Constituents of cupuliferae, XIII: New and revised structures of acylated flavonoids from Quercus Suber L.

From leaves of Quercus suber L. in addition to ten known glycosides, two new acylated flavonoids have been isolated and identified as 3-O-kaempferol 2-O-(trans-p-coumaroyl)-β-D-glucopyranoside (1) and 3-O-kaempferol 2,3-di-O-acetyl-4-O-(cis-p-coumaroyl)-6-O-(trans-p-coumaroyl)-β-D-glucopyranoside (3). The structures of the previously described 3-O-kaempferol 2,4-di-O-(trans-p-coumaroyl)-β-D-glucopyranoside2) and 3-O-kaempferol 3,6-di-O-acetyl-2,4-di-O-(trans-p-coumaroyl)-β-D-glucopyranoside3) were revised to 3-O-kaempferol 2,6-di-O-(trans-p-coumaroyl)-β-D-glucopyranoside (4) and 3-O-kaempferol 3,4-di-O-acetyl-2,6-di-O-(trans-p-coumaroyl)-β-D-glu-copyranoside (5).