Studies On Chemical Constituents From Berchemia Lineata (L.) DC.and Their Bioactivities

Berchemia lineata（L.）DC.（Tie bao jin）is an important ethnic medicine commonly used in southwest minority areas of China.It can be used for the treatment of bronchitis,pneumonia,rheumatoid arthritis and cardiovascular disease.In this paper,the chemical constituents of n-butanol and ethyl acetate extracts were separated and purified by solvent extraction,macroporous resin,normal and reversed-phase silica gel column chromatography,Sephadex LH-20 gel column chromatography and high-performance liquid chromatography.Twenty-three compounds were isolated and purified from the stems and leaves of this plant,and their structures were identified by modern spectral methods,quantum chemical calculations,and physical and chemical properties,including 8 new compounds（1-8）and 15 known compounds（9-23）.Compound 1 possesses an unprecedented 3,4-dihydro-11H-benzo[b]pyrano[4,3-e]oxepin-11-one skeleton.The other new compounds belong to three structural types of natural products,including naphthopyrones（2-5）,flavonoids（6-7）and bibenzyl（8）.Among them,compounds 2 and 3 areα-type naphthopyranones,which are rare in natural products.They have been found only in marine organisms before,and it was the first time that this structural type of compound was found from plants.Compounds 4 and 5 are angularγ-type naphthopyranones,and compound 8 is bibenzyl glycoside.These two types of structures have not been isolated from B.lineata before.Compounds 6 and 7 are a pair of epimeric flavonoid glycosides.These new compounds were named as:bercheminol A（1）,bercheminol B（2）,bercheminol C（3）,bercheminol D（4）,bercheminol E（5）,bercheminol F（6）,bercheminol G（7）,bercheminol H（8）.In addition,the structural types of known compounds were also diverse,including angularγ-type naphthoquinone,linearγ-type naphthoquinone,bibenzyl,flavonoid,dihydroflavonoid,anthraquinone,terpene and phenolic compounds.The results indicate that the structural types of chemical components in this medicinal plant are diverse,which is worthy of further exploration and research.Compounds 4-8 were new phenolic glycosides containing glucose and rhamnose,respectively.To determine the absolute configuration of their sugars,the above new compounds were hydrolyzed by hydrochloric acid.The hydrolysate,D-glucose and L-rhamnose were then derivatized with L-cysteine methyl ester hydrochloride and thiocyanate,respectively.Finally,the retention times of the derivatized products of the sample and standard sugar were analyzed by HPLC,and it was confirmed that compounds 4,5,8 contained D-glucose and compound 6,7 contained L-rhamnose.A cellular level of inflammation model was established by LPS-induced RAW264.7 cells,and the NO inhibition activity of 17 compounds was evalutaed by Griess method.It was found that there was no apparent cytotoxicity on RAW264.7cells at concentration of 50μM.Among them,compounds 9 and 15 showed strong NO inhibitory activity with inhibitory rate values of more than 90%.The inhibitory rates of flavonoids 6,7,14,16 and 17 were ranged from 54.2%to 80.6%.The inhibitory rates of bibenzyl 8 and anthraquinone 18 were 64.6%and 57.6%respectively.These compounds might be the basic active components for the anti-inflammatory activity of B.lineata.Using p-nitrophenyl-α-D-glucopyranoside（PNPG）as the substrate and acarbose as the positive control,α-glucosidase inhibitory activities of these isolated compounds were evaluated.As a result,compounds 9,11,14,15 and 17 had moderate inhibitory activitiesy onα-glucosidase with IC₅₀ values of 22.5,28.0,36.5,32.7 and 31.9μM,respectively.