Structural mechanism governing the quaternary organization of monocot mannose-binding lectin revealed by the novel monomeric structure of an orchid lectin. (1/12)

Two isoforms of an antifungal protein, gastrodianin, were isolated from two subspecies of the orchid Gastrodia elata, belonging to the protein superfamily of monocot mannose-specific lectins. In the context that all available structures in this superfamily are oligomers so far, the crystal structures of the orchid lectins, both at 2.0 A, revealed a novel monomeric structure. It resulted from the rearrangement of the C-terminal peptide inclusive of the 12th beta-strand, which changes from the "C-terminal exchange" into a "C-terminal self-assembly" mode. Thus, the overall tertiary scaffold is stabilized with an intramolecular beta-sheet instead of the hybrid observed on subunit/subunit interface in all known homologous dimeric or tetrameric lectins. In contrast to the constrained extended conformation with a cis peptide bond between residues 98 and 99 commonly occurring in oligomers, a beta-hairpin forms from position 97 to 101 with a normal trans peptide bond at the corresponding site in gastrodianin, which determines the topology of the C-terminal peptide and thereby its unique fold pattern. Sequence and structure comparison shows that residue replacement and insertion at the position where the beta-hairpin occurs in association with cis-trans inter-conversion of the specific peptide bond (97-98) are possibly responsible for such a radical structure switch between monomers and oligomers. Moreover, this seems to be a common melody controlling the quaternary states among bulb lectins through studies on sequence alignment. The observations revealed a structural mechanism by which the quaternary organization of monocot mannose binding lectins could be governed. The mutation experiment performed on maltose-binding protein-gastrodianin fusion protein followed by a few biochemical detections provides direct evidence to support this conclusion. Potential carbohydrate recognition sites and biological implications of the orchid lectin based on its monomeric state are also discussed in this paper.  (+info)

Gastrodia elata blume and an active component, p-hydroxybenzyl alcohol reduce focal ischemic brain injury through antioxidant related gene expressions. (2/12)

Ischaemic stroke is a leading cause of death and long-lasting disability. Gastrodia elata blume (GEB) is a Chinese herb that is widely used to treat convulsive disorders, such as epilepsy, and p-hydroxybenzyl alcohol (HBA) is the active ingredient in GEB. The present study was conducted to evaluate the effects of GEB and HBA on the brain damage and transcriptional levels of Protein disulfide isomerase (PDI) and 1-Cys peroxiredoxin (1-Cys Prx) genes known to play a role in antioxidant systems after transient focal ischemia in the rat brain. Focal ischemia was induced in rats by middle cerebral artery occlusion (MCAO). All animals underwent ischemia for 1 h, followed by 24 h of reperfusion. Coronal brain slices were stained with 2,3,5-triphenyltetrazolium chloride or total RNA was extracted for the analysis of gene expression. Histopathologic analysis revealed a significant (p<0.05) decrease in infarct size in the ipsilateral brain with GEB extracts or HBA. Moreover, the levels of PDI and 1-Cys Prx transcription were significantly increased in the GEB extract- or HBA-treated group compared with the untreated group (p<0.05). This study therefore indicated that GEB and HBA provide neuroprotection by preventing brain damage through the increased expression of genes encoding antioxidant proteins after transient focal cerebral ischemia and may be effective as neuroprotective agents at the cellular and molecular levels in the brain.  (+info)

Anxiolytic-like effects of Gastrodia elata and its phenolic constituents in mice. (3/12)

The purpose of this study was to characterize the putative anxiolytic-like effects of the aqueous extract of the rhizome of Gastrodia elata along with its phenolic constituents, 4-hydroxybenzyl alcohol (HA) and 4-hyroxybenzaldehyde (HD), using an elevated plus maze (EPM) in mice. The mice were administered either the aqueous G. elata extract orally or received an intraperitoneal injection of the phenolic constituents, 1 h before the behavioral evaluation in the EPM. A single treatment of the aqueous G. elata extract significantly increased the percentage of time spent and arm entries into the open arms of the EPM versus the saline controls. Among the phenolic constituents of G. elata, HA and HD significantly increased the percentage of time spent and arm entries into the open arms of the EPM versus saline controls (p<0.05). Moreover, there were no changes in the locomotor activity and myorelaxant effects in any group compared with the saline controls. In addition, the anxiolytic-like effects of G. elata extract were blocked by both WAY 100635 (0.3 mg/kg, i.p.), a 5-HT(1A) receptor antagonist, and flumazenil (10 mg/kg, i.p.), a GABA(A) receptor antagonist. The anxiolytic-like effects of HA were inhibited by WAY 100635 and the effects of HD were antagonized by flumazenil. These results indicate that G. elata is an effective anxiolytic agent, and suggests that the anxiolytic-like effects of G. elata via the serotonergic nervous system depends on HA and those effects of G. elata via the GABAergic nervous system depends on HD.  (+info)

A new citryl glycoside from Gastrodia elata and its inhibitory activity on GABA transaminase. (4/12)

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.  (+info)

Identification of Armillaria nabsnona in gastrodia tubers. (5/12)

The symbiosis between Armillaria species and an achlorophylous orchid Gastrodia elata BLUME has been reported. The main species described as a symbiont is Armillaria mellea (VAHL: FR.) KUMMER, known widely as a primary root rot pathogen. Samples collected from the rhizomorphs attached to the tuber of G. elata were separated and analyzed. Molecular analysis based on sequencing of the intergenic spacer 1 (IGS-1) and internal transcribed spacer (ITS) regions of the ribosomal DNA (rDNA) was performed, coupled with restriction fragment length polymorphism (RFLP) of the IGS-1 region. Cultural morphology and features of basidiomata were also used to characterize the isolates. Phylogenetic analysis and morphological data strongly suggested that the fungus present in the tubers of G. elata is Armillaria nabsnona. This is the first report of occurrence of this Armillaria species in association with G. elata.  (+info)

Evidence for novel and specialized mycorrhizal parasitism: the orchid Gastrodia confusa gains carbon from saprotrophic Mycena. (6/12)

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Protective effects of gastrodia elata on aluminium-chloride-induced learning impairments and alterations of amino acid neurotransmitter release in adult rats. (7/12)

PURPOSE: High brain levels of aluminum (Al) can be neurotoxic and cause learning and memory deficits. Gastrodia elata (GE) is a Chinese herb widely used for improving mental function in traditional Chinese medicine. We measured changes in Al-induced neurotransmitter alteration and performance on a learning and memory task to elucidate the mechanism of Al toxicity and to assess whether these alterations could be attenuated by GE. METHODS: Thirty-six adult, male rats were randomly divided into six groups. Four Al-exposed groups were given aluminum chloride at 5 mg/kg/day or 10 mg/kg/day (i.p.) for two months, with two of these groups (one for each dose of Al) receiving GE (0.4 g/kg, via oral intubation, with the GE powder mixed in the drinking water) while the other two groups received vehicle. A GE control group was given injections of saline plus GE and a saline control group was given injections of saline and with 3 injection days and one day off. A step-down test was used to measure learning and memory ability. Al concentrations in the neocortex were assayed with a graphite furnace atomic absorption spectrophotometer. Amino acid neurotransmitter levels in the neocortex were determined by high performance liquid chromatogram-fluorescence. RESULTS: Al-exposed rats showed impaired learning and memory ability as indicated by shorter step down latency and more retention errors. Cortical concentrations (mean +/- SEM) of Al were: 56.22 +/- 34.10 ng/g (wet weight) in the Saline control group; 172.87 +/- 111.06 in the 5 mg/kg/dayAl group; 289.15 +/- 102.55 in the 10 mg Al group; 74.98 +/- 19.00 in the GE control group; 232.55 +/- 35.74 in 5 mg Al+GE group; and 291.35 98.38 in 10 mg Al+GE group respectively. Al exposure produced a significant increase in cortical GABA levels. Gastrodia elata reduced learning and memory deficits without affecting brain Al levels. CONCLUSIONS: Rats exposed to AlCl_{3} suffer from deficits in learning and memory, accompanied by increases in GABA levels in the neocortex. Gastrodia elata is effective in improving memory functions and normalizing GABA levels.  (+info)

WSS45, a sulfated alpha-D-glucan, strongly interferes with Dengue 2 virus infection in vitro. (8/12)

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