Provided herein are steroidal compounds that are androsta-5,7-dienes or pregna-5,7-dienes and ultraviolet B (UVB) conversion products thereof and cholecalciferol derivatives hydroxylated at one or more of C1, C17, C20, C23, C24, C25, and C26 which includes pharmaceutical, cosmeceutical or nutraceutical compositions of the steroidal compounds as shown in Tables 1A, 2A and 3. Also provided is a method for producing hydroxylated metabolites of cholecalciferol via CYP11A1, CYP24, CYP27A1, or CYP27B1 enzyme systems where the hydroxylase has an activity to hydroxylate position C1 or C20 or other position of the sidechain of a secosteroid or its 5,7-dieneal precursor and the hydroxylated metabolites so produced. Methods are provided for inhibiting proliferation of either a normally or abnormally proliferating cell, for modifying immune activity, or for treating a condition associated with the proliferating or quiescent cell or immune cells by contacting the cell with or administering any of the compounds described herein.