Bioactive assessment of hexahydroquinoline derivatives prepared <i>via</i> a biochar/Fe ₃ O ₄ @APTMS magnetic catalyst: focus on antidiabetic and antibacterial properties

This study aims to develop a green and effective magnetic catalyst, biochar/Fe₃O₄@APTMS, for the one-pot synthesis of bioactive hexahydroquinolines derivatives. Following synthesis, some biological activities were assessed including antibacterial activity and antidiabetic potential through polyol inhibition assays. The reaction involved four-component condensation of ammonium acetate, malononitrile or ethylcyanoacetate, dimedone (5,5-dimethyl-1,3-cyclohexanedione) and some aromatic aldehydes by refluxing in ethanol to afford products in high yields (91-97%) in a short time (10 minutes). Additionally, heterogeneous catalyst provides several advantages, including operational simplicity, rapid reaction times, easy product isolation, and recyclability of unreacted starting materials. The nano catalyst was fully characterized with Fourier Transform Infrared Spectroscopy (FT-IR), Raman, Field Emission Scanning Electron Microscopy (FE-SEM), and energy dispersive X-ray mapping (EDX-Map) while the characterization of the products with Nuclear magnetic resonance spectroscopy (¹³C NMR and ¹H NMR) confirmed their structure. Some of the compounds tested showed moderate but significant antidiabetic activity against aldose reductase (IC₅₀ values 4.03 to 18.29 μg mL^-1) and antibacterial activity against Gram-positive strains of bacteria, <i>Staphylococcus aureus</i> and <i>Enterococcus faecalis</i>, with inhibition zones up to 15.5 mm. These results showed promise for the compounds being used as dual-function therapeutic agents for diabetic complications and microbial infection.