Flavonoid glycosides from Adina racemosa and their inhibitory activities on eukaryotic protein synthesis

3‴-O-Foliamenthoyl-Rutin, a New Flavonoid Glycoside from the Roots of Nymphoides peltata

Nymphoides peltata (Menyanthaceae) has been used as a medicinal herb in traditional medicines to treat conditions such as strangury, polyuria, swelling, and as a diuretic and antipyretic. In our ongoing research to discover novel structural and/or biological natural products in natural resources, five flavonoids, quercetin (1), quercitrin (2), isoquercetin (3), quercetin-3-O-vicianoside (4), and rutin (5), as well as a new flavonoid glycoside, 3‴-O-foliamenthoyl-rutin (6), were isolated from the MeOH extract of N. peltata roots. The chemical structure of the new compound (6) was determined by analyzing 1D and 2D NMR spectra and high-resolution (HR) electrospray ionization mass spectroscopy (ESIMS), along with a chemical reaction. The wound-healing activities of the isolated compounds (1-6) were evaluated using a HaCaT cell scratch test. Among the isolates, isoquercetin (3), quercetin-3-O-vicianoside (4), and 3‴-O-foliamenthoyl-rutin (6) promoted HaCaT cell migration over scratch wounds, with compound 4 being the most effective. Our findings provide experimental data supporting the potential of quercetin-3-O-vicianoside (4) as a wound-healing agent.

Antiviral phenolics from Antenoron filiforme var. neofiliforme

Two new phenolics, 1,3-di-O-p-coumaroyl-2',6'-di-O-acetylsucrose (1) and quercetin 3-O-β-D-apiofuranoyl-(1→2)-α-L-rhamnopyranoside (2), along with nine known compounds (3-11), were isolated from the whole plants of Antenoron filiforme var. neofiliforme. Their chemical structures were characterized on the basis of various spectroscopic techniques. This is the first report of the isolation of phenylpropanoid sucrose (1, 3-4) from the genus Antenoron. The bioassay results showed that compound 11 exhibited antiviral activity against the Coxsackie virus B3 (CVB3).

Secondary metabolites from Rubiaceae species

This study describes some characteristics of the Rubiaceae family pertaining to the occurrence and distribution of secondary metabolites in the main genera of this family. It reports the review of phytochemical studies addressing all species of Rubiaceae, published between 1990 and 2014. Iridoids, anthraquinones, triterpenes, indole alkaloids as well as other varying alkaloid subclasses, have shown to be the most common. These compounds have been mostly isolated from the genera Uncaria, Psychotria, Hedyotis, Ophiorrhiza and Morinda. The occurrence and distribution of iridoids, alkaloids and anthraquinones point out their chemotaxonomic correlation among tribes and subfamilies. From an evolutionary point of view, Rubioideae is the most ancient subfamily, followed by Ixoroideae and finally Cinchonoideae. The chemical biosynthetic pathway, which is not so specific in Rubioideae, can explain this and large amounts of both iridoids and indole alkaloids are produced. In Ixoroideae, the most active biosysthetic pathway is the one that produces iridoids; while in Cinchonoideae, it produces indole alkaloids together with other alkaloids. The chemical biosynthetic pathway now supports this botanical conclusion.

Acylated flavonol glycosides from the forage legume, Onobrychis viciifolia (sainfoin)

Ten acylated flavonol glycosides were isolated from aqueous acetone extracts of the aerial parts of the forage legume, Onobrychis viciifolia, and their structures determined using spectroscopic methods. Among these were eight previously unreported examples which comprised either feruloylated or sinapoylated derivatives of 3-O-di- and 3-O-triglycosides of kaempferol (3,5,7,4'-tetrahydroxyflavone) or quercetin (3,5,7,3',4'-pentahydroxyflavone). The diglycosides were acylated at the primary Glc residue of O-α-Rhap(1→6)-β-Glcp (rutinose), whereas the triglycosides were acylated at the terminal Rha residues of the branched trisaccharides, O-α-Rhap(1→2)[α-Rhap(1→6)]-β-Galp or O-α-Rhap(1→2)[α-Rhap(1→6)]-β-Glcp. Identification of the primary 3-O-linked hexose residues as either Gal or Glc was carried out by negative ion electrospray and serial MS, and cryoprobe NMR spectroscopy. Analysis of UV and MS spectra of the acylated flavonol glycosides provided additional diagnostic features relevant to direct characterisation of these compounds in hyphenated analyses. Quantitative analysis of the acylated flavonol glycosides present in different aerial parts of sainfoin revealed that the highest concentrations were in mature leaflets.

FLAVONOL GLYCOSIDES FROM THE NATIVE AMERICAN PLANT GAURA LONGIFLORA

Phytochemical investigation of the native American plant Gaura longiflora led to the isolation of three new and eight known flavonol glycosides. The structures of the new compounds were established primarily by spectroscopic data as quercetin 3-O-(2″-O-α-l-rhamnopyranosyl-6″-O-E-p-coumaroyl)-β-D-glucopyranoside (1), kaempferol 3-O-(2″-O-α-l-rhamnopyranosyl-6″-O-E-p-coumaroyl)-β-d-gluco-pyranoside (2) and quercetin 3-O-(2″-O-α-l-rhamnopyranosyl-6″-O-Z-p-coumaroyl)-β-D-glucopyrano-side (3).

Glycosides from the bark of Adina polycephala

Four new dimeric phenolic glycosides (1- 4), a new iridoid diglycoside (5), and 15 known glycosides have been isolated from an ethanolic extract of the bark of Adina polycephala. Their structures were determined by spectroscopic and chemical methods. Compounds 1, 3, and 5 showed in vitro inhibitory activity against the release of beta-glucuronidase in rat polymorphonuclear leukocytes induced by platelet-activating factor.