Pasuchaca (Geranium dielsiaum Knuth): A New Source of Astilbin with Antiglycation Activity

Pasuchaca (Geranium dielsianum Knuth), a traditional Peruvian medicinal plant from the Geraniaceae family used for diabetes management, was investigated for its antiglycative properties. This study aimed to screen, isolate, and identify the active antiglycative compounds from its aerial parts. By coupling a methylglyoxal (MGO)-HPLC screening assay with high-speed counter-current chromatography (HSCCC), seven dihydroflavonol derivatives were separated and identified from the 80% methanol extract. The compounds were identified as 2,3-dihydromyricetin 3-O-α-rhamnopyranoside (1), (+)-taxifolin 3-O-β-D-xylopyranoside (2), astilbin (6), isoastilbin (8), 3″-acetyl astilbin (9), and 2″-acetyl astilbin (11). Astilbin was identified as the major constituent, with remarkably high contents of 252.41 mg/g in the 80% methanol extract and 541.04 mg/g in the partitioned upper layer fraction. Astilbin demonstrated potent antiglycation activity across all stages of protein glycation (early, middle, late, and whole stages), significantly surpassing the positive control aminoguanidine. Furthermore, the formation of MGO-astilbin adducts was confirmed by LC-ESI-MS, validating its role as an effective MGO scavenger. This report is the first to isolate these phytochemicals from Pasuchaca. The findings establish astilbin as the key antiglycative component of Pasuchaca, substantiating its traditional use and highlighting its potential as a source of functional food ingredients or natural therapeutics for mitigating glycative stress.