gamma-Pyrones from Gonystylus keithii, as new inhibitors of parathyroid hormone (PTH)-induced Ca release from neonatal mouse calvaria.

New gamma-pyrones, 9'-oxopodopyrone (3) and 8-methyl-9'-oxopodopyrone (4) were isolated from the leaves of Gonystylus keithii, along with known gamma-pyrones, 10'-oxopodopyrone (1) and 8-methyl-10'-oxopodopyrone (2). These gamma-pyrones markedly inhibited the bovine parathyroid hormone (PTH)-induced Ca release from neonatal mouse calvaria in vitro. It is the first time that gamma-pyrones showed inhibitory effects on bone resorption, and these compounds may be seed compounds of new drugs for osteoporosis.