Occurrence of cytotoxic 9-oxononanoyl secosterol aldehydes in human low-density lipoprotein

► Human LDL cholesteryl esters were treated with ozone and the products identified. ► The products were also detected in human LDL samples by LC-ESI-MS/MS. ► The products 9-oxononanoyl secosterol-A and -B were cytotoxic to HL-60 cells. ► These products may play roles in the pathogenesis of inflammatory disorders.