Bioactive Glucitol-Core Containing Gallotannins and other Phytochemicals from Silver Maple ( Acer saccharinum ) Leaves

Abstract

In the course of our group's investigation of members of the maple (Acer) genus, a series of glucitol-core containing gallotannins (GCGs) were isolated and identified (by NMR and HREISMS). Among higher plants, only certain maple species are known to produce GCGs, compounds with potential nutraceutical and cosmetic applications due to their reported antioxidant, antidiabetic, anti-α-glucosidase, anti-glycation, anticancer, and skin health promoting effects. Herein, we sought to investigate whether the previously un-investigated silver maple (Acer saccharinum) species was also a source of GCGs. Nine phenolic compounds, including six GCGs, were identified (by HPLC-DAD analyses using previously isolated standards) as ginnalins A-C (1-3), maplexins B, D, and F (4-6), methyl syringate (7), methyl gallate (8), and 3-methoxy-4-hydroxyphenol-1-β-D-(6-galloyl)-glucopyranoside (9). In addition, one sesquiterpenoid, namely, pubineroid A (10), was isolated and identified (by NMR).