ABSTRACT
NADPH oxidases are pharmacological targets for the treatment of inflammation-based diseases. This work presents the synthesis and study of a caffeic acid/phthalimide hybrid compound (C2) as a potential inhibitor of NADPH oxidases. Throughout the study, we have compared compound C2 with its precursor caffeic acid (C1). The redox properties were compared using three different antioxidant methodologies and showed that C2 was slightly less effective than C1, a well-established and robust antioxidant. However, C2 was three-fold more effective than albumin (used as a model protein). This chemical feature was decisive for the higher efficiency of C2 as an inhibitor of the release of superoxide anions by stimulated neutrophils and enzymatic activity of cell-free NADPH oxidase. Docking simulation studies were performed using the crystal structure of the recombinant dehydrogenase domain of the isoform NOX5 of C. stagnale, which retains the FAD cofactor (PDB: 5O0X). Considering that C2 could bind at the FAD redox site of NOX5, studies were conducted by comparing the interactions and binding energies of C1 and C2. The binding energies were -50.30 (C1) and -74.88 (C2) (kJ mol-1), which is in agreement with the higher efficacy of the latter as an NADPH oxidase inhibitor. In conclusion, incorporating the phthalimide moiety into caffeic acid was decisive for its effectiveness as an NADPH oxidase inhibitor.
ABSTRACT
The total phenolic content (TP) and antioxidant activity of the ethanolic extract and fractions that were obtained from the leaves of Nectandra hihua were assessed using different methods. The ethanolic extract (EE) and ethyl acetate fraction (EAF) had the best antioxidant capacity, which was comparable to butylated hydroxytoluene and quercetin (ABTS+ 2.55⯱â¯0.06, 3.54⯱â¯0.03â¯mmol TE/g; DPPH IC50 10.27⯱â¯0.05, 9.88⯱â¯0.02⯵g/mL; FRAP 2.17⯱â¯0.08, 2.38⯱â¯0.04â¯mmol TE/g; ORAC 5.16⯱â¯0.08, 5.35⯱â¯0.07â¯mmol TE/g; TP 568.05⯱â¯18.15, 397.20⯱â¯17.88â¯mg GAE/g, respectively). The cytoprotective effect, reactive oxygen species (ROS) and lipid peroxidation inhibitions on L929 fibroblasts irradiated with UVB (600â¯mJ/cm2) in pre- and post-treatments with EE and EAF were determined. These plant materials demonstrated high ROS scavenging activity and lipid peroxidation inhibition on L929 fibroblasts in both treatments, especially with pre-treatment (EE 38.47⯱â¯1.95% and EAF 40.20⯱â¯4.5% inhibition of ROS production, and EE 39.03⯱â¯3.33% and EAF 41.67⯱â¯7.6% of lipid peroxidation inhibition), indicating the best cytoprotection with pre-treatment (13.52⯱â¯1.66% and 13.34⯱â¯2.61% increases in cell viability). The antioxidant flavonoids quercitrin, avicularin, juglalin, afzelin and astragalin were isolated from EAF. The results obtained indicate that EE and EAF present photodamage attenuating potential against UVB-induced oxidative stress and can be useful as a starting point for developing dermatological products to prevent oxidative skin damage.
