Sweet potato skin provides health benefits in Caenorhabditis elegans model

Abstract

We apply the Caenorhabditis elegans(C. elegans) model to assess functional foods and agricultural by products that potentially increase satiety, regulate food intake and improve insulin sensitivity. Sweet potato (Ipomoea batatas) is one of the most important food crops in the world offering fiber, carbohydrates, protein, vitamins, iron, and calcium. The sweet potato skin (SPS) a by‐product of processing is rich in anti‐oxidant phenolic compounds, fibers and other nutrients. We evaluated the effect of SPS on intestinal fat deposition (IFD), lifespan, and mRNA expression of ckr‐1, gcy‐8, cpt‐1, and cpt‐2 in the C. elegans model. Animals were fed with SPS (0%, 0.5%, 1%, and 3%) or SPS plus 2% glucose. Pharyngeal pumping rate (PPR), a surrogate marker of lifespan, was monitored periodically. At the end of the study, Nile red, a fluorescent lipid staining dye, was applied to the worms. Fluorescent microscopy of Nile red was used as a qualitative measure of the IFD. The SPS sustained PPR in wild type C. elegans (N2), sir‐2.1(ok434)IV or daf‐16(mgDf50)I null mutants. In the presence of 2% glucose, the PPR was elevated in sir‐2.1(ok434)IV or daf‐16(mgDf50)I. The IFD was reduced in wild type C. elegans (N2), but increased in sir‐2.1(ok434)IV by SPS treatments. These data suggested that SPS reduces IFD and sustain lifespan in C. elegans model. The use of the SPS as a food ingredient has potential to help control weight in humans. The neuronal control of the fat deposition requires further clarification. The nematode strains used in this work were provided by the Caenorhabditis Genetics Center (University of Minnesota, MN), which is funded by the NIH National Center for Research Resources (NCRR). Support: LSU AgCenter, LA BoR (LEQSF(2010–13)‐RD‐B‐02), and ConAgra Foods® Inc., ConAgra Mills™.