Stilbenes from Paphiopedilum exul roots

Abstract

Keywords: Paphiopedilum exul; Orchidaceae; trans-stilbenes

Five trans-stilbenes including (E)-3-methoxy-5-hydroxystilbene (1), (E)-3,5'-dimethoxy-5,2'-dihydroxystilbene (2), thunalbene (3), (E)-3-methoxy-5,2'-dihydroxystilbene (4) and (E)-3-methoxy-2-(4-hydroxybenzyl)-5,2'-dihydroxystilbene (5) were isolated from the roots of Paphiopedilum exul (family Orchidaceae). Their chemical structures were identified by spectroscopic methods including ¹H-NMR, ¹³C-NMR and 2D-NMR. This study is the first report of chemical constituents of this lady’s slipper orchid native to the south of Thailand.

                        R₁         R₂         R₃                                                             5

            1          H          H          H

            2          OH       H          OCH₃

            3          H          OH       H

            4          OH       H          H