Fraxini cortex: Progresses in phytochemistry, pharmacology and ethnomedicinal uses

ETHNOPHARMACOLOGICAL RELEVANCE

Fraxini cortex, which has been widely used as a traditional Chinese medicine for 2000 years, is made from the dried bark of four plant species: Fraxinus chinensis subsp. rhynchophylla (Hance) A.E.Murray, Fraxinus chinensis Roxb., Fraxinus chinensis subsp. chinensis and Fraxinus stylosa Lingelsh.. In Chinese traditional medicine, it possesses the properties of heat-clearing and dampness-drying, asthma relief and cough suppression, as well as vision improvement. It is utilized for treating bacterial disorders, enteritis, leukorrhea, chronic bronitis, painful red eyes with swelling, lacrimation due to windward exposure, psoriasis, and other diseases or related symptoms.

AIM OF THE STUDY

Fraxini cortex is abundant in chemical constituents and has garnered significant attention from plant chemists, particularly regarding coumarins, as evidenced by the recently identified three coumarin compounds. Considering the current dearth of systematic reporting on studies pertaining to Fraxini cortex, herein we provide a comprehensive summary of the advancements in phytochemistry, pharmacology, detection methods, and ethnomedicinal applications of Fraxini cortex.

MATERIALS AND METHODS

We conducted a comprehensive search across online data sources (Web of Science, Public Medicine (PubMed), China National Knowledge Infrastructure (CNKI), as well as Chinese dissertations) and traditional Chinese medicine classics to gather the necessary literature resources for this review.

RESULTS

Briefly, The Fraxini cortex yielded a total of 132 phytochemicals, including coumarins, lignans, secoiridoids, phenylethanol glycosides, flavonoids, triterpenoids, and other compounds. Among them, the main active ingredients are coumarins which possess a diverse range of pharmacological activities such as anti-inflammatory effects, anti-tumor properties, prevention of tissue fibrosis and oxidation damage as well as cardioprotective effects.

CONCLUSIONS

All types of research conducted on Fraxini cortex, particularly in the field of ethnopharmacology, phytochemistry, and pharmacology, have been thoroughly reviewed. However, certain traditional applications and pharmacological activities of Fraxini cortex lack scientific evaluation or convincing evidence due to incomplete methodologies and ambiguous results, as well as a lack of clinical data. To validate its pharmacological activity, clinical efficacy, and safety profile, a systematic and comprehensive research evaluation is imperative. As an important traditional Chinese medicine, Fraxini cortex should be further explored to facilitate the development of novel drugs and therapeutics for various diseases. Greater attention should be given to how it can be better utilized.

The Related Mechanisms Predicted through Network-Based Pharmacological Analysis and the Anti-Inflammatory Effects of Fraxinus rhynchophylla Hance Bark on Contact Dermatitis in Mice

Fraxinus rhynchophylla Hance bark has been used to treat patients with inflammatory or purulent skin diseases in China, Japan, and Korea. This study was undertaken to determine the mechanism responsible for the effects of F. rhynchophylla and whether it has a therapeutic effect in mice with contact dermatitis (CD). In this study, the active compounds in F. rhynchophylla, their targets, and target gene information for inflammatory dermatosis were investigated using network-based pharmacological analysis. Docking analysis was conducted using AutoDock Vina. In addition, the therapeutic effect of an ethanolic extract of F. rhynchophylla (EEFR) on skin lesions and its inhibitory effects on histopathological abnormalities, inflammatory cytokines, and chemokines were evaluated. Finally, its inhibitory effects on the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signalling pathways were observed in RAW 264.7 cells. In our results, seven active compounds were identified in F. rhynchophylla, and six were associated with seven genes associated with inflammatory dermatosis and exhibited a strong binding affinity (<-6 kcal/mol) to prostaglandin G/H synthase 2 (PTGS2). In a murine 1-fluoro-2,4-dinitrobenzene (DNFB) model, topical EEFR ameliorated the surface symptoms of CD and histopathological abnormalities. EEFR also reduced the levels of tumour necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-6, and monocyte chemotactic protein (MCP)-1 in inflamed tissues and inhibited PTGS2, the nuclear translocation of NF-κB (p65), and the activation of c-Jun N-terminal kinases (JNK) in RAW 264.7 cells. In conclusion, the bark of F. rhynchophylla has potential use as a therapeutic or cosmetic agent, and the mechanism responsible for its effects involves the suppression of inflammatory mediators, nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor (IκB)-α degradation, the nuclear translocation of NF-κB, and JNK phosphorylation.

Inhibition of the Type III Secretion System of Salmonella enterica Serovar Typhimurium via Treatment with Fraxetin

The increasingly serious problem of bacterial drug resistance has led to the development of antivirulence agents. The Salmonella enterica serovar Typhimurium Salmonella pathogenicity island (SPI)-encoded type III secretion system (T3SS) and its effector proteins are important virulence factors for S. Typhimurium invasion and replication in host cells and for antivirulence drug screening. Fraxetin is isolated from Fraxinus spp. Extensive studies have reported its multiple pharmacological activities. However, it remains to be elucidated whether fraxetin affects the function of the S. Typhimurium T3SS. In this study, the anti-infection mechanism of fraxetin on S. Typhimurium and its T3SS was investigated. Fraxetin inhibited the S. Typhimurium invasion of HeLa cells without affecting the growth of bacteria in vitro. Further findings on the mechanism showed that fraxetin had an inhibitory effect on the S. Typhimurium T3SS by inhibiting the transcription of the pathogenesis-related SPI-1 transcriptional activator genes hilD, hilC, and rtsA. Animal experiments showed that fraxetin treatment protected mice against S. Typhimurium infection. Collectively, we provide the first demonstration that fraxetin may serve as an effective T3SS inhibitor for the development of treatments for Salmonella infection. IMPORTANCE The increasingly serious problem of bacterial antibiotic resistance limits the clinical application of antibiotics, which increases the need for the development of antivirulence agents. The type III secretion system (T3SS) plays a critical role in host cell invasion and pathogenesis of Salmonella and becomes a popular target for antivirulence agents screening. Our study found, for the first time, that fraxetin inhibited S. Typhimurium invasion by inhibiting the transcription of genes in a feed-forward regulatory loop. Further in vivo testing showed that fraxetin decreased bacterial burdens in the spleen and liver of S. Typhimurium-infected mice and improved survival outcomes in an in vivo mouse model of S. Typhimurium infection. Collectively, these results demonstrate that fraxetin inhibits S. Typhimurium infection by targeting the T3SS and may serve as a potential agent for the treatment of S. Typhimurium infection.

Isolation and Characterization of Antibacterial Compounds from Aspergillus fumigatus: An Endophytic Fungus from a Mangrove Plant of the Sundarbans

The Sundarbans, a UNESCO world heritage site, is one of the largest mangrove forests in one stretch. Mangrove plants from this forest are little studied for their endophytic fungi. In this study, we isolated fourteen endophytic fungi from the plants Ceriops decandra and Avicennia officinalis collected from the Sundarbans. Five of them were identified as Aspergillus sp. and one as Penicillium sp. by macroscopic and microscopic observation. Antibacterial activity of the crude extracts obtained from these endophytes was determined against Staphylococcus aureus, Micrococcus luteus, Escherichia coli, and Pseudomonas aeruginosa using resazurin-based microtiter assay. The isolated endophytes showed varying degrees of antibacterial activity with MICs ranging between 5 and 0.078 mg/mL. Molecular identification of the most active endophyte revealed its identity as Aspergillus fumigatus obtained from the leaves of C. decandra. Acute toxicity study of the ethyl acetate extract of A. fumigatus in mice revealed no mortality even at the highest dose of 2000 mg/kg bodyweight, though some opposing results are found in the subacute toxicity study. The extract was subjected to silica gel and Sephadex column chromatography resulting in the isolation of three pure compounds. LC-MS analysis of these pure compounds revealed their identity as fumigaclavine C, azaspirofuran B, and fraxetin. This is the first report of fraxetin from A. fumigatus. All three identified compounds were previously reported for their antibacterial activity against different strains of both Gram-positive and Gram-negative bacteria. Therefore, the observed antibacterial activity of the ethyl acetate (EtOAc) extract of A. fumigatus could be due to the presence of these compounds. These results support the notion of investigating fungal endophytes from the Sundarbans for new antimicrobial compounds.

Fraxetin suppresses reactive oxygen species-dependent autophagy by the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells

Isoflurane, a common volatile anesthetic, has been widely used to provide general anesthesia in operations. However, exposure to isoflurane may cause widespread neurotoxicity in the developing animal brain. Fraxetin, a natural coumarin derivative extracted from the bark of Fraxinus rhynchophylla, possesses versatile pharmacological properties including anti-oxidative, anti-inflammatory, and neuroprotective effects. However, the effect and action mechanism of fraxetin on neurotoxicity induced by isoflurane are unknown. Reactive oxygen species (ROS) generation, cell viability, lactate dehydrogenase (LDH) release, and apoptosis were estimated by 2',7'-dichlorofluorescin-diacetate (DCFH-DA) staining, MTT, LDH release, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) staining assays, respectively. The protein levels of light chain 3 (LC3)-I, LC3-II, p62, protein kinase B (Akt), and phosphorylated Akt (p-Akt) were detected by western blot analysis. Isoflurane induced ROS, LDH release, apoptosis, and autophagy, but inhibited the viability in HT22 cells, which were overturned by fraxetin or ROS scavenger N-acetyl-L-cysteine. Fraxetin suppressed isoflurane-induced PI3K/Akt inactivation in HT22 cells. PI3K/Akt inactivation by LY294002 resisted the effects of fraxetin on isoflurane-induced autophagy and autophagy-modulated neurotoxicity in HT22 cells. In conclusion, fraxetin suppressed ROS-dependent autophagy by activating the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells.

In Vitro and In Vivo Antifibrotic Effects of Fraxetin on Renal Interstitial Fibrosis via the ERK Signaling Pathway

Fraxetin, a natural derivative of coumarin, is known to have anti-inflammatory, anti-oxidant, and hepatoprotective effects in multiple diseases and in liver fibrosis. Whether fraxetin exerts similar effects against renal fibrosis is unknown. In a Unilateral Ureteral Obstruction (UUO) mouse model of renal fibrosis, fraxetin decreased UUO-induced renal dysfunction with a marked reduction in renal interstitial collagen fibers as detected by Masson’s Trichrome staining. Fraxetin treatment also inhibited the expression of α-SMA, Collagen I, Collagen IV, fibronectin, N-cadherin, vimentin, phosphorylated-ERK, and increased the expression of E-cadherin in UUO mice, as shown by immunohistochemical staining and western blot analysis. In vitro studies showed that fraxetin and indoxyl sulfate had no cytotoxic effects on MES13 kidney cells, but that fraxetin significantly decreased IS-induced cell motility and decreased protein expression of α-SMA, N-cadherin, vimentin, and Collagen IV via the ERK-mediated signaling pathway. These findings provide insight into the mechanism underlying fraxetin-induced inhibition of fibrogenesis in renal tissue and suggest that fraxetin treatment may be beneficial for slowing CKD progression.

Fraxetin inhibits interleukin-1β-induced apoptosis, inflammation, and matrix degradation in chondrocytes and protects rat cartilage in vivo

Osteoarthritis (OA) is a disease characterized by degeneration of the joint complex due to cartilage destruction. Fraxetin, a widely used and studied coumarin compound extracted from a traditional Chinese herb (Qin Pi), has shown anti-inflammatory and antioxidant properties, but its effects on OA have not been studied. In the present study, western blotting, immunofluorescence, and terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) were used to evaluate the effects of fraxetin on IL-1β-induced apoptotic activity, inflammatory responses, and catabolism in rat chondrocytes. The results showed that fraxetin prevented IL-1β-induced apoptosis of chondrocytes and inhibited inflammatory mediator release by regulating the Toll-like receptor 4 (TLR4)/myeloid differentiation primary response 88 (MyD88)/nuclear factor (NF)-κB pathway in chondrocytes. Additionally, fraxetin suppressed the upregulation of matrix metalloproteinase 13 (MMP13) and degradation of collagen II in the extracellular matrix (ECM). Moreover, the effects of fraxetin in vivo were assessed in a monosodium iodoacetate (MIA)-induced rat model of OA using hematoxylin and eosin (H&E) and Safranin O-fast green staining and magnetic resonance imaging (MRI). The results showed that fraxetin protected the cartilage against destruction. In conclusion, fraxetin could be a potential therapeutic for OA.

Natural products: The role and mechanism in low-density lipoprotein oxidation and atherosclerosis

Atherosclerosis is a chronic inflammatory, metabolic, and epigenetic disease, which leads to the life-threatening coronary artery disease. Emerging studies from bench to bedside have demonstrated the pivotal role of low-density lipoprotein (LDL) oxidation in the initiation and progression of atherosclerosis. This article hereby reviews oxidation mechanism of LDL, and the pro-atherogenic and biomarker role of oxidized LDL in atherosclerosis. We also review the pharmacological effects of several representative natural products (vitamin E, resveratrol, quercetin, probucol, tanshinone IIA, epigallocatechin gallate, and Lycopene) in protecting against LDL oxidation and atherosclerosis. Clinical and basic research supports the beneficial effects of these natural products in inhibiting LDL oxidation and preventing atherosclerosis, but the data are still controversial. This may be related to factors such as the population and the dosage and time of taking natural products involved in different studies. Understanding the mechanism of LDL oxidation and effect of oxidized LDL help researchers to find novel therapies against atherosclerosis.

Coumarins as Modulators of the Keap1/Nrf2/ARE Signaling Pathway

The Keap1/Nrf2/ARE system is a central defensive mechanism against oxidative stress which plays a key role in the pathogenesis and progression of many diseases. Nrf2 is a redox-sensitive transcription factor controlling a variety of downstream antioxidant and cytodefensive genes. Nrf2 has a powerful anti-inflammatory activity mediated via modulating NF-κB. Therefore, pharmacological activation of Nrf2 is a promising therapeutic strategy for the treatment/prevention of several diseases that are underlined by both oxidative stress and inflammation. Coumarins are natural products with promising pharmacological activities, including antioxidant, anticancer, antimicrobial, and anti-inflammatory efficacies. Coumarins are found in many plants, fungi, and bacteria and have been widely used as complementary and alternative medicines. Some coumarins have shown an ability to activate Nrf2 signaling in different cells and animal models. The present review compiles the research findings of seventeen coumarin derivatives of plant origin (imperatorin, visnagin, urolithin B, urolithin A, scopoletin, esculin, esculetin, umbelliferone, fraxetin, fraxin, daphnetin, anomalin, wedelolactone, glycycoumarin, osthole, hydrangenol, and isoimperatorin) as antioxidant and anti-inflammatory agents, emphasizing the role of Nrf2 activation in their pharmacological activities. Additionally, molecular docking simulations were utilized to investigate the potential binding mode of these coumarins with Keap1 as a strategy to disrupt Keap1/Nrf2 protein-protein interaction and activate Nrf2 signaling.

Isolation and Purification of Bioactive Compounds from the Stem Bark of Jatropha podagrica

This paper reports the successive isolation and purification of bioactive compounds from the stem bark of Jatropha podagrica, a widely known medicinal plant. The ethyl acetate extract of the stem bark exhibited the strongest antioxidant activity assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and ferric reducing antioxidant power (FRAP) assays (IC₅₀ = 46.7, 66.0, and 492.6, respectively). By column chromatography (CC) with elution of hexane and ethyl acetate at 8:2, 7:3, and 6:4 ratios, the isolation of this active extract yielded five fractions (C1–C5). Chemical structures of the constituents included in C1–C5 were elucidated by gas chromatography-mass spectrometry (GC-MS), electrospray ionization-mass spectrometry (ESI-MS), and nuclear magnetic resonance (NMR) and resolved as methyl gallate (C1, C2, C3, C4), gallic acid (C1, C2), fraxetin (C2, C3, C4, C5), and tomentin (C3). Mixture C2 (IC₅₀ DPPH and ABTS = 2.5 µg/mL) and C3 (IC₅₀ FRAP = 381 µg/mL) showed the highest antioxidant properties. Among the isolated fractions, C4 was the most potential agent in growth inhibition of six bacterial strains including Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Listeria monocytogenes,Bacillus subtilis, and Proteus mirabilis (MIC = 5, 20, 30, 20, 25, and 20 mg/mL, respectively). All identified constituents exerted an inhibitory activity on the growth of Lactuca sativa, of which the mixture C3 performed the maximal inhibition on shoot (IC₅₀ = 49.4 µg/mL) and root (IC₅₀ = 47.1 µg/mL) growth. Findings of this study suggest that gallic acid, methyl gallate, fraxetin, and tomentin isolated from J. podagrica possessed antioxidant, antibacterial, and growth inhibitory potentials.

Pharmacological and Nutritional Effects of Natural Coumarins and Their Structure-Activity Relationships

Coumarins are fused benzene and pyrone ring systems with a wide spectrum of bioactivities, including antitumor, anti-inflammation, antiviral, and antibacterial effects. In this paper, the current development of coumarin-based drugs is introduced, and their structure-activity relationship is discussed by reviewing the relevant literature published in the past 20 years. Coumarin molecules can be customized by the target site to prevent systemic side effects by virtue of structural modification. The ortho-phenolic hydroxyl on the benzene ring has remarkable antioxidant and antitumor activities. Coumarins with aryl groups at the C-4 position have good activities in anti-HIV, antitumor, anti-inflammation, and analgesia. C-3 phenylcoumarins have strong anti-HIV and antioxidant effects. Tetracycline pyranocoumarins can significantly inhibit HIV; osthol structural analogues have antimicrobial activity. Praeruptorin C and its derivatives play an important role in lowering blood pressure and dilating coronary arteries, and khellactone derivatives have significant inhibitory effects on AIDS, cancer, and cardiovascular diseases. It is concluded that the specific site on the core structure of coumarin exhibits one or more activities due to the electronic or steric effects of the substituents. This review is intended to be conducive to rational design and development of more active and less toxic agents with a coumarin scaffold.

Fraxinus: A Plant with Versatile Pharmacological and Biological Activities

Fraxinus, a member of the Oleaceae family, commonly known as ash tree is found in northeast Asia, north America, east and western France, China, northern areas of Pakistan, India, and Afghanistan. Chemical constituents of Fraxinus plant include various secoiridoids, phenylethanoids, flavonoids, coumarins, and lignans; therefore, it is considered as a plant with versatile biological and pharmacological activities. Its tremendous range of pharmacotherapeutic properties has been well documented including anticancer, anti-inflammatory, antioxidant, antimicrobial, and neuroprotective. In addition, its bioactive phytochemicals and secondary metabolites can be effectively used in cosmetic industry and as a competent antiaging agent. Fraxinus presents pharmacological effectiveness by targeting the novel targets in several pathological conditions, which provide a spacious therapeutic time window. Our aim is to update the scientific research community with recent endeavors with specifically highlighting the mechanism of action in different diseases. This potentially efficacious pharmacological drug candidate should be used for new drug discovery in future. This review suggests that this plant has extremely important medicinal utilization but further supporting studies and scientific experimentations are mandatory to determine its specific intracellular targets and site of action to completely figure out its pharmacological applications.

Coumarins as potential antidiabetic agents

OBJECTIVES

Even with great advances in modern medicine and therapeutic agent development, the search for effective antidiabetic drugs remains challenging. Coumarins are secondary metabolites found widely in nature plants and used mainly in anticoagulation and antithrombotic therapy. Over the past two decades, however, there has been an increasing body of literatures related to the effects of coumarins and their derivatives on diabetes and its complications. This review aimed to focus on research findings concerning the effects of coumarins against diabetes and its complications using in-vitro and in-vivo animal models, and also to discuss cellular and molecular mechanisms underlying these effects.

KEY FINDINGS

The search for new coumarins against diabetes and it complications, either isolated from traditional medicine or chemically synthesized, has been constantly expanding. The cellular and molecular mechanisms involved include protecting pancreatic beta cells from damage, improving abnormal insulin signalling, reducing oxidative stress/inflammation, activating AMP-activated protein kinase (AMPK), inhibiting α-glucosidases and ameliorating diabetic complications.

CONCLUSIONS

The effects and mechanisms of coumarins and their derivatives upon diabetes and its complications are discussed in current review. Further investigations remain to be carried out to develop a promising antidiabetic agent based on coumarin cores.

Fraxetin Induces Heme Oxygenase-1 Expression by Activation of Akt/Nrf2 or AMP-activated Protein Kinase α/Nrf2 Pathway in HaCaT Cells

Background

Fraxetin (7,8-dihydroxy-6-methoxy coumarin), a coumarin derivative, has been reported to possess antioxidative, anti-inflammatory and neuroprotective effects. A number of recent observations suggest that the induction of heme oxygenase-1 (HO-1) inhibits inflammation and tumorigenesis. In the present study, we determined the effect of fraxetin on HO-1 expression in HaCaT human keratinocytes and investigated its underlying molecular mechanisms.

Methods

Reverse transcriptase-PCR and Western blot analysis were performed to detect HO-1 mRNA and protein expression, respectively. Cell viability was measured by the MTS test. The induction of intracellular reactive oxygen species (ROS) by fraxetin was evaluated by 2′,7′-dichlorofluorescin diacetate staining.

Results

Fraxetin upregulated mRNA and protein expression of HO-1. Incubation with fraxetin induced the localization of nuclear factor-erythroid-2-related factor-2 (Nrf2) in the nucleus and increased the antioxidant response element-reporter gene activity. Fraxetin also induced the phosphorylation of Akt and AMP-activated protein kinase (AMPK)α and diminished the expression of phosphatase and tensin homolog, a negative regulator of Akt. Pharmacological inhibition of Akt and AMPKα abrogated fraxetin-induced expression of HO-1 and nuclear localization of Nrf2. Furthermore, fraxetin generated ROS in a concentration-dependent manner.

Conclusions

Fraxetin induces HO-1 expression through activation of Akt/Nrf2 or AMPKα/Nrf2 pathway in HaCaT cells.

Glycosylation enables aesculin to activate Nrf2

Since aesculin, 6,7-dihydroxycoumarin-6-O-β-glucopyranoside, suppresses inflammation, we asked whether its anti-inflammatory activity is associated with the activation of nuclear factor-E2-related factor 2 (Nrf2), a key anti-inflammatory factor. Our results, however, show that aesculin marginally activated Nrf2. Since glycosylation can enhance the function of a compound, we then asked whether adding a glucose makes aesculin activate Nrf2. Our results show that the glycosylated aesculin, 3-O-β-d-glycosyl aesculin, robustly activated Nrf2, inducing the expression of Nrf2-dependent genes, such as heme oxygenase-1, glutamate-cysteine ligase catalytic subunit, and NAD(P)H quinone oxidoreductase 1 in macrophages. Mechanistically, 3-O-β-d-glycosyl aesculin suppressed ubiquitination of Nrf2, retarding degradation of Nrf2. Unlike aesculin, 3-O-β-d-glycosyl aesculin significantly suppressed neutrophilic lung inflammation, a hallmark of acute lung injury (ALI), in mice, which was not recapitulated in Nrf2 knockout mice, suggesting that the anti-inflammatory function of the compound largely acts through Nrf2. In a mouse model of sepsis, a major cause of ALI, 3-O-β-d-glycosyl aesculin significantly enhanced the survival of mice, compared with aesculin. Together, these results show that glycosylation could confer the ability to activate Nrf2 on aesculin, enhancing the anti-inflammatory function of aesculin. These results suggest that glycosylation can be a way to improve or alter the function of aesculin.

Hepatoprotective standardized EtOH-water extract from the seeds of Fraxinus rhynchophylla Hance

Fraxinus rhynchophylla Hance (Oleaceae), its stem barks are known as Cortex fraxini (秦皮 qín pí) listed in Chinese Pharmacopoeia. Phytochemical study has indicated that methanol extracts from Qinpi has protective effect on acute liver injury. The present study investigates the hepatoprotective activity of EtOH–water extract from the seeds of F. rhynchophylla Hance against carbon tetrachloride-induced liver injury in mice. The EtOH–water extract significantly alleviated liver damage as indicated by the decreased levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the malondialdehyde (MDA) content, and increased the levels of superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GSH-Px), and reduced the pathological tissue injury induced by CCl₄. Quantitative analysis of seven major constituents (1–7) in EtOH–water extract (EWE) was developed by high performance liquid chromatography-diode-array detector (HPLC-DAD). The current research indicates that the EWE from the seeds of F. rhynchophylla Hance decreased liver index, inhibited the increase of serum aminotransferase induced by CCl₄, and decreased hepatic MDA content, SOD and GSH-Px activities. These results suggested that the pretreatment with EWE protected mice against CCl₄-induced liver injuries. Based on the results, the EtOH–water extract from the seeds of F. rhynchophylla Hance is efficacious for prevention and treatment of CCl₄-induced hepatic injury in mice. Secoiridoid and tyrosol glucosides might be the active ingredients responsible for the biological and pharmacological activities of hepatoprotection.

Esculin improves dyslipidemia, inflammation and renal damage in streptozotocin-induced diabetic rats

Background

Increasing studies have shown that dyslipidemia and inflammatory responses play important roles in the progression of microvascular diabetic complications. Esculin (ES), a coumarin derivative, was extracted from Fraxinus rhynchophylla. The present study was to evaluate the potential effects of ES on lipid metabolism, inflammation responses and renal damage in streptozotocin (STZ)-induced experimental diabetic rats and explore the possible mechanism.

Methods

Diabetic rat model was established by administration high-glucose-fat diet and intraperitoneal injection of STZ 45 mg/kg. ES was administrated to diabetic rats intragastrically at 10, 30 and 90 mg/kg for 10 weeks respectively. The levels of triglycerides (TG), total cholesterol (T-CHO), low density lipoproteins (LDL), and high-density-cholesterol (HDL-C) in serum were measured. IL-1, IL-6, ICAM-1, NO, NAGL, and AGEs level in serum were detected by ELISA assay. The accumulation of AGEs in kidney tissue was examined by immunohistochemistry assay.

Results

The results showed that ES could decrease TG, T-CHO, LDL levels in serum of diabetic rats in a dose dependent manner. ES also decreased IL-1, IL-6, ICAM-1, NO and NGAL levels in serum of diabetic rats in a dose dependent manner. Furthermore, ES at 30 and 90 mg/kg significantly decreased AGEs level in serum and alleviated AGEs accumulation in renal in diabetic rats.

Conclusions

Our findings indicate that ES could improve dyslipidemia, inflammation responses, renal damage in STZ-induced diabetic rats and the possible mechanism might be associated with the inhibition of AGEs formation.

Bioinformatics analyses provide insight into distant homology of the Keap1-Nrf2 pathway

An essential requirement for the evolution of early eukaryotic life was the development of effective means to protect against metabolic oxidative stress and exposure to environmental toxicants. In present-day mammals, the master transcription factor Nrf2 regulates basal level homeostasis and inducible expression of numerous detoxifying and antioxidant genes. To examine early evolution of the Keap1-Nrf2 pathway, we present bioinformatics analyses of distant homology of mammalian Keap1 and Nrf2 proteins across the Kingdoms of Life. Software written for this analysis is made freely available on-line. Furthermore, utilizing protein modeling and virtual screening methods, we demonstrate potential for Nrf2 activation by competitive inhibition of its binding to Keap1, specifically by UV-protective fungal mycosporines and marine mycosporine-like amino acids (MAAs). We contend that coevolution of Nrf2-activating secondary metabolites by fungi and other extant microbiota may provide prospective compound leads for the design of new therapeutics to target activation of the human Keap1-Nrf2 pathway for treating degenerative diseases of ageing.

Esculetin inhibits the inflammatory response by inducing heme oxygenase-1 in cocultured macrophages and adipocytes

Obesity is associated with chronic low-grade inflammation of adipose tissue. In this study, we investigated the anti-inflammatory effects of esculetin (ECT) through up-regulation of heme oxygenase-1 (HO-1) in cocultured macrophages and adipocytes. RAW264.7 macrophages and differentiated 3T3-L1 adipocytes were cocultured in serum-free Dulbecco's modified Eagle's medium with or without ECT for 24 h. Nitric oxide (NO), tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1) production was measured in the coculture supernatant. ECT decreased the secretion of NO, TNF-α, and MCP-1. The expression of adipogenic proteins, including peroxisome proliferator-activated receptors γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα) in cocultured adipocytes and inducible nitric oxide synthase (iNOS) in cocultured macrophages, was inhibited by ECT. Additionally, HO-1 expression was induced in cocultured macrophages and adipocytes. Silencing of HO-1 expression increased the production of NO, TNF-α, and MCP-1 in cocultured cells, in spite of the presence of ECT. This study demonstrated that ECT exhibited anti-inflammatory properties by inhibiting the production of proinflammatory cytokines in the interaction between adipocytes and macrophages through HO-1 expression. ECT may have the potential to improve chronic inflammation in obesity.

Antioxidant activity of fraxetin and its regeneration in aqueous media. A density functional theory study

Fraxetin is an excellent and versatile antioxidant in aqueous media. In addition it regenerates, scavenging two radical equivalents per cycle.

Hairy root culture: bioreactor design and process intensification

The cultivation of hairy roots for the production of secondary metabolites offers numerous advantages; hairy roots have a fast growth rate, are genetically stable, and are relatively simple to maintain in phytohormone free media. Hairy roots provide a continuous source of secondary metabolites, and are useful for the production of chemicals for pharmaceuticals, cosmetics, and food additives. In order for hairy roots to be utilized on a commercial scale, it is necessary to scale-up their production. Over the last several decades, significant research has been conducted on the cultivation of hairy roots in various types of bioreactor systems. In this review, we discuss the advantages and disadvantages of various bioreactor systems, the major factors related to large-scale bioreactor cultures, process intensification technologies and overview the mathematical models and computer-aided methods that have been utilized for bioreactor design and development.

Protective effects of Atractylodes macrocephala polysaccharide on liver ischemia-reperfusion injury and its possible mechanism in rats

Atractylodes macrocephala polysaccharide (AMP), a traditional Chinese medicine, is thought to have protective effects against liver injury. Therefore, this study was designed to explore the effects of AMP on hepatic ischemia-reperfusion injury (IRI) and elucidate the possible mechanisms. Ninety-six Sprague-Dawley rats were randomly divided into four groups with 24 rats per group: a normal control group, an IRI group, an AMP-treated group (0.4 g/kg/d) and a bifendate-treated group (100 mg/kg). Rats were treated with AMP or bifendate once daily for seven days by gastric gavage. The normal control group and the IRI model group received an equivalent volume of physiological saline. At 1, 6 and 24 h after surgery, the rats were killed and liver tissue samples were obtained to determine interleukin-1 (IL-1) expression by Western blotting and nuclear factor-κB (NF-κB) expression by immunohistochemistry. Liver morphology was assessed by microscopy and transmission electron microscopy. Blood samples were obtained to measure liver function (alanine aminotransferase, aspartate aminotransferase, total bilirubin and direct bilirubin). AMP significantly reduced the elevated expression of markers of liver dysfunction and the hepatic morphologic changes induced by hepatic IRI in rats. AMP also markedly inhibited IRI-induced lipid peroxidation and altered the activities of the antioxidant enzyme superoxide dismutase and malondialdehyde levels. Moreover, pretreatment with AMP suppressed the expression of interleukin-1β and NF-kB in IRI-treated rats. These results suggest that AMP exerts protective and therapeutic effects against hepatic IRI in rats, which might be associated with its antioxidant properties and inhibition of NF-κB activation. More studies are needed to better understand the mechanisms underlying the protective effects of AMP on hepatic IRI.

Inhibition of neointimal formation by trans-resveratrol: role of phosphatidyl inositol 3-kinase-dependent Nrf2 activation in heme oxygenase-1 induction

Neointima, defined as abnormal growth of the intimal layer of blood vessels, is believed to be a critical event in the development of vascular occlusive disease. Although resveratrol's inhibitory effects on proliferation and migration of vascular smooth muscle cells has been reported, its activity on neointimal formation is still unclear. Oral administration of trans-resveratrol significantly suppressed intimal hyperplasia in a wire-injured femoral artery mouse model. In cultured vascular smooth muscle cells, trans-resveratrol inhibited platelet-derived growth factor-stimulated DNA synthesis and cell proliferation with down-regulation of cyclin D and pRB. Moreover, platelet-derived growth factor-induced production of reactive oxygen species was inhibited by trans-resveratrol and the compound induced heme oxygenase-1 (HO-1). The anti-proliferative activity of trans-resveratrol was reversed by an HO-1 inhibitor, ZnPPIX. Subcellular fractionation and reporter gene analyses revealed that trans-resveratrol increased the level of nuclear Nrf2 and antioxidant response element reporter activity, and that these were essential for the induction of HO-1. Trans-resveratrol also enhanced the activities of phosphatidyl inositol 3-kinase and extracellular signal regulated kinase, and phosphatidyl inositol 3-kinase was required for Nrf2/antioxidant response element-dependent HO-1 induction. These data have significant implications for the elucidation of the pharmacological mechanism by which trans-resveratrol prevents vascular occlusive diseases.