications related to diabetes and hence can be developed into a potent oral antidiabetic drug.

Amelioration by catalpol of atherosclerotic lesions in hypercholesterolemic rabbits

The aim of the present study was to evaluate the effects of catalpol administration on atherosclerosis. Atherogenesis was induced by a high-cholesterol chow in male New Zealand White rabbits that were randomly assigned to receive atorvastatin (5 mg/kg/day), catalpol (5 mg/kg/day), or vehicle by oral gavage for 12 weeks. The rabbits were sacrificed after 12 weeks, and the thoracic aorta and serum were collected for further pathological and molecular biological analysis. Catalpol administration resulted in significantly attenuated atherosclerotic lesions. Total cholesterol, triglycerides, and low-density lipoprotein cholesterol were remarkably reduced, and high-density lipid cholesterol was elevated in the catalpol-treated group. Catalpol reduced the levels of tumor necrosis factor-α, interleukin-6, monocyte chemoattractant protein-1, soluble vascular cell adhesion molecule-1, and soluble intercellular adhesion molecule-1 in the serum, as well as vascular cell adhesion molecule-1, monocyte chemoattractant protein-1, tumor necrosis factor-α protein, inducible nitric oxide synthase, matrix metalloproteinases-9, and nuclear factor-κB protein65 in the aortic arch. In addition, catalpol treatment reduced the lipid peroxidation levels, while elevating antioxidant capacity. Catolpol pretreatment inhibited the nuclear translocation and DNA binding activity of nuclear factor-κB protein in oxygenized low-density lipoprotein-stimulated EA.hy926 cells. Furthermore, catolpol pretreatment activated nuclear factor erythroid 2-related factor 2 and upregulated the expression of its downstream antioxidant enzyme heme oxygenase. In summary, catalpol attenuated atherosclerotic lesions by the inhibition of inflammatory cytokines and oxidative stress status in a rabbit atherosclerotic model and enhanced the antioxidant capacity in oxygenized low-density lipoprotein-stimulated EA.hy926 cells. These results suggest that catalpol may be used to prevent and attenuate atherosclerosis.

Anti-atherosclerotic effect of geniposidic acid in a rabbit model and related cellular mechanisms

CONTEXT

Geniposidic acid, one of the main active ingredients in Gardenia jasminoides J. Ellis (Rubiaceae), may also possess important pharmacological activities for cardiovascular disorders similar to other derivatives, such as geniposide.

OBJECTIVE

To evaluate its anti-atherosclerosis (anti-AS) effect, the related pharmacological activities and possible cellular mechanisms were studied.

MATERIALS AND METHODS

Thirty rabbits were randomly divided into normal control group, model control group, and geniposidic acid subgroups. In the AS model, its effects on the intima/media thickness ratio and aortic morphology were observed. In the study of primary cultured endothelial cells (ECs) and human umbilical artery smooth muscle cells (HUASMCs), its activities on both ECs and HUASMCs proliferation, HUASMCs' migration were also studied.

RESULTS

Compared with the model control group, the plaque area, intima/media thickness ratio, and intimal foam cells number in geniposidic acid (80, 160, and 240 mg/kg) subgroups were significantly improved (p < 0.05). By HE staining, the activities of geniposidic acid on relieving ECs shedding and improving aortic morphology disorders were also demonstrated. From the results of CCK-8 testing, only 100 μg/ml geniposidic acid performed significant inhibition on SMC proliferation. The relative IC50 of geniposidic acid on SMC inhibition was 87.73 μg/ml. Geniposide acid also showed promotion effect on ECs proliferation, and the related ED50 of geniposidic acid was 86.05 μg/ml. Besides, only 50 and 100 μg/ml geniposidic acid showed obvious inhibition on SMC migration from the upper chamber (p < 0.05).

DISCUSSION AND CONCLUSION

The effects of geniposidic acid on protecting vascular endothelium and reversing plaque formation in an atherosclerotic model were demonstrated.

[Impact of drug molecules on HP-β-CD compound inclusion]

To study the interaction of drugs of different properties, namely puerarin, borneol and catalpol in the process of in- clusion, in order to explore the inclusion regularity of multi-component and multi-property traditional Chinese medicine compound in- clusions. With HP-β-CD as the inclusion material, the freeze-drying method was used to prepare the inclusion. The inclusion between puerarin, borneol and catalpol was tested by measuring the inclusion concentration, DSC and X-ray diffraction. According to the find- ings, when insoluble drugs puerarin and borneol were included simultaneously, and puerarin was overdosed, puerarin included was almost equal to puerarin included, and borneol was not included. When puerarin was under-dosed, and HP-β-CD was overdosed, borne- ol was included, and the simultaneous inclusion was lower than the separate inclusion of borneol. When water-soluble drug catalpol was jointly included with puerarin or borneol, the simultaneous inclusion was almost the same with their separate inclusion, without charac- teristic peak of catalpol in DSC and X-ray diffraction patterns. There is a competition in the simultaneous inclusion between water-solu- ble drugs puerarin and borneol and a stronger competition in puerarin. The water-soluble drug catalpol could be included with HP-β-CD with no impact on the inclusion of puerarin or borneol.

Attenuation of reserpine-induced pain/depression dyad by gentiopicroside through downregulation of GluN2B receptors in the amygdala of mice

Epidemiological studies demonstrate that pain frequently occurs comorbid with depression. Gentiopicroside (Gent) is a secoiridoid compound isolated from Gentiana lutea that exhibits analgesic properties and inhibits the expression of GluN2B-containing N-methyl-D-aspartate (NMDA) receptors in the anterior cingulate cortex of mice. However, the effects of Gent on the reserpine-induced pain/depression dyad and its underlying mechanisms are unclear. Reserpine administration (1 mg/kg subcutaneous daily for 3 days) caused a significant decrease in the nociceptive threshold as evidenced by the reduced paw withdrawal latency in response to a radiant heat source and mechanical allodynia. Behavioral detection indicated a significant increase in immobility time during a forced swim test, as well as decreased time in the central area and total travel distance in an open field test. Furthermore, reserpinized animals exhibited increased oxidative stress. Systemic Gent administration dose-dependently ameliorated the behavioral deficits associated with reserpine-induced pain/depression dyad. At the same time, the decrease in biogenic amine levels (norepinephrine, dopamine, and serotonin) was integrated with the increase in caspase-3 levels and GluN2B-containing NMDA receptors in the amygdala of the reserpine-injected mice. Gent significantly reversed the changes in the levels of biogenic amines, caspase-3, and GluN2B-containing NMDA receptors in amygdala. However, Gent did not affect the expression of GluN2A-containing NMDA receptors. The inhibitory effects of Gent on oxidative stress were occluded by simultaneous treatment of GluN2B receptors antagonist Ro25-6981. Our study provides strong evidence that Gent inhibits reserpine-induced pain/depression dyad by downregulating GluN2B receptors in the amygdala.

Eucommia ulmoides cortex, geniposide and aucubin regulate lipotoxicity through the inhibition of lysosomal BAX

In this study we examined the inhibition of hepatic dyslipidemia by Eucommia ulmoides extract (EUE). Using a screening assay for BAX inhibition we determined that EUE regulates BAX-induced cell death. Among various cell death stimuli tested EUE regulated palmitate-induced cell death, which involves lysosomal BAX translocation. EUE rescued palmitate-induced inhibition of lysosomal V-ATPase, α-galactosidase, α-mannosidase, and acid phosphatase, and this effect was reversed by bafilomycin, a lysosomal V-ATPase inhibitor. The active components of EUE, aucubin and geniposide, showed similar inhibition of palmitate-induced cell death to that of EUE through enhancement of lysosome activity. Consistent with these in vitro findings, EUE inhibited the dyslipidemic condition in a high-fat diet animal model by regulating the lysosomal localization of BAX. This study demonstrates that EUE regulates lipotoxicity through a novel mechanism of enhanced lysosomal activity leading to the regulation of lysosomal BAX activation and cell death. Our findings further indicate that geniposide and aucubin, active components of EUE, may be therapeutic candidates for non-alcoholic fatty liver disease.

Synthesis of novel anticancer iridoid derivatives and their cell cycle arrest and caspase dependent apoptosis

Nyctanthes arbortristis Linn (Oleaceae) is widely distributed in sub-Himalayan regions and southwards to Godavari, India commonly known as Harsingar and Night Jasmine. In continuation of our drug discovery programme on Indian medicinal plants, we isolated arbortristoside-A (1) and 7-O-trans-cinnamoyl 6β-hydroxyloganin (2) from the seeds of N. Arbortristis, which exhibited moderate in vitro anticancer activity. Chemical transformation of 2 led to significant improvement in the activity in derivative 8 and 15 against HepG2 (human hepatocellular carcinoma), MCF-7 (breast adenocarcinoma) cell lines. The compounds 8 and 15 were also capable of cell cycle arrest and caspase dependent apoptosis in HepG2 cell lines. These iridoid derivatives hold promise for developing safer alternatives to the marketed drugs.

Relationship between [corrected] spatial memory in diabetic rats and protein kinase Cγ, caveolin-1 in the hippocampus and neuroprotective effect of catalpol

BACKGROUND

The mechanisms underlying diabetic encephalopathy are largely unknown, and no effective treatments are available. Catalpol has received much attention due to its numerous biological effects, especially in neuroprotective studies. The aim of this study was to investigate the effects of catalpol on cognitive functions in diabetic rats and the underlying mechanisms.

METHODS

A rat model of diabetes was established by streptozotocin injection, followed by intraperitoneal infusion of catalpol after 10 weeks. Two weeks later, the Morris water maze was used to test the spatial learning performance. Nissl staining was performed to evaluate the morphological changes in the hippocampus. Expression of protein kinase Cγ (PKCγ) and caveolin-1 (Cav-1) in the hippocampus were assessed by reverse transcription PCR and Western blotting. Activities of anti-oxidative enzymes such as glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) and levels of malonaldehyde (MDA) were measured using commercial kits.

RESULTS

Significant hippocampal neuronal injury was observed in rats with streptozotocin-induced diabetes. Moreover, cognitive dysfunction was associated with markedly increased oxidative stress in the brain. Catalpol treatment significantly attenuated cognitive deficits, neuronal damage, and oxidative stress in the brain of diabetic rats. Biochemical analyses showed that catalpol reversed the down-regulation of PKCγ and Cav-1 expression in the diabetic rats.

CONCLUSIONS

Spatial memory in diabetic rats is associated with the expression of PKCγ and Cav-1. Catalpol treatment markedly attenuated oxidative stress, reversed the alteration of PKCγ, Cav-1 and spatial memory deficits.

Effect of catalpol on diabetic nephropathy in rats

PURPOSE

To investigate the effect of catalpol on diabetic nephropathy in rats.

METHODS

Male Sprague-Dawley rats were randomly divided into two groups and fed with normal pallet diet (NPD) or high-fat diet (HFD) for 4 weeks respectively. Then the HFD-fed rats were injected with 35 mg/kg streptozotocin (STZ) for establishing diabetic model. The diabetic rats were randomly divided into five groups: model group, model plus catalpol 30, 60, 120 mg/kg groups and model plus metformin 200 mg/kg group. The NPD-fed rats were randomly divided into two groups: normal control group and normal plus catalpol 60 mg/kg control group. After administration for 10 weeks, random blood glucose (RBG), glycated serum protein (GSP), 24h urinary protein excretion (UPE), serum creatinine (Scr), blood urea nitrogen (BUN), and kidney weight index (KWI) were determined. The kidney pathological changes were evaluated by periodic acid-Schiff (PAS) staining. The concentrations of angiotensin II (Ang II), transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), fibronectin (FN), collagen type IV (Col IV) in renal cortex were determined. Real time RT-PCR was used to detect the mRNA expressions of TGF-β1 and CTGF.

RESULTS

Catalpol could significantly reduce the KWI, improve the kidney function and pathological change, decrease the tissue level of Ang II, TGF-β1, CTGF, FN, Col IV. Catalpol could also down regulate the mRNA expressions of TGF-β1 and CTGF in renal cortex.

CONCLUSION

Catalpol may have beneficial effects against diabetic nephropathy. The mechanisms may be related to reducing the extracellular matrix accumulation by restraining the expression of TGF-β1, CTGF and Ang II.

Geniposidic acid protects against D-galactosamine and lipopolysaccharide-induced hepatic failure in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Geniposidic acid (GA) is an iridoid glucoside isolated from Gardeniae jasminoides Ellis (Rubiaceae) that has long been used to treat inflammation, jaundice and hepatic disorders.

AIMS OF THE STUDY

This study examined the cytoprotective properties of GA against D-galactosamine (GalN)/lipopolysaccharide (LPS)-induced fulminant hepatic failure.

MATERIALS AND METHODS

Mice were given an intraperitoneal injection of GA (12.5, 25, 50 mg/kg) 1h before receiving GalN (800 mg/kg)/LPS (40 μg/kg). Liver and blood samples were collected 1 and 8 h after GalN/LPS injection.

RESULTS

The survival rate of the GA group was significantly higher than the control. GalN/LPS increased serum aminotransferase activity, serum tumor necrosis factor-α level and hepatic lipid peroxidation and decreased hepatic glutathione content. These changes were attenuated by GA. GA augmented increases in serum interleukin-6 level, heme oxygenase-1 and NF-E2-related factor 2 protein expression. Mice treated with GA decreased cleaved caspase-8 and caspase-3 protein expression and showed significantly fewer apoptotic cells. GA increased Bcl-xL protein expression and decreased Bax protein expression. Moreover, GA treatment enhanced phosphorylation of signal transducer and activator of transcription 3.

CONCLUSION

Our findings suggest that geniposidic acid alleviates GalN/LPS-induced liver injury by enhancing antioxidative defense system and reducing apoptotic signaling pathways.

Geniposide, an iridoid glucoside derived from Gardenia jasminoides, protects against lipopolysaccharide-induced acute lung injury in mice

Geniposide, a main iridoid glucoside component of gardenia fruit, has been shown to possess anti-inflammatory activity. However, its potential use for acute lung injury (ALI) has not yet been studied. The aim of this study was to evaluate the anti-inflammatory properties of geniposide using a mouse ALI model. ALI was induced by intranasal injection of lipopolysaccharide (LPS). Pretreatment of mice with geniposide (20, 40, or 80 mg/kg) resulted in a marked reduction in inflammatory cells and total protein concentration in the bronchoalveolar lavage fluid (BALF) of mice. Levels of inflammatory mediators, including tumour necrosis factor- α (TNF- α), interleukin-6 (IL-6), and interleukin-10 (IL-10), were significantly altered after treatment with geniposide. Histological studies using hematoxylin and eosin (H&E) staining demonstrate that geniposide substantially inhibited LPS-induced alveolar wall changes, alveolar haemorrhage, and neutrophil infiltration in lung tissue, with evidence of reduced myeloperoxidase (MPO) activity. In addition, we investigated potential signal transduction mechanisms that could be implicated in geniposide activity. Our results suggest that geniposide may provide protective effects against LPS-induced ALI by mitigating inflammatory responses and that the compound's mechanism of action may involve blocking nuclear factor-kappaB (NF- κB) and mitogen-activated protein kinases (MAPK) signalling pathway activation.

Primary study for the therapeutic dose and time window of picroside II in treating cerebral ischemic injury in rats

The aim of this study was to explore the optimal therapeutic dose and time window of picroside II for treating cerebral ischemic injury in rats according to the orthogonal test. The middle cerebral artery occlusion (MCAO) models were established by intraluminally inserting a thread into middle cerebral artery (MCA) from left external carotid artery (ECA). The successful rat models were randomly divided into 16 groups according to the orthogonal layout of [L₁₆(4⁵)] and treated by injecting picroside II intraperitoneally with different doses at various times. The neurological behavioral function was evaluated by Bederson’s test and the cerebral infarction volume was measured by tetrazolium chloride (TTC) staining. The expressions of neuron specific enolase (NSE) and neuroglial mark-protein S-100 were determined by immunohistochemisty assay. The results indicated that the optimal compositions of the therapeutic dose and time window of picroside II in treating cerebral ischemic injury were ischemia 1.5 h with 20 mg/kg body weight according to Bederson’s test, 1.0 h with 20 mg/kg body weight according to cerebral infarction volume, 1.5 h with 20 mg/kg body weight according to the expressions of NSE and S-100 respectively. Based on the principle of the minimization of medication dose and maximization of therapeutic time window, the optimal composition of the therapeutic dose and time window of picroside II in treating cerebral ischemic injury should be achieved by injecting picroside II intraperitoneally with 20 mg/kg body weight at ischemia 1.5 h.

Effect of iridoid glucoside on streptozotocin induced diabetic rats and its role in regulating carbohydrate metabolic enzymes

Vitex negundo is a medicinal plant used to treat many ailments. An active compound of iridoid glucoside was isolated from V. negundo leaves and its efficacy was investigated in streptozotocin induced diabetic rats with special reference to carbohydrate metabolizing enzymes. The optimum dose of iridoid glucoside was determined by oral glucose tolerance test. The effects of iridoid glucoside were compared with glibenclamide Administration of iridoid glucoside (50mg/kg body weight) to diabetic rats for 30 days resulted in significant reduction in the levels of plasma glucose, glycosylated hemoglobin and increase in the levels of insulin and hemoglobin. Administration of iridoid glucoside showed a significant increase in the levels of glycolytic enzymes and glycogen content and decrease in the levels of gluconeogenic enzymes in the liver of diabetic treated rats. Further, iridoid glucoside showed antihyperlipidemic activity as evidenced by significant reduction in serum total cholesterol, triglyceride, low density lipoprotein and very low density lipoprotein coupled together with elevation of high density lipoprotein in diabetic rats. A significant decrease was observed in the activities of aspartate aminotransferase, alanine aminotransferase and decrease in the levels of serum urea and creatinine in diabetic treated rats when compared to diabetic untreated rats. Treatment of iridoid glucoside alleviated body weight loss in diabetic rats. The effect produced by iridoid glucoside on various parameters was comparable to that of glibenclamide. These results indicate that iridoid glucoside possess antihyperlipidemic effect in addition to its antidiabetic effect.

Iridoid glycosides fraction of Folium syringae leaves modulates NF-κB signal pathway and intestinal epithelial cells apoptosis in experimental colitis

BACKGROUND AND AIMS

Iridoid glycosides (IG), the major active fraction of F. syringae leaves has been demonstrated to have strong anti-inflammatory properties to ulcerative colitis (UC) in our previous study. The aim of this study was to investigate whether IG modulates the inflammatory response in experimental colitis at the level of NF-κB signal pathway and epithelial cell apoptosis.

METHODS

UC in rats was induced by administration with dextran sulfate sodium (DSS) in drinking water. The inflammatory damage was assessed by disease activity index (DAI), macroscopic findings, histology and myeloperoxidase (MPO) activity. The effect of IG on pro-inflammatory cytokines TNF-α, IL-8, COX-2 and regulatory peptide TGF-β1 was measured. Epithelial cell apoptosis and the protein and mRNA expressions of Fas/FasL, Bcl-2/Bax, caspase-3, NF-κB p65, IκBα, p-IκBα and IKKβ were detected by TUNEL method, immunohistochemistry, Western blotting and real-time quantitative PCR, respectively.

RESULTS

IG significantly ameliorated macroscopic damage and histological changes, reduced the activity of MPO, and strongly inhibited epithelial cell apoptosis. Moreover, IG markedly depressed TNF-α, IL-8, COX-2 and TGF-β1 levels in the colon tissues in a dose-dependent manner. Furthermore, IG significantly blocked of NF-κB signaling by inhibiting IκBα phosphorylation/degradation and IKKβ activity, down-regulated the protein and mRNA expressions of Fas/FasL, Bax and caspase-3, and activated Bcl-2 in intestinal epithelial cells.

CONCLUSIONS

These results demonstrated for the first time that IG possessed marked protective effects on experimental colitis through inhibition of epithelial cell apoptosis and blockade of NF-κB signal pathway.

Plasma glucose lowering mechanisms of catalpol, an active principle from roots of Rehmannia glutinosa, in streptozotocin-induced diabetic rats

Catalpol is one of the active principles from roots of Rehmannia glutinosa Steud (Scrophulariaceae) that is widely used to treat diabetic disorders in Chinese traditional medicine using the name of Di-Huang, which is used to investigate the mechanisms for lowering of plasma glucose in streptozotocin-induced diabetic rats (STZ-diabetic rats). Catalpol decreased plasma glucose in a dose-related manner, and this action was reduced by pretreatment with naloxone or naloxonazine. An increase of plasma β-endorphin by catalpol was also observed in parallel. The plasma glucose lowering action of catalpol was deleted in bilateral adrenalectomized rats. Moreover, catalpol enhanced β-endorphin release from the isolated adrenal medulla of STZ-diabetic rats. Otherwise, plasma glucose lowering action of catalpol failed to produce in opioid μ-receptor knockout mice. Also, repeated administration of catalpol for 3 days in STZ-diabetic rats resulted in a marked reduction of phosphoenolpyruvate carboxykinase (PEPCK) expression in liver and an increased expression of glucose transporter subtype 4 (GLUT 4) in skeletal muscle. These effects were also reversed by blockade of opioid μ-receptors. Our results suggested that catalpol increased glucose utilization through increase of β-endorphin secretion from adrenal gland in STZ-diabetic rats.

Neuroprotective properties of picroside II in a rat model of focal cerebral ischemia

The aim of this study was to explore the effect of picroside II on neuronal apoptosis and the expression of caspase-3 and poly ADP-ribose polymerase (PARP) following middle cerebral artery occlusion/reperfusion in male Wistar rats. Picroside II (10 mg/kg) was administered intravenously into the tail vein of the animals. The neurological function deficits were evaluated with the Bederson’s test and the cerebral infarction volume was visualized with tetrazolium chloride (TTC) staining. The apoptotic cells were counted by in situ terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end labeling (TUNEL) assay. The immunohistochemistry stain and enzyme linked immunosorbent assay (ELISA) was used to determine the expressions of caspase-3 and PARP in brain tissue. The results indicated that rats in the control group showed neurological function deficit and cerebral infarction in ischemic hemisphere after two hours ischemia followed by 22 hours reperfusion. Caspase-3 and PARP expressions were also profound in the cortex, the striatum and the hippocampus, along with increased apoptotic cells in this group. Bederson’s score, infarction volume, and expressions of caspase-3 and PARP, as well as apoptosis in the treatment group were, however, significantly decreased compared to those in the control group indicating that intravenous treatment with picroside II might be beneficial to inhibit neuronal apoptosis and, thus, to improve the neurological function of rats upon cerebral ischemia reperfusion injury.