Investigation on in Vitro Antioxidant Activity and Chemical Composition of Different Polar Parts of Extract of Rosa cymosa Roots / 中国实验方剂学杂志

ABSTRACT

Objective:To investigate the antioxidant activity and chemical composition of 75% ethanol extract of <italic>Rosa cymosa</italic> roots and its different polar parts. Method:The 75% ethanol extract of <italic>R. cymosa</italic> roots was divided into dichloromethane， ethyl acetate， <italic>n</italic>-butanol and water parts by organic solvent extraction. <italic>In vitro</italic> antioxidant activity of each fraction was determined by 1，1-diphenyl-2-picrylhydrazyl （DPPH） and 2，2'-azino-bis（3-ethylbenzothiazoline-6-sulfonic acid） （ABTS） free radical scavenging assays， as well as ferric reducing antioxidant power （FRAP） test. The contents of total triterpenes， total phenols， total tannins and condensed tannins in each fraction were determined by spectrophotometry. SPSS 24.0 software was used to conduct Pearson correlation analysis between the antioxidant activity of each fraction and the content of the main components， and then the main active fraction and the main active components were determined. The chemical constituents of the active fraction was analyzed by ultra performance liquid chromatography-quadrupole-time-of-flight mass spectrometry （UPLC-Q-TOF-MS/MS）， and the structures of the main chromatographic peaks were predicted. Result:Each fraction of <italic>R. cymosa</italic> roots had certain antioxidant activity， and there was a significant dose-effect relationship within a certain concentration range， but the antioxidant activity of different polar parts was different. In DPPH and ABTS free radical scavenging tests， the antioxidant activity of each fraction and vitamin C （VC， the positive drug） was ranked as ethyl acetate fraction>VC><italic>n</italic>-butanol fraction>ethanol extract>water fraction>dichloromethane fraction. In FRAP test， the activity of ethyl acetate fraction was weaker than that of VC， and the other order was unchanged. The contents of total triterpenes， total phenols， total tannins and condensed tannins in ethyl acetate fraction were 3.81%， 50.33%， 3.32%， and 39.79%， in <italic>n</italic>-butanol fraction were 0.88%， 41.42%， 2.25% and 23.55%， in ethanol extract were 2.90%， 41.95%， 3.43% and 20.14%， in water fraction were 0， 26.80%， 16.90% and 7.57%， and in dichloromethane fraction were 21.23%， 12.90%， 1.59%， and 6.17%， respectively. Correlation analysis results showed that the contents of total phenols and condensed tannins were positively correlated with the antioxidant activity， the contents of total triterpenes were negatively correlated with the antioxidant activity， and the correlation between total tannins and antioxidant activity was not obvious. A total of 26 compounds were identified from the ethyl acetate fraction by UPLC-Q-TOF-MS/MS， including 11 condensed tannins， 4 hydrolysable tannins， 6 triterpenes， 3 flavonoids， 1 benzoic acid derivative and 1 chlorogenic acid analogue. Conclusion:Ethyl acetate fraction is the main antioxidant active site of <italic>R. cymosa</italic> roots， and phenols mainly composed of condensed tannins are the main active components. The results can provide experimental basis for the development of natural antioxidants.