Identification of phenolic compounds and their relationships to in-vitro digestibility of sorghum leaves from bird-resistant and non-bird-resistant varieties

Soluble phenolics in leaf blades and sheaths from the crop residues of 24 sorghum varieties were studied. Apigenin, luteolin, apigenin and luteolin 7-O-glucosides, p-coumaric acid, butin and apigeninidin were identified. This is the first report of butin in sorghum tissues. Derivatives of the following compounds were also detected but not characterised further: apigeninidin, luteolinidin, chalcone, flavanone and/or dihydroflavonol, cinnamic acid, apigenin and luteolin. The composition of phenolics was clearly different between leaf blades (LB) and sheaths (LS), and also between leaf sheaths of bird-resistant (BR) and non-bird-resistant (NBR) varieties. Routes of flavonoid biosynthesis in BR and NBR varieties appear to diverge at the flavanone/dihydroflavonol level. Several negative correlations were found between HPLC peaks and in-vitro digestibilities, ie true dry matter and neutral-detergent fibre digestibility. These were highly significant with butin and significant with several luteolin derivatives but only with one apigenin derivative. Butin in turn was highly negatively correlated with colorimetric measurements of 3-desoxyanthocyanidins. This may suggest that butin—rather than the 3-desoxyanthocyanidins as previously reported—is implicated in reducing dry matter digestibility. Selecting varieties low in luteolin derivatives and butin and rich in apigenin should enhance the digestibilities of sorghum crop residues.     

Phenolic characterisation of red wines from different grape varieties cultivated in Mendoza province (Argentina)

BACKGROUND: Knowledge of the chemical composition of wine and its association with the grape variety/cultivar is of paramount importance in oenology and a necessary tool for marketing. Phenolic compounds are very important quality parameters of wines because of their impact on colour, taste and health properties. The aim of the present work was to study and describe the non‐flavonoid and flavonoid composition of wines from the principal red grape varieties cultivated in Mendoza (Argentina). RESULTS: Sixty phenolic compounds, including phenolic acids/derivatives, stilbenes, anthocyanins, flavanols, flavonols and dihydroflavonols, were identified and quantified using high‐performance liquid chromatography with diode array detection coupled with electrospray ionisation mass spectrometry (HPLC‐DAD/ESI‐MS). Marked quantitative differences could be seen in the phenolic profile among varieties, especially in stilbenes, acylated anthocyanins and other flavonoids. CONCLUSION: The polyphenolic content of Malbec wines was higher compared with the other red varieties. Dihydroflavonols represent a significant finding from the chemotaxonomic point of view, especially for Malbec variety. This is the first report on the individual phenolic composition of red wines from Mendoza (Argentina) and suggests that anthocyanins, flavanols and phenolic acids exert a great influence on cultivar‐based differentiation. Copyright © 2011 Society of Chemical Industry