Synthesis and biological evaluation of thieno [2',3':4,5]pyrimido[1,2-b][1,2,4]triazines and thieno[2,3-d][1,2,4]triazolo[1,5-a]pyrimidines as anti-inflammatory and analgesic agents.

A new series of thieno[2',3':4,5]pyrimido[1,2-b][1,2,4]triazines and thieno[2,3-d][1,2,4]triazolo[1,5-a]pyrimidines was synthesized. The newly synthesized compounds were evaluated for their anti-inflammatory and analgesic activity using diclofenac Na as a reference standard. Additionally, the ulcerogenic effects and acute toxicity (ALD50) values of the active compounds were also determined. In general, the thieno[2,3-d][1,2,4]triazolo[1,5-a]pyrimidine derivatives exhibited better biological activities than the thieno[2',3':4,5]pyrimido[1,2-b][1,2,4]triazines. Collectively, the thienotriazolopyrimidine derivatives 9, 13 and 14a were proved to display distinctive anti-inflammatory activity at the acute and subacute models as well as good analgesic profile with a delayed onset of action. Moreover, they revealed good gastrointestinal safety profile and are well tolerated by experimental animals with high safety margin (ALD50 > 0.3 g/kg).