Role of glucose transporters in the intestinal absorption of gastrodin, a highly water-soluble drug with good oral bioavailability

Microfluidic Preparation and Evaluation of Multivesicular Liposomes Containing Gastrodin for Oral Delivery across the Blood-Brain Barrier

In this study, multivesicular liposomes (MVLs) were prepared by microfluidic technology and used for delivering gastrodin (GAS), a water-soluble drug, across the blood-brain barrier (BBB). The formulations and preparation parameters in preparing gastrodin multivesicular liposomes (GAS-MVLs) were both optimized. Some properties of GAS-MVLs including morphology, particle size, encapsulation efficiency, and in vitro release were evaluated. An in vitro BBB model was established by coculturing mouse brain endothelial cells (bEnd.3) and astrocytes (C8-D1A). The permeability of GAS-MVLs across the BBB model was evaluated. Finally, the permeability of GAS-MVLs across BBB was evaluated by in vivo pharmacokinetics in mice. The concentrations of GAS in the blood and brain were determined by high-performance liquid chromatography (HPLC), and then brain-targeting efficiency (BTE), relative uptake rate (Re), and peak concentration ratio (Ce) were calculated. The results showed that, using a Y-type microfluidic chip and setting the flow rate ratio of the second aqueous phase to the W/O emulsion phase at 23, with a total flow rate of 0.184 m/s, the prepared GAS-MVLs showed an obvious multivesicular structure and a relatively narrow distribution of particle sizes. The prepared GAS-MVLs were spherical with a dense structure. The average particle size was 2.09 ± 0.17 μm. The average encapsulation rate was (34.47 ± 0.39)%. The particle size of MVLs prepared by the microfluidic method was much smaller than that prepared by the traditional method, which was usually larger than 10 μm. After 6 h from the beginning of the administration, the apparent transmittance of GAS-MVLs in the in vitro BBB model was 67.71%, which was 1.92 times higher than that of the GAS solution. In vivo pharmacokinetic study showed that the intracerebral area under curve (AUC) of GAS-MVLs was 5.68 times higher than that of the GAS solution, and the e peak concentration (Cmax) was 2.036 times higher than that of the GAS solution. BTE was 1.945, intracerebral Re was 5.688, and Ce was 2.036. Both in vitro and in vivo experiment results showed that GAS-MVLs prepared by microfluidic technology in this study significantly delivered GAS across BBB and enriched GAS in the brain. It provides a possibility for brain-targeting delivery of GAS in the prevention and treatment of central nervous system diseases by oral administration and lays the foundation for further development of oral brain-targeted preparations of GAS.

Gastrodin, a Promising Natural Small Molecule for the Treatment of Central Nervous System Disorders, and Its Recent Progress in Synthesis, Pharmacology and Pharmacokinetics

Gastrodia elata Blume is a traditional medicinal and food homology substance that has been used for thousands of years, is mainly distributed in China and other Asian countries, and has always been distinguished as a superior class of herbs. Gastrodin is the main active ingredient of G. elata Blume and has attracted increasing attention because of its extensive pharmacological activities. In addition to extraction and isolation from the original plant, gastrodin can also be obtained via chemical synthesis and biosynthesis. Gastrodin has significant pharmacological effects on the central nervous system, such as sedation and improvement of sleep. It can also improve epilepsy, neurodegenerative diseases, emotional disorders and cognitive impairment to a certain extent. Gastrodin is rapidly absorbed and widely distributed in the body and can also penetrate the blood-brain barrier. In brief, gastrodin is a promising natural small molecule with significant potential in the treatment of brain diseases. In this review, we summarised studies on the synthesis, pharmacological effects and pharmacokinetic characteristics of gastrodin, with emphasis on its effects on central nervous system disorders and the possible mechanisms, in order to find potential therapeutic applications and provide favourable information for the research and development of gastodin.

Effects of Commonly used Surfactants, Poloxamer 188 and Tween 80, on the Drug Transport Capacity of Intestinal Glucose Transporters

Some glycoside drugs can be transported through intestinal glucose transporters (IGTs). The surfactants used in oral drug preparations can affect the function of transporter proteins. This study aimed to investigate the effect of commonly used surfactants, Poloxamer 188 and Tween 80, on the drug transport capacity of IGTs. Previous studies have shown that gastrodin is the optimal drug substrate for IGTs. Gastrodin was used as a probe drug to evaluate the effect of these two surfactants on intestinal absorption in SD rats through pharmacokinetic and in situ single-pass intestinal perfusion. Then, the effects of the two surfactants on the expression of glucose transporters and tight-junction proteins were examined using RT-PCR and western blotting. Additionally, the effect of surfactants on intestinal permeability was evaluated through hematoxylin-eosin staining. The results found that all experimental for Poloxamer 188 (0.5%, 2.0% and 8.0%) and Tween 80 (0.1% and 2.0%) were not significantly different from those of the blank group. However, the AUC(0-∞) of gastrodin increased by approximately 32% when 0.5% Tween 80 was used. The changes in IGT expression correlated with the intestinal absorption of gastrodin. A significant increase in the expression of IGTs was observed at 0.5% Tween 80. In conclusion, Poloxamer 188 had minimal effect on the drug transport capacity of IGTs within the recommended limits of use. However, the expression of IGTs increased in response to 0.5% Tween 80, which significantly enhanced the drug transport capacity of IGTs. However, 0.1% and 2.0% Tween 80 had no significant effect.

Effects of Three Kinds of Carbohydrate Pharmaceutical Excipients-Fructose, Lactose and Arabic Gum on Intestinal Absorption of Gastrodin through Glucose Transport Pathway in Rats

BACKGROUND

Some glucoside drugs can be transported via intestinal glucose transporters (IGTs), and the presence of carbohydrate excipients in pharmaceutical formulations may influence the absorption of them. This study, using gastrodin as probe drug, aimed to explore the effects of fructose, lactose, and arabic gum on intestinal drug absorption mediated by the glucose transport pathway.

METHODS

The influence of fructose, lactose, and arabic gum on gastrodin absorption was assessed via pharmacokinetic experiments and single-pass intestinal perfusion. The expression of sodium-dependent glucose transporter 1 (SGLT1) and sodium-independent glucose transporter 2 (GLUT2) was quantified via RT‒qPCR and western blotting. Alterations in rat intestinal permeability were evaluated through H&E staining, RT‒qPCR, and immunohistochemistry.

RESULTS

Fructose reduced the area under the curve (AUC) and peak concentration (Cmax) of gastrodin by 42.7% and 63.71%, respectively (P < 0.05), and decreased the effective permeability coefficient (Peff) in the duodenum and jejunum by 58.1% and 49.2%, respectively (P < 0.05). SGLT1 and GLUT2 expression and intestinal permeability remained unchanged. Lactose enhanced the AUC and Cmax of gastrodin by 31.5% and 65.8%, respectively (P < 0.05), and increased the Peff in the duodenum and jejunum by 33.7% and 26.1%, respectively (P < 0.05). SGLT1 and GLUT2 levels did not significantly differ, intestinal permeability increased. Arabic gum had no notable effect on pharmacokinetic parameters, SGLT1 or GLUT2 expression, or intestinal permeability.

CONCLUSION

Fructose, lactose, and arabic gum differentially affect intestinal drug absorption through the glucose transport pathway. Fructose competitively inhibited drug absorption, while lactose may enhance absorption by increasing intestinal permeability. Arabic gum had no significant influence.

Chemistry, Biological Activities, and Pharmacological Properties of Gastrodin: Mechanism Insights

Gastrodin, a bioactive compound derived from the rhizome of the orchid Gastrodia elata, exhibits a diverse range of biological activities. With documented neuroprotective, anti-inflammatory, antioxidant, anti-apoptotic, and anti-tumor effects, gastrodin stands out as a multifaceted therapeutic agent. Notably, it has demonstrated efficacy in protecting against neuronal damage and enhancing cognitive function in animal models of Alzheimer's disease, Parkinson's disease, and cerebral ischemia. Additionally, gastrodin showcases immunomodulatory effects by mitigating inflammation and suppressing the expression of inflammatory cytokines. Its cytotoxic activity involves the inhibition of angiogenesis, suppression of tumor growth, and induction of apoptosis. This comprehensive review seeks to elucidate the myriad potential effects of Gastrodin, delving into the intricate molecular mechanisms underpinning its pharmacological properties. The findings underscore the therapeutic potential of gastrodin in addressing various conditions linked to neuroinflammation and cancer.

Gastrodin: a comprehensive pharmacological review

Tianma is the dried tuber of Gastrodia elata Blume (G. elata), which is frequently utilized in clinical practice as a traditional Chinese medicine. Gastrodin (GAS) is the main active ingredient of Tianma, which has good pharmacological activity. Therefore, for the first time, this review focused on the extraction, synthesis, pharmacological effects, and derivatives of GAS and to investigate additional development options for GAS. The use of microorganisms to create GAS is a promising method. GAS has good efficacy in the treatment of neurological diseases, cardiovascular diseases, endocrine diseases, and liver diseases. GAS has significant anti-inflammatory, antioxidant, neuroprotective, vascular protective, blood sugar lowering, lipid-regulating, analgesic, anticancer, and antiviral effects. The mechanism involves various signaling pathways such as Nrf2, NF-κB, PI3K/AKT, and AMPK. In addition, the derivatives of GAS and biomaterials synthesized by GAS and PU suggested a broader application of GAS. The research on GAS is thoroughly summarized in this paper, which has useful applications for tackling a variety of disorders and exhibits good development value.

Effects of Nutraceutical Compositions Containing Rhizoma Gastrodiae or Lipoic Acid in an In Vitro Induced Neuropathic Pain Model

BACKGROUND

Peripheral neuropathy is caused by a malfunction in the axons and myelin sheaths of peripheral nerves and motor and sensory neurons. In this context, nonpharmacological treatments with antioxidant potential have attracted much attention due to the issues that some conventional pharmaceutical therapy can generate. Most of these treatments contain lipoic acid, but issues have emerged regarding its use. Considering this, the present study evaluated the beneficial effects of nutraceuticals based on Gastrodiae elata dry extract 10:1 or lipoic acid in combination with other substances (such as citicholine, B vitamins, and acetyl L-carnitine).

METHOD

To assess the combination's absorption and biodistribution and exclude cytotoxicity, its bioavailability was first examined in a 3D intestinal barrier model that replicated oral ingestion. Subsequently, a 3D model of nerve tissue was constructed to investigate the impacts of the new combination on the significant pathways dysregulated in peripheral neuropathy.

RESULTS

Our findings show that the novel combination outperformed in initial pain relief response and in recovering the mechanism of nerve healing following Schwann cell injury by successfully crossing the gut barrier and reaching the target site.

CONCLUSION

This article describes a potential alternative nutraceutical approach supporting the effectiveness of combinations with Gastrodiae elata extract in decreasing neuropathy and regulating pain pathways.

Strain differences in the drug transport capacity of intestinal glucose transporters in Sprague-Dawley versus Wistar rats, C57BL/6J versus Kunming mice

Designing oral drug delivery systems using intestinal glucose transporters (IGTs) may be one of the strategies for improving oral bioavailability of drugs. However, little is known about the biological factors affecting the drug transport capacity of IGTs. Gastrodin is a sedative drug with a structure very similar to glucose. It is a highly water-soluble phenolic glucoside. It can hardly enter the intestine through simple diffusion but exhibits good oral bioavailability of over 80%. We confirmed that gastrodin is absorbed via the intestinal glucose transport pathway. It has the highest oral bioavailability among the reported glycosides' active ingredients through this pathway. Thus, gastrodin is the most selective drug substrate of IGTs and can be used to evaluate the drug transport capacity of IGTs. Obviously, strain is one of the main biological factors affecting drug absorption. This study firstly compared the drug transport capacity of IGTs between SD rats and Wistar rats and between C57 mice and KM mice by pharmacokinetic experiments and single-pass intestinal perfusion experiments of gastrodin. Then, the sodium-dependent glucose transporter type 1 (SGLT1) and sodium-independent glucose transporters type 2 (GLUT2) in the duodenum, jejunum, ileum and colon of these animals were quantified using RT-qPCR and Western blot. The results showed that the oral bioavailability of gastrodin in Wistar rats was significantly higher than in SD rats and significantly higher in KM mice than in C57 mice. Gastrodin absorption significantly differed among different intestinal segments in SD rats, C57 mice and KM mice, except Wistar rats. RT-qPCR and Western blot demonstrated that the intestinal expression distribution of SGLT1 and GLUT2 in SD rats and C57 mice was duodenum ≈ jejunum > ileum > colon. SGLT1 expression did not differ among different intestinal segments in KM mice, whereas the intestinal expression distribution of GLUT2 was duodenum ≈ jejunum ≈ ileum > colon. However, the expression of SGLT1 and GLUT2 did not differ among different intestinal segments in Wistar rats. It was reported that the intestinal expression distribution of SGLT1 and GLUT2 in humans is duodenum > jejunum > ileum > colon. Hence, the intestinal expression distribution of SGLT1 and GLUT2 of SD rats and C57 mice was more similar to that in humans. In conclusion, the drug transport capacity of IGTs differs in different strains of rats and mice. SD rats and C57 mice are more suitable for evaluating the pharmacokinetics of glycosides' active ingredients absorbed via the intestinal glucose transport pathway.

GLUT4 mediates the protective function of gastrodin against pressure overload-induced cardiac hypertrophy

Gastrodia elata exhibits extensive pharmacological activity; its extract gastrodin (GAS) has been used clinically to treat cardiovascular diseases. In the present study, we examined the effect of GAS in a mice model of pathological cardiac hypertrophy, which was induced using transverse aortic constriction (TAC). Male C57BL/6 J mice underwent either TAC or sham surgery. GAS was administered post-surgically for 6 weeks and significantly improved the deterioration of cardiac contractile function caused by pressure overload, cardiac hypertrophy, and fibrosis in mice. Treatment with GAS for 6 weeks upregulated myosin heavy chain α and down-regulated myosin heavy chain β and atrial natriuretic peptide, while insulin increased the effects of GAS against cardiac hypertrophy. In vitro studies showed that GAS could also protect phenylephrine-induced cardiomyocyte hypertrophy, and these effects were attenuated by BAY-876, and increased by insulin. Taken together, our results suggest that the anti-hypertrophic effect of gastrodin depends on its entry into cardiomyocytes through GLUT4.

Potential Targets and Action Mechanism of Gastrodin in the Treatment of Attention-Deficit/Hyperactivity Disorder: Bioinformatics and Network Pharmacology Analysis

Objective

Gastrodin is a main medicinal component of traditional Chinese medicine (TCM) Gastrodia elata Blume (G. elata), presenting the potential for the treatment of attention-deficit/hyperactivity disorder (ADHD). However, the underlying targets and action mechanisms of the treatment have not been identified.

Methods

The gastrodin-related microarray dataset GSE85871 was obtained from the GEO database and analyzed by GEO2R to obtain differentially expressed genes (DEGs). Subsequently, the targets of gastrodin were supplemented by the Encyclopedia of Traditional Chinese Medicine (ETCM), PubChem, STITCH, and SwissTargetPrediction databases. ADHD-associated genes were collected from six available disease databases (i.e., TTD, DrugBank, OMIM, PharmGKB, GAD, and KEGG DISEASE). The potential targets of gastrodin during ADHD treatment were obtained by mapping gastrodin-related targets with ADHD genes, and their protein–protein interaction (PPI) relationship was constructed by the STRING database. The GO function and KEGG pathway enrichment analyses were performed using the ClueGO plug-in in the Cytoscape software and DAVID database, respectively. Finally, the binding affinity between gastrodin and important targets was verified by molecular docking.

Results

A total of 460 gastrodin-related DEGs were identified from GSE85871, and 124 known gastrodin targets were supplemented from 4 databases, including ETCM. A total of 440 genes were collected from the above 6 disease databases, and 267 ADHD-relevant genes were obtained after duplicate removal. Through mapping the 584 gastrodin targets to the 267 ADHD genes, 16 potential therapeutic targets were obtained, among which the important ones were DRD2, DRD4, CHRNA3, CYP1A1, TNF, IL6, and KCNJ3. The enrichment analysis results indicated that 16 potential targets were involved in 25 biological processes (e.g., dopamine (DA) transport) and 22 molecular functions (e.g., postsynaptic neurotransmitter receptor activity), which were mainly localized at excitatory synapses. The neuroactive ligand-receptor interaction, cholinergic synapse, and dopaminergic synapse might be the core pathways of gastrodin in ADHD treatment. Through molecular docking, it was preliminarily verified that gastrodin showed good binding activity to seven important targets and formed stable binding conformations.

Conclusions

Gastrodin might exert an anti-ADHD effect by upgrading the dopaminergic system and central cholinergic system, inhibiting the inflammatory response and GIRK channel, and exerting a synergistic effect with other drugs on ADHD. For this reason, gastrodin should be considered a multitarget drug for ADHD treatment.

Identification of a novel glucuronyltransferase from Streptomyces chromofuscus ATCC 49982 for natural product glucuronidation

Glycosylation is an effective way to increase the polarity of natural products. UDP-glucuronyltransferases (UGTs) are commonly observed and extensively studied in phase II drug metabolism. However, UGTs in microorganisms are not well studied, which hampered the utilization of this type of enzyme in microbial glucuronidation of natural products. Screening of five actinomycete strains showed that Streptomyces chromofuscus ATCC 49982 can convert diverse plant polyphenols into more polar products, which were characterized as various glucuronides based on their spectral data. Analysis of the genome of this strain revealed a putative glucuronidation gene cluster that contains a UGT gene (gcaC) and two UDP-glucuronic acid biosynthetic genes (gcaB and gcaD). The gcaC gene was cloned and heterologously expressed in Escherichia coli BL21(DE3). Incubation of the purified enzyme with resveratrol and UDP-glucuronic acid led to the production of resveratrol-4'-O-β-D-glucuronide and resveratrol-3-O-β-D-glucuronide, allowing GcaC to be characterized as a flexible UGT. The optimal in vitro reaction pH and temperature for GcaC are 7.5 and 30 °C, respectively. Its activity can be stimulated by Ca²⁺, Mg²⁺, and Mn²⁺, whereas Zn²⁺, Cu²⁺, and Fe²⁺ showed inhibitory effects. Furthermore, GcaC has a broad substrate specificity, which can glucuronidate various substrates besides resveratrol, including quercetin, ferulic acid, vanillic acid, curcumin, vanillin, chrysin, zearalenone, and apigenin. The titers of resveratrol-4'-O-β-D-glucuronide and resveratrol-3-O-β-D-glucuronide in E. coli-GcaC were 78.381 ± 0.366 mg/L and 14.991 ± 0.248 mg/L from 114.125 mg/L resveratrol within 3 h. Therefore, this work provides an effective way to produce glucuronides of resveratrol and other health-benefitting natural products. KEY POINTS: • A novel versatile microbial UDP-glucuronyltransferase was discovered and characterized from Streptomyces chromofuscus ATCC 49982. • The UDP-glucuronyltransferase was expressed in Escherichia coli and can convert resveratrol into two glucuronides both in vitro and in vivo. • The UDP-glucuronyltransferase has a highly flexible substrate specificity and is an effective tool to prepare mono- or diglucuronides of bioactive molecules.

Characterization by HPLC of p-Hydroxybenzyl Alcohol Biotransformation to Gastrodin In Vivo

Gastrodin (GAS) and its aglycone, p-hydroxybenzyl alcohol (HBA), are both bioactive compounds extracted from Gastrodia elata Blume (GEB). In the current Chinese pharmacopoeia, they are regarded as quality control markers for GEB. In this study, we developed a high-performance liquid chromatography method coupled with a diode array detector to quantify GAS and HBA concentrations in plasma following oral ingestion by rats. For the first time, GAS was detected in vivo after HBA administration. GAS and HBA both had similar pharmacological effects, but the influence of the glucose moiety resulted in different pharmacokinetic characteristics. In this study, the effects of GAS and HBA at different administration durations were investigated in zebrafish larvae. These compounds were found to induce a sedative effect but had different onset times. In conclusion, a biotransformation of HBA to GAS could be observed in the rats. This may be a new insight into the pharmacokinetic characteristics of these bioactive compounds and also relates to the different ways in which they take effect.

Comparative study on the intestinal absorption of three gastrodin analogues via the glucose transport pathway

Gastrodin is the main active constituent of Tianma, a famous traditional Chinese herbal medicine. Our previous research has found that gastrodin is absorbed rapidly in the intestine by the sodium-dependent glucose transporter 1 (SGLT1). In the current report, gastrodin is the best glycoside compound absorbed via the glucose transport pathway. This study aimed to investigate the effect of the slight difference in chemical structure on the drug intestinal absorption via the glucose transport pathway. Traditional biopharmaceutical and computer-aided molecular docking methods were used to evaluate the intestinal absorption characteristics of three gastrodin analogues, namely, salicin, arbutin and 4-methoxyphenyl-β-D-glucoside (4-MG). The oil-water partition coefficient (logP) experiments showed that the logP values of the gastrodin analogues followed the order: 4-MG > salicin > arbutin. In vitro Caco-2 cell transport experiments demonstrated that the apparent permeability coefficient (P_app) value of arbutin was higher than those of salicin and 4-MG. In situ single-pass intestinal perfusion experiments showed that the absorption of arbutin and 4-MG was better than that of salicin and that the absorption of the three compounds in the colon was lower than that in the small intestine. Quantitative real-time polymerase chain reaction results confirmed that the SGLT1 mRNA expression in the small intestine of rats was obviously higher than that in the colon of rats. In vivo pharmacokinetic experiments demonstrated that the oral bioavailability of salicin was lower than those of arbutin and 4-MG. In vitro and in vivo experiments showed that glucose or phlorizin (SGLT1 inhibitor) could decrease the intestinal absorption of the three compounds. Contrary to the above biopharmaceutical experiments, the computer-aided molecular docking test showed that the affinity of salicin to the vSGLT receptor was stronger than those of arbutin and 4-MG. In conclusion, the SGLT1 can facilitate the intestinal absorption of salicin, arbutin and 4-MG, and the slight difference in chemical structure can affect absorption.

Role of Glucose Transporters in Drug Membrane Transport

BACKGROUND

Glucose is the main energy component of cellular activities. However, as a polar molecule, glucose cannot freely pass through the phospholipid bilayer structure of the cell membrane. Thus, glucose must rely on specific transporters in the membrane. Drugs with a similar chemical structure to glucose may also be transported through this pathway.

METHODS

This review describes the structure, distribution, action mechanism and influencing factors of glucose transporters and introduces the natural drugs mediated by these transporters and drug design strategies on the basis of this pathway.

RESULTS

The glucose transporters involved in glucose transport are of two major types, namely, Na+-dependent and Na+-independent transporters. Glucose transporters can help some glycoside drugs cross the biological membrane. The transmembrane potential is influenced by the chemical structure of drugs. Glucose can be used to modify drugs and improve their ability to cross biological barriers.

CONCLUSION

The membrane transport mechanism of some glycoside drugs may be related to glucose transporters. Glucose modification may improve the oral bioavailability of drugs or achieve targeted drug delivery.

Role of Intestinal Microbiota in Metabolism of Gastrodin In Vitro and In Vivo

Alteration in the number and composition of intestinal microbiota affects the metabolism of several xenobiotics. Gastrodin, isolated from Gastrodia elata, is prone to be hydrolyzed by intestinal microbiota. In the present study, the role of intestinal microbiota in gastrodin metabolism was investigated in vitro and in vivo. Gastrodin was incubated in an anaerobic condition with intestinal contents prepared from vehicle- and antibiotics-treated rats and the disappearance of gastrodin and formation of 4-hydroxybenzyl alcohol (4-HBA) was measured by liquid chromatography coupled to mass spectroscopy (LC-MS/MS). The results showed that almost all gastrodin incubated with control intestinal contents was metabolized to its aglycone in time- and concentration-dependent manners. In contrast, much less formation of 4-HBA was detected in intestinal contents from antibiotics-treated rats. Subsequently, in vivo pharmacokinetic study revealed that the antibiotic pretreatment of rats significantly affected the metabolism of gastrodin to 4-HBA. When administered orally, gastrodin was rapidly absorbed rapidly into plasma, metabolized to 4-HBA, and disappeared from the body within six hours. Interestingly, the pharmacokinetic parameters of 4-HBA were changed remarkably in antibiotics-treated rats, compared to control rats. The results clearly indicated that the antibiotics treatment of rats suppressed the ability of intestinal microbiota to metabolize gastrodin to 4-HBA and that, thereby, the pharmacodynamic action was significantly modulated.

Protein hydrolysates and ultrafiltered < 1 KDa fractions from Phaseolus lunatus, Phaseolus vulgaris and Mucuna pruriens exhibit antihyperglycemic activity, intestinal glucose absorption and α-glucosidase inhibition with no acute toxicity in rodents

BACKGROUND

Protein hydrolysates from food plants, such as legumes, have emerged as a new alternative to treat hyperglycemia, an important risk factor contributing to the development of type 2 diabetes mellitus (T2DM) and its complications. The aim of this work was to assess the antihyperglycemic activity and inhibition of α-glucosidase, and intestinal glucose absorption, and acute toxicity of total hydrolysates and < 1 kDa fractions from Phaseolus lunatus L., Phaseolus vulgaris L., and Mucuna pruriens (L.) DC., obtained by hydrolysis with Alcalase®-Flavourzyme® or pepsine-pancreatin enzymatic systems.

RESULTS

In vivo results showed that three of six total hydrolysates and four of six < 1 kDa fractions suppressed starch-induced postprandial hyperglycemia (ED₅₀ range between 1.4 and 93 mg kg^-1 ). In vitro, total hydrolysates and fractions, particularly from M. pruriens, inhibited carbohydrate intestinal absorption (from 19.2 to 40%), and α-glucosidase activity (IC₅₀ from 0.86 to 75 mg mL^-1 ). Finally, none of the hydrolysates and fractions tested did not show any signs of toxicity (LD₅₀ > 5000 mg kg^-1 ).

CONCLUSION

These results suggest that hydrolysates and < 1 kDa fractions from P. lunatus, P. vulgaris and M. pruriens are suitable candidates to treat or prevent T2DM. © 2018 Society of Chemical Industry.

Gastrodin inhibits high glucose‑induced human retinal endothelial cell apoptosis by regulating the SIRT1/TLR4/NF‑κBp65 signaling pathway

Diabetic retinopathy (DR), one of the most common complications of late‑phase diabetes, is associated with the ectopic apoptosis of microvascular cells. Gastrodin, a phenolic glucoside derived from Gastrodia elata Blume, has been reported to have antioxidant and anti‑inflammation activities. The aim of the present study was to investigate the effects of gastrodin on high glucose (HG)‑induced human retinal endothelial cell (HREC) injury and its underlying mechanism. The results demonstrated that HG induced cell apoptosis in HRECs, which was accompanied by increased levels of reactive oxygen species production. Gastrodin treatment significantly alleviated HG‑induced apoptosis and oxidative stress. Furthermore, HG stimulation decreased the levels of SIRT1, which was accompanied by an increase in Toll‑like receptor 4 (TLR4) expression and the levels of phosphorylated nuclear factor (NF)‑κBp65. However, the administration of gastrodin significantly inhibited the activation of the sirtuin 1 (SIRT1)/TLR4/NF‑κBp65 signaling pathway in HRECs exposed to HG. Collectively, the present study demonstrated that gastrodin may be effective against HG‑induced apoptosis and its action may be exerted through the regulation of the SIRT1/TLR4/NF‑κBp65 signaling pathway.

A Review on Central Nervous System Effects of Gastrodin

Rhizoma Gastrodiae (also known as Tian ma), the dried rhizome of Gastrodia elata Blume, is a famous Chinese herb that has been traditionally used for the treatment of headache, dizziness, spasm, epilepsy, stoke, amnesia and other disorders for centuries. Gastrodin, a phenolic glycoside, is the main bioactive constituent of Rhizoma Gastrodiae. Since identified in 1978, gastrodin has been extensively investigated on its pharmacological properties. In this article, we reviewed the central nervous system (CNS) effects of gastrodin in preclinical models of CNS disorders including epilepsy, Alzheimer's disease, Parkinson's disease, affective disorders, cerebral ischemia/reperfusion, cognitive impairment as well as the underlying mechanisms involved and, where possible, clinical data that support the pharmacological activities. The sources and pharmacokinetics of gastrodin were also reviewed here. As a result, gastrodin possesses a broad range of beneficial effects on the above-mentioned CNS diseases, and the mechanisms of actions include modulating neurotransmitters, antioxidative, anti-inflammatory, suppressing microglial activation, regulating mitochondrial cascades, up-regulating neurotrophins, etc. However, more detailed clinical trials are still in need for positioning it in the treatment of neurological disorders.

Effect of glycation inhibitors on aging and age-related diseases

Vast evidence supports the view that glycation of proteins is one of the main factors contributing to aging and is an important element of etiopathology of age-related diseases, especially type 2 diabetes mellitus, cataract and neurodegenerative diseases. Counteracting glycation can therefore be a means of increasing both the lifespan and healthspan. In this review, accumulation of glycation products during aging is presented, pathophysiological effects of glycation are discussed and ways of attenuation of the effects of glycation are described, concentrating on prevention of glycation. The effects of glycation and glycation inhibitors on the course of selected age-related diseases, such as Alzheimer's disease, Parkinson's disease and cataract are also reviewed.

Down-regulation of Slit-Robo pathway mediating neuronal cytoskeletal remodeling processes facilitates the antidepressive-like activity of Gastrodia elata Blume

Nowadays, depression is a serious psychological disorder that causes extreme economic loss and social problems. Previously, we discovered that the water extract of Gastrodia elata Blume (WGE) improved depressive-like behavior by influencing neurotransmitters in rats subjected to the forced swimming test. To elucidate possible mechanisms, in the present study, we performed a proteomics and bioinformatics analysis to identify the related pathways. Western blot-validated results indicated that the core protein network modulated by WGE administration was closely associated with down-regulation of the Slit-Robo pathway, which modulates neuronal cytoskeletal remodeling processes. Although Slit-Robo signaling has been well investigated in neuronal development, its relationship with depression is not fully understood. We provide a potential hint on the mechanism responsible for the antidepressive-like activity of WGE. In conclusion, we suggest that the Slit-Robo pathway and neuronal cytoskeleton remodeling are possibly one of the pathways associated with the antidepressive-like effects of WGE.

The transport and efflux of glycosylated luteinising hormone-releasing hormone analogues in caco-2 cell model: contributions of glucose transporters and efflux systems

Luteinising hormone-releasing hormone (LHRH) analogues have wide therapeutic applications in the treatment of prostate cancers and endocrine disorders. The structure of LHRH was modified using a glycosylation strategy to increase the permeability of the peptide across biological membranes. Lactose, galactose and glucose units were coupled to LHRH peptide, and the impact of glucose transporters, GLUT2 and SGLT1, was investigated in the transport of the analogues. Results showed the contribution of both transporters in the transport of all LHRH analogues. In the presence of glucose transporter inhibitors, reduction in the apparent permeability (Papp ) was greatest for compound 6, which contains a glucose unit in the middle of the sequence (Papp = 58.54 ± 4.72 cm/s decreased to Papp = 1.6 ± 0.345 cm/s). The basolateral to apical flux of the glycosylated derivatives and the impact of two efflux pumps was also examined in Caco-2 cell monolayers. The efflux ratios (ERs) of all LHRH analogues in Caco-2 cells were in the range of 0.06-0.2 except for compound 4 (galactose modified, ER = 8.03). We demonstrated that the transport of the glycosylated peptides was facilitated through glucose transporters. The proportion of glucose and lactose derivatives pumped out by efflux pumps did not affect the Papp values of the analogues.

Gastrodin prevents motor deficits and oxidative stress in the MPTP mouse model of Parkinson's disease: involvement of ERK1/2-Nrf2 signaling pathway

AIMS

Current no effective therapy is available to halt the progression of Parkinson's disease (PD). Oxidative stress has been implicated in the etiology of PD. The present study evaluates the hypothesis that prevention of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced motor deficits by gastrodin might mainly result from its antioxidant property via interrupting extracellular signal regulated protein kinases (ERK) 1/2-nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway.

MAIN METHODS

Pretreatment of mouse model of PD is established by treating C57BL/6 mice with 4 doses of MPTP (30 mg/kg per day, i.p.), with gastrodin (60 mg/kg per day) administered by daily intraperitoneal injection for 2 weeks. Motor behavior of mice was monitored by open-field test and rotarod test. Real-time polymerase chain reaction and Western blotting were used to analyze the expression of genes.

KEY FINDINGS

MPTP-induced motor deficits were partially and significantly forestalled by gastrodin. Gastrodin treatment prevented MPTP-induced oxidative stress, as measured by malondialdehyde in midbrain. Interestingly, MPTP-intoxicated mice treated with gastrodin robustly increased heme oxygenase 1, superoxide dismutase, glutathione levels, and Nrf2 nuclear translocation in striatum of MPTP-intoxicated mice. Furthermore, results herein suggest that the antioxidant pathway activated by gastrodin involves ERK1/2 phosphorylation.

SIGNIFICANCE

Gastrodin protects midbrain of MPTP-intoxicated mice against oxidative stress, in part, through interrupting ERK1/2-Nrf2 pathway mechanism, which will give us an insight into the potential of gastrodin in terms of opening up new therapeutic avenues for PD.