Ingredients Identification And Antioxidant Interaction Of Coreopsis Tinctoria Nutt.

Coreopsis tinctoria Nutt. is a annual Composite, which has special aroma and originating from Midwest of America. And it also has large cultivation in Xinjiang pro of China. As many studies reported that they exhibit a diverse range of bioactivities, with antioxidant and antihypertensive being the most particularly significant. What's more, the flavonoids of Coreopsis tinctoria Nutt. have best antioxidant active. However, there is few studies of its antioxidant interaction. In this study, obtaining the crude extracts from Coreopsis tinctoria Nutt. by the extraction of n-butanol, eight pure compounds had been abtained from the n-butanol extract of Coreopsis tinctoria Nutt. by variety of separation and purification methods(column chromatography, sephadex LH-20, TLC, and so on). Then 1D and 2D nuclear magnetic resonance(1H NMR, 13 C NMR, 1H-1H COSY, HSQC, HMBC, NOESY), infrared(IR), ultraviolet(UV),mass spectrometry(MS) and vibrational circular dichroism spectra(VCD) as well as related literature search were used to identify the chemical structure of the compounds; After that, aim to study the antioxidant interaction of flavonoids, five flavonoids isolated from Coreopsis tinctoria Nutt. were selected,including marein, maritimetin, taxifolin, butein and okanin. Making the DPPH scavenging capacity as an indicator, the Chou-Talalay method was used to analyze antioxidant interactions between them. Moreover,using B3 LYP / 6-311 G ++(2d, 2p) // B3 LYP / 6-31 G method of density functional theory calculated and optimized energy of five flavonoids of Coreopsis tinctoria Nutt., including marein, maritimetin, taxifolin,butein and okanin. By the analysis of the molecular geometry, BDE of different position of the phenolic hydroxyl group, HOMO and LUMO frontier molecular orbital diagram and its energy gap, theoretical antioxidant activity of flavonoids were elucidated. And experimental results are as follows:(1) Eight compounds were identified to be: 6E,12E-tetradecadiene-8,10-diyne-1-hydroxy-3S-O-?-Larabino-pyranosyl(1), coreosides B(2), coreosides A(3), 1-hydroxy sterol glucosides(4), coretinphenol(5),pheophytin a(6), methyl-p-coumarate(7), isookanin(8), respectively. And coreosides E is new compounds.(2) The results revealed that there was moderate synergistic antioxidant interaction between maritimetin and butein, taxifolin and butein with CIwt values of scavenging DPPH 0.824 and 0.749,respectively. Besides, when maritimetin and butein mixed up, the concentration was greater than 1, and the CIwt value was less than 0.90, which showed a synergistic interaction. While three compounds combined to scavenge DPPH, all CIwt values were greater than 1.0, indicating that there was no synergistic antioxidant interaction of these three compounds.(3) The results showed that: Antioxidant activity of flavonoids of Coreopsis tinctoria Nutt. related to the number of hydroxy group and the number of the hydrogen bonds; the activity of hydroxyl groups in different positions are different, and the BDE of 4'-hydroxyl in ring B of all five flavonoids are minimal, so4'-hydroxyl is their main antioxidation active site; And 3-hydroxyl group in ring C did not increase the antioxidant activity of taxifolin.