Diarylheptanoids from the Seeds of Alpinia katsumadai as Heat Shock Factor 1 Inducers

Seven new diarylheptanoids, (-)-(R)-4 ''-hydroxyyashabushiketol (1), (3S,5S)-alpinikatin (2), katsumain C (3), 7-epi-katsumain C (4), ent-alpinnanin B (5), ent-alpinnanin A (6), and ent-calyxin H (8), were isolated from the EtOAc extract of the seeds of Alpinia katsumadai together with three known compounds, alpinnanin B (7), epicalyxin H (9), and calyxin H (10). Each isomer mixture of 3 and 4,5-7, and 8-10 was separated successfully by preparative HPLC using a chiral column. The three isomer mixtures (3 and 4, 5-7, 8-10) at 1 mu M increased expression of heat shock factor 1 (HSF1) with fold increases of 1.438, 1.190, and 1.316, respectively, which was accompanied with increased expression of heat shock protein (HSP) 27 (1.403-, 1.250-, and 1.270-fold, respectively) and HSP70 (1.373-, 1.313-, and 1.229-fold, respectively) without cellular cytotoxicity, suggesting a possible application of these compounds as HSP inducers. Celastrol was used as a positive control of HSP induction, producing fold increases of 1.066 (HSF1), 1.216 (HSP27), and 1.371 (HSP70) at 1 M. Compounds 1 and 2 did not affect the induction of HSF1 protein.