α-Glucosidase Inhibitory Activity of Resin From Sakhalin fir Tree (Abies sachalinensis) and its Bioactive Compounds

This study investigated in vitro the α-glucosidase inhibitory activity of resin from the Sakhalin fir tree (Abies sachalinensis). The resin showed extremely high activity (IC₅₀ of 17.3 µg/mL). We isolated 8 compounds from the resin and identified them. All of the compounds isolated from A. sachalinensis resin are reported for the first time in the present study. In an α-glucosidase inhibitory assay, 6 compounds—(holophyllane C (1), (−)-(24E)-23-oxo-3,4-seco-9βH-lanosta-4(28),6,8(14),24-tetraen-3,26-dioic acid (2), abiesonic acid (3), (−)-(24E)-23-oxo-3,4-seco-9βH-lanosta-4(28),7,24-triene-3,26-dioic acid (4), 3,4-seco-4(28),6,8(14),22Z,24-mariesapentaen-26,23-olide-3-oic acid (5), and (−)-abiesonic acid 3-methyl ester (6))—showed high activity (their IC₅₀ values were 25.1, 20.9, 82.4, 20.5, 27.3, and 20.5 µg/mL, respectively). These compounds should contribute to the resin’s α-glucosidase inhibitory activity. From an industrial point of view, these findings provide new data to support that the resin of A. sachalinensis is a rich source of α-glucosidase inhibitors, which are highly valuable for their potential to be developed as functional health foods.