| Parnassia palustris Linn is a medicinal plant of the genus Parnassia in the family Celastraceae,mainly distributed in Inner Mongolia,Xinjiang,Shanxi,Hebei and Northeast China.P.palustris is a traditional Mongolian medicine with a long history of application.Its major effects include "popi",calming "xieri",and clearing heat.The "popi" effect is interpreted as an anti-tumor effect in modern Mongolian medicine pharmacology.There are limited reports on the chemical composition of P.palustris,from which only 32 compounds such as flavonoids,iridoids and phenolic acids have been isolated,and there is still much research space.In this paper,the most prominent active part was selected for systematic chemical separation and structural identification by evaluating the tumor cytotoxic activities of extract and parts of P.palustrisis,based on the traditional efficacy.The isolated compounds were then evaluated for their tumor cytotoxic activities.This paper aimed to discover compounds with tumor cytotoxic activities,enrich the active chemical library,and provide a theoretical basis for further development and utilization of P.palustrisis.The main research results of this paper are as follows:1.95%ethanol extract of P.palustris(EEP)was extracted to obtain petroleum ether fraction(PEF),ethyl acetate fraction(EAF),n-butanol fraction(NBF),and aqueous fraction(AF).A CCK-8 assay was performed to evaluate the tumor cytotoxic activities of extract and various parts,using HepG-2 cell line.Results showed the IC50 values of EEP,PEF,EAF and NBF against HepG-2 cells ranged from 92.93 ± 7.61～377.93 ± 13.43 μg/mL,and AF didn’t show tumor cytotoxic activity.EAF was the most active part,and significantly different from EEP,PEF and NBF(p<0.001).Therefore,EAF was selected for chemical research in the following study.2.The systematic separation of EAF was carried out using a combination of silica gel,ODS,Sephadex LH-20 and semi-preparative HPLC to obtain monomeric compounds.Their structures were identified using modern spectroscopic techniques such as NMR and HR-ESI-MS.A total of 27 monomeric compounds were isolated and identified from the EAF,including 15 flavonoids(MHC-1～MHC-11、MHC24-27),namely quercetin(1),kaempferol(2),luteolin(3),chrysoside(4),quercetin-3-O-β-D-glucoside(5),quercetin-3-O-α-L-rhamno side(6),quercetin-7-O-α-L-rhamnoside(7),kaempferol-3-O-α-L-rhamnoside(8),kaempferol-7-O-α-L-rhamnoside(9),kaempferol-3,7-O-α-L-dirhamnoside(10)and monkshood(11),1-hydroxyl-3,5,8-trimethoxyxanthone(24),naringenin(25),1,3,8-trihy droxy-4,5-dimethoxy-9H-xanthen-9-one(26),and rutin(27);five phenolic acids(MHC-12-MHC-16),namely gallic acid(12),protocatechuic acid(13),4-hydroxy benzaldehyde(14),ferulic acid(15)and chlorogenic acid(16);two sterols(MHC-17 and MHC-18),β-sitosterol(17)and β-carotene(18);five other compounds(MHC-19～MHC-23),5-hydroxymethylfurfural(19),isotretinoin(20),n-hexadecane(21),dibutyl phthalate(22),and diisobutyl phthalate(23).Seventeen compounds(MHC-3,MHC-7,MHC-9～MHC-11,MHC-13～MHC-15,MHC-18～MHC-26)were isolated for the first time from the genus Parnassia.3.The activity screening results of monomer compounds showed that MHC-15 had a significant cytotoxic activity with an IC50 value of 9.16±2.24μM.Compounds MHC-1,MHC-2,MHC-3,MHC-4,MHC-7,MHC-8,MHC-9,MHC-11,MHC-16,MHC-17 and MHC-24 had moderate cytotoxic activities with IC50 values in the range of 15.65±1.37～50.53±1.17 μM.Compounds MHC-5,MHC-6,MHC-10,MHC-13,MHC-14,MHC-18 and MHC-20 showed weak cytotoxic activities with IC50 values in the range of 52.13 ± 2.67～90.11 ±1.16 μM.In contrast,compounds MHC-12 and MHC-19 didn’t show cytotoxic activities.Preliminary structure-activity relationship analysis showed that the tumor cytotoxic activity of flavonoids may be related to the hydroxyl and sugar position and number.This paper enriches the chemical results of P.palustris,provides modern scientific evidence for its "popi" traditional efficacy,and offers a theoretical basis for further development and utilization of P.palustris. |
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