A Phenylethanoid Glycoside and Other Constituents from the Fruits of Forsythia koreana

The Oleaceae is a family of medium size with 25 genera and about 600 species. With regard to chemical constituents, it has been quite extensively investigated. It is mainly characterized by the presence of iridoid glucosides and phenylethanoid derivatives in the form of esters and glycosides of tyrosol (p-hydroxyphenyl-ethanol) and in particular the closely related dopaol (3,4-dihydroxyphenyl-ethanol).Coumarins and lignan glucosides are also common in the family, but they appear to have a more limited distribution [1 – 2]. The fruits of Forsythia koreana Nakai (Oleaceae) are known to have diuretic and damp-heat clearing actions, and have been used for the treatment of dysuria, edema, urinary tract infection, and retention of fluid in oriental traditional medicine [3]. This plant is known to possess antibacterial, antiinflammatory, and diuretic activities [4]. However, the mechanisms of action of this plant are still unknown. We describe here the isolation and structure elucidation of two new compounds from the methanol extract of the dried fruits of F. koreana, β -(3,4-dihydroxyphenyl)ethyl-O-α-rhamnopyranosyl-(1→4)-2-O(E)-caffeoyl-α-arabinopyranoside (1) and (2R,3S)-3hydroxy-2-hydroxypropylpyrrolidine (2) together with six known compounds (3 – 8).