Dietary flavonoid and isoflavone glycosides are hydrolysed by the lactase site of lactase phlorizin hydrolase

Abstract

Lactase phlorizin hydrolase (LPH; EC 3.2.1.62) is a membrane-bound, family 1 L L-glycosidase found on the brush border of the mammalian small intestine. LPH, purified from sheep small intestine, was capable of hydrolysing a range of flavonol and isoflavone glycosides. The catalytic efficiency (k cat / K m ) for the hydrolysis of quercetin-4P P-glucoside, quercetin-3-glucoside, genistein-7-glucoside and daidzein-7-glucoside was 170, 137, 77 and 14 (mM 31 s 31 ) respectively. The majority of the activity occurred at the lactase and not phlorizin hydrolase site. The ability of LPH to deglycosylate dietary (iso)flavonoid glycosides suggests a possible role for this enzyme in the metabolism of these biologically active compounds.z 2000 Federation of European Biochemical Societies.

Absorption of kaempferol from endive, a source of kaempferol-3-glucuronide, in humans

“…The most likely explanation is preferential absorption of kaempferol-3-glucoside present in the endive soup at 14% of total kaempferol. Quercetin glucosides are preferentially absorbed from the small intestine by mechanisms that almost certainly involve active transport (eg via SGLT1; Gee et al, 2000) and deglycosylation processes (eg lactase phlorizin hydrolase and cytosolic b-glucosidase; Day et al, 2000bDay et al, , 2003Nemeth et al, 2003). Kaempferol glucosides are almost certainly absorbed from the small intestine via similar processes due to the high degree of structural similarity between kaempferol glucosides and quercetin glucosides.…”

The Occurrence, Fate and Biological Activities ofC-glycosyl Flavonoids in the Human Diet

“…Whilst additional substitution, including O-and C-methylation (Erlund, 2004), prenylation (Stevens and Page, 2004), gallation (Singh et al, 2011), glucuronidation (Hegnauer and Gpayer-Barkmeijer, 1993) and polymerisation (Manach et al, 2004) at various positions about the backbone structure all also further expand the diversity of the flavonoid family, glycosylation is arguably the most significant single native structural feature in determining the pharmacokinetics of any flavonoid in the human diet. The addition of a sugar moiety is capable of fundamentally altering parent compound bioavailability following oral consumption by modulating critical physicochemical parameters such as structural polarity (Day et al, 2000). Flavonoid glycosylation usually proceeds by the attachment of a sugar substituent to a hydroxyl group during in planta flavonoid synthesis, thus conferring Oglycosylation via preservation of the hydroxyl oxygen in the glycosidic linkage.…”

Verfügbarkeit phenolischer Komponenten aus Rotwein (Lemberger) und Rotem Traubensaft für den Menschen

“…Einige Autoren konnten zeigen, dass Querzetinglukoside mit dem intestinalen Glukosetransporter SGLT-1 interagieren, wodurch die intestinale Aufnahme verbessert wird [17,18]. Ebenso scheinen nach jüngeren Daten die intestinale Laktase-Phlorizin-Hydrolase (LPH) in der apikalen Membran intestinaler Epithelzellen und die zytosolische β-Glukosidase bei Resorption und Metabolismus von Flavonoiden eine nicht unwichtige Rolle zu spielen [19,20]. Unter Berücksichtigung des Zuckergehalts des getesteten Traubensafts und der Strukturähnlichkeit zu Querzetin andererseits ist es denkbar, dass die Anthozyane via Kotransport mit dem intestinalen, membrangebundenen SGLT-1 resorbiert wurden mit dem Ergebnis einer erhöhten Aufnahme aus dem Intestinaltrakt gegenüber dem verwendeten Rotwein [21].…”