Could solving one problem only cause another problem to be created? This is a fundamental question that we all must answer when trying something new – is there a possible trade off? We at SciZenna take questions like these seriously, as well as the rest of the scientific community. In a recent study, researchers from the University of Sulaimani investigated the antibacterial properties of black seed oil as well as the cytotoxicity of black seed oil to human cells. In general, the researchers wanted to test the hypothesis that not only does black seed oil exhibit antibacterial properties – but these antibacterial properties do not harm human cells.
The researchers first analyzed the chemical composition of black seed oil to confirm its constituents. Through Fourier-Transmission Infrared Spectorscopy (FTIR) analysis, the researchers confirmed the presence of various thymoquinone derivates, including dithymoquinone, thymohydroquinone, and of course, thymoquinone itself. Once the chemical composition was confirmed, the reserachers progressed to test the antibacterial effects against various strands of bacteria – strands including Escherichia coli(E. coli), pseudomonas aeruginosa (a disease causing, gram-negative bacteria), Salmonella entrica, Bacillus subtilis(a gram-positive bacteria), and Staphylococcus aureus (a dangerous gram-positive bacteria that can cause skin infections as well as heart valve infections). To test black seed oil’s antibacterial effects, the researchers cultivate each strand of bacteria on their own nutritional agar plates, then added 100 microliters of black seed oil to a single section of each plate – which the researchers coined the “inhibition zone”. The reserachers then observed the growth of bacteria to determine black seed oil’s antibacterial effectiveness.
What the researchers found was that the black seed oil was effective in disrupting the growth of gram-positive bacteria – bacteria such as Bacillus subtilis and the notorious Staphylococcus aureus. The exact mechanism for how black seed oil inhibits certain bacteria growth is still being investigated – but the initial hypothesis is indicating that the constituents of black seed oil, primarily thymoquinone, interact with the bacteria’s cell membrane – causing a disruption in the ion-transport chain which leads to the bacteria’s death. Further research is needed to understand black seed oil’s antibacterial selectivity of gram-positive bacteria versus gram-negative bacteria – however, the analysis for this research publication is not over.
The final question the researchers wanted to investigate was black seed oil’s cytotoxicity to human cells. In order to do so, the researchers examined black seed oil’s cytotoxicity tracking the percent of human peripheral blood mononuclear cells living at three different black seed oil concentrations (25, 50, an 100 micro-grams per milliliter). The researchers conducted triplicate measurements of a series of cell assay viability tests by exposing cells for 24, 48, and 72 hours at each dosage concentration. After analyzing the viability assays, the researchers found that black seed oil had no effect on the cell life spans. 
- Mohammed, S. J., Amin, H., Aziz, S. B., Sha, A. M., Hassan, S., Abdul Aziz, J. M., & Rahman, H. S. (2019). Structural Characterization, Antimicrobial Activity, and In Vitro Cytotoxicity Effect of Black Seed Oil. Evidence-based complementary and alternative medicine : eCAM, 2019, 6515671. doi:10.1155/2019/6515671