Syzysamalactone, an Unusual 11-Carbon d-Lactone Derivative from the Fresh Ripe Fruits of Syzygium samarangense (Wax Apple)

To study the chemical constituents from the ripe fresh fruits of Syzygium samarangense (wax apple) and their potential health effects, a phytochemical investigation was undertaken. A new (5-lactone derivative, syzysamalactone (1), along with a known biogenetically related (5-lactone derivative, 6-pentyl-a-pyrone (2), were isolated from the fresh ripe fruits of S. samarangense. Syzysamalactone (1) is an unusual 11-carbon (5-lactone derivative, and its chemical structure and absolute configuration were elucidated by spectroscopic data analysis. A plausible biogenetic pathway for 1 was also proposed. Furthermore, the potential neuroprotective effects of compounds 1 and 2 were assessed. As a result, compounds 1 and 2 displayed notable neuroprotective effects with EC50 values of 0.29 & PLUSMN; 0.03 and 1.28 & PLUSMN; 0.06 mu M, respectively, using the SH-SY5Y human neuroblastoma cell line. This is the first report of (5-lactone derivatives showing significant neuroprotective activities.