Chiral LC-MS-guided isolation of angular-type pyranocoumarins from Peucedani Radix
This study utilized a chiral liquid chromatography-mass spectrometry(LC-MS)-guided isolation strategy to accurately capture angular-type pyranocoumarins(APs)in Peucedani Radix(Chinese name:Qianhu).Sixteen APs were successfully purified from the ethyl acetate extract of Peucedani Radix through deploying various techniques such as silica gel,ODS,Sephadex LH-20,and achiral(chiral)semi-preparative liquid chromatography.After extensive structural measurements,such as 1H and 13C NMR spectroscopy,their structures were identified as(3'S)-3'-(2-methyl-butyroyl)-4'-oxo-3',4'-dihydroseselin(1A),(3'R)-3'-(2-methyl-butyroyl)-4'-oxo-3',4'-dihydrose-selin(1B),(3'S)-3'-isovaleryl-4'-oxo-lomatin(2A),(3'R)-3'-isovaleryl-4'-oxo-lomatin(2B),(3'S)-3'-angeloyloxy-4'-oxo-3',4'-dihydroseselin(3A),(3'R)-3'-angeloyloxy-4'-oxo-3',4'-dihydroseselin(3B),(3'S,4'S)-praeruptorin B(4A),(3'R,4'R)-praeruptorin B(4B),(3'S,4'S)-praeruptorin E(5A),(3'R,4'R)-praeruptorin E(5B),3'-isovaleryl-4'-angeloyl-cis-khellactone(6),3'-angeloyl-4'-(2-methyl-butyroyl)-cis-khellactone(7),(3'S,4'S)-praeruptorin A(8A),(3'R,4'R)-praeruptorin A(8B),(3'S,4'S)-khellactone(9A),and(3'R,4'R)-khellactone(9B),respectively.Thereof,compounds 1A and 1B were new compounds,while compound 2A represents a new configuration for a known planar structure.Compounds 2A and 2B were isolated for the first time from Peucedani Radix.Above all,chiral LC-MS-guided isolation strategy is advantageous at rapid capturing new compounds from herbal medicines,providing an effective means for the separation of novel structures,especially new enantiomers.
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