Aqueous extracts of lingonberry and blackberry leaves identified by high-content screening beneficially act on cholesterol metabolism

Decreasing circulating low-density lipoprotein (LDL) cholesterol levels leads to decreased risk of cardiovascular diseases. Natural compounds are capable of lowering LDL-cholesterol even on top of lifestyle modification or medication. To identify novel plant-derived compounds to lower plasma LDL cholesterol levels, we performed high-content screening based on the transcriptional activation of the promoter of the LDL receptor (LDLR). The identified hits were thoroughly validated in human hepatic cell lines in terms of increasing LDLR mRNA and protein levels, lowering cellular cholesterol levels and increasing cellular LDL uptake. By means of this incremental validation process in vitro, aqueous extracts prepared from leaves of lingonberries (Vaccinium vitis-idaea) as well as blackberries (Rubus fruticosus) were found to have effects comparable to lovastatin, a prototypic cholesterol-lowering drug. When applied in vivo in mice, both extracts induced subtle increases in hepatic LDLR expression. In addition, a significant increase in high-density lipoprotein (HDL) cholesterol was observed. Taken together, aqueous extracts from lingonberry or blackberry leaves were identified and characterized as strong candidates to provide cardiovascular protection.