A heartwood pigment in Dalbergia cell cultures

In an extensive survey of the genera Baphia. Caesalpinia, Dalbergia, haemat oxylon, and Pterocarpus, we have identified a number of species whose cell cultures accumulated pigments similar to those in heartwood, thirteen rosew ood (Dalhergia) species produced a purple quinonemethide pigment in the cal lus that was apparently identical between the species. The pigment was firs t purified from D. retusa cell culture and its structure was elucidated by mass, infrared, and derailed H-1 and C-13 NMR and NOE spectroscopic studies including 2D experiments (COSY, NOESY, HMQC. and HMBC). Retusapurpurin A ( 1a) is a C-30 isoflavan of novel skeleton whose formation can be rationaliz ed to occur via regioselective oxidative coupling of an isoflavan to 4,4 ' -dihydroxy-2 ' -methoxychalcone. Retusapurpurin A was also isolated from D. parviflora heartwood and cell culture indicating that stress metabolism pa thways that are shared with heartwood-type secondary metabolism subpathways are initiated in Dalbergia cell cultures. Therefore, Dalbergia cell cultur es afford a good model system for studying heartwood-type metabolic differe ntiation. (C) 2001 published by Elsevier Science Ltd. All rights reserved.