Quantitative Analysis of Adenosine and Cordycepin

Adenosine and cordycepin were quantified using the method described previously [26 (link)]. Briefly, whole GSC extract fermented with P. pentosaceus ON188 (ONE) were derivatized by N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA with 1% TMCS, Thermo) for trimethylsilylation [27 (link)]. A 0.5μL of derivatized mixture was injected using an Agilent 7693 ALS (Agilent Technologies, Wilmington, DE, USA) in splitless mode into an Agilent 7890B gas chromatograph (Agilent Technologies, Wilmington, DE, USA) for chromatographic separation using Rtx-5Sil MS column. Mass spectrometric analysis was conducted on a LECO Pegasus HT time-of-flight (TOF) mass spectrometer controlled by LECO ChromaTOF software version 4.50 (LECO, St. Joseph, MI, USA). Mass spectra were collected from 85 to 500 m/z at acquisition rate of 17 spectra/second of and detector voltage of 1800 V. Data pre-processing was conducted using ChromaTOF software upon data acquisition in which apex mass values, the entire spectrum, retention time, peak purity, and signal-to-noise ratio were acquired [28 (link)].