Phenylbutenoids from the rhizomes of Alpinia flabellata

A new phenylbutenoid dimer, (±)-trans-3-(2,4,5-trimethoxyphenyl)-4-[(E)-2,4,5-trimethoxystyryl]-cyclohexene has been isolated from the fresh rhizomes of Alpinia flabellata Ridley, along with alflabene and 2′,4′,5′-trimethoxyphenylbutadiene. Their structures were elucidated on the basis of spectroscopic and chemical methods. The natural occurrence of two racemic phenylbutenoid dimers in fresh rhizomes was confirmed by...