Identification of vitamin D₃ hydroxylated metabolites in Solanum glaucophyllum leaves: towards its biosynthetic pathway elucidation

Solanum glaucophyllum is a species of the Solanaceae family widely distributed in flooded areas of natural grasslands in the northeast of Argentina. Since 1960 its consumption by cattle has been associated with cattle specific vitamin D₃ intoxication known as enzootic calcinosis disease. This particular disease is related to alteration in absorption of vitamin D₃ and actually leads to the detriment of Argentina´s livestock economy.

Concerning bibliography background, vitamin D₃ is known to be present in species belonging to the Solanaceae family and has been identified in S. glaucophyllum from the enzymatic hydrolysis of the ethanol-water extract obtained from the leaves of this species. In addition, vitamin D₃ in S. glaucophyllum showed a similar photodependent process of synthesis to the vertebrates. Inspired on thrusting forward the study S. glaucophyllum biosynthetic pathway to vitamin D₃, the aim of the present work is to provide knowledge of vitamin D₃ toxicity related to concentration in the mentioned species located throughout the Río Salado basin. Herein we present the development of a reverse phase high performance liquid chromatography (RP-HPLC) method for the determination and analysis of vitamin D₃ and its hydroxylated metabolites. An exhaustive optimization of RP-HPLC method allow us to perform calcitriol (1a,25-(OH)₂D₃) and calcidiol (25-OHD₃) identification, both metabolites obtained by chemical hydrolysis of S. glaucophyllum leaves starting off its hydrophilic extract.

These results will improve a smart design management and monitoring scheme for S. glaucophyllum, achieving a more selective control of this weed, avoiding cattle declining in the Río Salado basin.