Consumption of carrots (Daucus carota L.) is in general believed to be beneficial for human health and several bioactive compounds have been identified e.g. the polyacetylene falcarinol, which exhibits anticancer activities both in vitro and in vivo [1,2]. Here we report a range of results suggesting a potential new field of application for carrots towards conditions associated with the metabolic syndrome e.g. insulin resistance and abdominal obesity. Dichloromethane (DCM) and methanol (MeOH) extracts of two varieties of carrots (var. bolero and purple haze) were made and tested in a number of different bioassays and one in vivo model system. DCM extracts of both carrot varieties were found to activate peroxisome proliferator-activated receptor (PPAR)γ without stimulating adipocyte differentiation, suggesting that they can have a positive effect on insulin sensitivity. At low concentrations (<0.5µg/mL) the DCM extract was able to enhance glucose uptake (GU) in porcine myotubes but at higher concentrations this was impaired. Biphasic concentration-dependent bioactivity has previously been reported for e.g. falcarinol [2]. The nematode Caenorhabditis elegans is a good model system for studying lipid metabolism and fat accumulation in vivo. At 200µg/mL, the DCM extract of var. Bolero was able to reduce fat accumulation, as measured by lipophilic dye Nile red, in C. elegans by 50%. The carrot polyacetylenes have structures similar to both the endogenous ligands of PPARγ as well as recently identified alkamides able to activate PPARγ and enhance insulin-stimulated GU in adipocytes [3], indicating that these could be responsible for the observed effects.
References: 1. Kobaek-Larsen M et al. (2005)J. Agric. Food Chem. 53: 1823–1827.
2. Hansen SL et al. (2003)J. Sci. Food Agric. 83: 1010–1017.
3. Christensen KB et al. (2009)J. Nat. Prod. 72: 933–937.
