An active principle ofNigella sativaL., thymoquinone, showing significant antimicrobial activity against anaerobic bacteria.
OBJECTIVE
Thymoquinone (TQ) is the major active principle ofNigella sativaseed (black seed) and is known to control many fungi, bacteria, and some viruses. However, the activity of TQ against anaerobic bacteria is not well demonstrated. Anaerobic bacteria can cause severe infections, including diarrhea, aspiration pneumonia, and brain abscess, particularly in immunodeficient individuals. The present study aimed to investigate thein vitroantimicrobial activity of TQ against some anaerobic pathogens in comparison to metronidazole.


METHODS
Standard, ATCC, strains of four anaerobic bacteria (Clostridium difficile,Clostridium perfringens,Bacteroides fragilis, andBacteroides thetaiotaomicron), were initially isolated on specialBrucellaagar base (with hemin and vitamin K). Then, minimum inhibitory concentrations (MICs) of TQ and metronidazole were determined against these anaerobes when grown inBrucellaagar, using serial agar dilution method according to the recommended guidelines for anaerobic organisms instructed by the Clinical and Laboratory Standards Institute.


RESULTS
TQ showed a significant antimicrobial activity against anaerobic bacteria although much weaker than metronidazole. MICs of TQ and metronidazole against various anaerobic human pathogens tested were found to be between 10-160 mg/L and 0.19-6.25 mg/L, respectively.


CONCLUSIONS
TQ controlled the anaerobic human pathogenic bacteria, which supports the use ofN. sativain the treatment of diarrhea in folk medicine. Further investigations are in need for determination of the synergistic effect of TQ in combination with metronidazole and the activity of derivatives of TQ against anaerobic infections.
Department of Pharmacology, College of Medicine, Northern Border University, Arar, Saudi Arabia.
Mohammad Akram
MA
Randhawa
Department of Community Medicine, College of Medicine, Northern Border University, Arar, Saudi Arabia.
Awwad Khalaf
AK
Alenazy
Department of Surgery, College of Medicine, Northern Border University, Arar, Saudi Arabia.
Majed Gorayan
MG
Alrowaili
Department of Microbiology, College of Medicine, Northern Border University, Arar, Saudi Arabia.
Jamith
J
Basha
Brucella blood agar; Nigella sativa; metronidazole; minimum inhibitory concentrations; thymoquinone