3-epi-25-hydroxy VitaminD3is the C-3 epimer of 25-hydroxy vitaminD3.1Dietary administration of 3-epi-25-hydroxy vitaminD3(0.5 and 1 IU g) decreases levels of serum parathyroid hormone (PTH) in male, but not female, weanling rats. 1.Djekic-Ivankovic, M., Lavery, P., Agellon, S., et al.The C-3α epimer of 25-hydroxycholecalciferol from endogenous and exogenous sources supports normal growth and bone mineral density in weanling ratsJ. Nutr.147(2)141-151(2017)
(1S)-Calcitriol (1α,25-Dihydroxy-3-epi-vitamin-D3) is a natural metabolite of 1α,25-dihydroxyvitaminD3 (1α,25(OH)2D3). (1S)-Calcitriol exhibits potent vitamin D receptor (VDR)-mediated actions such as inhibition of keratinocyte growth or suppression of parathyroid hormone secretion[1]. 3‐epi‐Calcitroic acid is an end product of (1S)-Calcitriol (1α,25-Dihydroxy-3-epi-vitamin-D3; 3‐epi‐1a,25(OH)2D3) metabolism by rat CYP24A1[1]. [1]. Steve Y Rhieu, et al. Metabolic stability of 3-epi-1α,25-dihydroxyvitaminD3 over 1 α 25-dihydroxyvitaminD3: metabolism and molecular docking studies using rat CYP24A1. J Cell Biochem. 2013 Oct;114(10):2293-305.