New Flavonol Glycosides from the Leaves of Triantha Japonica and Tofieldia Nuda

Abstract

Two new flavonol glycosides were isolated from the leaves of Triantha japonica, together with eight known flavonols, kaempferol 3-O-sophoroside, kaempferol 3-O-sambubioside, kaempferol 3-O-glucosyl-(1→2)-[glucosyl-(1→6)-glucoside], quercetin 3-O-sophoroside, quercetin 3-O-sambubioside, isorhamnetin 3-O-glucoside, isorhamnetin 3-O-sophoroside and isorhamnetin 3-O-sambubioside. The new compounds were identified as kaempferol 3-O-β-xylopyranosyl-(1→2)-[β-glucopyranosyl-(1→6)-β-glucopyranoside] (1) and isorhamnetin 3-O-β-xylopyranosyl-(1→2)-[β-glucopyranosyl-(1→6)-βglucopyranoside] (3) by UV, LC-MS, acid hydrolysis, and 1 H and 13 C NMR spectroscopy. Another two new flavonol glycosides were isolated from the leaves of Tofieldia nuda, and identified as kaempferol 3-O-β-glucopyranosyl-(1→2)-[β-glucopyranosyl-(1→6)-β-galactopyranoside] (4) and quercetin 3-O-βglucopyranosyl-(1→2)-[β-glucopyranosyl-(1→6)-β-galactopyranoside] (5). Though the genera Triantha and Tofieldia were treated as Tofieldia sensu lato, they were recently divided into two genera. It was shown by this survey that their flavonoid composition were also different to each other.

Characterization and Structural Analysis of a Novel exo-Type Enzyme Acting on β-1,2-Glucooligosaccharides from Parabacteroides distasonis

“…β-1,2-Glucan mainly exists as a cyclic form in some Gram-negative bacteria, such as Agrobacterium , Rhizobium , Sinorhizobium , and Brucella . − Cyclic β-1,2-glucan is known as a commensal factor in Rhizobium and as an infectious factor in Brucella abortus with respect to their hosts. , Production of this glucan in the periplasm or the extracellular space for osmotic regulation has also been reported. − The chain lengths of cyclic β-1,2-glucans are usually around degrees of polymerization (DPs) of 20, while it has been reported that Rhizobium meliloti produces longer cyclic β-1,2-glucans (DPs of around 40) . Cyclic β-1,2-glucan synthases are known as membrane proteins, and their reaction mechanisms are well-characterized. − Linear β-1,2-glucan (unless otherwise noted, β-1,2-glucan represents the linear form) is found in Acetobacter and Xanthomonas . , Production of β-1,2-glucan with β-1,6-glucosyl branches in Escherichia coli and Pseudomonas syringae has been reported, as well. ,, In addition, sophorosides such as kaempherol 3- O -sophoroside and stevioside are found in some plants. , …”

“…8,10,19 In addition, sophorosides such as kaempherol 3-Osophoroside and stevioside are found in some plants. 20,21 In spite of this distribution and the important physiological roles of β-1,2-glucan, a low abundance of β-1,2-glucan has limited investigation of β-1,2-glucan-degrading enzymes. We first identified a glycoside phosphorylase acting on β-1,2-glucan from Listeria innocua as a β-1,2-glucan-degrading enzyme.…”

New Flavonol Glycosides from the Leaves and Flowers of Primula sieboidii

“…Flavonoid 1 liberated quercetin, glucose and xylose by acid hydrolysis. An UV spectral survey, according to Mabry et al [3], showed that the 3-position of quercetin is glycosylated. In the LC-MS, the molecular ion peak appeared at m/z 757 [M-H] -, showing that 2 mol glucose and 1 mol xylose are attached to quercetin.…”