Aucubin, Catalpol, and GABA Contents in Different Plant Parts of Rehmannia glutinosa Cultivars

Background: Rehmannia glutinosa is a perennial herb belonging to the family Scrophulariaceae. Its root has been utilized as a traditional medicine but the aerial parts (flower, flower stalk, leaf) are not used. We aimed to determine the content of three compounds [aucubin, catalpol, and γ-aminobutyric acid (GABA)] in the different organs of R. glutinosa cultivars (Dakang, Tokang, and Suwon 9) Methods and Results: The flower, flower stalk, leaf, and root of R. glutinosa were harvested at the end of August. The aucubin and catalpol contents were analyzed by LC/MS, whereas the GABA content was analyzed by GC/MS. The aucubin content was the highest in the leaf, while catalpol and GABA were the highest in the flower. The aucubin contents of leaf in Dakang, Tokang, and Suwon 9 were 1.43, 0.81, and 1.07 mg/g, respectively. The catalpol contents of flower in Dakang, Tokang, and Suwon 9 were 41.06, 28.78, and 37.48 mg/g, respectively, the GABA contents were 0.79, 0.76, and 0.65 mg/g, respectively. Conclusions: The aucubin, catalpol, and GABA contents were higher in the leaf and flower than that in the root. This study show that R. glutinosa leaf and flower can be used as a potential supplement.