ABSTRACT
ObjectiveTo determine the chemical constituents of burdock （Arctium lappa） leaves， and elucidate dynamic accumulation rule of four main components， in order to provide the basis for determining the suitable harvest time of burdock leaves. MethodSilica gel， macroporous resin， Sephadex LH-20， octadecylsilane chemically bonded silica （ODS）， microporous resin （MCI） column chromatography and reversed-phase preparative high performance liquid chromatography （HPLC） were used to isolate the main chemical constituents in burdock leaves. Their chemical structures were elucidated by spectroscopic techniques. HPLC-diode array detector （DAD） was used to analyze the dynamic accumulation of four components in burdock leaf. HPLC-DAD was performed on a Shim-pack GIST C18 column （4.6 mm×250 mm， 5 μm） with mobile phase of acetonitrile （A）-0.3% phosphoric acid aqueous solution （B） （0-9 min， 13%A； 9-10 min， 13%-24%A； 10-30 min， 24%A）， flow rate of 1.0 mL·min-1， column temperature of 40 ℃， and detection wavelength at 328 nm. ResultSeventeen compounds were isolated from burdock leaves， and identified as caffeic acid （1）， rutin （2）， kaempferol-3-O-rutinoside （3）， quercetin-3-O-β-D-glucopyranoside （4）， kaempferol-3-O-β-D-glucopyranoside （5）， chlorogenic acid （6）， isochlorogenic acid A （7）， daucosterol （8）， ursolic acid （9）， anemarrhenoside B （10）， （-）-secoisolariciresinol （11）， vladinol D （12）， melitensin （13）， esculetin （14）， 1-（-2-ethylphenyl）-1，2-ethanediol （15）， 1-（-4-ethylphenyl）-1，2-ethanediol （16）， 3-hydroxy-1-（4-hydroxy-3，5-dimethoxyphenyl）-1-propanone （17）. The contents of chlorogenic acid， rutin and kaempferol-3-O-rutinoside in burdock leaves showed an upward trend from April to August， and reached the highest in August. And the content of isochlorogenic acid A firstly increased and then decreased from April to August， and reached the highest in July. ConclusionCompounds 10， 12-17 were isolated from Arctium for the first time. Taking the contents of chlorogenic acid， rutin， kaempferol-3-O-rutinoside， and isochlorogenic acid A as indicators， considering the comprehensive development and utilization of burdock roots and leaves， it is recommended to harvest burdock leaves in mid-August.