Phenolische Pflanzeninhaltsstoffe als natürliche Antioxidantien

Abstract

for the acrolein and cinnamaldehyde adducts and (6H) for crotonaldehyde adduct for the methyl hydrogens. In addition to the above the cinnamaldehyde adduct gave peaks at 6.7 ppm (5H) for phenyl. rig. 5. YMK spectra of the Uzels-Alder adducts isolated from the reaction products of acrolein, crotonaldehyde and cinnamaldehyde with methyl esters of isomerized and elaidinized safflower oil fatty acids taken in carbon tetrachloride -.U i s c u s s i o n The maximum yields of the Diels-Alder adducts with acrolein, crotonaldehyde or cinnamaldehyde are 40.2, 44.2 and 52.2 per cent respectively. The comparatively high yield (52.2 O/o) of cinnamaldehyde adduct may be due to the further activation of the double bond by the adjacent phenyl ring. Use of two moles of dienophile/ mole of methyl linoleate, carrying out the reaction at elevated temperature (21Oo-24O0 C) and prolonged reaction times usually favour the adduct formation along with a corresponding increase in the formation of polymeric and other materials (Experiments 1 1 , 28 and 37). With acrolein use of benzene favoured the formation of Diels-Alder adduct (Experiment 11). It is clear from the results that in all the experiments the methyl linoleate has not completely taken part in the Diels-Alder reaction. Prolonged reaction times resulted in the formation of higher percentages of the polymer without substantial increase in the Diels-Alder adducts. Elaidinization of the fatty acid ester is essential to obtain satisfactory yields of the adduct. When compared to the yield of the Diels-Alder adduct from acrylic, crotonic or cinnamic acids' (max. yield, varied from 57 to 64 O/o) the yields of the adducts from the corresponding aldehydes are less (max. yield varied from 40-52"/0). A c k n o w l e d g m e n t This research has been financed in part by grant from USDA under PL-480. The authors gratefully adcnowledge the help and advice of Dr. M . A. Sivasamban, Principal Investigator of this project.

Atividade antioxidante e conteúdo fenólico do resíduo agroindustrial da produção de vinho

“…Os principais subgrupos são as catequinas e proantocianidinas, as antocianidinas e os flavonóis ou flavonas (HERRMANN, 1994). O reconhecimento dos benefícios à saúde, por parte das catequinas e proantocianidanas, está levando ao uso de extratos de semente de uva como suplementação alimentar (LAPARRA; MICHAUD; MASQUELIER, 1979).…”

Antioxidant power quantification of decoction and cold infusions of Hibiscus sabdariffa flowers

“…The last are the most significant (Bitsch, 1996) and derive from 2-phenyl-benzopyran. The main subgroups are the colourless catechins and proanthocyanidins, the red to blue-coloured anthocyanidins and the light-yellow flavonols and flavones (Herrmann, 1994). Food products, such as fruit juices and vegetables, or dietary supplements, such as vitamins, are frequently employed for their preventive action because of the immediate effect on the redox status of the body fluids.…”

Comparison of Electrochemical Oxidation of Flavonols and Calculated Proton Affinity and Electron Transfer Enthalpy in Water

“…Antioxidant properties of vegetable food and spices are often the result of phenol ingredients. Here the antioxidant effect is based on flavonoids and phenolic acids 1. Flavonoids are a class of plant secondary metabolites, fulfilling important tasks in warding off pests or diseases, as well as attracting pollen distributing insects as colourings and flavourings 2.…”