A series of sixteen ring-substituted N-arylcinnamanilides, previously described as highly antimicrobially effective against a wide spectrum of bacteria and fungi, together with two new derivatives from this group were prepared and characterized. Moreover, the molecular structure of (2E)-N-(2-bromo-5-fluorophenyl)-3-phenylprop-2-enamide as a model compound was determined using single-crystal X-ray analysis. All the compounds were tested for their anti-inflammatory potential, and most tested compounds significantly attenuated the lipopolysaccharide-induced NF-κB activation and were more potent than the parental cinnamic acid. (2E)-N-[2-Chloro-5-(trifluoromethyl)phenyl]-3-phenylprop-2-enamide, (2E)-N-(2,6-dibromophenyl)-3-phenylprop-2-enamide, and (2E)-N-(2,5-dichlorophenyl)-3-phenylprop-2-enamide demonstrated the highest inhibition effect on transcription factor NF-κB at the concentration of 2 µM and showed a similar effectiveness as the reference drug prednisone. Several compounds also decreased the level of TNF-α. Nevertheless, subsequent tests showed that the investigated compounds affect neither IκBα level nor MAPKs activity, which suggests that the N-arylcinnamanilides may have a different mode of action to prednisone. The modification of the C (2,5) or C (2,6) positions of the anilide core by rather lipophilic and bulky moieties seems to be preferable for the anti-inflammatory potential of these compounds.Molecules 2019, 24, 4531 2 of 15 drugs are directly obtained from plants or fungi or are "nature-inspired" [11]. One such molecule is cinnamic acid (CA). It is a small organic molecule, which can be found in many kinds of plants in pure form or as a part of more complicated structures. CA and its natural and synthetic derivatives possess many interesting biological effects, such as antimicrobial [12,13], anticancer [14], anti-oxidant [13], and anti-inflammatory activities [15].N-Arylcinnamides represent a group of synthetic derivatives of CA. This group of compounds possesses several potentially active moieties-styryl, amide (peptide-like [16]) bond, and aryl [17][18][19][20][21][22]. Thus, cinnamides can be considered as a privilege structure or a scaffold (a part) of more complex molecules in medicinal chemistry [23,24] The series of N-arylcinnamide derivatives presented in this work was previously tested for their anti-microbial activity (compounds 1-15 and 17) [25,26], and three new derivatives 16 and 18 were prepared and characterized. Based on the concepts of polypharmacology, multifactorial diseases, and multitarget drugs [27], as well as the above-mentioned results, a group of eighteen N-arylcinnamanilides was chosen for the screening of their ability to moderate the inflammation-like reaction in vitro.
Results and Discussion
ChemistryThe investigated compounds (previously published compounds 1-15 and 17 [25] and two new compounds, 16 and 18) were prepared using a one-step microwave-assisted synthesis, see Scheme 1. Briefly, the carboxyl group of CA was activated with phosphorus trichloride, and then...