1,25-Dihydroxyvitamin D₃-glycoside: Identification of a calcinogenic principle of solanum malacoxylon

The water soluble calcinogenic factor present in the plant Solanum malacoxylon is partially purified by selective extraction and chromatography on silicic acid and then hydrolyzed with a mixed preparation of glycosidases from the sea worm, Charonia lampus. Hydrolysis produces a chloroform soluble factor with biologic characteristics of 1,25-dihydroxyvitamin D₃ (1,25-(OH)₂D₃), the hormonal form of vitamin D. Purification of this factor is accomplished by chromatography on Sephadex LH-20, silicic acid, and Celite columns, yielding 3 μg of active material. During the isolation, bioactivity (as assessed by the ability of fractions to compete with labeled 1,25-(OH)₂D₃ for binding to a specific intestinal receptor protein) migrates exactly with authentic tritiated 1,25-(OH)₂D₃. The purified factor has an ultraviolet absorption spectrum identical to that of 1,25-(OH)₂D₃ and analysis via direct probe mass spectrometry yields a parent molecular ion of m/e 416 and a fragmentation pattern indistinguishable from synthetic 1,25-(OH)₂D₃ hormone. We therefore conclude that the vitamin D-like principle in Solanum malacoxylon is a sterol-glycoside which contains the 1,25-(OH)₂D₃ molecule as its active sterol component.