Dear Mahmoud mostafa Mahmoud,

The dose is dependent on the animal used. The following three studies which indicate the animal kind and thymoquinone dose used.

2.5 mg/kg -5 mg/kg thymoquinone.

http://www.ncbi.nlm.nih.gov/pubmed/17562570

IMethods: Thirty guinea pigs were randomly divided to 3 groups; control (C), sensitized (S) and pretreated group with (TQ); 3 mg/kg, IP (S+TQ). Tracheal responsiveness to methacholine and ovalbumin (OA), total and differential cell count in bronchoalveolar lavage, lung pathological changes and blood Interleukin 4(IL-4) and Interferon gamma (IFNγ) level in three groups were measured.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4097975/

To investigate the cytoprotective effects of TQ against acetaminophen-induced hepatotoxicity, Wistar albino rats were given 500 mg/kg acetaminophen orally, followed by three doses of TQ at a total dose of 15 mg/kg within an 18 hr time interval (three times 5 mg/kg oral thymoquinone for every six hr).

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4387230/

Hoping this will be helpful,

Rafik

Thymoquinone: an emerging natural drug with a wide range of medical applications

Mohannad Khader1,* and Peter M Eckl2

Abstract

Nigella sativa has attracted healers in ancient civilizations and researchers in recent times. Traditionally, it has been used in different forms to treat many diseases including asthma, hypertension, diabetes, inflammation, cough, bronchitis, headache, eczema, fever, dizziness and influenza. Experimentally, it has been demonstrated that N. sativa extracts and the main constituent of their volatile oil, thymoquinone, possess antioxidant, anti-inflammatory and hepatoprotective properties.

In this review we aimed at summarizing the most recent investigations related to a few and most important effects of thymoquinone. It is concluded that thymoquinone has evidently proved its activity as hepatoprotective, anti-inflammatory, antioxidant, cytotoxic and anti-cancer chemical, with specific mechanisms of action, which provide support to consider this compound as an emerging drug. Further research is required to make thymoquinone a pharmaceutical preparation ready for clinical trials.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4387230/

Dear Mahmoud:

You can find the answer in this paper:

Title:

Effects of thymoquinone (volatile oil of black cumin) on rheumatoid arthritis in rat models.

Abstract

Many studies have been carried out in recent years on the pharmacological effects of Nigella sativa seeds that have uncovered their antiinflammatory and immunological effects. The objective of this study was to explore the antiinflammatory effects of thymoquinone on arthritis in rat models. Rats with arthritis induced by Freund's incomplete adjuvant were assigned to five groups: group 1: controls 0.9% NaCl (n = 7); group 2: 2.5 mg/kg thymoquinone (n = 7); group 3: 5 mg/kg thymoquinone (n = 7); group 4: Bacilli Chalmette Guerin (BCG) 6 x 105 CFU (n = 7); group 5: methotrexate 0.3 mg/kg (n = 7). Signs of inflammation on the claw and radiological signs were searched for and TNF-alpha and IL-1beta were measured. The results of the control and other groups were compared. As a result, thymoquinone, confirmed clinically and radiologically, suppressed adjuvant-induced arthritis in rats.

http://www.ncbi.nlm.nih.gov/pubmed/17562570

best regards,

Ashraf

Dear Mahmoud Mostafa Mahmoud

you can observe anti-oxidant effect of thymoquinone by using up to 10 mg/kg dose in rat models without any severe side effects.

with best regards

http://www.ncbi.nlm.nih.gov/pubmed/17291733