Antibacterial Activity of Nigella sativa L. Seed Extracts.

Most of the bacterial pathogens are resistant to existing synthetic antibacterial agents demanding an
increasing effort to seek effective phytochemicals as antibacterial agents against such pathogens. Nigella sativa
L. (black cumin) seeds play an important role in folk medicine and some of its major constituents are reported
to be pharmacologically active. In this present work, black cumin seed extracts were obtained using
supercritical carbon dioxide (SCCO2) and conventional soxtec extraction using various organic solvents. The
antibacterial activities of the extracts were investigated by the agar dilution method against Gram-positive
bacteria (Bacillus cereus F 4810 and Staphylococcus aureus FRI 722) and Gram-negative bacteria (Escherichia
coli MTCC 108 and Yersinia enterocolitica MTCC 859). SCCO2-1 (120 bar/40ºC) extract showed effective
growth inhibition than conventional solvent extracts against all the tested bacteria. Further the antibacterial
principle present in the extract was isolated and characterized found to be thymoquinone.