Cranberry Phenolic Compounds Decrease Fat Accumulation in Caenorhabditis elegans

Abstract

Cranberries are rich source of phenolic compounds (i.e. phenolic acids, flavonoids, anthocyanidins) and have been linked to many health benefits. A recent report suggested that cranberry bioactives inhibit adipogenesis in 3T3‐L1 cells. Thus, we investigated the mechanisms of cranberry bioactives on lipid metabolism using Caenorhabditis elegans model. We evaluated the effects of cranberry water soluble compounds (contains approximately 6.6% phenolic acids, 2.2% flavonoids and 0.6% anthocyanidins) on fat accumulation, pumping rate (food intake), and locomotive activity in wild type (N2). The effect of water‐soluble cranberry compounds on fat accumulation in deficiency strains, sbp‐1 (ep79), aak‐2 (ok524), daf‐16 (mgDf50), and nhr‐49 (ok2165) (which represent SREBP‐1, AMPKα, FOXO3a, and PPARα respectively in mammal) were also investigated. In wild type (N2), no difference in pumping rates or locomotive activities after treating with cranberry bioactives were observed, suggesting no influence on food intake or activity. Treatment with cranberry extract (0.004 and 0.016 mg/ml Gallic acid equivalent) dose‐dependently reduced overall fat accumulation in wild type (N2), 43% and 74% reduction compared to control, respectively. Treatment of cranberry extract decreased fat accumulation in aak‐2 mutants, but only minimal effects were observed in sbp‐1, daf‐16 and nhr‐49 strains. We further confirmed that cranberry bioactives down‐regulated sbp‐1 expression as observed in transgenic strain CE548 {epEx141 [sbp‐1::GFP::SBP‐1]}. These data suggest that water‐soluble cranberry phenolic compounds effectively reduce fat accumulation, are dependent on sbp‐1, daf‐16 and nhr‐49, but not aak‐2.