New perspectives for (S)-dolichol and (S)- nor dolichol synthesis and biological functions.

A procedure is described for the preparation of (S)-dolichol and (S)- nor dolichol starting from the polyprenyl fraction extracted from Gingko biloba integer or exhausted leaves. The procedure appears extremely valuable in obtaining the two chiral isoprenoid compounds in good chemical yields and retention of a high degree of enantiomeric excess. Also, the (S)- nor dolichol represents a good chiral precursor for the preparation of (14)C-labelled (S)-dolichol to be used in biological investigations into the (S)-dolichol catabolism in the functional living cell. Furthermore, the possible role of (S)-dolichol as a free radical scavenger in the cell membrane was preliminarily evaluated by means of a (1)H-NMR analytical method. Apparently, experimental results substantiate this hypothesis.