Analysis and improved characterization of minor antioxidants from leaves of Malus doumeri using a combination of major constituents' knockout with high-performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry.
Due to the complexity of natural products, efficient identification of bioactive compounds, especially for minor compounds, would require a huge effort. Here, we developed an effective strategy based on combining major constituents' knockout with high-performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry (HPLC-DAD-QTOF-MS/MS) to comprehensively identify minor antioxidants in Malus doumeri, one of the longest known and most used tonic plant in Taiwan. First, five major compounds (I-V) in M. doumeri were knocked out by two-step stepwise high-speed countercurrent chromatography (HSCCC). Second, minor antioxidants were screened by 1,1-diphenyl-2-picrylhydrazyl radical-HPLC (DPPH-HPLC) assay. Third, structures of thirty minor antioxidants, including 11 dihydrochalcones, 4 flavanones, 3 flavonols, 2 flavones, 3 aurones and 7 phenolic acids, were unambiguously or tentatively identified by matching their characteristic UV spectra, accurate mass signals and key diagnostic fragment ions with standards or previously reported compounds. Twenty-six of them, as far as was known, were discovered from M. doumeri for the first time. The results indicated that the proposed method was a useful approach to explore minor bioactive compounds from complex natural products.
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China.
Huading
H
Zhao
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China.
Xin
X
Hu
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China.
Xiaoqin
X
Chen
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China. Electronic address: yangyang09@csu.edu.cn.
Shuyun
S
Shi
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China.
Xinyu
X
Jiang
Research Institute of Chinese Medicine, Hunan Academy of Chinese Medicine, Changsha 410013, China.
Xuejuan
X
Liang
Research Institute of Chinese Medicine, Hunan Academy of Chinese Medicine, Changsha 410013, China.
Wei
W
Chen
Research Institute of Chinese Medicine, Hunan Academy of Chinese Medicine, Changsha 410013, China. Electronic address: zhangshuihan0220@126.com.
Shuihan
S
Zhang
D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D027845:Malus / Q000737:chemistry*; D013058:Mass Spectrometry; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D053719:Tandem Mass Spectrometry
D000975:Antioxidants; D010936:Plant Extracts
Antioxidant; DPPH–HPLC; HSCCC; Knockout; Malus doumeri