Isolation, Structural Elucidation of Small-molecule Sugars from the Seeds of Licorice.

Introduction: Much work on the chemical components and biological activities of licorice roots has been carried out, and many compounds have been isolated and confirmed from licorice roots already. However, little research on the isolation and confirmation of the chemical components from the seeds of licorice has been carried out till now. This work focuses on discovering new compounds from the seeds of licorice for the development of new drugs or drug candidates.

Methods: The extract of the licorice seeds was isolated by column chromatography (CC) together with recrystallization to obtain the pure compounds. Their structures were elucidated by NMR and single crystal X-ray diffraction (SC-XRD).

Results: Seven small-molecule sugars (1-7) [Methyl α-D-Galactopyranoside (1), Sucrose (2), α- L-Rhamnose (3), D-Xylose (4), α-D-Glucose (5), D-Galactose (6), D-Lyxose (7)] were isolated from the seeds of licorice for the first time. Their structures were confirmed by NMR and SCXRD.

Discussion: In this work, we isolated small-molecule sugars (1-7) from the seeds of licorice for the first time, and methyl α-D-Galactopyranoside (1) is a very scarce compound from the natural plant medicines, which was isolated from the seeds of licorice.

Conclusion: The roots of licorice have been used in clinics as a Chinese traditional plant medicine for a long time, and much work on the chemical components and biological activities have been conducted. However, little research on the isolation and confirmation of the chemical components from the seeds of licorice has been carried out. This work provides the scientific basis for in-depth research on licorice seeds.