Bioavailability of quercetin in humans and the influence of food matrix comparing quercetin capsules and different apple sources.

The objective of the four-way cross-over pilot study was the investigation of quercetin bioavailability after ingestion of apple quercetin incorporated in different matrices and quercetin dihydrate capsule. Six healthy volunteers were given a standard diet supplemented with 71μmol quercetin equivalents from vacuum impregnated apple chips, apple peel extract capsules and apple peel. Quercetin dihydrate capsules were used as control.

Enriched cereal bars are more effective in increasing plasma quercetin compared with quercetin from powder-filled hard capsules.

The flavonol quercetin, is one of the major flavonoids found in edible plants. The bioavailability of quercetin in humans may be influenced by the food matrix in which it is consumed as well as by its chemical and physical form. The objective of the present study was to investigate the biokinetics of quercetin from quercetin-enriched cereal bars and quercetin powder-filled hard capsules.

Antioxidant enzyme activities and antioxidant capacity in longissimus muscle from bulls fed diets rich in polyunsaturated fatty acids.

The effect of a treatment diet composed of grass silage and concentrate including rapeseed (with/without feeding restriction) was compared with a control diet of maize silage/grass silage (70:30) and concentrate including soybean, on the antioxidant enzyme activities of fresh longissimus muscle from German Simmental bulls. Additionally, the effect of diet on antioxidant capacity (AOC) of hydrophilic and lipophilic antioxidants was evaluated in fresh and stored beef muscle using the FRAP-ferric reducing ability and TEAC - Trolox-equivalent antioxidant capacity assays at different reaction times. Catalase and superoxide dismutase activities were significantly higher in the treatment diet groups, and glutathione peroxidase activity was not different.

Free and bound phenolic compounds in leaves of pak choi (Brassica campestris L. ssp. chinensis var. communis) and Chinese leaf mustard (Brassica juncea Coss).

Eleven pak choi cultivars and two leaf mustard cultivars grown under field conditions in China were investigated for the free polyphenol content in their outer and inner leaves, as well as in their leaf blades and leaf stalks. In most cases, there were no significant differences between the hydroxycinnamic acid derivative and flavonoid derivative contents in the outer and inner leaves for the 13 cultivars. However, the contents of blades and stalks differed: hydroxycinnamic acids and flavonoids were present in greater amounts in the leaf blade than in the leaf stalk.

Impact of fermentation on phenolic compounds in leaves of pak choi (Brassica campestris L. ssp. chinensis var. communis) and Chinese leaf mustard (Brassica juncea coss).

Four different cultivars of Chinese Brassica vegetables (two pak choi cultivars and two Chinese leaf mustard cultivars) were fermented according to a traditional Chinese method called pickling. The plant material was investigated before and after the fermentation procedure to determine the qualitative and quantitative changes in its polyphenols. A detailed description of the identified phenolic compounds of leaf mustard by HPLC-ESI-MS(n) is presented here for the first time, including hydroxycinnamic acid mono- and diglycosides (gentiobioses) and flavonoid tetraglycosides.

Identification of flavonoids and hydroxycinnamic acids in pak choi varieties (Brassica campestris L. ssp. chinensis var. communis) by HPLC-ESI-MSn and NMR and their quantification by HPLC-DAD.

Twenty-eight polyphenols (11 flavonoid derivatives and 17 hydroxycinnamic acid derivatives) were detected in different cultivars of the Chinese cabbage pak choi ( Brassica campestris L. ssp. chinensis var.

Nitration of gamma-tocopherol in plant tissues.

Nitration of gamma-tocopherol has been suggested to be an important mechanism for the regulation and detoxification of reactive nitrogen oxide species in animal tissues. To investigate whether this reaction does also occur in plants, reversed phase high-performance liquid chromatography (HPLC) and mass spectrometry (LC-MS) were used for analysis of 5-nitro-gamma-tocopherol (5-NgammaT) in leaves and seeds. 5-nitro-gamma-tocopherol (5-NgammaT) could be detected in an in vitro system where it was most likely generated by the reaction of gamma-tocopherol with a nitric oxide radical.