ABSTRACT
OBJECTIVE: To investigate the chemical constituents of Corydalis yanhusuo. METHOD: The compounds were isolated and purified by column chromatography over macroporous absorption resin, silica gel, and Sephadex LH-20. Their structures were elucidated on the basis of physicochemical properties and spectral data. RESULT: 22 compounds were isolated and identified as corydaline (1), tetrahydropalmatine (2), protopine (3), tetrahydrocorysamine (4), tetrahydrocoptisine (5) , tetrahydroberberine (6), tetrahydrocolumbamine (7), noroxyhydrastine (8), dehydrocorydaline (9), glaucine (10), columbamine (11), 8-oxocoptisine (12), 13-methyl-columbamine (13), coptisine (14), palmatine (15), herberine (16), oxoglaucine (17), 13-methyl-palmatrubine (18), dehydrocorybulbine (19), stepharanine (20), adenosine (21), and N5 -acetylornithine (22). CONCLUSION: Compounds 13, 20, 21, and 22 were isolated from this plant for the first time.
Subject(s)
Corydalis/chemistry , Plant Extracts/analysis , Plant Extracts/isolation & purification , Adenosine/analysis , Adenosine/isolation & purification , Alkaloids/analysis , Alkaloids/isolation & purification , Apomorphine/analogs & derivatives , Apomorphine/analysis , Apomorphine/isolation & purification , Aporphines/analysis , Aporphines/isolation & purification , Berberine/analysis , Berberine/isolation & purification , Berberine Alkaloids/analysis , Berberine Alkaloids/isolation & purification , Chromatography, Liquid/methods , Spectrometry, Mass, Electrospray Ionization/methodsABSTRACT
Two new compounds were isolated from the whole plant of Helichrysum arenarium (L.) Moench. By means of spectroscopic data (IR, UV, 1D and 2D NMR, HR-MS, ESI-MS, and NOESY) and chemical evidence, the structures were established as 6,7-dimethoxy-4-hydroxy-1-naphthoic acid (1) and (Z)-5-hydroxy-7-methoxy-4-[3-methyl-4-(O-beta-D-xylopyranosyl)but-2-enyl]isobenzofuran-1(3H)-one (2).
Subject(s)
Benzofurans/isolation & purification , Drugs, Chinese Herbal/isolation & purification , Glycosides/isolation & purification , Helichrysum/chemistry , Naphthalenes/isolation & purification , Benzofurans/chemistry , Drugs, Chinese Herbal/chemistry , Glycosides/chemistry , Molecular Structure , Naphthalenes/chemistry , Nuclear Magnetic Resonance, BiomolecularABSTRACT
Four lignin polymers, alkali lignin (AL), klason lignin (KL), organosolv lignin (OL), and milled wood lignin (MWL), were isolated from the same pine wood. Structural characterization by FTIR and (13)C NMR indicated that the four lignins have different structural features. Their pyrolysis behaviors were analyzed by TG-FTIR and Py-GC/MS. Thermally unstable ether bonds and side branches were well-preserved in AL and MWL, but were broken in OL and KL. Pyrolysis of AL and KL produce more phenols at low temperature by the breakage of ether bonds. AL and KL show lower activation energies in the main degradation stage, quantified by a distribution activation energy model with two linearly combined Gaussian functions. The evolution behaviors of typical gaseous products, CH4, CO2, and CO, were analyzed, and insights about the correlation between chemical structure and pyrolysis behavior were obtained.
Subject(s)
Lignin/chemistry , Wood/chemistry , Carbon Dioxide/chemistry , Kinetics , Magnetic Resonance Spectroscopy , Methane/chemistry , Phenols/chemistry , Pinus/chemistry , Spectroscopy, Fourier Transform Infrared , ThermogravimetryABSTRACT
The pyrolysis mechanism of hemicellulose has been investigated using two minimally damaged hemicellulose polymers isolated from two agricultural straw samples. The obtained hemicelluloses have been characterized by multiple methods, and the results showed that they were mainly composed of l-arabino-4-O-methyl-d-glucurono-d-xylan. Their O-acetyl groups and high degrees of polymerization and branching were well preserved. Their pyrolyses were subsequently investigated by TG-FTIR and Py-GC/MS. The evolutions of four typical volatile components and the distributions of eight product species were scrutinized. A DG-DAEM kinetic model was applied to quantify the contributions of two major pyrolytic routes for devolatilization during hemicellulose pyrolysis. A mean activation energy of 150kJ/mol for the formation of volatiles was derived. The thermal stability of each bond in four typical fragments of hemicellulose was assessed by DFT study, and the deduced decomposition pathways were in agreement with experimental analysis.