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PubMed1991

Variation in the nitrotoxin concentration of 13 species of Astragalus (Fabaceae) over a 6-year period.

The purpose of this study was to examine the variation in nitrite production in the leaves of various species of Astragalus over a 6-y period. It was discovered that in drought years the nitrate concentration in leaves was consistently higher than in wet years or those of adequate moisture. Among the plant examined, A. Hallii contained the greatest quantity in drought years (30-35 mg NO2/g leaf, dry wt basis) and A. aesclepiadoides had no detectable amounts in wet years. A two-way analysis of variance showed NO2 concentrations to be significantly different (p < 0.0001) in the two climatic years.

Analysis of Variance↗
PubMed1999

Characterization of Astragalus sinicus rhizobia by restriction fragment length polymorphism analysis of chromosomal and nodulation genes regions.

Two hundred and four isolates of rhizobia were sampled from root nodules of Astragalus sinicus grown in rice fields of six southern provinces of China. Genotypic diversity was determined by Southern hybridization using nodDBC genes as a probe, restriction fragment length polymorphism (RFLP) analysis of PCR-amplified 16S-23S rDNA intergenic spacers (IGS), and plasmid profile. Our results show that rhizobia associated with A. sinicus were very diverse, and 10 genotypes were resolved within the previously identified dominant 16S rDNA type. Diversity levels varied greatly between different geographical locations. The same nod gene genotypes were harbored by distinct chromosomal types, suggesting that lateral plasmid transfer occurred during the evolution process.

Blotting, Southern↗
PubMed1995

Cycloartane triterpene glycosides from Astragalus trigonus.

Three new cycloartane glycosides, trigonoside I, II and III, and the known astragalosides I and II were isolated from the roots of Astragalus trigonus. The structures of the new glycosides were totally elucidated by high field (600 MHz) NMR analyses as cycloastragenol-6-O-beta-xylopyranoside, cycloastragenol-3-O-[alpha-L-arabinopyranosyl(1-->2)-beta-D- xylopyranosyl]- 6-O-beta-D-xylopyranoside and cycloastragenol-3-O-[alpha-L-arabinopyranosyl (1-->2)-beta-D-(3-O-acetyl)-xylopyranosyl]-6-O-beta-D-xylopyranoside.

Carbohydrate Conformation↗
PubMed1990

Toxicity of fractions obtained from the legume species Astragalus lusitanicus Lam. lusitanicus.

Extracts of Astragalus lusitanicus Lam. lusitanicus, a European legume very common in southwestern Spain and Portugal, caused in mice acute toxicity, with convulsions and death in a few min, and delayed death after (10-15 days) with first symptoms appearing 6-8 days after a single i.v. dose. The toxic compounds could be separated by column chromatography or methanol solubility, but were unstable and could not be isolated in pure form. Plant toxicity could not be attributed to the previously described compounds pinitol, isormhamnetin glycosides or saccharinic acid lactone, which did not show toxicity in mice after i.v. administration.

Animals↗
PubMed1977

Biosynthesis and metabolism of cystathionine in Astragalus pectinatus.

Metabolism of L-[35S]cystathionine, L-[35S]cysteine and L-[35S]homocysteine has been investigated in Astragalus pectinatus. The results indicate that cystathionine undergoes both beta and gamma cleavage to give homocysteine and cysteine. Results also show that cystathionine is synthesized from both cysteine and homocysteine. Furthermore, in addition to the incorporation of 35S into cystathionine, incorporation of 35S from cysteine into methionine and from homocysteine into S-methylcysteine is not only in agreement with the above cystathionine cleavage activities, but also suggests, that transsulfuration in A. pectinatus proceeds in both directions, eg. cysteine leads to cystathionine leads to homocysteine and homocysteine leads to cystathionine leads to cysteine. It is suggested, that the latter reaction may be contributing to the net synthesis of cysteine.

Cystathionine↗
PubMed1994

Antimicrobial isoflavans from Astragalus species.

Two new antimicrobial isoflavans, 1-[(3R)-7,8-dimethoxybenzopyranyl]-4- hydroxybenzoquinone (astragaluquinone) and (3S)-7,1'-dihydroxy-8,3'-dimethoxyisoflavan (8-methoxyvestitol), and the known 7-hydroxy-2',3',4'-trimethoxyisoflavan were isolated from roots of Astragalus alexandrinus and A. trigonus. The structures of the new isoflavans were established by spectroscopic methods.

Anti-Bacterial Agents↗
PubMed2000

Flavonoid glycosides and saponins from Astragalus shikokianus.

A new flavonol glycoside, kaempferol 3-O-alpha-L-rhamnopyranosyl -(1-->6)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-galactopyranosyl-7-O-a lpha-L-rhamnopyranoside, named astrasikokioside I, was isolated from aerial part of Astragalus shikokianus, together with two flavonol glycosides, kaempferol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-galactopyranosyl-7-O-alpha-L- rhamnopyranoside, robinin, and three triterpenoid glycosides, soyasaponin I, sophoraflavoside II and robinioside E.

Chromatography, Thin Layer↗
PubMed2001

Chemical diversification trends in Astragalus caprinus (Leguminosae), based on the flavonoid pathway.

Flavonoid glycosides of Astragalus caprinus (Leguminosae) were investigated; more than 30 glycosides were found in leaf material, based on the aglycones kaempferol, quercetin and their methylated derivatives. Among them 14 compounds were found in significant amounts and showed a contrasting distribution. They could be ordered into three groups: polyglycosides, acylated polyglycosides and methylated polyglycosides. The distribution of these compounds was studied within a large collection of individual plants harvested in Tunisia; the results showed a relationship between metabolic trends and ecological diversification.

Journal Article↗
PubMed2001

Cycloartane saponins from Astragalus peregrinus as modulators of lymphocyte proliferation.

From Astragalus peregrinus, four cycloartane-type saponins have been isolated and their structures elucidated by spectral means as 20(R),24(S)-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,25-tetrol 3-O-beta-D-glucopyranoside (1), 20(R),24(S)-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,25-tetrol 3-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranoside (2), 20(R),24(S)-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,25-tetrol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside (3) and 20(R),25-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,24(S)-tetrol (24-O-acetyl)- 3-O-alpha-L-rhamnopyranosyl-(1-->2)-(6'-O-acetyl)-beta-D-glucopyranoside (4). Compounds 2 and 3 showed to stimulate the proliferation of mouse splenocytes and were not significantly cytotoxic.

Adjuvants, Immunologic↗
PubMed2000

Molecular cloning and characterization of two cDNAs encoding asparagine synthetase from Astragalus sinicus nodules.

Two cDNAs that encode asparagine synthetase were cloned from root nodules of Astragalus sinicus cv. Japan (Renge-sou). The expression of the transcripts was nodule-enhanced. The expression of both genes was reduced in nodules when (NH4)2SO4 was added to the culture medium. This is the first report of the inhibition of asparagine synthetase gene expression by ammonium in root nodules.

Journal Article↗
PubMed2001

Two new glycosides from Astragalus caprinus.

A new glycoside of flavonol (1) and a new glycoside of a cycloartane-type triterpene (2) were isolated from the leaves and the roots of Astragalus caprinus, respectively. Their structures were elucidated in turn by spectroscopic data interpretation as 3-O-[[beta-D-xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->6)][beta-D-apiofuranosyl(1-->2)]]-beta-D-galactopyranosyl kaempferol (1) and 3-O-(beta-D-xylopyranosyl)-24-O-(beta-D-glucopyranosyl)-20,25-epoxycycloartane-3beta,6alpha,16beta,24alpha-tetrol (2).

Flavonoids↗
PubMed2002

Four new flavonol glycosides from the leaves of Astragalus caprinus.

Four new flavonol 3-O-glycosides were isolated from the leaves of Astragalus caprinus. Their structures were elucidated by spectroscopic methods as rhamnocitrin-3-O-[3-hydroxy-3-methylglutaroyl(1-->6)][beta-D-apiofuranosyl(1-->2)]-beta-D-galactopyranoside (1), rhamnetin-3-O-[3-hydroxy-3-methylglutaroyl(1-->6)][beta-D-apiofuranosyl(1-->2)]-beta-D-galactopyranoside (2), kaempferol-3-O-[beta-D-xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->6)]-beta-D-galactopyranoside (3), and quercetin-3-O-[beta-D-xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->6)][beta-D-apiofuranosyl(1-->2)]-beta-D-galactopyranoside (4).

Fabaceae↗
PubMed1996

Four novel cycloartane glycosides from Astragalus oleifolius.

Four novel cycloartane-type triterpene glycosides, macrophyllosaponins A-D (1-4) were isolated from the roots of Astragalus oleifolius. By means of chemical (acetylation, alkaline hydrolysis) and spectroscopic methods (IR, 1D- and 2D-NMR, FABMS), their structures were established as 3-O-alpha-L-rhamnopyranosyl-24-O-(4"-O-acetyl)-beta-D-xylopyranosyl-1 alpha,3 beta,7 beta,24(S), 25-pentahydroxycycloartane (1), 3-O-alpha-L-rhamnopyranosyl-24-O-beta-D-xylopyranosyl-1 alpha,3 beta, 7 beta,24(S), 25-pentahydroxycycloartane (2), 3-O-alpha-L-rhamnopyranosyl-25-O-beta-D-glucoyranosyl-1 alpha, 3 beta,7 beta,24(S),25-pentahydroxycycloartane (3), and 3-O-alpha-L-rhamnopyranosyl-24-O-(2-O-beta-D-xylopyranosyl) -beta-D-xylopyranosyl-1 alpha,3 beta,7 beta,24(S), 25-pentahydroxycycloartane (4).

Carbohydrate Sequence↗
PubMed1999

Secondary metabolites from the roots of Astragalus trojanus.

Six novel cycloartane-type glycosides were isolated from the roots of Astragalus trojanus. Two of these, compounds 1 and 2, have (20R, 24S)-epoxy-3beta,6alpha,16beta,25-tetrahydroxycycloartane as the aglycon, while compounds 3-6 possess 3beta,6alpha,16beta,(24S), 25-pentahydroxycycloartane as the aglycon. The saccharide moieties linked to the C-3, C-6, and C-24 or C-25 positions of the aglycons in 1-6 contained either xylopyranose, glucopyranose, rhamnopyranose, or arabinopyranose units. Structure elucidation of compounds 1-6 was accomplished through the extensive use of 1D and 2D NMR techniques. In addition, a new oleanene glycoside (7) and a new tryptophan derivative (8) were also isolated and characterized.

Carbohydrate Sequence↗
PubMed1997

Cycloartane triterpene glycosides from the roots of Astragalus melanophrurius.

From the roots of Astragalus melanophrurius eight known saponins (1-8) were isolated. Based on spectral data (IR, 1H- and 13C-NMR, and FABMS), the structures were established as astrasieversianins II (1) and X (4), astragalosides I (2), II (3), IV (5) and VI (7), and cyclocanthosides E (6) and G (8). The isolates were evaluated in a broad range of bioassay systems and found to be inactive. Modest antibacterial activity was observed, however, as was immunomodulatory activity, as indicated by stimulation of isolated human lymphocytes.

Adjuvants, Immunologic↗
PubMed1998

AsNODc22, a novel nodulin gene of Astragalus sinicus, encodes a protein that localizes along the cell wall of bacteria-infected cells in a nodule.

A novel nodulin gene, AsNODc22, was isolated from Astragalus sinicus cv. Japan (Renge-sou) by differential screening. The transcript of AsNODc22 was nodule specific, and its size was approximately 0.8 knt. AsNODc22 encoded an unknown ORF containing a putative signal peptide and a pair of similar hepta-peptides (CSAQVSC, CSAQLSC). For immunological study, antiserum against AsNODc22 protein was prepared in mice. By immunoblot analysis, the antiserum detected a nodule specific band at approximately 18 kDa. Immunofluorescence microscopy was used to observe localization of the gene product in the nodule. The signals were seen along the cell wall of bacteria-infected cells, but no significant signals were seen on uninfected cells.

Amino Acid Sequence↗
PubMed2000

Increasing tryptophan synthesis in a forage legume Astragalus sinicus by expressing the tobacco feedback-insensitive anthranilate synthase (ASA2) gene.

A cDNA clone that encodes a feedback-insensitive anthranilate synthase (AS), ASA2, isolated from a 5-methyl-tryptophan (Trp) (5MT)-resistant tobacco cell line under the control of the constitutive cauliflower mosaic virus 35S promoter, was introduced into the forage legume Astragalus sinicus by Agrobacterium rhizogenes with kanamycin selection. The 35S-ASA2 gene was expressed constitutively as demonstrated by northern-blot hybridization analyses and the presence of feedback-insensitive AS. Hairy root lines transformed with 35S-ASA2 grew in concentrations of up to 100 microM 5MT, whereas the controls were completely inhibited by 15 microM 5MT. Expression of the feedback-insensitive ASA2 resulted in a 1.3- to 5.5-fold increase in free Trp. Kinetic studies of the AS activity demonstrate the Trp feedback alterations and indicate that the ASA2 alpha-subunit can interact with the native A. sinicus beta-subunit to form an active enzyme. The ASA2 transcript and high free Trp were also detected in the leaves, stems, and roots of plants regenerated from the transformed hairy roots. Thus, we show for the first time that ASA2 can be used to transform plants of a different species to increase the levels of the essential amino acid Trp and impart 5MT resistance.

Anthranilate Synthase↗