Antimicrobial Properties and Therapeutic Potential of Bioactive Compounds in Nigella sativa: A Review

Abstract

Nigella sativa (N. sativa; Ranunculaceae), commonly referred to as black cumin, is one of the most widely used medicinal plants worldwide, with its seeds having numerous applications in the pharmaceutical and food industries. With the emergence of antibiotic resistance in pathogens as an important health challenge, the need for alternative microbe-inhibitory agents is on the rise, whereby black cumin has gained considerable attention from researchers for its strong antimicrobial characteristics owing to its high content in a wide range of bioactive compounds, including thymoquinone, nigellimine, nigellidine, quercetin, and O-cymene. Particularly, thymoquinone increases the levels of antioxidant enzymes that counter oxidative stress in the liver. Additionally, the essential oil in N. sativa seeds effectively inhibits intestinal parasites and shows moderate activity against some bacteria, including Bacillus subtilis and Staphylococcus aureus. Thymoquinone exhibits minimum inhibitory concentrations (MICs) of 8-16 μg/mL against methicillin-resistant Staphylococcus aureus (MRSA) and exhibits MIC 0.25 µg/mL against drug-resistant mycobacteria. Similarly, quercetin shows a MIC of 2 mg/mL against oral pathogens, such as Streptococcus mutans and Lactobacillus acidophilus. Furthermore, endophytic fungi isolated from N. sativa have demonstrated antibacterial activity. Therefore, N. sativa is a valuable medicinal plant with potential for medicinal and food-related applications. In-depth exploration of the corresponding therapeutic potential and scope of industrial application warrants further research.

Keywords: Nigella sativa; antibiotic; antimicrobial; bioactive compounds; medicinal plant; microorganisms; thymoquinone.

Figure 1

Nigella sativa used in different traditional medical systems for the treatment of various diseases.

Figure 2

(a) Chemical structures of key bioactive compounds from Nigella sativa. (b) The graph illustrates the relative prevalence of thymoquinone, p-cymene, camphene, thymol, terpinol, and alpha-thujene, highlighting their significance among the wide range of bioactive constituents found in Nigella sativa. The compounds were quantified using different techniques, such as gas chromatography (GC) and mass spectrometry (MS), followed by different extraction methods, such as supercritical fluid and Soxhlet extraction.

Figure 2

(a) Chemical structures of key bioactive compounds from Nigella sativa. (b) The graph illustrates the relative prevalence of thymoquinone, p-cymene, camphene, thymol, terpinol, and alpha-thujene, highlighting their significance among the wide range of bioactive constituents found in Nigella sativa. The compounds were quantified using different techniques, such as gas chromatography (GC) and mass spectrometry (MS), followed by different extraction methods, such as supercritical fluid and Soxhlet extraction.

Figure 3

Schematic illustration of the proposed immunomodulatory pathways of thymoquinone. Thymoquinone stimulates B and T lymphocyte activation, promotes antibody production, regulates the release of cytokines (TNF, IL-1, and IL-6), and increases the cytotoxicity of NK cells.

Figure 4

Nigella sativa exhibits protective effects against bacteria, fungi, parasites, and viruses through diverse and potent defense mechanisms.

Figure 5

The schematic illustration demonstrates how thymoquinone reduces nitric oxide (NO) and inflammatory mediators, potentially alleviating symptoms and decreasing the likelihood of additional health complications in tuberculosis (TB). Additionally, the image emphasizes targeting type 2 alveolar cells by mycobacterium tuberculosis (MTB), underscoring the promising potential of thymoquinone in combating this infectious respiratory disease.