Synthesis, anti-inflammatory activity, and molecular docking studies of some novel Mannich bases of the 1,3,4-oxadiazole-2(3H)-thione scaffold.

A series of novel ibuprofen and salicylic acid-based 3,5-disubstituted-1,3,4-oxadiazole-2(3H)-thione derivatives was synthesized, and they were evaluated as potential anti-inflammatory agents. Following the structure identification studies employing IR, 1 H nuclear magnetic resonance (NMR), 13 C NMR, and elemental analysis, the title compounds were tested by cyclooxygenase (COX)-1 and COX-2 inhibition assays concomitant to lipopolysaccharide (LPS)-induced nitric oxide and prostaglandin production prevention experiments. The results indicated that the majority of the compounds displayed either a superior or comparable activity in preventing both LPS-induced NO production and COX-1 activity in comparison to the activities of the reference molecules. Furthermore, docking studies were also performed to reveal possible interactions with the COX enzymes.

Marginally designed new profen analogues have the potential to inhibit cyclooxygenase enzymes.

The current structure-activity relationship of profens (i.e., 2-arylpropionic acid derivatives, a class of non-steroidal anti-inflammatory drugs) discusses the importance of α-monomethyl substitution on these compounds, since the activities obtained through their corresponding arylacetic acid derivatives (i.e., α-demethylated derivatives) or α,α-dimethyl-substituted compounds are less than what is observed for the parent profens. Unfortunately, this implies a generalization in structure-activity relationships of profens in such a way that a mono-(non-methyl)alkyl group or dialkyl substituent replaced at the α-position of a profen analogue results in abolished activity. Therefore, within this study, we aimed to question this generalization employing ibuprofen, flurbiprofen, and naproxen as model compounds. A series of α-(non-methyl)alkyl-substituted ibuprofen and flurbiprofen analogues as well as α,α-dialkyl-substituted ibuprofen, flurbiprofen, and naproxen derivatives were synthesized and screened for their potential to inhibit cyclooxygenase enzymes. In addition, since profens have negligible potential to inhibit lipoxygenase enzymes, the effect of such derivatization was also questioned in lipoxygenase inhibition assays. The findings only partially agreed with the current structure-activity approach of profens and the activity results of some compounds were found as beyond ordinary.