Tailoring the Substitution Pattern on 1,3,5-Triazine for Targeting Cyclooxygenase-2: Discovery and Structure–Activity Relationship of Triazine–4-Aminophenylmorpholin-3-one Hybrids that Reverse Algesia and Inflammation in Swiss Albino Mice

Here,
we report analgesic and anti-inflammatory activity of a series
of compounds obtained by appending 4-aminophenylmorpholin-3-one and
acyclic, cyclic, or heterocyclic moieties on 1,3,5-triazine. The structures
of compounds 4b and 6b are optimized for
the best inhibition of COX-2 with IC50 values of 0.06 and
0.08 μM, respectively, and selectivity over COX-1 of 166 and
>125, respectively. At the dose of 5 mg kg–1,
these
compounds significantly reduced acetic acid induced writhings, and
their ED50 values were found to be 2.2 and 1.9 mg kg–1, respectively. Besides the cell-based and animal-based
experiments showing the modes of action of these compounds targeting
COX-2, the interaction behavior of 4b with COX-2 was
also characterized, with physicochemical experiments including ITC,
NMR, UV–vis, and molecular-modeling studies. Characteristically,
these compounds interact with R120, Y355, and W385, the residues responsible
for holding the substrate and mediating the process of electron transfer
during the metabolic phase of the enzyme.

本研究报道了一类通过将4-氨基苯基吗啉-3-酮（4-aminophenylmorpholin-3-one）与无环、环状或杂环基团连接至1,3,5-三嗪（1,3,5-triazine）骨架所得到的化合物的镇痛与抗炎活性。化合物4b与6b的结构经过优化，以实现对环氧合酶-2（COX-2）的最优抑制效果，其半最大抑制浓度（IC50）分别为0.06 μM与0.08 μM，相对于环氧合酶-1（COX-1）的选择性比值分别为166与>125。在5 mg·kg⁻¹的给药剂量下，此类化合物可显著抑制乙酸诱导的扭体反应，其半数有效剂量（ED50）分别为2.2 mg·kg⁻¹与1.9 mg·kg⁻¹。除了通过细胞实验与动物实验阐明了这类化合物靶向COX-2的作用机制外，本研究还通过等温滴定量热法（ITC）、核磁共振波谱法（NMR）、紫外-可见分光光度法（UV–vis）以及分子建模研究，表征了化合物4b与COX-2的相互作用行为。特征性地，此类化合物可与酶代谢阶段负责结合底物并介导电子传递过程的残基R120、Y355及W385产生相互作用。