Six undescribed dimeric 2-(2-phenylethyl)chromone derivatives from agarwood of Gyrinops walla

Six undescribed dimeric 2-(2-phenylethyl)chromone derivatives, gyrinwallachromones A-F (1-6), were isolated from Sri Lankan agarwood of Gyrinops walla. Their structures were elucidated by comprehensive spectroscopic analyses, including HRESIMS, 1D and 2D NMR, and ECD data. Compounds 1-6 were characterized as dimeric 2-(2-phenylethyl)chromone derivatives consisting of a tetrahydrochromone unit and a flindersia-type 2-(2-phenylethyl)chromone unit. Structurally, compound 1 was distinguished by a C-8-O-C-6″ ether linkage between the two chromone units, whereas compounds 2-5 were connected through a C-8-O-C-7″ and compound 6 were connected through a C-8-O-C-4‴ ether bond. Notably, compounds 4 and 5 featured a 5-OCH₃ substitution pattern on the tetrahydrochromone moiety, a relatively rare structural feature among agarwood-derived chromone dimers. The isolated compounds were evaluated for their inhibitory effects on LPS-induced nitric oxide (NO) production in RAW 264.7 macrophages and their antibacterial activity against Helicobacter pylori. Compounds 1-6 exhibited weak inhibitory effects on NO production at non-cytotoxic concentrations. The IC₅₀ values of compounds 3 and 4 were 68.44 ± 2.71 and 16.34 ± 2.70 μM, respectively, whereas the positive control quercetin showed an IC₅₀ value of 10.57 ± 0.58 μM. In the anti-H. pylori assay, compounds 1-6 showed antibacterial activity. These findings expand the chemical diversity of agarwood-derived dimeric 2-(2-phenylethyl)chromones and provide further insight into the phytochemical constituents of G. walla agarwood.