Yuka Sasakawa^{1, 2,}, Akari Kominami^{1, 2}, Michiyo Abe^{1, 2}, Kaori Yamamoto², Mayumi Nakao², Fumiko Nakaoka², Shigetoshi Okumura^{2, 3}, Lekh Raj Juneja^{2, 3}, Jun Kunisawa¹

The anti-obesity effect of Glycyrrhiza uralensis (Ural licorice) extract at the intake level of low risk has not been clarified. In the present study, the anti-obesity effects of Ural licorice, its extracts, its fractions and Glycyrrhizic acid at intake levels of low risk were examined in high-fat high-sucrose (HFS) diet-induced obese mice. Ural licorice extract, which was given the brand name “LICONINE^™,” was the most effective extract; it decreased body weight, visceral fat weight, number of adipocyte crown-like structures, and adipocyte size in visceral fat. Low doses of LICONINE also had anti-obesity effects. The terpenoid fraction, but not flavonoid fraction, of LICONINE had an anti-obesity effect that did not depend exclusively on Glycyrrhizic acid. Next, we examined the effects of Ural licorice extracts, LICONINE fractions, and constituents of LICONINE terpenoid fraction on production of monocyte chemoattractant protein-1 in 3T3-L1 mouse adipocytes. LICONINE and its terpenoid fraction had anti-obesity and anti-inflammatory effects in both HFS diet-induced obese mice and 3T3-L1 adipocytes. Our results demonstrate for the first time that Licorice saponin G2, Licorice saponin H2, and Glycyrrhizic acid (all constituents of LICONINE terpenoid fraction) had anti-inflammatory effects in 3T3-L1 adipocytes. In summary, at the intake level of low risk (human equivalent to less than 1 g licorice per day), LICONINE is an effective extract of Ural licorice and the terpenoid fraction is an effective fraction of LICONINE for treating obesity. Further research is needed to identify the mechanism underlying the anti-obesity and anti-inflammatory effects of LICONINE and its terpenoid fraction.

glycyrrhiza uralensis, ural licorice extract, LICONINE, high-fat high-sucrose diet-induced obese mice, obesity, 3T3-L1 mouse adipocytes, monocyte chemoattractant protein-1