In the presence of transition metal ions and peroxides, polyphenols, well-known dietary antioxidants, can act as pro-oxidants. We investigated the effect of 13 polyphenols and their metabolites on oxidative degradation of deoxyribose by an •OH generating Fenton system (Fe2+-ethylenediaminetetraacetic acid (EDTA)-H₂O₂). The relationship between phenolics pro-oxidant/anti-oxidant effects and thei...

Extraction of phenolics from Idesia polycarpa defatted fruit residue was optimized by the maximization of the yield in total phenolics, using the response surface methodology. The optimized conditions were 50% ethanol, 5 h extraction time, 1 : 40 liquid to solid ratio, and 80°C extraction temperature. The experimental average total phenolics yield was 54.49 ± 4.26 mg/g. These antioxidant proper...

The changing dynamics of organic acids, sugars, phenolics and antioxidant potential in apples from technological to edible maturity was studied. During the time of storage, the content of citric and malic acids generally decreased. The content of sucrose, fructose and glucose decreased significantly in some varieties, while it increased in others. The content of total sugars changed only slight...

Many of the marker compounds analyzed in herbal products are redox-active phenolic molecules, which are commonly found in plants as components of glycosides and starch polymers. Variability in degree of sample hydrolysis can occur due to differences in water content, pH, and temperature. Sonication versus shaking during extraction can also influence hydrolysis and oxidation of sensitive compoun...

The effects of blanching, freezing, and frozen storage on the retention of radical-scavenging activity (RSA), total phenolics, and ascorbic acid in bitter gourd were investigated. Blanching of sliced bitter gourd resulted in considerable losses of RSA and total phenolics, and most extensively, of ascorbic acid. In the subsequent frozen storage at -18 degrees C, RSA and total phenolic content of...

There are evidences showing that adverse impacts of aluminum (Al) on plants growth and development are associated with its effect on plasma membrane and cell wall. Influence of Al on peroxidation of membrane lipids, wall-bound phenolics, lignin, soluble phenolics and the activity of certain enzymes involved in metabolism of phenols, i.e., phenylalanine ammonia lyase (PAL) and polyphenol oxidase...

Carbon allocation to soluble phenolics (total phenolics, proanthocyanidins (PA)) and total non-structural carbohydrates (TNC; starch and soluble sugars) in needles of widely planted, highly productive loblolly pine (Pinus taeda L.) genotypes could impact stand resistance to herbivory, and biogeochemical cycling in the southeastern USA. However, genetic and growth-related effects on loblolly pin...

Rising levels of atmospheric CO2 can alter plant growth and partitioning to secondary metabolites. The protein competition model (PCM) and the extended growth/differentiation balance model (GDBe) are similar but alternative models that address ontogenetic and environmental effects on whole-plant carbon partitioning to the phenylpropanoid biosynthetic pathway, making many divergent predictions. ...

The activities of catalase, peroxidase, and polyphenoloxidase were studied in attached and detached rice (Oryza sativa L. cv. Ratna) leaves. Catalase activity decreased while peroxidase and polyphenoloxidase activities increased during senescence of both attached and detached rice leaves. Kinetic (5 mum) and benzimidazole (1 mm), which are known to delay the senescence of detached rice leaves, ...