Specific Hydroxy Fatty Acids in Royal Jelly Activate TRPA1

Abstract

This is the first report of TRPA1 activation by fatty acids. Activation of TRPA1 and TRPV1 induces thermogenesis and energy expenditure enhancement. In this study, we searched for novel agonists of TRPA1 and TRPV1 from a nonpungent food, royal jelly (RJ). We measured the activation of human TRPA1 and TRPV1 by RJ extracts and found that the hexane extract contains TRPA1 agonists. The main functional compounds in the hexane extract were trans-10-hydroxy-2-decenoic acid (HDEA) and 10-hydroxydecanoic acid (HDAA). These are characteristic fatty acids of RJ. Their EC50 values were about 1,000 times larger than that of AITC, and their maximal responses were equal. They activated TRPA1 more strongly than TRPV1. Their EC50 values for TRPV1 were 2 times larger, and the maximal response was less than half of that for TRPA1. Next, we studied the potencies of other lipid components for both receptors. Most of them have higher affinity to TRPA1 than TRPV1. Among them, dicarboxylic acids showed equal efficacy for both receptors, but those are present in only small amounts in RJ. We concluded that the main function of RJ is TRPA1 activation by HDEA and HDAA, the major components of the RJ lipid fraction.

Bioactive compounds and health-promoting properties of royal jelly: A review

“…4), 24% gluconic acid, 22% 10-hydroxydecanoic acid (HDAA), 5% dicarboxylic acids and several other acids. 10-HDA and HDAA are specific components of RJ (Terada, Narukawa, & Watanabe, 2011).…”

“…The results suggested that 3,10-DDA stimulates maturation and Th1 polarising capability of human MoDCs in vitro, which could be beneficial for anti-tumour and antiviral immune responses. Terada et al (2011) stated that activation of TRPA1 and TRPV1 induces thermogenesis and energy expenditure enhancement. They searched for novel agonists of TRPA1 and TRPV1 from RJ.…”

Freeze-Dried Royal Jelly Maintains Its Developmental and Physiological Bioactivity inDrosophila melanogaster

“…12) RJ consists of 50-60% (w/w) water, 18% (w/w) proteins, 15% (w/w) carbohydrates, 3-6% (w/w) lipids, and 1.5% (w/w) other compounds such as minerals and vitamins. 13,14) A search for the bioactive compound(s) in RJ recently resulted in the isolation of a 57-kDa protein designated royalactin, which is considered to be the major inducer of queen differentiation in honeybees.…”

Isolation and characterization of proteins and lipids from honeybee (Apis mellifera L.) queen larvae and royal jelly

“…It is a rich source of proteins which are composed of a major royal jelly protein (MRJP) family (Li, Wang, Zhang, & Pan, 2007;Nozaki et al, 2012). In addition, RJ contains a unique hydroxy fatty acid, trans-10-hydroxy-2-decenoic acid (HDA) (Terada, Narukawa, & Watanabe, 2011). Substantial evidence indicated that these bioactive components might have many beneficial effects, including antibacterial, antiinflammatory, antioxidant, immunostimulatory and liver regeneration promoting activities (Fujiwara et al, 1990;Majtán, Kovácová, Bíliková, & Simúth, 2006;Kamakura, Suenobu, & Fukushima, 2001;Ramadan & Al-Ghamdi, 2012).…”