ABSTRACT
Endothal (1diacid) and [3H]cantharidic acid ([3H]CA) bind with high affinity to the catalytic subunit of protein phosphatase 2A (PP2A). PP2A in liver cytosol was greatly stabilized with 30% glycerol as a preliminary step in the potential use of endothal-type derivatives for affinity chromatography. We report here the first introduction of a functionalizable group into endothal which allows retention of binding site affinity (assayed as [3H]CA binding in mouse liver cytosol). 2-Carboxymethylendothal anhydride (7) was prepared in two steps and 97% overall yield from cis-aconitic anhydride and furan. The potency of 7 was retained on conversion to two 2-carboxymethyl esters but not to two 2-(n-alkylcarboxamidomethyl) analogues.
Subject(s)
Affinity Labels/chemistry , Dicarboxylic Acids/chemistry , Phosphoprotein Phosphatases/metabolism , Affinity Labels/chemical synthesis , Affinity Labels/metabolism , Animals , Catalytic Domain , Dicarboxylic Acids/chemical synthesis , Dicarboxylic Acids/metabolism , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/metabolism , Enzyme Stability , Hydrogen-Ion Concentration , In Vitro Techniques , Liver/enzymology , Magnetic Resonance Spectroscopy , Mice , Phosphoprotein Phosphatases/antagonists & inhibitors , Phosphoprotein Phosphatases/chemistry , Protein Phosphatase 2 , Structure-Activity Relationship , TemperatureABSTRACT
We describe several novel analogs of the seco-steroid 1,25(OH)2-vitamin D3[1,25(OH)2D3] and their effects on differentiation and proliferation of HL-60 human myeloid leukemic cells in vitro as well as their effects on calcium metabolism in vivo. The 1 alpha-25(OH)2-16ene-23yne-26,27F6-vitamin D3 is the most potent analog reported to date, having about 80-fold more activity than the reference 1,25(OH)2D3 for inhibition of proliferation and induction of differentiation of HL-60 cells. Also, this analog decreased RNA expression of MYC oncogene in HL-60 by 90% at 5 x 10(-10) mol/L. Intriguingly, intestinal calcium absorption and bone calcium mobilization mediated in vivo by 1 alpha-25(OH)2-16ene-23yne-26,27F6-D3 was found to be markedly (15-fold) less than that of 1,25(OH)2D3. In addition, 1 alpha-25(OH)2D3 bound to 1,25(OH)2D3 receptors of both HL-60 and intestine more avidly than did 1 alpha-25(OH)2-16ene-23yne-26,27F6-D3. This novel analog may open up new therapeutic strategies for several hematopoietic, skin, and bone abnormalities and may provide a new tool to understand how vitamin D3 seco-steroids induce cellular differentiation.
Subject(s)
Bone Marrow/pathology , Calcitriol/pharmacology , Calcium/metabolism , Leukemia, Promyelocytic, Acute/pathology , Bone Marrow/metabolism , Bone Marrow/ultrastructure , Calcitriol/analogs & derivatives , Calcitriol/metabolism , Cell Differentiation/drug effects , Cell Division/drug effects , Humans , Leukemia, Promyelocytic, Acute/metabolism , Proto-Oncogene Proteins c-myc/metabolism , Receptors, Calcitriol , Receptors, Steroid/metabolism , Tumor Cells, CulturedABSTRACT
The yields of disaccharide glycosylation products in tetramethylammonium bromide or silver triflate-collidine activated reactions between hindered alcohols and glycosyl halides were not greatly ++affected when a pressure of 15 kbar was applied. The formation of orthoester products was greatly increased under pressure. When orthoester formation was not possible both disaccharides and the related N-glycosyl collidinium salts were found.
Subject(s)
Alcohols/chemistry , Pyridines/chemistry , Carbohydrate Sequence , Disaccharides/chemical synthesis , Glycosylation , Molecular Sequence Data , Molecular Structure , Salts/chemical synthesisABSTRACT
The thioanhydride of the herbicide endothall is highly toxic to mice on intraperitoneal (ip) administration, with an LD50 of 0.31 mg/kg compared to 4.0 and 14 mg/kg for the corresponding anhydride and dicarboxylic acid, respectively. This unusually high toxicity of the thioanhydride relative to the anhydride and dicarboxylic acid is observed also for the 5,6-dehydro analogue and less so for the 2-methyl and 5-endo-(cyanomethyl) analogues but not for five related series of 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acids, anhydrides, and thioanhydrides with various 2-, 3-, 5- and 6-substituents. Synthesis of [exo,exo-5,6-3H]endothall thioanhydride ([3H]ETA) allowed radioligand binding studies with mouse liver cytosol, which was found to have a high-affinity binding site (apparent dissociation constant 32 nM, maximum number of binding sites 2.8 pmol/mg of protein, greater than 95% specific binding). The potency of 18 endothall analogues as dicarboxylic acids and anhydrides for inhibiting [3H]ETA binding in vitro is a very good predictor of their mouse toxicity (r = 0.95, n = 16; two related compounds are of low activity in both assays) in a similar manner to earlier studies with [3H]-2,3-dimethylendothall anhydride (cantharidin) (r = 0.83, n = 15). This correlation does not extend to most of the thioanhydrides, particularly the 2,3-dimethyl and 2,3-trimethylene compounds, which are the most stable to hydrolytic cleavage. The [3H]ETA binding site of liver cytosol is inhibited 75-80% by LD50 doses of 2,3-dimethylendothall anhydride and thioanhydride but only 24% by an LD50 dose of endothall thioanhydride, with assays 30 min after ip treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Dicarboxylic Acids/toxicity , Liver/metabolism , Anhydrides/metabolism , Anhydrides/toxicity , Animals , Binding Sites , Cantharidin/toxicity , Dicarboxylic Acids/metabolism , Hydrolysis , Lethal Dose 50 , Male , Mice , Structure-Activity RelationshipABSTRACT
The biological activity and the binding affinity for the 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] intestinal receptor of a new fluorine-containing vitamin D compound, namely 6-fluoro-vitamin D3 (6-F-D3), is reported. A significant interaction of 6-F-D3 with the 1,25(OH)2D3 receptor was found, with a relative competitive index (RCI) of 0.26 +/- 0.04, which is intermediate between 25-hydroxyvitamin D3 (0.14 +/- 0.01) and 1 alpha-hydroxyvitamin D3 (0.46 +/- 0.08), where the RCI of 1,25(OH)2D3 is defined to be 100. In contrast, vitamin D3 was unable to interact with the 1,25(OH)2D3 receptor. Also, the biological activity of 6-F-D3 was assessed in vivo in the vitamin D-deficient chick. 6-F-D3 at doses up to 130 nmol displayed no biological action on either intestinal calcium absorption (ICA) or bone calcium mobilization (BCM) over the time interval of 14-48 h after dosing. However, when 130 nmol 6-F-D3 was given 2 h before and 6 h after vitamin D3 (1.62 nmol), a significant inhibition of vitamin D-mediated ICA was noted. Also, a dose of 130 nmol 6-F-D3 given 2 h before and 6 h after 1,25(OH)2D3 (0.26 nmol) significantly inhibited ICA, as measured at 12 h. 6-F-D3 is the first vitamin D analog found which has an ability to both bind to the 1,25(OH)2D3 receptor and to antagonize the production of biological responses by 1,25(OH)2D3.
Subject(s)
Calcitriol/metabolism , Cholecalciferol/antagonists & inhibitors , Cholecalciferol/pharmacology , Intestinal Mucosa/metabolism , Receptors, Steroid/metabolism , Animals , Biological Assay , Calcium/metabolism , Chickens , Cholecalciferol/toxicity , Intestinal Absorption/drug effects , Kinetics , Receptors, Calcitriol , Receptors, Steroid/drug effects , Vitamin D Deficiency/metabolismABSTRACT
Control of the band width of the irradiating light between 280 and 310 nm and of the temperature of the reaction permits formation of 1 alpha-hydroxyprevitamin D3 in yields of over 80%, at 40-60% conversion of the 1 alpha-hydroxyprovitamin D3. The procedures developed permit doubling the photochemical yield of the 1 alpha-hydroxyvitamin D3 compounds which are the major circulatory forms of vitamin D3.
