Overview of the preclinical pharmacological properties of Nigella sativa (black seeds): a complementary drug with historical and clinical significance.

Nigella sativa (N. sativa, black seeds; or sometimes known by many other names such as the blessed seed by the Arabs, black cumin in the Holy Bible, black caraway and Kalonji in South Asia) has been traditionally used for many years not only as a food but also as complementary drug. It is the objective of this communication to review the evidence-based pre-clinical pharmacological actions of N. sativa as a basis of its existing and potential new human clinical uses. Primary PubMed literature searches and secondary Medline searches were conducted to define N. sativa pre-clinical pharmacological and toxicological actions using a retrospective narrative review of the published studies. The ground seeds, its oil and its various extracts exhibit very broad pharmacological actions in laboratory studies, which are predictive of human clinical efficacy. In laboratory studies, N. sativa possesses anti-inflammatory, analgesic, anti-diabetic, anti-hyperlipidemic, anti-convulsant, anti-microbial, anti-ulcer, anti-hypertensive, anti-asthmatic and anti-cancer activities. Its mode of action is mediated via several mechanisms, which include anti-oxidant, immunomodulating, cytoprotective and an inhibitory effect on some mediators of inflammation. Although the seeds contain many chemical components, thymoquinone and alpha-hederin are proven to be pharmacologically active. Despite N. sativa broad and worldwide pharmacological characterization, only limited non-clinical safety studies were reported. N. sativa has many potentially important therapeutic applications. The black seeds clearly warrant formal preclinical drug development consideration to investigate the pharmacology of its components, to standardize the contents of the dosage forms, to define the methods of the pharmaceutical preparation, to determine its pharmacokinetics characteristics and its safety profile. It is our opinion that N. sativa should be considered for clinical development initially for unmet therapeutic uses, especially in the fields of oncology, neurology, rheumatology, pulmonary medicine, infectious diseases and endocrinology.