A short review: the biological activity of vitamin D and its decomposition products.

A vitamin D3 metabolite 1α,25-dihydroxyvitamin D3 exhibits numerous hormonal actions to various tissues and cells such as induction of calcium ion absorption, bone metabolism, activation of innate immune system. Because hormonal actions of 1α,25-dihydroxyvitamin D3 are too complex, it is difficult to better understand overall views of intermolecular networks on the cell activation by 1α,25-dihydroxyvitamin D3. In this review we concisely outline the most fundamental molecular mechanisms for the cell activation by 1α,25-dihydroxyvitamin D3 based on the previous and recent studies. In addition, we expound biological activity of 25-hydroxyvitamin D3 and 1α,25-dihydroxyvitamin D3 that differs from hormonal actions. In addition, recent studies by our group revealed that vitamin D decomposition products confer extremely selective bactericidal action to Helicobacter pylori, a pathogen causative gastritis, peptic ulcers and gastric cancers in human. Vitamin D decomposition products induce the bacteriolysis as targeting of characteristic glycerophospholipids composed of the bacterial biomembranes. In the future we will expect to be capable of developing novel antibacterial agents targeting a characteristic glycerophospholipid of the pathogenic bacteria using vitamin D decomposition products as fundamental structures.