Biological Activities and In Silico Molecular Docking of an Aqueous Extract of Nigella sativa L. Seeds: A Focus on Antioxidant, Cytotoxic, and Diuretic Effects

Abstract

Background: Nigella sativa L. is a medicinal plant widely recognized for its diverse pharmacological properties. This study aimed to evaluate the antioxidant, diuretic, and cytotoxic effects of an aqueous seed extract and its effects on selected biochemical parameters in rats. The pharmacokinetic potential of identified bioactive compounds was also investigated in silico. Methods: The aqueous extract was prepared by maceration. Antioxidant activity was assessed using DPPH, reducing power, and total antioxidant capacity (TAC) assays. We evaluated the diuretic effect in vivo in Wistar rats by measuring urinary concentrations of Na+, K+, Cl−, and creatinine, using furosemide as a reference drug. Cytotoxicity was assessed in splenocytes and thymocytes. We analyzed seven identified compounds in silico for physicochemical properties, Lipinski compliance, intestinal absorption, cytochrome P450 inhibition, and blood–brain barrier permeability. Results: The extract showed significant antioxidant activity, with a DPPH IC50 of 0.254 ± 0.002 mg/mL and a TAC of 125.01 ± 4.220 mg AAE/g. It significantly increased urinary electrolyte and urinary concentration, indicating a diuretic effect lower than that of furosemide. Plasma analyses showed decreased electrolyte concentrations and increased creatinine levels. Cell viability exceeded 90%, indicating no significant cytotoxicity. Most compounds complied with Lipinski’s rule of five and showed favorable predicted intestinal absorption, with limited cytochrome P450 inhibition. Several compounds were predicted to cross the blood–brain barrier. Conclusions: The aqueous extract of N. sativa demonstrated antioxidant and diuretic activities without significant cytotoxicity. These findings support its pharmacological potential and warrant further investigation of its mechanisms of action and therapeutic relevance.