ABSTRACT
Chalcane-containing dimers are major compounds identified from dragon's blood, the red resin that accumulates in Dracaena trees after injury. The key step for the formation of these dimers was a p-quinone methide (p-QM, 3) mediated nonenzymatic Michael addition. Compound 3 is derived from the spontaneous dehydration of chalcane alcohol-M274 (2). Two dihydroflavonol-4-reductases, discovered in D. cambodiana, reduce dihydrochalcone-M272 (7) to 2. Moreover, the application potential of p-QMs was demonstrated using a 3-like p-QM to synthesize diverse dimeric derivatives.
Subject(s)
Dracaena , Indolequinones , Plant Extracts , Resins, PlantABSTRACT
Five optically active epoxy-5,6,7,8-tetrahydro-2-(2-phenylethyl)chromone derivatives (1-5) with four chirality centers in the condensed cyclohexene ring were isolated from artificial holing agarwood originating from Aquilaria sinensis (Lour.) Gilg. Their structures were elucidated by spectroscopic techniques (UV, IR, 1D and 2D NMR) and MS analyses. The absolute configuration of 2 was elucidated by TDDFT-ECD calculations and ECD spectra of 1, 3-5 allowed their configurational assignment as well. All of the new compounds contained a condensed oxirane ring, and compound 1 was the only 6,7-epoxy-2-(2-phenylethyl)-5,6,7,8-tetrahydrochromone derivative that has ever been found in agarwood. AChE inhibitory activity was tested for the first time of these new compounds by using modified Ellman's colorimetric method. Compounds 3 and 5 exhibited inhibitory activity against AChE with IC50 value of 441.6, and 155.6⯵M, respectively.
Subject(s)
Chromones/pharmacology , Thymelaeaceae/chemistry , Wood/chemistry , China , Cholinesterase Inhibitors/isolation & purification , Cholinesterase Inhibitors/pharmacology , Chromones/isolation & purification , Molecular Structure , Phytochemicals/isolation & purification , Phytochemicals/pharmacologyABSTRACT
Four new bi-phenylethylchromones (1-4) were isolated from the EtOAc extract of artificial agarwood induced by holing method originating from Aquilaria sinensis (Lour.) Gilg. The structures of new compounds were unambiguously elucidated by one- and two-dimensional NMR and HRESIMS measurements, and the absolute configuration was determined by analysis of circular dichroism (CD) spectra. All compounds were tested for acetylcholinesterase (AChE) inhibitory activity using modified Ellman's colorimetric method and α-glucosidase inhibitory activity using PNPG method. Compounds 2-4 exhibited different levels of inhibitory activity against AChE with the inhibition ratios in the range of 10-45%. However, none of the compounds was active against the α-glucosidase.
Subject(s)
Chromones/chemistry , Thymelaeaceae/chemistry , Wood/chemistry , Cholinesterase Inhibitors/chemistry , Cholinesterase Inhibitors/isolation & purification , Chromones/isolation & purification , Glycoside Hydrolase Inhibitors/chemistry , Glycoside Hydrolase Inhibitors/isolation & purification , Molecular StructureABSTRACT
Thirteen previously undescribed 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromones named tetrahydrochromone A-M, together with nine known ones, were isolated from artificial agarwood (induced by holing) originating from Aquilaria sinensis (Lour.) Gilg. The structures of these compounds were unambiguously determined based on extensive NMR spectroscopic analyses, and the absolute configuration was resolved by CD analyses, X-ray crystallographic, chemical and Mosher's method. Tetrahydrochromone A, B, K-M, and Oxidoagarochromone An exhibited inhibitory activity against AChE with the percentage inhibition range from 17.5% to 47.9% (with Tacrine as the positive control; inhibition ratio: 66.7%) when tested at 50 µg/mL. Tetrahydrochromone A-E, F-J feature one methoxy and three hydroxys linked at the cyclohexene ring rather than usual four hydroxys, and tetrahydrochromone K-M represent the first examples of 7,8-epoxy tetrahydrochromones.
Subject(s)
Cholinesterase Inhibitors/isolation & purification , Chromones/isolation & purification , Drugs, Chinese Herbal/isolation & purification , Thymelaeaceae/chemistry , Wood/chemistry , Acetylcholinesterase , Cholinesterase Inhibitors/chemistry , Cholinesterase Inhibitors/pharmacology , Chromones/chemistry , Drugs, Chinese Herbal/chemistry , Drugs, Chinese Herbal/pharmacology , Flavonoids , Molecular Structure , Nuclear Magnetic Resonance, BiomolecularABSTRACT
A total of fifty-six chromones, including seven 5,6,7,8-tetrahydro-2-(2-phenylethyl)-chromones (THPECs), five 5,6-epoxy-2-(2-phenylethyl)chromones (EPECs), seven 5,6:7,8-diepoxy-2-(2-phenylethyl)chromones (DEPECs) and thirty-seven 2-(2-phenylethyl)chromones of the flidersia type (FTPECs), were characterized by HPLC/DAD/ESI/MS/MS in three agarwood samples (from Aquilaria crassna) induced by artificial holing with different holing times. The characteristic fragmentation behavior of DEPECs and EPECs, and the methods to distinguish these four types of chromones by MS analysis were described for the first time. In addition, it was found that the relative contents of DEPECs and EPECs were down-regulated, while the relative contents of THPECs and FTPECs were up-regulated for the samples from two, four and five years of the agarwood formation time. However, the relative contents of six most widespread and abundant FTPECs presented roughly upward based on the formation time. These results could be referenced to distinguish different agarwood samples collected from different formation time.
Subject(s)
Chromones/chemistry , Plant Extracts/chemistry , Thymelaeaceae/chemistry , Wood/chemistry , Chromatography, High Pressure Liquid , Fermentation , Molecular Structure , Spectrometry, Mass, Electrospray Ionization , Tandem Mass SpectrometryABSTRACT
Two new sesquiterpenoids, 3-oxo-7-hydroxylholosericin A (1) and 1,5;8,12-diepoxy-guaia-12-one (2), together with seven known sesquiterpenoids 3-9, were isolated from Chinese agarwood induced by artificial holing originating from Aquilaria sinensis (Lour.) Gilg. Their structures were identified by spectroscopic techniques (UV, IR, 1D and 2D NMR) and MS analyses. The absolute configuration of compound 1 was determined by comparison of its measured CD curve with that of calculated data for 1 and ent-1. The NMR data of 3 were reported in this study for the first time. Compounds 1, 2, 4-6, together with the EtOAc extract showed moderate inhibitory activities against acetylcholinesterase, and compounds 4-6, 8 exhibited antibacterial activities against Staphylococcus aureus or Ralstonia solanacearum.
Subject(s)
Sesquiterpenes/isolation & purification , Sesquiterpenes/pharmacology , Thymelaeaceae/chemistry , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Cholinesterase Inhibitors/chemistry , Cholinesterase Inhibitors/isolation & purification , Cholinesterase Inhibitors/pharmacology , Drugs, Chinese Herbal/analysis , Molecular Structure , Ralstonia solanacearum/drug effects , Sesquiterpenes/chemistry , Staphylococcus aureus/drug effectsABSTRACT
Seven new 2-(2-phenylethyl)chromone derivatives (1-7) including a chlorinated one (4), together with eight known ones (8-15), were isolated from the EtOAc extract of artificial agarwood originating from Aquilaria sinensis (Lour.) Gilg. All structures including the absolute configurations were unambiguously elucidated by spectroscopic (NMR, UV, IR, MS) methods, Mosher's method, and comparison with reported data in the literatures. Among those, compounds 8, 12, and 14 exhibited significant inhibition against α-glucosidase in vitro with IC50 values of 0.15, 0.05, and 0.09 mM, respectively (with acarbose as the positive control; IC50: 0.98 mM). In addition, compounds 3, 9, 11, and 14 showed weak inhibitory activity against AChE; and compounds 12 and 13 displayed weak cytotoxicity against human gastric cell line (SGC-7901) among three types of tested human cancer cell lines (BEL-7402, K562, and SGC-7901).