Fig. 8.

Cytotoxicity data for (left) 18 and (right) 19 indicated that neither shows significant toxicity up to 100 μM in A549 lung epithelial cells. The lethal dose (LD₅₀) value could not be calculated, as cell viability was not reduced to < 50% (indicated by the red dashed line). It was not possible to test at higher compound concentrations due to insolubility in the test buffer. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)