Dermostatin B

We report a new, integrated strategy for assigning the configuration of 1,3-skipped polyol chains and illustrate the approach with the configurational assignments of both dermostatins A and B. The method is designed around the (13)C acetonide analysis, which allows one to reliably determine the relative stereochemistry of an isolated 1,3-diol and is extended using DQF-COSY, HMQC, and ROESY experiments that allow each acetonide of a polyacetonide derivative to be unambiguously assigned as either syn or anti. Using this strategy, the relative configuration of the dermostatin A C13-C32 polyol chain was determined using just two polyacetonide derivatives. The absolute configuration of dermostatin A is 15S,16S,17R,19R,21R,23S,25S,27R,29R,31R,34S,35S, and the configuration of dermostatin B is 15S,16S,17R,19R,21R,23S,25S,27R,29R,31R,34S,35S,36S. The 2D (13)C acetonide analysis is a very powerful new tool for the stereochemical assignment of alternating polyol chains.

HPLC of crude Dermostatin indicated presence of three pairs of components. Hence, attempts were made to purify Dermostatin. Purification of crude Dermostatin has been carried out using column chromatography and counter current distribution methods. Each of these fractions were tested for activity. The major fraction which showed greater activity was taken for the preparation of Dermostatin nona-acetate. Structural characterisation of Dermostatin nona-acetate has been carried out using UV-visible spectroscopy in different solvents to obtain the characteristic spectrum of a carbonyl conjugated hexaene at room temperature. Structural and configurational studies of Dermostatin nona-acetate using 500 MHz 1H NMR and 125 MHz 13C NMR has been used in the assignment of various functional groups in Dermostatin A and B as well as to provide corroboration to the earlier structural elucidation.