Abstract
Our continuous efforts for search of new bioactive compounds led to isolation of a polyene-polyol, prorocentrol, from P. hoffmannianum (CCMP 683). Although a ketone-hemiacetal tautomerism was observed during the course of NMR measurements, NMR measurements in pyridine-d_5/D_2O (6:1) at room temperature gave simplified NMR spectra. Detailed COSY and TOCSY analyses led to four 114 spin-networks, which were constructed to gross structure on the basis of HMBC correlations. The stereoconfigurational analysis of prorocentrol was undertaken by extensive utilization of 2D-NMR methods. The conformation of cyclic ethers in the molecule was analyzed based on NOESY correlations and ^3J_<H,H・> A JBCA method was applied for elucidation of the relative configurations of chiral centers in acyclic portions. Where HETLOC did not give sufficient intensity, qualitative utilization of the relationship between HMBC signal intensity and corresponding ^<2,3>J_<C,H> turned out to be effective especially for the methyl bearing portions. Moreover, the universal NMR database method was also applied on the continuous polyol segments as an alternative way for the JBCA to reveal the relative configuration. As a particular property of prorocentrol, suggestive evidences for an association of prorocentrol and okadaic acid were indicated from chromatographic behaviors and changes of NMR chemical shifts.
