Planejamento e síntese de novos derivados relacionados ao piroxicam

Abstract

Piroxicam is a drug belonging to the group of oxicams, derived from phenolic acids, in the class of NSAIDs. Although not the drug of choice in some treatments, the drug is indicated for the treatment of acute musculoskeletal disorders, post-traumatic and postoperative pain, rheumatoid arthritis and osteoarthritis, primary dysmenorrhea, endometriosis and hemorrhagic cyst. Like non-steroidal anti-inflammatory drugs, piroxicam is able to inhibit prostaglandin synthesis from arachidonic acid by competitively reversible inhibition of COX activity, with some predominance to inhibit COX-2 activity. Photosensitivity is one of the adverse effects caused by the drug, being observed in about 1% of patients. In addition, various techniques have been used to improve the stability of piroxicam without diminishing its potential. Thus, the objective of this paper is to plan, synthesize and evaluate more stable derivatives related to the phototoxicity of the study drug. Calculations of electronic properties such as high energy occupied molecular orbital (HOMO), low energy occupied molecular orbital (LUMO) and ionization potential (IP), as well as reactivity index calculations (Mulliken, CHELPG and Fukui) were calculated. performed using the Gaussview and Gaussian 2009 packages. The proposed derivatives have been synthesized through classical reactions such as esterification and nucleophilic substitution and are in the process of purification. The results of the HOMO and LUMO values showed that the D4 molecule has a better electronic distribution, with the second lowest HOMO value and the highest LUMO value, and can be considered the most stable. The D6 molecule proved to be the most reactive derivative and this can be explained by the presence of two hydroxyls in the naphthalene ring of the derivative, influencing the reactivity of the molecule. Based on the GAP values, the nitrated derivative (D2) presented lower value (3.36 eV), indicating high reactivity. The D4 molecule presented the highest GAP value, confirming its stability. In the analysis of Mulliken, CHELPG and Fukui loads of piroxicam, differences in substitution orientation were observed, probably due to the difference in calculations performed for each index. In the theoretical results of the chemical reactivity study using UV-Vis, piroxicam and its naphthalenic derivative showed completely different profiles, referring to its three main peaks, being the most expressive in the C = C system, indicating that in the benzothiazine system it functions as a reactive alkene after energy absorption.Thus, the molecular modification by the naphthalene system presented a compound with higher chemical stability and lower reactivity.