IN VITRO ANTITUBERCULOUS ACTIVITY OF THYMOQUINONE, AN ACTIVE PRINCIPLE OF NIGELLA SATIVA

Abstract

Background: Nigella sativa seed has been used in folk medicine against many ailments including
infections. The present study was aimed to investigate activity of thymoquinone, in vitro, against
clinical isolates of Mycobacterium tuberculosis. Methods: Mycobacteria obtained from patients of
King Fahd Hospital of University, Alkhobar, Saudi Arabia were subcultured at 37 °C in MGIT tubes
containing Middlebrook broth and OADC growth supplement and growth detected by BACTEC
MicroMGIT fluorometer on day 10. Mycobacteria were then inoculated in MGIT tubes containing
thymoquinone 2.5, 5, 10, 20, 40, 80 ï­g/ml, streptomycin 1.25 ï­g/ml or controls in Middlebrook broth
plus supplement, incubated at 37 °C for 14 days and read daily for fluorescence. In addition, isolates
were inoculated in culture tubes containing Middlebrook agar (plus supplement) in presence of
thymoquinone 2.5, 5, 10, 20, 40, 80 ï­g/ml, streptomycin 1.25 ï­g/ml or controls, and incubated at 37 °C
for 4 weeks. Results: In Middlebrook broth, fluorescence test for tuberculosis was negative with
thymoquinone 20, 40 and 80 ï­g/ml and streptomycin 1.25 ï­g/ml up to day 14th. With controls,
thymoquinone 2.5, 5 and 10 ï­g/ml fluorescence was detectable from day 10 to 14. In Middlebrook
agar, there was no visible growth of tubercle bacillus with thymoquinone 20, 40 and 80 ï­g/ml and
streptomycin 1.25 ï­g/ml, however, with controls, thymoquinone 2.5 and 5 ï­g/ml abundant and with 10
ï­g/ml few colonies were observed. Conclusions: Thymoquinone possesses activity against M.
tuberculosis with MIC of 20 ï­g/ml and has potential for further investigation. Our study confirms the
benefit of N. sativa in native medicine against chest infection.
Keywords: Nigella sativa, thymoquinone, Mycobacterium tuberculosis, Micro MGIT fluorometer,
Middlebrook broth, Middlebrook agar