Quantitative Monitoring of Cyclic Glycine-Proline in Marine Mangrove-Derived Fungal Metabolites

This study developed and validated a robust UPLC-MS/MS method for quantifying cyclic glycine-proline (cGP) in mangrove -derived Penicillium and Aspergillus strains. The method demonstrated excellent linearity, precision, and recovery, with detection limits as low as 4.8 ng/mL. When applied to fungal extracts, Penicillium pedernalense achieved 67.45 1.11 ng/mL (yielding 29.31 0.61 mg/L), surpassing Penicillium steckii at 31.71 0.31 ng/mL (yielding 8.51 0.15 mg/L). This quantitative approach for metabolite analysis provides a viable method for screening these fungal strains, highlighting their potential for sustainable production of cyclic glycine-proline (cGP).