Figure 2
Post-run selected ion chromatogram (SIC), with m/z 70, from the lizard femoral gland extract of S. virgatus (A), S. merriami (B) and the reference standard compounds cyclic dipeptide 1 (C), and cyclic dipeptide 2 (D). Cyclic dipeptide 1, identified as cyclo(L-Leu-L-Pro), with retention time (Rt) 47.99 min and cyclic dipeptide 2, identified as cyclo(L-Pro-L-Pro), with Rt 48.12 min, are not fully resolved in S. virgatus but exhibit characteristic mass spectra as seen in other congeners, e.g. S. merriami22 (B)—shown here for comparison purposes—where they occur at higher concentrations. Peak areas for cyclic dipeptide 1 were 0.09 × 106 and 0.26 × 106 for S. virgatus and S. merriami, respectively. Peak areas for cyclic dipeptide 2 were 0.27 × 106 and 1.1 × 106 for S. virgatus and S. merriami, respectively.
