title: Oral and intraperitoneal LD50 of thymoquinone, an active principle of Nigella sativa, in mice and rats.
abstract: BACKGROUND
  Thymoquinone is the major active principle of Nigella sativa (N. sativa) and constitutes about 30% of its volatile oil or ether extract. N. sativa oil and seed are commonly used as a natural remedy for many ailments. Using modern scientific techniques, a number of pharmacological actions of N. sativa have been investigated including immunostimulant, anti-inflammatory, anticancer, antioxidant, antihistaminic, antiasthmatic, hypoglycemic, antimicrobial and antiparasitic. There are only few reports regarding the toxicity of thymoquinone.
  
  
  METHODS
  The present study was carried out to determine LD50 of thymoquinone both in mice and rats, orally as well as intraperitoneall, by the method of Miller and Tainter. Autopsy and histopathology of liver, kidney, heart and lungs were also determined.
  
  
  RESULTS
  The LD50 in mice after intraperitoneal injection was determined to be 104.7 mg/kg (89.7-119.7, 95% confidence interval) and after oral ingestion was 870.9 mg/kg (647.1-1094.8, 95% confidence interval). Whereas, LD50 in rats after intraperitoneal injection was determined to be 57.5 mg/kg (45.6-69.4, 95% confidence intervals) and after oral ingestion was 794.3 mg/kg (469.8-1118.8, 95% confidence intervals). The LD50 values presented here after intraperitoneal injection and oral gavages are 10-15 times and 100-150 times greater than doses of thymoquinone reported for its anti-inflammatory, anti-oxidant and anti-cancer effects.
  
  
  CONCLUSIONS
  Thymoquinone is a relatively safe compound, particularly when given orally to experimental animals.
authors.affiliation: Department of Biochemistry, College of Medicine, King Faisal University, Dammam, Saudi Arabia.
authors.forename: Amein
authors.initials: A
authors.lastname: Al-Ali
authors.forename: Abdul Aziz
authors.initials: AA
authors.lastname: Alkhawajah
authors.forename: Mohammad Akram
authors.initials: MA
authors.lastname: Randhawa
authors.forename: Nisar Ahmed
authors.initials: NA
authors.lastname: Shaikh
mesh_terms: D000284:Administration, Oral; D000818:Animals; D016227:Benzoquinones / Q000008:administration & dosage / Q000633:toxicity*; D005260:Female; D007274:Injections, Intraperitoneal; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D031881:Nigella sativa; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D016227:Benzoquinones; D010936:Plant Extracts; C003466:thymoquinone