Effects of extracts rich in phytosterols, flavonoids and saponins from black bean (Phaseolus vulgaris L.) seed coats on gene expression involved in β‐oxidation and lipogenesis

Abstract

Liver X receptors (LXR) α and β are transcription factors that regulate the expression of key genes involved in hepatic fatty acid synthesis (FAS, SREBP‐1c) and reverse‐transport cholesterol(ABCG5/G8) that are activated by their natural ligands the oxysterols. Thus, the aim of the present work was to evaluate the effects of two extracts, one rich in flavonoids and saponins (FSE) and other rich in phytosterols (PHE) associated to black bean seed coats, on the expression of LXR‐regulated hepatic genes (ABCG5, SREBP‐1c and FAS) as well as CPT1, the rate‐limiting enzyme of the β‐oxidation of long‐chain fatty acids in primary rat hepatocytes. The results showed that FSE decreased the LXR‐regulated hepatic gene expression in a dose‐dependent manner. Interestingly, CPT1 was overexpressed when PHE was tested. Both extracts were able to suppress the effects of T090131, a synthetic LXR ligand that increased the expression of genes involved in hepatic lipogenesis. Our data suggest that addition of bioactive compounds from black bean has the capacity to decrease the activity of LXR, particularly the alpha isoform, and increased the expression of genes involved in β‐oxidation. The research support was provided by the Nutrigenomics chair at Tecnológico de Monterrey.