Establishment and application of a rapid identification strategy for Pterosins using UPLC-QTOF-MS/MS techniques

Pterosins, 1H-inden-1-one-type sesquiterpenes, are characteristic components of ferns with unique structures and notable pharmacological activity. Despite the diversity and wide distribution of ferns, relatively few natural pterosins have been identified, likely due to inefficient identification methods. This study developed a high-throughput strategy for rapid pterosin identification by combining ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). By analyzing characteristic fragmentation patterns and diagnostic ions, the method enables efficient structural elucidation and targeted screening of pterosins in complex plant matrices. Results showed that the positive ion mode was more effective than the negative ion mode for detecting pterosins due to the abundance of characteristic fragment ions. Five diagnostic ions (m/z 156, 141, 143, 128, and 115) were identified, with the ion m/z 128 serving as key evidence for distinguishing the parent nucleus of pterosins. Differences in fragment ion abundance and specific ions formed by alpha cleavage were used to identify isomers based on glycosyl-binding and hydroxyl substitution sites. This method was applied to the extract of Pteris grevilleana pretreated with D101 macroporous resin column chromatography, resulting 46 pterosins, including 34 known and 12 novel compounds. The proposed LC-MS strategy not only enhances analytical throughput and compound coverage but also provides an effective tool for pterosin separation, rapid analysis, and structural identification. Its broad applicability across Pteris species supports its use in metabolite analysis and quality evaluation.