Microbial transformation and bioactivation of isoflavones from Pueraria flowers by human intestinal bacterial strains

Abstract

The flowers from Pueraria, which are called Puerariae Flos, have been used since ancient times for recovery from alcohol intoxication. We elucidated the microbial transformation of the main isoflavones (1, 1a and 2) by using 29 commercially available human intestinal bacterial strains together with the bioactivation of the hepatoprotective activity of their metabolites. Tectoridin (1a), which contains only one glucosyl moiety, was metabolized to its aglycone 1b by various bacterial strains. On the other hand, the metabolism of 1 and 2, which both have disaccharide groups, was limited to specific bacterial strains. The metabolites 1c and 2c obtained from the Peptostreptococcus productus strain were completely different from those produced by the other strains. These metabolites were identified as 6-hydroxygenistein and 6-hydroxybiochanin A, respectively. The glycosides 1, 1a and 2 did not show any hepatoprotective activity, whereas aglycones 1b and 2b showed moderate activity. Furthermore, the hepatoprotective activity of the demethylated metabolites 1c and 2c was extremely potent. Although not all people have P. productus in their gastrointestinal tract, the O-demethylated compounds might become one of the bioactivated metabolites when Puerariae Flos is administered orally.

Simultaneous analysis of isoflavones and saponins in Pueraria flowers using HPLC coupled to an evaporative light scattering detector and isolation of a new isoflavone diglucoside

“…Comparison of amounts of saponins and isoflavones in extracts of Pueraria flowers Table 2 indicates the amounts of saponins (1-3) and isoflavones (4)(5)(6)(7)(8)(9)(10)(11)(12) in each specimen. The amounts of total isoflavones in each year obtained from the collected flowers of P. lobata (#1-7) were almost consistent (1.84-2.86%).…”

“…Some biological activities of Puerariae Flos and its constituents have already been elucidated, and include detoxification of alcohol [1][2][3][4][5][6], hepatoprotection [2,3,7,8], anticomplementary activity [9], and estrogenic activity [10]. Very recently, we reported microbial transformation of isoflavones and bioactivation by intestinal bacteria [11]. Both types of Puerariae Flos contain a large amount of isoflavones and saponins (Fig.…”

“…The isoflavones of P. thomsonii have an hydroxy group at the 4 0 -position, whereas those of P. lobata have a methoxy group at the same position [11].…”

Evaluation of the Estrogenic Activity of Pueraria (Kudzu) Flower Extract and Its Major Isoflavones Using ER-Binding and Uterotrophic Bioassays

“…Previous studies have shown that the hydrolysis of the sugar moiety is required for isoflavone bioavailability and that isoflavone glycosides are not absorbed intact across the enterocyte in healthy adults [6]. When cultured with enteric bacteria, tectoridin and TGXG are metabolized into tectorigenin and 6HGDG is metabolized into the aglycone isoflavone 6-hydroxygenistein [7,8]. Consequently, the major isoflavones in PFE are likely to be absorbed into the bloodstream in the forms of tectorigenin and 6-hydroxygenistein.…”

Biotransformation of mulberroside A from Morus alba results in enhancement of tyrosinase inhibition

“…Bioconversion is an eco-friendly and efficient method for enhancing the bioavailability of glycosylated stilbenes. Bioconversion of prodrugs enhances bioavailability [15], and bioconversion processes have been applied in various fields to improve the biological activity of bioactive molecules [2,20,25,30]. Enzymatic conversion of glycosides into aglycones enhances their biological activities [18,21,22].…”