Gastrodia elata prevents rat pheochromocytoma cells from serum-deprived apoptosis: the role of the MAPK family

A new method for studying the mechanism of “Feature Identification based quality assessment” of Traditional Chinese Medicine, taking Gastrodiae Rhizoma as an example

Aim of the study

The research group proposed that the mechanism of “Feature Identification based Quality Assessment” (FIQA) of Traditional Chinese Medicine (TCM) can be explained according to the relationship between the “Feature” of TCM and the Pharmacodynamic Components representing the holistic effect of TCM. Gastrodiae Rhizoma (GR) was selected as the research object to reveal the close relationship between “Feature” and the quality of TCM.

Materials and methods

In this study, the “Feature” such as “Shape”, “Color”, “Odour” and “Taste” of GR are quantified by the electronic nose, electronic tongue, and other instruments. Then, the Pharmacodynamic Components Group (PCG) of GR was determined which could reflect the holistic effect of GR by spectrum effect relationship analysis. By analyzing the correlation between the “Feature” and the content of PCG, the mechanism of FIQA of GR was determined.

Results

The quantitative results of “Shape”, “Color”, “Odour” and “Taste” of GR from different sources were significantly different. Six components were selected as the PCG, which can represent the holistic effect of GR in the aspect of the neuroprotective effect. There was a good correlation between the components in the PCG and “Feature”.

Conclusions

The quality of GR can be determined quantitatively according to its “Shape”, “Color”, “Odour” and “Taste”. The mechanism of FIQA of TCM can be explained according to the relationship between the Shape of TCM and the Pharmacodynamic Components representing the quality of TCM. The revelation of this mechanism reflects the holistic characteristics of the multi-component synergistic effect of TCM. This study provides a reference research method for revealing the mechanism of FIQA of TCM.

Proapoptotic effects of 2,5‑hexanedione on pheochromocytoma cells via oxidative injury

N‑hexanes are prominent environmental pollutants that are able to cause neurotoxicity in vivo and in vitro. Central and peripheral neuropathies induced by n‑hexane exposure are a major health concern. 2,5‑Hexanedione (2,5‑HD) is the most significant neurotoxic metabolite of n‑hexane; however, little is known regarding the underlying mechanism of its neurotoxicity. Thus, the aim of the present study was to investigate the damaging effects of 2,5‑HD on pheochromocytoma PC12 cells, and to explore the underlying mechanism. Cell viability was tested using a Cell Counting Kit‑8 method, and the leakage of lactate dehydrogenase (LDH) from cells was measured using an LDH assay kit. Glutathione peroxidase (GSHPx) and superoxide dismutase (SOD) activities, and the level of malondialdehyde (MDA) were determined using corresponding assay kits. Apoptotic cells were detected using an annexin V‑fluorescein isothiocyanate/propidium iodide (PI) apoptosis kit, and were subsequently observed by fluorescence microscopy. The relative expression levels of cleaved‑caspase‑3, Bcl‑associated‑X protein (Bax) and Bcl‑2 were identified by western blotting. The results revealed that 2,5‑HD was able to decrease the viability of PC12 cells and promoted the leakage of LDH in a concentrationdependent manner. Further analysis demonstrated that 2,5‑HD decreased the activity of the antioxidative enzymes, SOD and GSHPx, and led to an increase in the levels of MDA in the supernatant of cultured PC12 cells. The annexin V/PI staining results revealed that the numbers of apoptotic cells were increased following treatment with 2,5‑HD. In addition, 2,5‑HD (5 and 10 mmol/l) led to significant increases in the expression levels of caspase‑3 and Bax, with the concomitant downregulation of Bcl‑2. The antioxidant N‑acetylcysteine was identified to antagonize 2,5‑HD‑stimulated cleaved‑caspase‑3 and Bax upregulation, and Bcl‑2 downregulation. Collectively, the results of the present study suggested that 2,5‑HD exerts proapoptotic effects on PC12 cells via oxidative injury. These findings may be applied in the development of novel therapeutic strategies to treat neurological disorders associated with nhexane exposure.

Morphological control of mitochondria as the novel mechanism of Gastrodia elata in attenuating mutant huntingtin-induced protein aggregations

BACKGROUND

According to Compendium of Materia Medica, Gastrodia elata (GE) Blume as a top grade and frequently prescribed herbal medicine has been used in treating dizziness, headaches, and epilepsy, indicating a neuroprotective effect. Because GE is capable of suppressing a hyperactive liver and thus calming endogenous wind, and because Huntington's disease (HD) can be classified as a phenomenon of disturbed liver wind, it is suggested that GE might be beneficial in treating HD. However, although current studies support GE for the prevention of diverse neurodegenerations such as HD, its detailed mechanisms remain elusive.

PURPOSE

To investigate the molecular mechanism of GE in preventing HD by focusing on mitochondrial morphology, which is highly associated with HD etiology and thus proposed as a therapeutic target of neurodegenerations.

STUDY DESIGN/METHODS

The overexpression of the mutant huntingtin (mHTT) gene in rat pheochromocytoma (PC12) cells was used as an in vitro cell model of HD. A filter retardation assay was applied to measure protein aggregations during HTT expression. Cotransfection with mitochondrial fusion and fission genes was used to test their relationships with HTT aggregates by monitoring with a confocal laser scanning microscope and filter retardation assay. Western blot analysis was used to estimate protein expression under different drug treatments or cotransfections with other related genes.

RESULTS

The overexpression of mutant but not normal HTT genes significantly resulted in protein aggregations in PC12 cells. GE dose-dependently attenuated mHTT-induced protein aggregations and free radical formations. GE significantly reversed mHTT-induced mitochondrial fragmentation and dysregulation of mitochondrial fusion and fission molecules. The overexpression of mitochondrial fusion genes attenuated mHTT-induced protein aggregations. Further, Mdivi-1, a DRP1 fission molecule inhibitor, significantly reversed mHTT-induced protein aggregations and mitochondrial fragmentation.

CONCLUSION

GE attenuated mHTT aggregations through the control of mitochondrial fusion and the fission pathway.

Identification and Characterization of Key Chemical Constituents in Processed Gastrodia elata Using UHPLC-MS/MS and Chemometric Methods

Gastrodia elata Blume belongs to the Orchidaceae family. G. elata is often processed when used in traditional Chinese medicine (TCM). In the current study, a traditional processing method, known as "Jianchang Bang," was applied. Steamed and dried (S&D) G. elata was processed with ginger juice for up to 5 days (GEP5D). An UHPLC-MS/MS combined with a chemometric method was developed for the analysis of processed G. elata along with the raw material as well as steamed and dried G. elata. As a result, the primary marker compounds were identified with the aid of TOF-MS and MS/MS analyses. Compared with the raw material of G. elata with GEP5D, three new parishin-type compounds were identified according to their retention time, accurate mass, and fragmentation patterns. The chromatographic peak areas for marker compounds, including S-(gastrodin)-glutathione, S-(4-hydroxybenzylamine)-glutathione, and parishin-type compounds, changed significantly. This result indicated that by applying the "Jianchang Bang" method, changes in chemical composition in G. elata contents were observed. The study also demonstrated that chemometric analysis is helpful in understanding the processing mechanism and will provide scientific support for the clinical application of G. elata.

Gastrodia elata alleviates mutant huntingtin aggregation through mitochondrial function and biogenesis mediation

BACKGROUND

According to the Compendium of Materia Medica, Gastrodia elata (GE) Blume is a top-grade herbal medicine frequently used to treat dizziness, headaches, tetanus, and epilepsy, suggesting that it affects neurological functions. Although studies have supported its effects in preventing diverse neurodegenerations such as Huntington's disease (HD), its mechanisms require further investigation.

PURPOSE

To investigate the ability of the molecular mechanism of GE to prevent mutant huntingtin (mHTT) protein aggregation by focusing on mitochondrial function and biogenesis, which have been proposed as the therapeutic targets of HD.

STUDY DESIGN/METHODS

mHtt overexpression in pheochromocytoma (PC12) cells was used as an in vitro cell model of HD. A retardation assay was applied to measure protein aggregation during Htt expression. Cotransfection with transcriptional genes was used to test their relationships with HTT aggregates by monitoring with a confocal laser scanning microscope. Western blot analysis was used to estimate protein expression under different drug treatments or when cotransfected with other related genes.

RESULTS

Mutant, abnormal Htt overexpression resulted in significant protein aggregation in PC12 cells. GE dose-dependently attenuated mHTT aggregates and increased cyclic-AMP response element-binding protein (CREB) phosphorylation. Adenosine A_2A-R receptor (A_2A-R) antagonist counteracted these phenomena. CREB overexpression significantly attenuated mHTT aggregation. GE increased the promoter activity and expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). Furthermore, wild-type PGC-1α but not mutant PGC-1α overexpression attenuated mHTT aggregates.

CONCLUSION

GE attenuated mHtt aggregation by mediating mitochondrial function and biogenesis through the A_2A-R/PKA/CREB/PGC-1α-dependent pathway.

Gastrodin causes vasodilation by activating KATP channels in vascular smooth muscles via PKA-dependent signaling pathway

Gastrodin, one of the major components extracted from the Chinese herb Gastrodia elata Bl., has been widely used as an anticonvulsant, sedative, analgesic and hypotensive. In our study, we aimed to investigate the effects and possible mechanisms of gastrodin on vascular K_ATP channels. Tension experiments were used on rat mesenteric artery rings without an endothelium. Patch clamp experiments were executed to investigate the influences of gastrodin on the membrane current in mesenteric artery smooth muscle cells. Gastrodin induced vasorelaxation in a concentration dependent manner when rat mesenteric artery rings were pre-contracted with Phenylephrine. The vasorelaxation effect was partially diminished by pre-treating with a K_ATP channel inhibitor, or a PKA inhibitor. With whole-cell patch-clamp recording techniques, we found that gastrodin is a activator of K_ATP in rat mesenteric artery smooth muscle cells, and this effect was eliminate by pre-treating with H89or PKI, PKA inhibitor. In addition, when rat vascular smooth muscle cells were treated with 100 μM gastrodin for 24 h, maximum K_ATP current density increased by 28.1%. The results indicate that gastrodin exerts vasorelaxation effect through activation of PKA and subsequent opening of smooth muscle K_ATP channels.

Antitumor and Immunomodulatory Effect of Gastrodia elata on Colon Cancer In Vitro and In Vivo

Gastrodia elata Blume (GE) is a well-known kind of herb that has been used in traditional medicine for thousands of years. The extrusion of raw materials from it could improve flavor and enhance bioavailability in food and drug development. The purpose of this study is to investigate antitumor and immune boosting effects of extruded GE in human colon carcinoma cells, splenocytes, and mice-bearing CT26 colon carcinoma cell. Treatment with 100[Formula: see text][Formula: see text]g/mL of extruded GE decreased cell viability and induced the expression of Caspase-3 and Bax in HT29 cells ([Formula: see text]). When we performed DAPI staining, apoptotic bodies with condensed chromatin and fragmented nuclei, known as indicative of apoptotic morphology, increased 24[Formula: see text]h after treatment with 100[Formula: see text][Formula: see text]g/mL of extruded GE. Treatments with extruded GE significantly promoted splenocyte proliferation and IL-2 or IFN-[Formula: see text] secretion, compared with that of control cells ([Formula: see text]). The administration of extruded GE of 200 mg/kg/day decreased tumor growth and Ki-67 or [Formula: see text]-catenin expression in mice ([Formula: see text]). Additionally, we investigated the contents of compounds in extruded GE extracts using ultra performance liquid chromatography. The contents of p-hydroxylbenzyl alcohol and p-hydroxybenzaldehyde in extruded GE were 2.97[Formula: see text]mg/g and 0.04[Formula: see text]mg/g, respectively. It was supposed that antitumor and immunomodulatory effects of extruded GE might exert by the p-hydroxylbenzyl alcohol and p-hydroxybenzaldehyde of many compositions analyzed from extruded GE. These results suggest that extruded GE have the potential to be developed into a natural pharmaceutical and functional food as a cancer chemopreventive agent.

The aqueous extract of rhizome of Gastrodia elata Blume attenuates locomotor defect and inflammation after traumatic brain injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Traumatic brain injury (TBI) has an incident rate of 200-300 people per 100,000 annually in the developed countries. TBI has relatively high incidence at an early age and may cause long-term physical disability. Patients suffered from severe TBI would have motor and neuropsychological malfunctions, affecting their daily activities. Traditionally, Gastrodia elata Blume is a Chinese Medicines which was used for the head diseases, while their efficiency on reducing brain damage was still largely unknown. In the present study, we aimed to examine the effect of water extract of G. elata Blume (GE) against TBI and elucidate its underlying mechanism.

MATERIALS AND METHODS

Sprague-Dawley rats were treated with GE for 7 days, immediately after controlled cortical impact-induced TBI. Impaired neurobehavioral functioning was measured on day 3 and 6 after TBI. Histology of TBI was examined to assess the extent of inflammation, and the expressions of pro-inflammatory cytokines were examined by immunofluorescence study on day 7.

RESULTS

GE treatment significantly improved the impaired locomotor functions induced by TBI. GE treatment reduced inflammation and gliosis in the penumbral area. The increase in brain levels of pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha observed in non-GE treated TBI rats were also reversed.

CONCLUSIONS

GE treatment attenuated the locomotor deficit caused by TBI. The anti-inflammatory activity might be mediated by inhibition of pro-inflammatory cytokines responses in the TBI-brain.

Method development and validation for the high-performance liquid chromatography assay of gastrodin in water extracts from different sources of Gastrodia elata Blume

Gastrodia elata Blume is commonly used as a medical herb in China for ameliorating headaches, dizziness, and convulsions. In previous studies, water extracts of G. elata Bl. (WGE) have demonstrated potential to act as therapeutic agents to improve depression-like symptoms in rats. As gastrodin (GAS) is a major active compound in WGE, its quantitation in WGE is important for quality control. The objective of this study was to develop an optimized and validated reversed-phase high-performance liquid chromatography method for the analysis of GAS in different sources of WGE. We evaluated the GAS content in varieties of G. elata Bl. including G. elata Bl. f. glauca S. Chow and G. elata Bl. f. elata. We also evaluated the GAS content of the latter variety from two different origins, Yun-nan and Hu-nan. The results indicate that the amount of GAS analyzed in WGE from G. elata Bl. f. glauca S. Chow is five times higher than that of G. elata Bl. f. elata from Yun-nan and Hu-nan. A significant difference in GAS content was observed between varieties of G. elata Bl., although not between locations of origin.

Discovery of highly potent tyrosinase inhibitor, T1, with significant anti-melanogenesis ability by zebrafish in vivo assay and computational molecular modeling

Tyrosinase is involved in melanin biosynthesis and the abnormal accumulation of melanin pigments leading to hyperpigmentation disorders that can be treated with depigmenting agents. A natural product T1, bis(4-hydroxybenzyl)sulfide, isolated from the Chinese herbal plant, Gastrodia elata, is a strong competitive inhibitor against mushroom tyrosinase (IC₅₀ = 0.53 μM, Ki = 58 ± 6 nM), outperforms than kojic acid. The cell viability and melanin quantification assay demonstrate that 50 μM of T1 apparently attenuates 20% melanin content of human normal melanocytes without significant cell toxicity. Moreover, the zebrafish in vivo assay reveals that T1 effectively reduces melanogenesis with no adverse side effects. The acute oral toxicity study evidently confirms that T1 molecule is free of discernable cytotoxicity in mice. Furthermore, the molecular modeling demonstrates that the sulfur atom of T1 coordinating with the copper ions in the active site of tyrosinase is essential for mushroom tyrosinase inhibition and the ability of diminishing the human melanin synthesis. These results evident that T1 isolated from Gastrodia elata is a promising candidate in developing pharmacological and cosmetic agents of great potency in skin-whitening.

Gastrodiae Rhizoma (tiān má): a review of biological activity and antidepressant mechanisms

Gastrodiae Rhizoma, also called chì jiàn (赤箭), guǐ dū yóu (鬼督郵), or tiān má (天麻) in Chinese, is considered a top grade (上品 shàng pǐn) medicine described to enter liver channel (肝經 gān jīng) in classic literatures of traditional Chinese medicine and has been used for centuries. Many studies investigating its various bioactivities and active compounds have been conducted worldwide. This article reviews these biological activities and details the antidepressant pharmacology of Gastrodiae Rhizoma. Gastrodiae Rhizoma treatment exerts an effective inhibition of diverse diseases and disorders, including convulsion, oxidative stress, mental disorders, amnesia, cardio-cerebral-vascular diseases, and inflammation, among others. The antidepressant effect of Gastrodiae Rhizoma was evaluated in animal models and several mechanisms of activity were found, including the modulation and regulation of monoamine oxidase activity, monoamine concentration and turnover, antioxidatant activity, GABAergic system induction, BDNF induction, neuroprotection and anti-inflammatory activity.

Gastrodin ameliorates anxiety-like behaviors and inhibits IL-1beta level and p38 MAPK phosphorylation of hippocampus in the rat model of posttraumatic stress disorder

Gastrodin, a main constituent of a Chinese herbal medicine, has been shown to be effective in treating various mood disorders. The purpose of the present study was to determine whether gastrodin could ameliorate stress-associated behavior in a rat model of enhanced single prolonged stress (ESPS)-induced posttraumatic stress disorder (PTSD). Following ESPS, rats were administered orally with gastrodin (50, 100, or 200 mg/kg daily) or vehicle for 2 weeks. Animals were then tested in the open field and elevated plus-maze, and the levels of IL-6 and IL-1beta, the expression of iNOS, p38 and phospho-p38 (p-p38) in hippocampus were also tested. ESPS exposure resulted in pronounced anxiety-like behavior, elevated IL-6 and IL-1beta levels, and the higher expression of iNOS and p-p38 in hippocampus. However, repeated treatment with gastrodin, particularly at higher doses, reversed the aforementioned changes, including anxiety-like behavior, levels of IL-6 and IL-1beta, and the expression of iNOS and the p38 MAPK phosphorylation. These results indicate that gastrodin possesses anxiolytic effect and may be an effective herbal preparation for the treatment of PTSD.

Gastrodia elata prevents huntingtin aggregations through activation of the adenosine A₂A receptor and ubiquitin proteasome system

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata Blume (Fam. Orchidaceae) is a traditional Chinese herbal medicine for treating headaches, dizziness, tetanus, epilepsy, and numbness of the limbs, which suggests that it has neuroprotective effect.

AIM OF THE STUDY

To validate the neuroprotection of Gastrodia elata in preventing neurodegenerations, such as Huntington's disease (HD).

MATERIALS AND METHODS

MTT assay was used to validate the protection of Gastrodia elata. In pheochromocytoma (PC12) cell. Transient transfection of mutant huntingtin (Htt) in PC12 cell was used as an in vitro model of HD. Filter retardation assay was used to measure Htt-induced protein aggregations. Proteasome activity was monitored by transfection of pZsProSensor-1 and imaged by a confocal laser scanning microscope.

RESULTS

This protection of Gastrodia elata could be blocked by an A(2A)-R antagonist and a protein kinase A (PKA) inhibitor, indicating an A(2A)-R signaling event. Gastrodia elata could reverse mutant Htt-induced protein aggregations and proteasome de-activation through A(2A)-R signaling. In addition, activation of PKA tended to activate proteasome activity and reduce mutant Htt protein aggregations. The proteasome inhibitor, MG 132, blocked Gastrodia elata-mediated suppression of mutant Htt aggregations.

CONCLUSION

Gastrodia elata prevented mutant Htt aggregations and increased proteasomal activity by targeting the A(2A)-R through PKA-dependent pathway.

The neuroprotective effects of an extract of Gastrodia elata

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata (GE) Blume (family Orchidaceae) is a traditional Chinese herbal medicine for treating headaches, dizziness, tetanus, and epilepsy, indicating neuronal protective functions.

AIM OF THE STUDY

To evaluate the neuroprotection of GE and its molecular mechanism in preventing serum deprivation-induced PC12 cell apoptosis.

MATERIALS AND METHODS

An MTT assay and Hoechst staining were used to respectively validate serum deprivation-induced cell death and apoptosis. Cyclic (c)AMP formation and protein kinase (PK)A activity were also measured after GE treatment. Western blotting was used to detect the phosphorylation of the cAMP response element-binding (CREB) protein. Transient transfection of a dominant negative CREB was used to validate the importance of CREB.

RESULTS

GE targeted the adenosine A(2A) receptor (A(2A)-R). GE increased cAMP formation, PKA activity, and phosphorylation of the CREB protein. GE-induced CREB protein phosphorylation and protection was blocked by a PKA inhibitor and overexpression of the dominant negative CREB, respectively.

CONCLUSIONS

These results support the neuroprotective effects of GE. The protective mechanism might be mediated through an A(2A)-R/cAMP/PKA/CREB-dependent pathway.

A new drug design targeting the adenosinergic system for Huntington's disease

Background

Huntington's disease (HD) is a neurodegenerative disease caused by a CAG trinucleotide expansion in the Huntingtin (Htt) gene. The expanded CAG repeats are translated into polyglutamine (polyQ), causing aberrant functions as well as aggregate formation of mutant Htt. Effective treatments for HD are yet to be developed.

Methodology/Principal Findings

Here, we report a novel dual-function compound, N⁶-(4-hydroxybenzyl)adenine riboside (designated T1-11) which activates the A_2AR and a major adenosine transporter (ENT1). T1-11 was originally isolated from a Chinese medicinal herb. Molecular modeling analyses showed that T1-11 binds to the adenosine pockets of the A_2AR and ENT1. Introduction of T1-11 into the striatum significantly enhanced the level of striatal adenosine as determined by a microdialysis technique, demonstrating that T1-11 inhibited adenosine uptake in vivo. A single intraperitoneal injection of T1-11 in wildtype mice, but not in A_2AR knockout mice, increased cAMP level in the brain. Thus, T1-11 enters the brain and elevates cAMP via activation of the A_2AR in vivo. Most importantly, addition of T1-11 (0.05 mg/ml) to the drinking water of a transgenic mouse model of HD (R6/2) ameliorated the progressive deterioration in motor coordination, reduced the formation of striatal Htt aggregates, elevated proteasome activity, and increased the level of an important neurotrophic factor (brain derived neurotrophic factor) in the brain. These results demonstrate the therapeutic potential of T1-11 for treating HD.

Conclusions/Significance

The dual functions of T1-11 enable T1-11 to effectively activate the adenosinergic system and subsequently delay the progression of HD. This is a novel therapeutic strategy for HD. Similar dual-function drugs aimed at a particular neurotransmitter system as proposed herein may be applicable to other neurotransmitter systems (e.g., the dopamine receptor/dopamine transporter and the serotonin receptor/serotonin transporter) and may facilitate the development of new drugs for other neurodegenerative diseases.

Preventive effect of gastrodin on cognitive decline after cardiac surgery with cardiopulmonary bypass: a double-blind, randomized controlled study

Cognitive decline is a common complication after cardiac surgery with cardiopulmonary bypass (CPB), but as such no pharmacological therapy has been shown to be efficacious in preventing the decline. However, gastrodin has been shown to have multi-pharmacological effects on neurological functions. We undertook this study to test the hypothesis that gastrodin would potentially prevent CPB-associated neurocognitive decline. We randomly assigned 200 patients undergoing mitral valve replacement surgery to receive either gastrodin (40 mg/kg) or saline after the induction of anesthesia and subsequently evaluated cognitive function before surgery, at discharge, and at 3rd month after surgery by using a battery of five neurocognitive tests, or adverse effects of gastrodin postoperatively. Neurocognitive decline in postoperative function was defined as a drop of 1 SD or more in the scores on tests of any one of the four domains of cognitive function. Cognitive decline occurred in 9% of the patients in the gastrodin group in contrast to 42% in the control group (P<0.01) at discharge. Cognitive outcome could be determined at 3rd month in 87 patients in the gastrodin group and 89 in the control group. Cognitive decline was detected in 6% in the gastrodin group and 31% in the control group (P<0.01). The incidences of possible adverse effects were similar between two groups. These results indicate that gastrodin is an effective and a safe drug for the prevention of neurocognitive decline in patients undergoing mitral valve replacement surgery with CPB.

Inhibitors of microglial neurotoxicity: focus on natural products

Microglial cells play a dual role in the central nervous system as they have both neurotoxic and neuroprotective effects. Uncontrolled and excessive activation of microglia often contributes to inflammation-mediated neurodegeneration. Recently, much attention has been paid to therapeutic strategies aimed at inhibiting neurotoxic microglial activation. Pharmacological inhibitors of microglial activation are emerging as a result of such endeavors. In this review, natural products-based inhibitors of microglial activation will be reviewed. Potential neuroprotective activity of these compounds will also be discussed. Future works should focus on the discovery of novel drug targets that specifically mediate microglial neurotoxicity rather than neuroprotection. Development of new drugs based on these targets may require a better understanding of microglial biology and neuroinflammation at the molecular, cellular, and systems levels.

Determination and pharmacokinetics of gastrodin in human plasma by HPLC coupled with photodiode array detector

In present study, an HPLC method coupled with photodiode array detector (HPLC-PDA) was established for determination and pharmacokinetics of gastrodin (GAS) in human plasma after an oral administration of GAS capsule. In the method, ethanol and dichloromethane were respectively used for deproteinization and purification during the sample preparation procedure. Separation of GAS was achieved on an AichromBond-AQ C18 column (5 microm, 150 mm x 4.6 mm) with the mobile phase of methanol-0.1% phosphoric acid solution (2:98, v/v) at a flow rate of 0.8 ml/min. The wavelength was set at 220 nm and the injection volume was 20 microl. Under the conditions, the calibration curve was linear within the concentration range of 50-4000 ng/ml with the correlation coefficient (r) of 0.99554 (weight=1/X(2)) and the lower limit of quantification (LLOQ) was 50 ng/ml. The inter- and intra-day precisions were less than 11% and the accuracies (%) were within the range of 95.55-103.78%. The extraction recoveries were over 65% with RSDs less than 5.50%. The GAS was proved to be stable under tested conditions. Thus, the method was valid enough to be applied for pharmacokinetic study of GAS in human plasma. The pharmacokinetic parameters of GAS in human plasma after an oral administration of 200 mg GAS capsule were described as: C(max), 1484.55+/-285.05 ng/ml; T(max), 0.81+/-0.16 h; t(1/2alpha), 3.78+/-2.33 h; t(1/2beta), 6.06+/-3.20 h; t(1/2Ka), 0.18+/-0.53 h; K(12), 0.18+/-0.41/h; K(21), 0.20+/-0.16/h; K(10), 4.11+/-15.81/h; V1/F, 180.35+/-89.44 L; CL/F, 62.50+/-140.03 l/h; AUC(0-->t), 5619.41+/-1972.88 (ng/ml) h; and AUC(0-->infinity), 7210.26+/-3472.74 (ng/ml) h, respectively. These will be useful for the clinical application of GAS.

Determination and pharmacokinetics of gastrodin and p-hydroxybenzylalcohol after oral administration of Gastrodia elata Bl. extract in rats by high-performance liquid chromatography-electrospray ionization mass spectrometric method

In this report, a high-performance liquid chromatography-electrospray ionization mass spectrometric (HPLC-MS) method was used to determine gastrodin (GAS) and p-hydroxybenzylalcohol (HBA) in rat plasma after oral administration of Gastrodia elata Bl. (Chinese name: Tianma) extract. Up to 200 microl of plasma containing GAS, HBA and pyromucic acid (as internal standard, IS) were deproteinized with six volumes of methanol. Calibration curves showed linearity within the concentration range tested 2.00-200.00 microg/ml for GAS and 0.832-104.00 microg/ml for HBA in plasma with a correlation coefficient (r) greater than 0.9997. The limit of quantification of 2.00 and 0.83 microg/ml for GAS and HBA had been achieved, respectively. The intra-day and inter-day precisions of the method were determined to be less than 17.82% for GAS and 10.21% for HBA. The recoveries were in the range of 91.12-108.64% with RSD less than 7.80% for GAS and 92.91-106.14% with RSD less than 4.30% for HBA. Evidence showed that a rapid, simple and reproducible LC-MS assay was established to determine GAS and HBA in rat plasma.

Determination of gastrodin and vanillyl alcohol in Gastrodia elata Blume by pressurized liquid extraction at room temperature

Pressurized liquid extraction (PLE) at room temperature with a laboratory-assembled system was applied for the extraction of gastrodin (GA) and vanillyl alcohol (VA) in Gastrodia elata Blume. The proposed system setup for this current work was simpler as no heating and backpressure regulator was required. Extraction with PLE was carried out dynamically at a flow rate of 1.5 mL/min, at room temperature, under an applied pressure of 10-20 bars with an extraction time of 40-50 min. The extraction efficiencies of the proposed method using 20% aqueous ethanol were compared with heating under reflux using organic solvents such as methanol and ethanol/water (20:80) for different batches of medicinal plant materials. For the determination of GA and VA in G. elata Blume, the extraction efficiencies of PLE at room temperature were observed to be comparable with heating under reflux. The method precision was found to vary from 1.6 to 8.6% (RSD, n = 6) on different days. The marker compounds present in the various medicinal plant extracts were determined by gradient elution HPLC and HPLC/MS/MS. Our work demonstrated the possibility of implementation of PLE at room temperature and the advantages of minimizing the use of organic solvents in the extraction process.

Anti-inflammatory and anti-angiogenic activities of Gastrodia elata Blume

Gastrodia elata Blume rhizome has been traditionally used as a folk medicine for centuries in Oriental countries. Its ethanol extract (GEE) and subsequent fractions were used to evaluate anti-angiogenic, anti-inflammatory and related activities of Gastrodia elata. GEE potently inhibited angiogenesis in the chick chorioallantoic membrane assay, and its n-butanol fraction (BuOH) exerted the higher inhibitory effect. In a dose-dependent manner, GEE inhibited vascular permeability induced by acetic acid. GEE and its BuOH fraction exerted an inhibitory activity on exudate production, leukocyte migration and nitric oxide (NO) level in rat air-pouch model. GEE caused a dose-dependent inhibition of acetic acid-induced abdominal writhing in mice. In addition, GEE inhibited NO production and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) upon stimulation by lipopolysaccharide (LPS) in RAW264.7 macrophages. In summary, we demonstrate some novel pharmacological activities of Gastrodia elata, such as anti-angiogenic, anti-inflammatory and analgesic activities, and in vivo and in vitro inhibitory activity on NO production.

A new citryl glycoside from Gastrodia elata and its inhibitory activity on GABA transaminase

A new citryl glycoside, trimethylcitryl-beta-D-galactopyranoside (1) along with a known phenolic compound, gastrodigenin (2) have been isolated from the active fraction of the rhizomes of Gastrodia elata (Orchidaceae). Their structures were elucidated on the basis of spectroscopic data and chemical reaction. 1 inhibited GABA transaminase activity by 56.8% at the final concentration of 10 microg/ml.

The protective effects of phenolic constituents fromGastrodia elata on the cytotoxicity induced by KCl and glutamate

Seven phenolic compounds (1-7) were isolated from the tubers of Gastrodia elata. Their structures were elucidated on the basis of MS and NMR spectral data. p-Ethoxymethyl phenyl-O-beta-D-glucoside (1) was proved to be a new compound, with N-(p-hydroxybenzyl)-adenosine (7) isolated from this plant for the first time. In this study, the protective effects of the six constituents (1-6) on PC12 cells against the cytotoxicity induced by KCl and glutamate were also investigated. The viability of the PC12 cells was significantly enhanced by pretreatment with the six phenolic constituents.

GM1 ganglioside-mediated accumulation of amyloid β-protein on cell membranes

The conversion of soluble, nontoxic amyloid beta-protein (Abeta) to aggregated, toxic Abeta is the key step in the development of Alzheimer's disease. Liposomal studies proposed that Abeta specifically recognizes a cholesterol-dependent cluster of monosialoganglioside GM1 and a conformationally altered form of Abeta promotes the aggregation of the protein. In this study, the accumulation of Abeta on living cells was investigated for the first time. The interaction of fluorescein-labeled Abeta (FL-Abeta) with rat pheochromocytoma PC12 cells was visualized using confocal laser microscopy. FL-Abeta was found to colocalize with GM1-rich domains on cell membranes and to accumulate in a concentration- and time-dependent manner, leading to cytotoxicity. Cholesterol depletion significantly reduced Abeta accumulation. These observations corroborate the GM1-mediated Abeta accumulation model.