Quercetin qu

Gallic acid and Folin-Ciocalteu were purchased from Sigma-Aldrich USA and Merck (Damstadt, Germany) respectively. Potassium ferricyanide, potassium acetate, phosphate buffer, catechin (CA), ferrous ammonium sulphate, ascorbic acid (AA), aluminium chloride (AlCl₃), Trichloro acetic acid (TCA), sodium phosphate, ammonium molybdate, tannic acid, quercetin (QU), ethylenediamine tetra acetic acid (EDTA), acetyl acetone and ferric chloride (FeCl₃) were purchased from Sigma Chemical Co. (St. Louis, MO, USA).

Fetal bovine serum (FBS), f-MLP (N-Formylmethionyl-leucyl-phenylalanine), luminol, HEPES solution, RPMI 1640 medium, and L-glutamine were purchased from Sigma-Aldrich Chemie GmbH (Steinheim, Germany). Phosphate-buffered saline (PBS Ca²⁺-free) and penicillin-streptomycin were purchased from Gibco (Grand Island, USA). Lipopolysaccharide (LPS from Escherichia coli 0111:B4) was purchased from Merck (Kenilworth, USA). Pancoll human was obtained from PAN Biotech (Aidenbach, Germany). Human Quantikine ELISA Kits and propidium iodide were purchased from BD Biosciences (San Jose, USA). Dexamethasone (DEX) and quercetin (QU) (> 95% UHPLC purity) were purchased from Sigma-Aldrich GmbH (Steinheim, Germany). Acetonitrile, methanol, and formic acid for UHPLC were purchased from Merck (Darmstadt, Germany). Water for UHPLC was purified with a Millipore Simplicity System (Bedford, USA). All solvents used for chromatography were of HPLC grade. Absorbance and luminescence were measured using a BioTek microplate reader (Highland Park, USA). Flow cytometry was performed using a BD FACSCalibur apparatus (BD Biosciences, San Jose, USA). Brain-heart infusion broth (BHI) and Mueller-Hinton broth (MH cation-adjusted) were purchased from Becton Dickinson (Franklin Lakes, USA).

Quercetin (Qu) and l-arginine (l-Arg) were purchased from Sigma (St. Louis, MO, USA) and LOBA Chemie (India), respectively. Copper oxide nanoparticles (CuO: size 20–30 nm, purity 99.5%, spherical in shape, black powder, specific surface 43.2 m²/g, phase monoclinic, batch # 123332390) were obtained from ROTH (Germany).