Identification of 3-hydroxy-4[3,4-dihydro-3-oxo-2H-1,4-benzoxazin-4-yl]-2,2-dimethyldihydro-2H-benzopyran derivatives as potassium channel activators and anti-inflammatory agents

The present study described the design, synthesis and identification of 3-hydroxy-4[3,4-dihydro-3-oxo-2H-1,4-benzoxazin-4-yl]-2,2-dimethyldihydro-2H-benzopyran derivatives. Their biological activity was tested for KATP channel opener as antihypertensives, COX-1 and COX-2 activity. The results were compared with the activity of cromakalim, ibuprofen and celecoxib. The study aimed at exploring the influence of introduction of a benzoxazine substituent at position 6 of various derivatives of benzopyrans in order to improve biological activity. Several compounds were found to be equipotent or even more potent than cromakalim. Out of these nitro-substituted benzopyrans, nitro substitution at benzoxazino group possessed potent antihypertensive activity in the R/S isomers. With amino derivatives, activity remains constant when compared with standard cromakalim. Similarly, compounds 17b, 17c, 17e and 17h have exhibited around 40 % inhibition of COX-1 as compared to the inhibition of COX-2. Only two compounds 17g and 17i exhibited effective inhibition more than 50 % of COX-2 compared with the inhibition of COX-1 at a concentration of 0.3 mg/ml.