1ALPHA,25-DIHYDROXYVITAMIN D-3 LIKE COMPONENT PRESENT IN PLANT SOLANUM-GLAUCOPHYLLUM

The ability of an acqueous extract prepared from dried leaves of the South American shrub S. glaucophyllum to interact with a chick intestinal receptor system highly specific for the biologically active form of vitamin D, 1.alpha.,25-dihydroxyvitamin D3 (1.alpha.,25-(OH)2D3), was monitored under both in vivo and in vitro conditions. The pretreatment of chicks with the S. glaucophyllum extract reduced the amount of subsequently administered radioactive 1.alpha.,25-dihydroxyvitamin D3 localized in the intestinal chromatin fraction by 90% when compared with vitamin D-deficient controls. In addition, the active principle in the aqueous extract competed effectively with 1.alpha.,25-(OH)2D3 in a reconstituted intestinal receptor system in vitro. The plant factor(s) was as effective as 1.alpha.,25-(OH)2D3 in decreasing the renal 25-hydroxycholecalciferol-1.alpha. hydroxylase activity levels when administered to vitamin D-deficient chicks. By means of the in vitro intestinal receptor assay, it was possible to estimate that there are approximately 10 to 60 mg of the biologically active material in 1 kg of dried S. glaucophyllum leaves. The plant factor(s) may be a structural analog of 1.alpha.,25-(OH)2D3 and suggest the feasibility of its isolation.