Prenylflavonoids: a new class of non-steroidal phytoestrogen (Part 1). Isolation of 8-isopentenylnaringenin and an initial study on its structure-activity relationship - Kitaoka,M.; Kadokawa,H.; Sugano,M.; Ichikawa,K.; Taki,M.; Takaishi,S. (Planta Medica, 1998)