The 2H-1,4-benzoxazine derivatives are novel drugs structurally similar to nucleotides; however, their actions on the pancreatic beta-cell ATP-sensitive-K+(KATP) channel and on glucose disposal are unknown. Therefore, the effects of the linear/branched alkyl substituents and the aliphatic/aromatic rings at position 2 of the 2H-1,4-benzoxazine nucleus on the activity of these molecules against the pancreatic beta-cell KATP channel and the Kir6.2C36 subunit were investigated using a patch-clamp technique. The effects of these compounds on glucose disposal that followed glucose loading by i.p. GTT and on fasted glycemia were investigated in normal mice. The 2-n-hexyl analog blocked the KATP(IC50=10.1x10-9M) and Kir6.2C36(IC50=9.6x10-9M) channels which induced depolarization. In contrast, the 2-phenyl analog was a potent opener(DE50=0.04x10-9M), which induced hyperpolarization. The ranked order of the potency/efficacy of the analog openers was 2-phenyl>2-benzyl>2-cyclohexylmethyl. The 2-phenylethyl and 2-isopropyl analogs were not effective as blockers/openers. The 2-n-hexyl (2-10 mg kg-1) and 2-phenyl analogs (2-30 mg kg-1) reduced and enhanced the glucose AUC curves, respectively, following the glucose loading in mice. These compounds did not affect the fasted glycemia as is observed with glibenclamide. The linear alkyl chain and the aromatic ring at position 2 of the 1,4-benzoxazine nucleus are the determinants, which respectively confer the KATP channel blocking action with glucose lowering effects and the opening action with increased glucose levels. The opening/blocking actions of these compounds mimic those that were observed with ATP and ADP. The results support the use of these compounds as novel anti-diabetic drugs.
- Received July 7, 2011.
- Revision received October 24, 2011.
- Accepted October 24, 2011.
- The American Society for Pharmacology and Experimental Therapeutics