ABSTRACT
OBJECTIVE:To develop a detection LC-MS/MS method for global DNA methylation in medicinal plants. METH-ODS:Genomic DNA was isolated using plant DNA extraction kit,and then hydrolyzed by 88% formic acid at 140 ℃. After dried with nitrogen,extracted DNA was dissolved again with mobile phase. LC separation was performed on HILIC column with mobile phase consisted of 7 mmol/L ammonium formate-acetonitrile (gradient elution) at flow rate of 0.3 ml/min. The analysis was con-ducted by tandem MS with positive ion electrospray ionization in multiple reaction monitoring(MRM)mode. The ratio of genomic DNA methylation in 10 commonly used medicinal plants was calculated. RESULTS:The linear ranges of Cyt and 5mC were 1-500 ng/ml(r=0.999 5)and 0.2-100 ng/ml(r=0.999 6). The relative standard deviations(RSDs)of accuracy were 1.12% and 3.68%(n=6). The RSDs of intra-day precision were 2.36% and 4.02% for Cyt and 5mC,respectively (n=5). The RSDs of inter-day precision were 1.04% and 3.54% for Cyt and 5mC,respectively (n=3). The RSDs of repeatability test were 1.53% and 3.27%for Cyt and 5mC,respectively(n=6). The recoveries of Cyt and 5mC were 98.7%-102.1% and 91.2%-103.5%. The percentages of global DNA methylation in 10 medicinal plants were ranged from 17.63% to 25.18%. CONCLUSIONS:LC-MS/MS method is simple,rapid,sensitive and precise,and can be used for the detection of global DNA methylation in medicinal plants.