Determination of anthocyanins in wine based on flow-injection, liquid--solid extraction, continuous evaporation and high-performance liquid chromatography--photometric detection

A continuous method, easy to automate, for the determination of anthocyanins in wine based on the coupling of continuous liquid–solid extraction, evaporation, HPLC individual separation and photometric detection is proposed. The target analytes are removed from the wine in a continuous fashion using a C₁₈ minicolumn and eluted with an aqueous solution (pH 2) with 16% acetonitrile. The eluted fraction is concentrated by solvent evaporation assisted by heat and dragging off the vapour using a flow of N₂. For in-line preconcentration, a continuous evaporation module was designed and located in the manifold between the solid-phase minicolumn and the injection valve of the chromatograph. In this way, injection of the sample into the dynamic system leads the plug through it for liquid–solid extraction of the anthocyanins, partial evaporation of the eluent (with a preconcentration factor as required) and transport to the high-pressure injection valve of the chromatograph, where individual separation and subsequent photometric detection take place. The method thus developed for the determination of malvidin-3-glucoside, cyanidin-3-glucoside and peonidin-3-glucoside anthocyanins in Spanish red wines is more sensitive than the batch manual method based on the same steps, has better linearity of the calibrations curves with lower detection limits and much wider determination range for the most abundant anthocyanins in wine. In addition, the method can be fully automated with low acquisition and maintenance costs.     

Caragisides A – C,New Isoflavone Glucosides from Caragana conferta with Inhibition of Platelet Aggregation

Caragisides A–C ( 1 – 3 , resp.), three new isoflavone glucosides, were isolated from the BuOH sub‐fraction of the EtOH extract of the whole plant of Caragana conferta, along with ononoside ( 4 ), reported for the first time from this species. The structures of the new compounds were elucidated by spectroscopic techniques including MS and 2D‐NMR spectroscopy. Compounds 1 – 3 showed significant inhibition of platelet aggregation.     

Novel Cyanoglucosides from the Leaves of Hydrangea macrophylla

Four non‐cyanogenic cyanoglucosides including hydranitrilosides A₁, A₂, B₁, and B₂ ( 1 – 4 , resp.), together with a new phenolic glucoside, 3‐hydroxy‐4‐methoxybenzoic acid 3‐O‐β‐D ‐glucopyranoside ( 5 ), were isolated from the leaves of Hydrangea macrophylla. Their structures were determined on the basis of chemical and spectral evidence.     

Alkyl Polyglycosides—Properties and Applications of a new Class of Surfactants

A new generation of nonionic surfactants that are widely applicable and simultaneously ecologically compatible has been developed in the alkyl polyglycosides. Their production from the renewable resources glucose and fatty alcohol and their ultimate biodegradation into carbon dioxide, water, and assimilated bacterial biomass is an example for a closed cycle. As a result of their physico-chemical properties and ecotoxicological evaluation, they have become very important as high-performance components of detergents and cosmetic preparations.     

Three New Monoterpene Glucosides from Lamium amplexicaule

Three new monoterpene glucosides, lamiuamplexosides A–C ( 1 – 3 ), along with thirteen known glucosides, were isolated from the whole plant of Lamium amplexicaule L. The structures of 1 – 3 were elucidated on the basis of spectroscopic, chemical, and physicochemical evidence.     

Three New Alkaloids from the Leaves of Uncaria rhynchophylla

Three new alkaloids, 2′‐O‐β‐D ‐glucopyranosyl‐11‐hydroxyvincoside lactam ( 1 ), 22‐O‐demethyl‐22‐O‐β‐D ‐glucopyranosylisocorynoxeine ( 2 ), and (4S)‐corynoxeine N‐oxide ( 3 ) were isolated from the leaves of Uncaria rhynchophylla, together with four known tetracyclic oxindole or indole alkaloids, isocorynoxeine N‐oxide ( 4 ), rhynchophylline N‐oxide ( 5 ), isorhynchophylline N‐oxide ( 6 ), and dihydrocorynantheine ( 7 ), and an indole alkaloid glycoside, strictosidine ( 8 ). The structures of 1 – 3 were elucidated by spectroscopic methods including UV, IR, ESI‐TOF‐MS, 1D‐ and 2D‐NMR, as well as CD experiments. The activity assay showed that 8 (IC₅₀=8.3 μM ) exhibited potent inhibitory activity on lipopolysaccharide(LPS)‐induced nitrogen monoxide (NO) release in N9 microglia cells. However, only weak inhibitory activities were observed for 1 – 7 (IC₅₀>100 μM for 1 – 6 or >30 μM for 7 ).     

Three New ent‐Kaurane Diterpenoids from Siegesbeckia pubescens

Three new ent‐kaurane glucopyranosides, 2‐O‐[β‐D ‐apiofuranosyl‐(1→3)‐2‐O‐isovaleryl‐β‐D ‐glucopyranosyl]‐4‐epi‐atractyligenin ( 1 ), 2‐O‐[β‐D ‐apiofuranosyl‐(1→3)‐2‐O‐isovaleryl‐β‐D ‐glucopyranosyl]atractyligenin ( 2 ), and 2‐O‐[β‐D ‐apiofuranosyl‐(1→3)‐2‐O‐(3‐methylpentanoyl)‐β‐D ‐glucopyranosyl]‐4‐epi‐atractyligenin ( 3 ), along with 2‐O‐(2‐O‐isovaleryl‐β‐D ‐glucopyranosyl)‐4‐epi‐atractyligenin ( 4 ), were isolated for the first time from the aerial parts of Siegesbeckia pubescens. The structures were established by extensive spectroscopic analyses including 1D ‐ and 2D ‐NMR (HSQC, HMBC, and ROESY), and HR‐ESI‐MS, and by comparison with published data.     

High-performance liquid chromatographic analysis of secoisolariciresinol diglucoside and hydroxycinnamic acid glucosides in flaxseed by alkaline extraction

A HPLC method was developed for the analysis of secoisolariciresinol diglucoside (SDG) and hydroxycinnamic acid glucosides in milled defatted flaxseed flour. Direct extraction by 1 M NaOH for 1 h at 20 degrees C resulted in a higher yield than that obtained by hydrolysis of alcoholic extracts. An internal standard, o-coumaric acid, was used and the method was found to be easy, fast, and with good repeatability. On dry matter basis, different samples of flaxseeds varied considerably in their content of (+)-SDG (11.9-25.9 mg/g), (-)-SDG (2.2-5.0 mg/g), p-coumaric acid glucoside (1.2-8.5 mg/g), and ferulic acid glucoside (1.6-5.0 mg/g).     

Preparation and Evaluation of a Molecular Recognition Bionic Solid Phase Extraction Column for Separation of Glucosides

A molecular recognition bionic solid phase extraction (SPE) column for separation of glucosides has been prepared using a positively charged β‐glucosylamidine as the ligand in which a glycon moiety is connected via an N‐glycoside linkage. β‐Glucosylamidine, highly potent and selective inhibitors of β‐glycosidase, is immobilized through a one‐step synthesize procedure involving the addition of β‐glucosylamine and 2‐iminothiolane. HCl simultaneously to a matrix modified with maleimido groups via an appropriate spacer to give a molecular recognition absorbent for β‐glucosides. N‐octyl‐β‐D‐glucopyranoside and β‐D‐galactopyranoside or α‐D‐mannopyranoside was directly chromatographed through the bionic chromatographic column, resulting in a much stronger retention of β‐D‐glucopyranoside than β‐D‐galactopyranoside and α‐D‐mannopyranoside. The retained glucopyranoside could only be eluted by glucose solution. This indicates that the binding of the glucoside was of specific nature that corresponds to the glycon substrate specificity of the glucoside. The ease of preparation and the selective nature of the molecular recognition bionic chromatography should promise a large‐scale preparation of the molecular recognition adsorbent for the purification and removal of glucosides according to their glycon substrate specificity.