Extraction of cocoa proanthocyanidins and their fractionation by sequential centrifugal partition chromatography and gel permeation chromatography

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Cocoa beans contain secondary metabolites ranging from simple alkaloids to complex polyphenols with most of them believed to possess significant health benefits. The increasing interest in these health effects has prompted the need to develop techniques for their extraction, fractionation, separation, and analysis. This work provides an update on analytical procedures with a focus on establishing a gentle extraction technique. Cocoa beans were finely ground to an average particle size of <100 μm, defatted at 20°C using n-hexane, and extracted three times with 50 % aqueous acetone at 50°C. Determination of the total phenolic content was done using the Folin-Ciocalteu assay, the concentration of individual polyphenols was analyzed by electrospray ionization high performance liquid chromatography-mass spectrometry (ESI-HPLC/MS). Fractions of bioactive compounds were separated by combining sequential centrifugal partition chromatography (SCPC) and gel permeation column chromatography using Sephadex LH-20. For SCPC, a two-phase solvent system consisting of ethyl acetate/n-butanol/water (4:1:5, v/v/v) was successfully applied for the separation of theobromine, caffeine, and representatives of the two main phenolic compound classes flavan-3-ols and flavonols. Gel permeation chromatography on Sephadex LH-20 using a stepwise elution sequence with aqueous acetone has been shown for effectively separating individual flavan-3-ols. Separation was obtained for (-)-epicatechin, proanthocyanidin dimer B2, trimer C1, and tetramer cinnamtannin A2. The purity of alkaloids and phenolic compounds was determined by HPLC analysis and their chemical identity was confirmed by mass spectrometry

Glaciolacustrine deposits formed in an ice-dammed tributary valley in the south-central Pyrenees: new evidence for late Pleistocene climate

Combined geomorphic features, stratigraphic characteristics and sedimentologic interpretation, coupled with optically stimulated luminescence (OSL) dates, of a glacio-fluvio-lacustrine sequence (Linás de Broto, northern Spain) provide new information to understand the palaeoenvironmental significance of dynamics of glacier systems in the south-central Pyrenees during the Last Glacial Cycle (≈130 ka to 14 ka). The Linás de Broto depositional system consisted of a proglacial lake fed primarily by meltwater streams emanating from the small Sorrosal glacier and dammed by a lateral moraine of the Ara trunk glacier. The resulting glacio-fluvio-lacustrine sequence, around 55 m thick, is divided into five lithological units consisting of braided fluvial (gravel deposits), lake margin (gravel and sand deltaic deposits) and distal lake (silt and clay laminites) facies associations. Evolution of the depositional environment reflects three phases of progradation of a high-energy braided fluvial system separated by two phases of rapid expansion of the lake. Fluvial progradation occurred during short periods of ice melting. Lake expansion concurred with ice-dam growth of the trunk glacier. The first lake expansion occurred over a time range between 55 ± 9 ka and 49 ± 11 ka, and is consistent with the age of the Viu lateral moraine (49 ± 8 ka), which marks the maximum areal extent of the Ara glacier during the Last Glacial Cycle. These dates confirm that the maximum areal extent of the glacier occurred during Marine Isotope Stages 4 and 3 in the south-central Pyrenees, thus before the Last Glacial Maximum. The evolution of the Linás de Broto depositional system during this maximum glacier extent was modulated by climate oscillations in the northern Iberian Peninsula, probably related to latitudinal shifts of the atmospheric circulation in the southern North-Atlantic Ocean, and variations in summer insolation intensity

The depositional history of an esker near Ottawa, Canada

The 10 km long Stittsville Ridge, trending parallel to the last direction of ice advance into the Ottawa area, is here classified as an esker. The sediments of the ridge are interpreted as subaqueous outwash deposited from a subglacial or englacial meltwater conduit emptying into an inlet in the late Wisconsin glacier front. The ridge formed by the coalescence of subaqueous outwash fans as the ice retreated northward. Sedimentological variation along the ridge is attributed to a change in the morphology of the inlet as the ice front retreated, from an initially narrow, symmetrical shape to a broader and increasingly asymmetrical form. </jats:p

The Cypress Hills Formation (Upper Eocene to Miocene): a semi-arid braidplain deposit resulting from intrusive uplift

The Upper Eocene – Miocene Cypress Hills Formation of the Cypress Hills plateau, in southwestern Saskatchewan and southeastern Alberta, is interpreted as a braidplain deposit. The regional paleoslope dipped to the northeast, and the east–west distribution of outcrop exposes facies representing lateral variation across the slope of the braidplain. Overall, the average clast size of the deposits decreases from west to east, with western area sediments dominated by boulder-sized gravels deposited on longitudinal bars. The eastern outcrop area contains deposits of braided channels cut into and interbedded with finer interchannel material including lacustrine marlstones, silcretes, and debris-flow deposits, the latter commonly containing abundant fossils.The gravels of the Cypress Hills Formation are multicyclic; they were originally derived from the western ranges of the Rocky Mountains during Laramide orogenesis and later shed farther into the basin during rebound due to unloading of the Laramide thrusts by erosion. Most recent transport resulted from uplift by intrusive activity of the Sweetgrass Hills, the Bearpaw Mountains, and the Highwood Mountains in northern Montana. Transport from the uplifted source areas was largely restricted to valley-confined rivers with the braidplains beginning beyond the valley termini. The lateral extent of the gravel braidplain was limited by the position of valleys and resulted in the observed variation in facies. Climate, as indicated by the sedimentology, faunal assemblages, silcretes, and palynology, was semi-arid with seasonal rainfall. </jats:p