Active form of Vitamin D

Abstract

Since the discovery of 1, 25-dihydroxyvitamin D3, our knowledge of the metabolic activation and the mode of action of vitamin D has expanded dramatically during the past 15 years. About 40 kinds of the metabolites were isolated. Many analogs of those metabolites have been synthesized in order to obtain higher activity and to separate various biological activities. Recently, a specific receptor for 1, 25-(OH) 2D3 was demonstrated in many tissues and tumor cells, and the induction of cell differentiation of myeloid leukemia cells by 1, 25-(OH)2D3 was reported. Vitamin D analogs have been tested for the activity. Usually parallel activities were observed for the calcium regulation effect and cell differentiation. Synthetic analogs, 24-homo-1, 25-(OH)2D3, 26, 27-diethyl-1, 25-(OH)2D3, and 24, 24-F2-24-homo-1, 25-(OH)2D3 were found to be 10 fold more potent than 1, 25-(OH)2D3 in inducing differentiation of HL-60 cells, but almost inactive in calcium regulation. Thus, the separation of two major actions of 1, 25-(OH)2D3 could be achieved. © 1988, The Society of Synthetic Organic Chemistry, Japan. All rights reserved.