ABSTRACT
(±)-Decumicorine A (1) and (±)-epi-decumicorine A (2), two pairs of enantiomeric isoquinoline alkaloids featuring a novel phenylpropanoid-conjugated protoberberine skeleton, were isolated and purified from the rhizomes of Corydalis decumbens. The separation of (±)-1 and (±)-2 was achieved by chiral HPLC to produce four optically pure enantiomers. The structures and absolute configurations of compounds (-)-1, (+)-1, (-)-2, and (+)-2 were elucidated by spectroscopic analysis, ECD calculations, and X-ray crystallographic analyses. The two racemates were generated from a Diels-Alder [4 + 2] cycloaddition between jatrorrhizine and ferulic acid in the proposed biosynthetic pathways, which were fully verified by a biomimetic synthesis. Moreover, compound (+)-1 exhibited an antiviral entry effect on SARS-CoV-2 pseudovirus by blocking spike binding to the ACE2 receptor on HEK-293T-ACE2h host cells.
Subject(s)
Alkaloids , COVID-19 Drug Treatment , Corydalis , Alkaloids/chemistry , Angiotensin-Converting Enzyme 2 , Antiviral Agents/pharmacology , Berberine Alkaloids , Biomimetics , Corydalis/chemistry , Humans , Isoquinolines , Molecular Structure , Rhizome , SARS-CoV-2ABSTRACT
OBJECTIVE: To investigate the chemical constituents of Oldenlandia diffusa. METHOD: The column chromatography with polyamide Sephadex LH -20, silica gel as packing materials and HPLC, were used to separate and purify the chemical components. The structures were elucidated on the basis of physicochemical properties and spectral data. RESULT: Nine compounds were isolated and identified as 2, 6-dihydroxy-1-methoxy-3-methylanthraquinone (1), 2-hydroxy-1-methoxy-3-methylanthraquinone (2), 2-hydroxy-3-methylanthraquinone (3), quercetin-3-O-[2-O-(6-O-E-sinapoyl)-beta-D-glucopyranosyl]-beta-glucopyranoside (4), quercetin-3-O-[2-O-(6-O-E-feruloyl)-beta-D-glucopyranosyl]-beta-glucopyranoside (5), kaempferol-3-O-[2-O-(6-O-E-feruloyl)-beta-D-glucopyranosyl]-beta-galactopyranoside (6), quercetin-3-O-(2-O-beta-D-glucop-yranosyl)-beta-D-glucopyranoside (7), rutin (8) and quercertin (9). CONCLUSION: Compounds 1 and 8 were obtained from this plant for the first time, and compound 1 was a new compound.
