Figure 5.
The identification of phytuberin. (A) The zoomed-in extracted ESI−-MS TICs comparing non-treated (control) and 300 nM-treated samples. The encircled ion peak is present only in the treated sample: the intensity of the peak is significantly higher in the 300 nM-treated sample than in non-treated (control) sample. (B) MS-spectrum of the extracted ion peak, eluted at 17.1 min (293.1673 Da). Based on the spectrum of the extracted ion peak, the empirical formula calculated (and selected) was C17H25O4, with i-FIT of 0.0 and DBE of 5.5. Since the ion was generated by ESI− mode, the calculated empirical formula would contain one proton (H+) less. The corrected empirical formula is thus C17H26O4; and searching in databases (with structural correlation to MS spectrum) the compound was putatively identified as phytuberin (C17H26O4, 294.183 Da).