A robust clustering approach for NMR spectra of natural product extracts.

A robust method was developed to cluster similar NMR spectra from partially purified extracts obtained from a range of marine sponges and a plant biota. The NMR data were acquired using microtiter plate NMR (VAST) in protonated solvents. A sample data set which contained several clusters was used to optimize the protocol.

Prunolides A, B, and C: Novel Tetraphenolic Bis-Spiroketals from the Australian Ascidian Synoicum prunum.

Three novel tetraphenolic bis-spiroketals, prunolides A-C (1, 3, and 4) have been isolated from the Australian ascidian Synoicum prunum. The structures were determined from NMR spectroscopic data and from an X-ray analysis of prunolide A. The prunolides contain a unique 1,6,8-trioxadispiro[4.