Abstract
Moringa oleifera leaves have long been used in conventional medicine to treat a variety of ailments, including fever and sore throat. The close relationship between plants and human health has promoted the development of plant-based therapies, such as pharmaceuticals and nutritional supplements, thereby advancing traditional medicine and adding value to agriculture. In the present study, novel thiadiazole, Schiff base, and tetrazoline derivatives (H1, H2, and H3) were synthesized from nitrile-containing precursors obtained from the aqueous extract of Moringa oleifera leaves. The synthesis involved the reaction of the nitrile compound with thiourea in the presence of glacial acetic acid to form a heterocyclic thiadiazole intermediate, followed by condensation with an aromatic aldehyde to yield Schiff bases, and subsequent reaction with sodium azide to produce tetrazoline derivatives. The synthesized compounds were characterized by Fourier-transform infrared spectroscopy (FT-IR), melting point determination, and ¹H NMR spectroscopy. The biological activities of derivatives H1–H3 were evaluated against Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and the fungal strain Candida albicans. Compared with standard drugs—ciprofloxacin for antibacterial activity and ketoconazole for antifungal activity—compound H3 exhibited superior antibacterial and antifungal activities. In addition, H3 demonstrated excellent antioxidant activity relative to ascorbic acid. POM analysis was further employed to identify promising pharmacophore sites within the synthesized compounds, highlighting their potential for pharmaceutical applications.