The Vitamin C Analogue 2-O-ß-D-Glucopyranosyl-L-ascorbic Acid in Rhizomes, Stems and Leaves of Lycium barbarum.

Awareness of health benefits of goji berries coming from their bioactive compounds, mostly antioxidants like ascorbic acid, has grown. Recently, an ascorbic acid analogue from goji berries, the 2-O-ß-D-glucopyranosyl-L-ascorbic acid has been reported. In rats, the analogue is absorbed intact and in the form of free vitamin C and consequently has been proposed as a provitamin C. Synthesis of the analogue is demanding and laborious and therefore reliable natural sources are searched. Knowledge concerning the analogue's occurrence in other parts of goji plant is lacking. The aim of this study was to evaluate the contents of 2-O-ß-D-glucopyranosyl-L-ascorbic acid in rhizomes, stems and leaves from Lycium barbarum. Rhizomes, stems and leaveswere extracted and the content of 2-O-ß-D-glucopyranosyl-L-ascorbic acid and non glucosylated, free ascorbic acid was determined by HPLC-DAD. 2-O-ß-D-glucopyranosyl-L-ascorbic acid was found in all goji plant tissues investigated. Based on dry weight, 3.34 mg/100 g were found in the leaves, 4.05 mg/100 g in the stems and up to 12.6 mg/100 g in the rhizomes. Nevertheless, the analogue content in goji berries is much higher (40 to 280 mg/100 g dry weight). The present study confirmed the presence of 2-O-ß-D-glucopyranosyl-L-ascorbic acid in rhizomes, stems and leaves of Lycium barbarum. However, their content compared to goji berries is considerably lower.

Analytical Platforms at Swiss Universities of Applied Sciences.

Numerous projects and industrial and academic collaborations benefit from state-of-the-art facilities and expertise in analytical chemistry available at the Swiss Universities of Applied Sciences. This review summarizes areas of expertise in analytical sciences at the University of Applied Sciences and Arts Northwestern Switzerland (FHNW), the University of Applied Sciences and Arts Western Switzerland (HES-SO), and the Zurich University of Applied Sciences (ZHAW). We briefly discuss selected projects in different fields of analytical sciences.

Chemical Modification of Polyhydroxyalkanoates (PHAs) for the Preparation of Hybrid Biomaterials.

Polyhydroxyalkanoates (PHAs) are biopolyesters produced by bacteria as intracellular granules under metabolic stress conditions. Many carbon sources such as alkanes, alkenes, alcohols, sugars, fatty acids can be used as feedstock and thus a wide variety of polyesters and monomer units can be potentially synthetized. The work presented here describes the process to chemically modify such biopolymers in order to render them readily available for the preparation of bio-molecular conjugates as promising new classes of biocompatible biomaterials. Such hybrid biomaterials belong to the rapidly growing class of biocompatible polymers, which are of great interest for medical and therapeutic applications. In this work, the biosynthesis of a new PHA homopolymer and the chemical modification, an epoxidation reaction, are described.

A biocatalytic route towards rose oxide using chloroperoxidase.

The chiral monoterpene alcohol citronellol was converted to the corresponding bromohydrin by the haem-thiolate enzyme chloroperoxidase (CPO) from Caldariomyces fumago in the presence of hydrogen peroxide and bromide ions. A conversion rate of 51% could be achieved under adapted reaction conditions, which easily yield product in the gramme per litre range while only needing catalytic amounts of enzyme. The bromohydroxylation was shown to be highly regioselective yielding 6-bromo-3,7-dimethyloctane-1,7-diol as the sole product. Product identity was confirmed by GC-MS, (1)H- and (13)C-NMR spectroscopy and the synthesis of reference compounds. However, the reaction was shown to be non-stereospecific because enantiopure (R)- and (S)-citronellol, respectively, gave 1:1-diasteromeric mixtures of the corresponding bromohydrins. A racemic mixture of (R/S)-citronellol was bromohydroxylated without any detectable enantiodiscrimination. The total lack of stereospecificity and enantiodiscrimination points to a reaction mechanism where the oxidised bromide intermediate is not a ligand to the Fe(III)-haem at the distal site but is released from the enzyme active site. The final bromide transfer occurs probably outside the active site via a diffusible oxidised bromide species and the demonstrated regioselectivity is purely chemically controlled. The generated bromohydrins can be straightforward converted via two reactions steps into rose oxide which is a highly valuable flavour and fragrance substance.

Inactivation of viruses and bacteria on strawberries using a levulinic acid plus sodium dodecyl sulfate based sanitizer, taking sensorial and chemical food safety aspects into account.

The efficacy of levulinic acid (LVA) in combination with sodium dodecyl sulfate (SDS) in removal of foodborne viruses, enteric bacterial pathogens and their surrogates on fresh strawberries was investigated. Inoculated strawberries were treated with potable water, sodium hypochlorite solution (50ppm), 0.5% LVA plus 0.5% SDS solution, and 5% LVA plus 2% SDS solution respectively for 2min, followed by spray-rinsing with potable water. Water washing removed at least 1.0-log of the tested viral and bacterial strains from the strawberries' surfaces. The 50ppm chlorine wash induced 3.4, 1.5 and 2.1-log reductions for hepatitis A virus (HAV), murine norovirus-1 (MNV-1) and MS2 bacteriophage, respectively. In comparison, the tested bacterial strains showed uniform reductions around 1.6-log CFU/ml. The 0.5% LVA plus 0.5% SDS wash induced 2.7, 1.4 and 2.4-log reductions for HAV, MNV-1 and MS2, which were comparable with the reductions induced by chlorine (P>0.05). For bacteria, over 2.0-log reductions were obtained for Enterococcus faecium, Listeria monocytogenes and Salmonella, while Escherichia coli O157:H7 and Escherichia coli P1 showed reductions of 1.9 and 1.8-log CFU/ml. Higher concentration of LVA plus SDS showed no significantly higher reductions (P>0.05). Sensory tests of washed strawberries and chemical residue analysis of LVA on strawberries after washing were also performed. In conclusion, this study demonstrates good performance of 0.5% LVA plus 0.5% SDS to reduce the levels of enteric pathogens if present on strawberries without altering taste and introducing chemical safety issues.

Monoterpenes as novel substrates for oxidation and halo-hydroxylation with chloroperoxidase from Caldariomyces fumago.

Chloroperoxidase (CPO) from Caldariomyces fumago was analysed for its ability to oxidize ten different monoterpenes with hydrogen peroxide as oxidant. In the absence of halide ions geraniol and, to a lesser extent, citronellol and nerol were converted into the corresponding aldehydes, whereas terpene hydrocarbons did not serve as substrates under these conditions. In the presence of chloride, bromide and iodide ions, every terpene tested was converted into one or more products. (1S)-(+)-3-carene was chosen as a model substrate for the CPO-catalysed conversion of terpenes in the presence of sodium halides. With chloride, bromide and iodide, the reaction products were the respective (1S,3R,4R,6R)-4-halo-3,7,7-trimethyl-bicyclo[4.1.0]-heptane-3-ols, as identified by 1H and 13C nuclear magnetic resonance. These product formations turned out to be strictly regio- and stereoselective and proceeded very rapidly and almost quantitatively. Initial specific activities of halohydrin formation increased from 4.22 U mg-1 with chloride to 12.22 U mg-1 with bromide and 37.11 U mg-1 with iodide as the respective halide ion. These results represent the first examples of the application of CPO as a highly efficient biocatalyst for monoterpene functionalization. This is a promising strategy for 'green' terpene chemistry overcoming drawbacks usually associated with cofactor-dependent oxygenases, whole-cell biocatalysts and conventional chemical methods used for terpene conversions.