Two New Caffeoyl Threonate Esters from the Leaves of Toxicodendron vernicifluum

Toxicodendron vernicifluum, also called as Rhus verniciflua is a deciduous tree belonging to Anacardiaceae family. Two new caffeoyl threonate esters, rhuseols A (1) and B (2), together with 5-O-(E)-caffeoylquinic acid methyl ester (3) were isolated from the leaves of T. vernicifluum. The structures of isolated compounds were established by using 1D and 2D NMR in combination with HR-ESI-MS. Compounds 1 – 3 showed DPPH radical scavenging effects with IC₅₀ values of 47.9, 107.8 and 15.4 µM, respectively. Taken together, these compounds might contribute to the antioxidant properties of the leaves of T. vernicifluum, which will be useful for various oxidative stress mediated diseases.