BEHAVIOURAL AND BIOCHEMICAL INDICATIONS OF THE ANTIDEPRESSANT ACTIVITIES OF ESSENTIAL OIL FROM NIGELLA SATIVA LEAF IN RATS

Abstract

Background:  Nigella sativa (Ranunculaceae) is a medicinal plant traditionally used to treat neurological disorders such as depression, epilepsy, pain, neurotoxicity, and memory impairment.

Objective: This study aimed to evaluate the antidepressant potential of Nigella sativa leaf essential oil using in vitro enzyme-based analysis and in vivo experiments on animal models.

Materials and Methods: The chemical constituents of NSEO were identified by Gas Chromatography–Mass Spectrometry (GC–MS) using a Thermo Trace1300–TSQ 8000 system equipped with a 30 m × 0.25 mm BP-5MS column (0.25 μm film thickness). Antidepressant activity was initially assessed by evaluating inhibition of total MAO and MAO-A. For the in vivo study, fifty-four Wistar rats were randomly divided into six groups (n = 6): normal control, UCMS control, fluoxetine-treated, and NSEO-treated groups (100, 200, and 400 mg/kg, p.o.). Following 42 days of UCMS exposure, antidepressant activity was assessed using the tail suspension test. Brain oxidative stress markers, including thiobarbituric acid-reactive substances (TBARS), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and nitrite levels, were also determined.

Results: GC–MS analysis identified 84 volatile constituents, with thymoquinone, o-cymene, and α-pinene as the predominant compounds. NSEO selectively inhibited total MAO and MAO-A at 25–800 µg/mL, although reduced selectivity at 800 µg/mL suggested additional MAO-B inhibition. NSEO exhibited antidepressant-like effects by reducing immobility time, inhibiting MAO, highlighting its potential as a natural therapy for depression.

Conclusion: The volatile oil of Nigella sativa shows strong antidepressant effects by reducing depression and protecting key organ functions.