Toxicity of structurally related anthraquinones and anthrones to mammalian cells in vitro.

Anthraquinones and structurally related compounds were cytotoxic to mammalian cell lines using cloning efficiency and MTT reduction as endpoints. In V79 cells, the concentration of chemical causing 50% inhibition ranged from 0.21 to 21.6 mug/ml for cloning efficiency and from 0.86 to 14.6 mug/ml for MTT reduction. The anthrones anthralin and chrysarobin were 4.1 and 3.2 times more toxic, respectively, in the cloning efficiency assay than in the MTT assay. In contrast, the anthraquinones danthron and emodin were 2.8 and 2.1 times more toxic, respectively, in the MTT assay than in the cloning efficiency assay. Among the four mammalian cell lines tested using the MTT assay, the human leukaemia cell line (K562) was the most sensitive to the test chemicals. In contast, anthraquinone toxicity was reduced in rat hepatoma (H4IIE) cultures. In general, structures with carbonyl groups in positions 9 and 10 on the anthracene skeleton (anthraquinones) were less toxic than structures with carbonyl groups in position 9 only (anthrones). Toxicity was also influenced by the position of hydroxy substituents on the tricyclic skeleton. The results suggested that in vitro cytotoxicity assays are useful in elucidating the relationships between structure and biological activity for anthraquinones and related compounds.