Nicotiana glauca:: another plant species containing vitamin D3 metabolites

Vitamin D-3-related compounds have been detected in various plant species, mostly belonging to the Solanaceae. In this work we show that Nicotiana glauca, a widespread member of this taxonomic family, contains 7-dehydrocholesterol, vitamin D-3 and hydroxylated derivatives bearing precursor-product metabolic relationships in vertebrates. Leaves collected in the field and callus cultures were used. By means of specific radioreceptor binding assays and mass spectrometry of purified fractions obtained from plant tissue lipid extracts by Sephadex LH-20 and Sep-Pak C18 chromatography followed by HPLC, we established the presence of 7-dehydrocholesterol, vitamin D-3, 25(OH)-vitamin D-3 and 1 alpha,25(OH)(2)-vitamin D-3 (1 alpha,25(OH)(2)D-3), the latter being a hormonally relevant metabolite in animals. These results indicate that N. glauca may represent a useful species in which to characterize the biosynthetic pathway and physiological functions of vitamin D-3 compounds in plants. In addition, tissue culture of N. glauca could become a significant tool for biotechnological production of 1 alpha,25(OH)(2)D-3. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.