The prostaglandin-endoperoxide synthase (PGES) and cytochrome P-450 are key enzymes in human, which are responsible for analgesic effect and toxicity of acetaminophen, respectively. Acetaminophen or paracetamol is a widely used over-the-counter analgesic and antipyretic drug and appears to be safe if used in normal therapeutic doses, but large doses of ACP produce hepatic and/or renal injury in humans and in experimental animals. At moment, the design of new acetaminophen derivatives has few impacts for its clinical applications of safe acetaminophen derivative. Thus, in this work a series of acetaminophen derivatives based on chalcone and hydrazone analogy was been investigated using quantum chemical calculations at the DFT/B3LYP theory level, with the 6-31G* basis sets. The HOMO, IP, BDEOH, and spin density contribution for the oxidation of an initial electron or hydrogen atom abstraction from the phenolic hydroxyl group was related with the quenching reactivity of tyrosyl radical to give N-acetyl-p-benzosemiquinone imine (NAPSQI). The second hydrogen abstraction was related with the chemistry reaction between amide group and hydroxyl radical to give N-acetyl-p-benzoquinone imine (NAPQI). The lowest BDEOH values were related with higher quenching values of the tyrosyl radical and the stability was related with the spin density for the initial electron or hydrogen abstractions. The highest BDENH values were related with small NAPQI formation and LUMO values with reactivity of NAPQI-like Michael system. Our results showed that some analogous may be a good strategy for safer drug design of analgesic compounds. The compounds were synthesized and their antioxidant property was estimated using theoretical methods. Some compounds can be good antioxidant. A proposed mechanism for the interaction between hydrazone derivatives and PGES was realized using molecular properties.
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