Study On Chemical Constituents And Biological Activity Of The Rhizome Of Fresh Polygonatum Odoratum (Mill.) Druce

Polygonatum odoratum(Mill.)Druce(P.odoratum)is a perennial herb of Polygonatum in Liliaceae,and also a medicinal and edible homologous plant.The dried rhizome of P.odoratum can be used as medicine has the effects of nourishing yin and moistening dryness,producing saliva and quenching thirst.However,the fresh rhizome of P.odoratum can be eaten or processed into functional food,and has a wider application value.At present,domestic and foreign scholars’ research on the chemical composition and pharmacological action of P.odoratum mostly focuses on the dry rhizome,while there are still many gaps in the research on the fresh rhizome.In order to further explore the medicinal and edible value of P.odoratum,the chemical composition,content determination method and in vitro biological activity of fresh P.odoratum were studied in this paper.First of all,20 steroid saponins were extracted and isolated from the rhizome of P.odoratum by modern separation methods.Their chemical structures were identified by NMR and other spectroscopic characterization methods.Among them,seven compounds(YZ-1~YZ-7)are new compounds.Their structural characteristics as follow: YZ-1~YZ-4 are new spirosterol saponins and their C-14 positions have hydroxyl substitutions;The C-12 positions of YZ-1,YZ-2 and YZ-4 were replaced by carbonyl groups;In the parent structure of YZ-3 and YZ-4,a terminal alkene is formed between C-25 and C-27;YZ-5~YZ-7 are new furostanol saponins.They have the same parent nucleus structure,and C-14 position is replaced by hydroxyl groups;However,their C-3 position linked sugar groups are different;The Gal-C-6’ on the sugar chain of YZ-6 is replaced by acetyl group,and fucose is present in the sugar chain of YZ-5 and YZ-7,which is also the first time to isolate a steroid saponins containing fucose in the sugar group from P.odoratum.In this paper,the content of two furosterol compounds YZ-16 and YZ-17 in fresh P.odoratum was determined by solid phase extraction and high performance liquid chromatography(SPE-HPLC-ELSD).First of all,the best experimental conditions for SPE were determined by single factor investigation method: pure water was used as the extraction solvent,the ratio of liquid to material was 5(V/W,m L/g),the extraction time was 90 min,60 min and 30 min,respectively,using 15.0 g LK1300 S macroporous adsorption resin as the stationary phase of SPE column,135 m L of 15%Et OH-H2 O solution(V/V,m L/m L)as the eluent,120 m L 85% Et OH-H2 O solution(V/V,m L/m L)as eluent.Secondly,the optimum liquid chromatographic conditions were determined and the method was validated.The results showed that the linear ranges of compounds YZ-16 and YZ-17 were 0.42~20.80 and 0.38~20.20 μg,respectively.The RSD of precision,repeatability,stability and sample recovery are less than 2.0%,those results further proves that the method determined in this paper has high accuracy and good precision.The results showed that the contents of YZ-16 and YZ-17 in fresh P.odoratum from different areas were different.The average contents of YZ-16 and YZ-17 from three areas were 0.0405 mg?g-1 and 0.0613 mg?g-1,respectively.Finally,this paper studied the lipase inhibition effect of the total saponin extracts of P.odoratum and the isolated monomer compounds(YZ-1,3,5,6,7,8,9,10,12,14,15,16,17,18,19,20)by p-nitrophenol method.The experimental results showed that the crude extract had the lipase inhibition effect,and the inhibition rate reached 92% at the concentration of 17.5 mg?m L-1.Compounds YZ-9 and YZ-10 showed stronger lipase inhibition with IC50 values of 201.90 ± 0.036 μM and 151.20 ± 0.058 μM respectively.Other compounds reach 500 μM even showed no inhibition effect.By structure-activity relationship analysis,it can be inferred that the S-type spirosteroid saponins at C-25 and hydroxyl at C-14 are more likely to exhibit the lipase inhibitory effect.To sum up,this paper studied the chemical constituents of fresh P.odoratum,isolated and identified seven new steroidal saponin monomers from them,established a method for the determination of furostanol saponins in it and screened 16 steroidal saponin monomers for the inhibition of porcine pancreatic lipase.The research results in this paper filled the gap in the research of fresh P.odoratum,enriched the types of active components,laid a foundation for improving the quality standard,and expanded the application range of P.odoratum.