Studies On Chemical Constituents And Bioactivities From The Root Bark Of Dictamnus Dasycarpus

Aim：To isolate and identify the chemical constituents from the root bark of Dictamnusdasycarpus, and provide some basis to evaluate its effective components. In order toinvestigate the effects of different extraction solvents on the extraction rate of three maincompounds, a RP-HPLC method for the determination of the main compounds(limonin,obacunone, fraxinellone) was developed.Methods: Silica gel, Sephadex LH-20, ODS，p-HPLC were employed for the isolationand purification of chemical constituents. The structures were identified on the basis ofspectral data and physicochemical examination. The cytotoxicity of eight constituents werestudied on human lung cancer A549cell by MTT method, and dictamnin A, B were chosen tosome research on A549cell cycle by Flow Cytometry(FCM) analysis. A RP-HPLC methodfor the determination of the main compounds(limonin, obacunone, fraxinellone) was proposedto investigate the effects of different extraction solvents（methanol, ethanol, dichloromethane,acetone, acetonitrile） on the extraction rate of three main compounds.Results: Nineteen compounds were isolated and seventeen of them were identified asfollows: dictamninA(Ⅰ), dictamninB(Ⅱ), fraxinellone(Ⅲ), limonin(Ⅳ), fraxinellonone(Ⅴ),rutaevin(Ⅵ), obacunone(Ⅶ), dictamnine(Ⅷ),3β-hydroxy-cholesta-5-ene(Ⅸ),5-hydroxylmethylfuraldehyde(Ⅹ), rutin(Ⅺ), quercetin(Ⅻ), scopoletin(ⅩⅢ), daucosterol(ⅩⅣ), β-sitosterol(ⅩⅤ), dasycarine(ⅩⅥ),7α-obacunyl acetate(ⅩⅦ). Among themCompounds(Ⅰ) and (Ⅱ) were new compounds, and compounds (Ⅸ),(Ⅹ) were isolated fromthis genus for the first time.Eight compounds were performed on human lung cancer A549cell to do the research oncytotoxicity by MTT method, and the results showed that dictamnin A, dictamnin B were most active against human lung cancer A549cell, followed by dictamnine, the limonoids suchas obacunone，rutin fraxinellonone, limonin were less active, and fraxinellone inactive;dictamnin A and B were further studied to investigate the effects on human lung cancer A549cell with Flow Cytometry(FCM) analysis, the results showed among phase of cell cycle, theG1phase ratio were increased significantly, dictamnin A, B treatment caused85.5%and85.1%cells in G1phase as compared to control showing70.1%.A RP-HPLC method for the determination of the main compounds (limonin, obacunone,fraxinellone) was developed for the first time to investigate the effects of different solvents(methanol, ethanol, dichloromethane, acetone, acetonitrile) on the extraction rate of threemain compounds. The results showed that the optimal extraction solvent was methanol.Conclusion: The chemical constituents from the root bark of Dictamnus dasycarpus wasstudied and seventeen compounds were isolated and identified. Among them Compounds (Ⅰ)and (Ⅱ) were new compounds, and compounds (Ⅸ),(Ⅹ) were isolated from this genus forthe first time.Dictamnin A, dictamnin B are most active against human lung cancer A549cell,followed by dictamnine, the limonoids such as obacunone，rutin fraxinellonone, limonin areless active, and fraxinellone inactive; it may be associated with the inhibition of G1phase ofcell cycle that dictamnin A and B have cytotoxicity on A549.The RP-HPLC method was simple, rapid, accurate, and can be used for the quantitativedetermination of three main constituents,and the result showed that the optimal extractionsolvent was methanol.