Polyphenol content and total antioxidant potential of selected Italian wines.

The total antioxidant activity (TAA) of 13 typical Italian wines was determined (average 12.3 and 1.6 mM Trolox equivalents for red and white wines, respectively), and the resulting values were correlated with total phenols (1365-3326 and 96-146 mg/L for red and white wines, respectively), flavanols (203-805 and 11-49 mg/L, for red and white wines, respectively), and flavonols. Only the red wines contained appreciable amounts of flavonols (average 15.3 mg/L), with quercetin and rutin being the most abundant, followed by myricetin, kaempferol, and isorhamnetin accounting for only 0.7-3% of TAA. The TAA of investigated wines are well correlated with phenol (r=0.9902) and flavanol (r=0.9270) content. These results confirm that red wine polyphenols are in vitro significant antioxidants and may explain the beneficial effects of a moderate daily intake of red wines, probably through a sparing action of highly bioavailable vitamins C, E, and beta-carotene

Antioxidant activity of selected medicinal plants

Commonly used medicinal plant extracts with standardized content of polyphenols were investigated for their total antioxidant activity (TAA). Green tea, oligomeric procyanidins (from grape seed and pine bark), bilberry, and ginkgo exhibited TAA in the range of 5.12-2.57 mM Trolox, thereby indicating a valuable antioxidant capacity. Witch hazel, propolis EPID, artichoke, and hawthorn afforded lower TAA (1.54-0.44 mM Trolox), whereas echinacea, ginseng, passionflower, sweet clover, and eleuthero were rather uneffective (TAA < 0.32 mM Trolox). Excipients normally used to prepare the extracts did not interfere with the assay, and a good correlation between the content of polyphenols and the TAA was assessed. The measured TAA was higher than those calculated from the content and antioxidant potential of specific components, as exemplified for green tea and ginkgo extracts. This may be attributed to the presence in these extracts of other substances with antioxidant capacity. On the other hand, some components (such as ginkgolides in ginkgo extract) insensitive to the TAA assay played an important antioxidant role in vivo. These results suggest that TAA determination is of interest for a comparative evaluation of in vitro antioxidant potential, but it needs to be combined with in vivo data for adequate assessment of the antioxidant capacity of medicinal plant extracts

Analysis of the polyphenolic fraction of propolis from different sources by liquid chromatography tandem mass spectrometry

A reverse phase LC\u2013DAD\u2013MS method for quantification of phenolic acids and flavonoids in propolis raw materials was developed. The propolis samples from different geographical areas were extracted with ethanol for 2 h at 70 \u25e6C and the resulting solutions analyzed on a 5 micromC18 symmetry 250mm 74.6mm column. The separation was performed by means of a linear gradient elution and DAD and MS data were acquired in the 200\u2013450 nm and 100\u20131000 Da range, respectively. The identity of most of the compounds was assessed by comparing their chromatographic and UV behaviour with that of authentic standards. When the standards were not available, the identity was achieved by means of chromatographic and on-line UV data combined with mass spectrometry. European, Chinese and Argentinean propolis are characterized by the presence of phenolic acids and flavonoids and the most abundant were chrysin (2\u20134%), pinocembrin (2\u20134%), pinobanksin-acetate (1.6\u20133%) and galangin (1\u20132%). Some Brazilian propolis contains mainly artepillin C, different caffeoyl quinic acids and some flavonoids. When considering the total flavonoid content as quality index, we suggest that propolis with a content less than 11% should be considered of low quality, whereas propolis with a content of 11\u201314%, 14\u201317% or >17% should be classified as propolis of acceptable, good and high quality, respectively. The reported LC\u2013DAD\u2013MS analysis method may be applied for the phytochemical screening of raw propolis and its commercial formulations