Synthesis of phlorizin derivatives and their inhibitory effect on the renal sodium/D-glucose cotransport system.
To characterize further the Na+/D-glucose cotransport system in renal brush border membranes, phlorizin - a potent inhibitor of D-glucose transport - has been chemically modified without affecting the D-glucose moiety or changing the side groups that are essential for the binding of phlorizin to the Na+/D-glucose cotransport system. One series of chemical modifications involved the preparation of 3-nitrophlorizin and the subsequent catalytic reduction of the nitro compound to 3-aminophlorizin. From 3-aminophlorizin, 3-bromoacetamido-, 3-dansyl- and 3-azidophlorizin have been synthesized. In another approach, 3'-mercuryphlorizin was obtained by reaction of phlorizin with Hg(II) acetate. The phlorizin derivatives inhibit sodium-dependent but not sodium-independent D-glucose uptake by hog renal brush border membrane vesicles in the following order of potency: 3'-mercuryphlorizin = phlorizin greater than 3-aminophlorizin greater than 3-bromoacetamidophlorizin greater than 3-azidophlorizin greater than 3-nitrophlorizin greater than 3-dansylphlorizin. 3-Bromoacetamidophlorizin - a potential affinity label - also inhibits sodium-dependent but not sodium-independent phlorizin binding to brush border membranes. In addition, sodium-dependent phosphate and sodium-dependent alanine uptake are not affected by 3-bromoacetamidophlorizin. The results described above indicate that specific modifications of the phlorizin molecule at the A-ring or B-ring are possible that yield phlorizin derivatives with a high affinity and high specificity for the renal Na+/D-glucose cotransport system. Such compounds should be useful in future studies using affinity labeling (3-bromoacetamido- and 3-azidophlorizin) or fluorescent probes (3-dansylphlorizin).
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D010695:Phlorhizin / Q000031:analogs & derivatives* / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013552:Swine
D012964:Sodium; D010695:Phlorhizin; D005947:Glucose