New Monoterpene-Substituted Dihydrochalcones from Piper aduncum

Five New unusual monoterpene‐substituted dihydrochalcones, the adunctins A–E (1″S)‐1‐{2′‐hydroxy‐4′‐methoxy‐6′‐[4″‐methyl‐1″‐(1‴‐methylethyl)cyclohex‐3″ ‐en‐1″ ‐yloxy]phenyl}‐3‐phenylpropan‐1‐one (1), (5aR*,8R*,9aR*)‐3‐phenyl‐1‐[5′,8′,9′,9′a‐tetrahydro‐3′‐hydroxy‐1′‐methoxy‐8′‐(1″‐methylethyl)‐5′‐a‐methyldibenzo‐[b,d]furan‐4′‐yl]propan‐1‐one (2), (2′R*,4″S*)‐1‐{6′‐hydroxy‐4′‐methoxy‐4″‐(1‴‐methylethyl)spiro[benzo[b]‐furan‐2′(3′H),1″ ‐cyclohex‐2″ ‐en]‐7′‐yl}‐3‐phenylpropan‐1‐one (3), (2′R*,4″R*)‐1‐{6′‐hydroxy‐4′‐methylethyl‐4″‐(1‴‐methylethyl)spiro[benzo[b]furan‐2′(3′H),1″‐cyclohex‐2″‐en]‐7′‐yl}‐3‐phenypropan‐1‐one (4), and (5′aR*,6′S*, 9′R*,9′aS*)‐1‐[5′a,6′,7′,8′,9′a‐hexahydro‐3′,6′‐methoxy‐6′‐methyl‐9′‐(1″‐methylethyl)dibenzo[b,d]‐furan‐4′‐yl]‐3‐phenylpropan‐1‐one (5) were isolated from the leaves of Piper aduncum (Piperaceae) by preparative liquid chromatography. In addition, (−)‐methyllindaretin (6), trans‐phytol, and α‐tocopherol ( = vitamin E) were also isolated and identified. The structures were elucidated by spectroscopic methods, including 1D‐ and 2D‐NMR spectroscopy as well as single‐crystal X‐ray diffraction analysis. The antibacterial and cytotoxic potentials of the isolates were also investigated.