Obacunone, nomilin... Weird anabolic substances in ordinary citrus fruits

Until we saw its name on the label of a sports supplement, we had never heard of obacunone. And when we googled it out, we knew right away: this is something the readers of Ergogenics should know. Obacunone, a substance in citrus fruits, has an anabolic effect. It is not the only substance in citrus fruits with some muscle-strengthening potential.Obacunone

Obacunone is a limonoid. Researchers have found the substance in Citrus fruits, the fruit of Fortunella margarita and Casimiroa edulis. Producers of sports supplements usually use extracts from the bark of Phellodendron amurense as a source of obacunone.

Nowadays, obacunone is mainly found in sports supplements that should enhance insulin action and therefore improve body composition. Slintensity from EvoMuse is such a product. [Label]
For 4 weeks, Japanese researchers, affiliated with the Kikkoman Corporation and the University of Tokyo, gave KKAy mice, a type of lab mouse that is prone to type 2 diabetes, chow that had been mixed with obacunone. The Japanese had extracted the obacunone from the yuzu, a Japanese citrus fruit. If the mice had been human, they would have been given roughly one gram of obacunone daily. Supplements contain a fraction of that amount.

Obacunone supplementation reduced fat mass and increased muscle mass. The body weight of the mice did not change.

Obacunone increased insulin sensitivity [left].At the top right you see how, according to the researchers, obacunone produces those effects. Obacunone activates TGR5, a receptor that is actually intended for bile acids. The Japanese recently demonstrated that TGR5 plays a role in the growth and development of muscles - in mice. [J Biol Chem. 2018 Jun 29;293(26):10322-32.]

The liver releases a series of bile acids during and after intensive exercise. These bile acids have various positive health effects, one of which is that muscles receive an extra anabolic stimulus via TGR5. A bile acid that is involved in this is lithocholic acid.


There is another substance in food that stimulates TGR5. In 2013, the same Japanese research group published an animal study in which nomilin, another liminoid in citrus fruits, [structural formula shown here] increases insulin sensitivity via TGR5. [Vitam Horm. 2013;91:425-39.]] Just like obacunone, nomilin has already made its appearance in sports supplements.
"Dietary obacunone supplementation suppressed hyperglycemia and increased muscle mass in diabetic KKAy mice, and this effect is likely to be mediated, at least in part, by the potentiation of multiple pathways associated with TGR5", write the researchers.

"These results suggest that regular obacunone consumption could be beneficial in preventing the development of hyperglycemia, muscle atrophy, and obesity."

Biochem Biophys Res Commun. 2015 Aug 7;463(4):846-52.