Preparative isolation and purification of two isoflavones from Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao by high-speed counter-current chromatography
ABSTRACT Two isoflavones, calycosin-7-O-beta-D-glycoside and formononetin-7-O-beta-D-glycoside, were separated from n-butanol extract of the root of Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao by high-speed counter-current chromatography in two steps using two different solvent systems composed of ethyl acetate-ethanol-n-butanol-water (30:10:6:50, v/v) and ethyl acetate-ethanol-water (5:1:5, v/v). From 200 mg of crude extract, calycosin-7-O-beta-D-glycoside (12 mg) and formononetin-7-O-beta-D-glycoside (10 mg) were isolated at over 95% purity by HPLC analyses, and their structures were identified by MS, 1H NMR and 13C NMR.
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ABSTRACT: Radix Astragali is a popular herb used in traditional Chinese medicine for its proimmune and antidiabetic properties. However, methods are needed to help distinguish Radix Astragali from its varied adulterants. DNA barcoding is a widely applicable molecular method used to identify medicinal plants. Yet, its use has been hampered by genetic distance, base variation, and limitations of the bio-NJ tree. Herein, we report the validation of an integrated analysis method for plant species identification using DNA barcoding that focuses on genetic distance, identification efficiency, inter- and intraspecific variation, and barcoding gap. We collected 478 sequences from six candidate DNA barcodes (ITS2, ITS, psbA-trnH, rbcL, matK, and COI) from 29 species of Radix Astragali and adulterants. The internal transcribed spacer (ITS) sequence was demonstrated as the optimal barcode for identifying Radix Astragali and its adulterants. This new analysis method is helpful in identifying Radix Astragali and expedites the utilization and data mining of DNA barcoding.Evidence-based Complementary and Alternative Medicine 08/2014; 2014:843923. DOI:10.1155/2014/843923 · 1.88 Impact Factor
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ABSTRACT: The changes in calycosin and calycosin-7-O-beta-D-glucoside content as well as the expression of genes involved in their biosynthesis were monitored in roots, stems and leaves of Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao seedlings during 10 days of low temperature treatment. The concentrations of calycosin and its 7-O-beta-D-glucoside in the different tissues were analyzed using high-performance liquid chromatography. Higher glycoside contents were observed at 2 degrees C than that at 16 degrees C in all the tested tissues, however, the aglycone was scarcely detected in both leaves and stems at either 16 or 2 degrees C. cDNA fragments encoding four structural genes from the calycosin pathway, namely chalcone synthase, isoflavone synthase, isoflavone 3'-hydroxylase and UDP-glucose: calycosin-7-O-glucosyltransferase were isolated from A. membranaceus var. mongholicus seedlings by polymerase chain reaction (PCR) and sequenced. Real-time quantitative reverse transcript PCR demonstrated that in leaves and stems, five genes (including phenylalanine ammonia lyase), exhibited clear differences in their accumulation pattern in response to a low temperature stress, which was consistent with the increased content of calycosin-7-O-beta-D-glucoside. In the roots, transcription of the five genes was down-regulated at 2 degrees C, but the contents of calycosin and its glucosides were higher than that at 16 degrees C. These findings indicate that low temperature stress could induce accumulation of calycosin and its glucosides in different tissues of the seedlings of A. membranaceus var. mongholicus but the mechanisms regulating the accumulation were different.Plant Cell Reports 08/2007; 26(7):1111-20. DOI:10.1007/s00299-006-0301-8 · 2.94 Impact Factor