densitometric method for analysis of thymoquinone in Nigella sativa extracts and marketed formulations

Nigella sativa Linn. (Ranunculaceae) (N. sativa), commonly known as black seed or black cumin, is an herbaceous plant, mainly grows in the Middle East, Central Europe and Western Asia. It is widely used in indigenous system of medicine for treatment of numerous disorders for over 2 000 years[1-3]. Its seed oil had been widely used in Arab traditional of medicine for the treatment of arthritis, lung diseases and hypercholesterolemia[4]. Some of the reported pharmacological properties of N. sativa include hypotensive, anti-nociceptive, uricosuric, choleretic, antifertility, antidiabetic, anti-histaminic, anti-oxidant, anti-inflammatory, anti-microbial, anti-tumor and immunomodulatory effects[5]. Most pharmacological properties of the whole seeds or their extracts of N. sativa are mainly attributed to the its volatile oil, of which thymoquinone, about 27%-57%, is the most abundant component[6-8]. Standardization of herbal formulations in terms of quality of raw materials, manufacturing practices and composition is important to ensure quality and optimum levels of active principles for their bio-potency. Since thymoquinone is principal bioactive component of N. sativa seed, simple and robust method is required for quantification of this active constituent which has been used for quality control and standardization of crude drug and its formulation as a marker compound. A thorough literature survey revealed that, several analytical techniques for the determination of thymoquinone have been reported. These methods include high-performance PEER REVIEW ABSTRACT