Chemical quality evaluation and characteristics of interspecific hybrid (G. uralensis × G. glabra) C-18 strain as a new Licorice cultivar

The development of new cultivars is essential for establishing a method of producing licorice in Japan. A suitable new cultivar for domestic licorice production, known as the interspecific hybrid strain C-18, was developed by crossbreeding Glycyrrhiza uralensis Fisch. (as the seed parent, possessing a high glycyrrhizin (GL) content, strain OMP-28) and Glycyrrhiza glabra L. (as the pollen parent, known for vigorous growth, strain OMP-10). Both G. uralensis and G. glabra are specified in the Pharmacopoeia of Japan (18th edition) as the source plants for Glycyrrhizae Radix. After 2 years of cultivation, strain C-18 exhibited robust growth, with a fresh weight of 148.8 g and a stem diameter of 0.89 mm. The GL content in the dry weight was measured at 3.61%. Seedlings cultivated from rhizomes in the field for 2 years showed a tap root fresh weight per plant of 120 ± 21 g, with an average GL content relative to the dry weight of 2.68% ± 0.38%. Although glabridin, a characteristic compound of G. glabra, was not detected, glycycoumarin, a characteristic compound of G. uralensis, was detected via HPLC analysis. Strain C-18 contained glycycoumarin as a characteristic compound of G. uralensis but lacked glabridin, a compound characteristic of G. glabra. Additionally, 2,3-dehydrokievitone (1) and parvisoflavone A (2) were identified as distinctive components of the interspecific hybrid (G. uralensis × G. glabra) C-18.