Structure-activity relationship of novel menaquinone-4 analogues: modification of the side chain affects their biological activities.

We synthesized new vitamin K analogues with demethylation or reduction of the double bonds of the side chain of menaquinone-4 (MK-4) and evaluated their SXR-mediated transcriptional activity as well as the extent of their conversion to MK-4. The results indicated that the analogue with the methyl group deleted at the 7' site of the side chain part affected conversion activity to MK-4. In contrast, a decrease in the number of the double bonds in the side chain moiety appeared to decrease the SXR-mediated transcriptional activity.