Retrodihydrochalcones and homoisoflavones isolated from Thai medicinal plant Dracaena loureiri and their estrogen agonist activity.

Biological evaluation of the extract prepared from the stem wood of Dracaena loureiri, a Thai folkloric medicine called "Chan-daeng", revealed a significant capacity to inhibit [3H]-estradiol binding to the estrogen receptor. During the course of separation, two novel (1 and 2) and two known retrodihydrochalcones (3 and 4), in addition to three known homoisoflavones (5, 6, and 7), were isolated. The structures of compounds 1 and 2 were established by NMR and MS studies by correlating their spectroscopic properties with those of 3 and 4. Each isolate was assessed for its estrogenic activity. Compounds 1 and 6 exhibited activity comparable to that of genistein and daidzein.