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.

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.

UV-ABC screens of luteolin derivatives compared to edelweiss extract.

Pure luteolin is a remarkably heat (200°C/6 days) and UV stable UV-A screen, however, native luteolin enriched to 37% in an edelweiss extract lost its UV-A screen properties upon UV irradiation (∼4MJm(-2)). This contrasting behavior led to the examination of a series of purified luteolin derivatives as UV screen candidates. 3',4',5,7-Tetralipoyloxyflavones were synthesized from luteolin (3',4',5,7-tetrahydroxyflavone) and fatty acid chlorides. These acylated semi-biomolecules show a hypsochromic shift in UV-Vis spectra of about Δλ(A→B)=58nm and absorbed in the centre of the harmful UV-B band (λ(max)=295nm). Luteolin was also hydroxyethylated with Br(CH(2))(2)OH. This substitution has no effect on the λ(max)=330nm absorption of luteolin (UV-A band). Finally the natural 4'-O-ß-glucosyl-3',5,7-trihydroxyflavone was extracted from edelweiss and used as a purified natural benchmark. Glycosylated and hydroxyethylated luteolin are both UV stable. Fully acylated luteolin derivatives degrade upon UV exposure to a stable UV-C screen with a hypsochroic shift Δλ(B→C)=35nm. All in all, three molecular structures based on luteolin with sunscreen properties were found, distinguishable in: UV-A, UV-B, and UV-C filters. The natural product based UV-absorbers show promise as alternatives to synthetic molecules and nanoparticles in sunscreen products.