A 10-18:1 enriched fraction from beef fed a barley grain-based diet induces lipogenic gene expression and reduces viability of HepG2 cells.

Beef fat is a natural source of fatty acids, and is typically enriched with either 10-18:1 or 11-18:1. Little is known about the bioactivity of individual -18:1 isomers, and the present study compared the effects of 9-18:1, ()9-18:1 and -18:1 fractions isolated from beef fat enriched with either 10-18:1 (HT10) or 11-18:1 (HT11). All 18:1 isomers resulted in reduced human liver (HepG2) cell viability relative to control. Both 9-18:1 and HT11were the least toxic, 9-18:1had dose response increased toxicity, and HT10 had the greatest toxicity (<0.05). Incorporation of 18:1 isomers was 1.8-2.5 fold greater in triacylglycerol (TG) than phospholipids (PL), whereas Δ9 desaturation products were selectively incorporated into PL. Culturing HepG2 cells with 9-18:1 and HT10 increased (<0.05) the Δ9 desaturation index (9-16:1/16:0) compared to other fatty acid treatments. HT10 and 9-18:1 also increased expression of lipogenic genes (FAS, SCD1, HMGCR and SREBP2) compared to control (<0.05), whereas 9-18:1 and HT11 did not affect the expression of these genes. Our results suggest effects of HT11 and 9-18:1 were similar to BSA control, whereas HT10 and -9 18:1 (i.e. the predominant fatty acid isomer found in partially hydrogenated vegetable oils) were more cytotoxic and led to greater expression of lipogenic genes.