Comparative biotransformation of luteolin and apigenin from the flower extract and the stem‐and‐leaf extract of Dendranthema morifolium Ramat. Tzvel. in rats

Abstract

BACKGROUND The flower of Dendranthema morifolium Ramat Tzvel has been widely used as a nutritional health supplement worldwide. However, most of the studies have focused on the flower and the rest of the plant was neglected. Our hypothesis is that similar flavonoids may be present at different parts of D. morifolium, and the flavonoids may undergo a similar biotransformation pathway within the body. To investigate this hypothesis, an in vivo pharmacokinetic experimental model was developed to explore the comparative biotransformation of luteolin and apigenin after administration of D. morifolium extracts (10 g kg⁻¹, p.o.) in freely moving rats. Because luteolin and apigenin mainly underwent phase II metabolism, the metabolic enzymes of β‐glucuronidase/sulfatase or β‐glucuronidase were used to hydrolyze the plasma sample, depending on the biotransformation pathway involved. RESULTS The results revealed that luteolin and apigenin mainly went through glucuronide and sulfate conjugations, respectively, in both the extract of flowers and the stem‐and‐leaf group. In addition, the area under the concentration curve (AUC_last) of luteolin glucuronides and sulfates in the group administered the stem‐and‐leaf extract was approximately 4.6 times higher than that of the flower extract group. The dominant products of biotransformation for apigenin were sulfates. CONCLUSION These findings support our hypothesis that not only the flower parts of D. morifolium, but also the stem‐and‐leaf parts contain rich flavones, including glycosides and aglycone, and they undergo similar biotransformation pathways. © 2021 Society of Chemical Industry