In vitro genotoxicity testing of Lawsonia inermis and Henna extracts in HepG2 cells by the comet assay.

Henna is extracted from the crushed leaves of Lawsonia inermis Linn. (Lythraceae) and the principal natural dye contained at 1.0-1.4% is 2-hydroxy-1,4-naphthoquinone (lawsone), a red-orange pigment insoluble in water. Henna is also used in the traditional medicine as an antirheumatic and antineuralgic agent. Antimicrobial, antifungine as well as antiviral properties have been reported for Henna. Henna is largely considered to be safe, however it has been reported to cause a wide spectrum of adverse effects, such as allergic contact dermatitis from temporary Henna tattoos; Henna has also been reported to cause urticarial rash, severe angioneurotic edema and hemolytic anemia. The aim of this study was to evaluate the possible genotoxic activity of extracts of L. inermis and a commercial Henna product in an in vitro model. Induced primary DNA damage was evaluated in human liver cells (HepG2 cell line) by comet assay. In order to assess if some processing stages affect genotoxicity, both extracts of leaves of L. inermis and a commercial Henna product were analyzed. L. inermis did not show any genotoxic activity after 4 or 24 h exposure in HepG2 cells in the evaluated dose range. Similarly, Henna did not show any genotoxic activity as well. The results of this study are largely negative in terms of genotoxicity, however further study in animal model is needed to rule out in vivo genotoxicity.