In vitro toxicity, genotoxicity and antigenotoxicity of Nigella sativa extracts from different geographic locations

Nigella sativa or black cumin is used as a spice and as a natural remedy against a great variety of illnesses. However, plants growing at different locations, i.e., coping with different environmental stress conditions, may have different contents of specialized compounds include alkaloids, flavonoids, and terpenoids. Therefore their properties and biological effects may be different. We used the neutral red uptake test, the bacterial Vitotox and Ames assays and the micronucleus and comet tests in human C3A cells to investigate the in vitro cytotoxicity, genotoxicity and antigenotoxicity of aqueous seed extracts of this plant originating from three different regions in Morocco. Nigella sativa seed extracts showed different degrees of cytotoxicity depending on the location where the test samples came from. Overall they were not genotoxic but some indications of both antigenotoxicity and co-genotoxicity were found. In this the results are somewhat in contradiction with previous reports. Actually, our results show that many factors may influence the outcome of an investigation. The location of the samples, but also the applied test system and other experimental conditions are examples of factors that should be taken into account when evaluating the biological properties and potentials for nutritional and medicinal application in humans. This obviously complicates these kind of investigations and assessment and shows that it may be time to develop and agree on common protocols and procedures rather than performing experiments solely based on a laboratory's capacity, availabilities and opportunities. (C) 2019 SAAB. Published by Elsevier B.V. All rights reserved.