Robert Aeschbach

Evaluation of Antioxidant Activity of Rosemary Extracts, Carnosol and Carnosic Acid in Bulk Vegetable Oils and Fish Oil and Their Emulsions

The antioxidant effectiveness of two rosemary extracts, carnosol and carnosic acid, was significantly influenced by the type of system tested (bulk oils vs oil-in-water emulsions), by the oil substrates, the methods used to follow oxi-dation, and the concentrations of test compounds. The rosemary extracts and compounds effectively inhibited conjugated diene hydroperoxide formation in corn oil, soya bean oil, peanut oil and fish oil, when tested in bulk. Test compounds also inhibited hexanal formation in bulk vegetable oils, and propanal and pentenal formation in bulk fish oils. In contrast, these test compounds were either inactive or promoted oxidation in the corresponding vegetable oil-in-water emulsions. In fish oil emulsions, however, the rosemary compounds inhibited the formation of conjugated diene and pentenal but not that of propanal. Interfacial phenomena may explain why the hydrophilic rosemary antioxidants afford more protection in the bulk oil systems by being oriented in the air–oil interface, and less protection in the oil-in-water emulsion systems by partitioning into the water phase.

Inhibition of peroxynitrite dependent DNA base modification and tyrosine nitration by the extra virgin olive oil-derived antioxidant hydroxytyrosol

Hydroxytyrosol is one of the o-diphenolic compounds in extra virgin olive oil and has been suggested to be a potent antioxidant. The superoxide radical (O2*-) and nitric oxide (NO*) can react very rapidly to form peroxynitrite (ONOO ), a reactive tissue damaging species thought to be involved in the pathology of several chronic diseases. Hydroxytyrosol was highly protective against the peroxynitrite-dependent nitration of tyrosine and DNA damage by peroxynitrite in vitro. Given that extra virgin olive oil is consumed daily by many humans, hydroxytyrosol derived from this diet could conceivably provide a defense against damage by oxidants in vivo. The biological activity of hydroxytyrosol in vivo will depend on its intake, uptake and access to cellular compartments.

Diterpenoide im kaffee

SummaryA method for the determination of free and total atractyligenin in green and roast coffee is described. Free atractyligenin is extracted from aqueous extracts with ethyl acetate, then separated by thin layer chromatography and determined by reflectance photometry. Total atractyligenin is determined in the same way after enzymatic hydrolysis. In 5 samples ofArabica green coffee 0–0.01 g/kg free and 0.4–0.7 g/kg total atractyligenin have been found. In 6 samples ofRobusta green coffee no free and only in I sample traces of total atractyligenin could be detected. Green coffee of the speciesExcelsa (5 samples, free: 0.01–0.02; total: 1.2–1.6 g/kg) andLiberica (1 sample, free: 0.02; total: 1.4 g/kg) contained greater amounts. The contents in the speciesArabusta lie between those inArabica andRobusta. Several samples of roasted coffee and 7 commercial blends contained an average of about twice the amount of total and 5–10 times the amount of free atracytyligenin as compared to the amount present in green coffee. The content of free atractyligenin increases with the degree of roast, the content of total atractyligenin decreases.ZusammenfassungEine Methode zur Bestimmung von freiem und gesamtem Atractyligenin in Roh- und Röstkaffee wird beschrieben. Freies Atractyligenin wird aus einem wäßrigen Extrakt mit Ethylacetat ausgeschüttelt, dünnschichtchromatographisch von anderen Stoffen getrennt und durch Remissionsspektralphotometrie bestimmt. Das gesamte Atractyligenin wird nach enzymatischer Hydrolyse der Glykoside auf dieselbe Weise erfaßt. In 5 Sorten vonArabica-Rohkaffee fanden sich 0–0,01 g/kg freies und 0,4–0,7 g/kg gesamtes Atractyligenin. Während 6 Sorten vonRobusta-Rohkaffee kein freies und nur in einem Fall Spuren von Gesamt-Atractyligenin enthielten, fanden sich in Rohkaffees der ArtenExcelsa (5 Proben, frei: 0,01–0,02, gesamt: 1,2–1,6 g/kg) undLiberica (1 Probe, frei: 0,02; gesamt: 1,4 g/kg) größere Gehalte. Die Gehalte in einerArabusta-Probe lagen zwischen denen inArabica undRobusta. In gerösteten Proben derselben Kaffeearten wurden durchschnittlich rund 2 mal so große Gehalte an gesamtem und rund 5–10 mal so große Gehalte an freiem Atractyligenin gefunden, ebenso in 7 Röstkaffee-Mischungen des Handels. Der Gehalt an freiem Atractyligenin nimmt mit dem Röstgrad zu, derjenige an gesamtem ab.