Soluble and insoluble-bound phenolic extracts of several varieties of millet (kodo, finger, foxtail, proso, pearl, and little millets) whole grains were evaluated for their phenolic contents and antioxidative efficacy using trolox equivalent antioxidant capacity (TEAC), reducing power (RP), and beta-carotene-linoleate model system as well as ferrous chelating activity. In addition, ferulic and p-coumaric acids were present in soluble and bound phenolic fractions of millets, and their contents were determined using high-performance liquid chromatography (HPLC) and HPLC-mass spectrometry (MS). Kodo millet had the highest total phenolic content, whereas proso millet possessed the least. All millet varieties showed high antioxidant activities, although the order of their efficacy was assay dependent. HPLC analysis of millet phenolic extracts demonstrated that the bound fractions contained more ferulic and p-coumaric acids compared to their soluble counterparts. The results of this study showed that soluble as well as bound fractions of millet grains are rich sources of phenolic compounds with antioxidant, metal chelating, and reducing power. The potential of whole millets as natural sources of antioxidants depends on the variety used. The importance of the insoluble bound fraction of millet as a source of ferulic acid and p-coumaric acid was established, and their contribution to the total phenolic content must be taken into account in the assessment of the antioxidant activity of millets.

Starchy roots and tuber crops play a pivotal role in the human diet. There are number of roots and tubers which make an extensive biodiversity even within the same geographical location. Thus, they add variety to the diet in addition to offering numerous desirable nutritional and health benefits such as antioxidative, hypoglycemic, hypocholesterolemic, antimicrobial, and immunomodulatory activities. A number of bioactive constituents such as phenolic compounds, saponins, bioactive proteins, glycoalkaloids, and phytic acids are responsible for the observed effects. Many starchy tuber crops, except the common potatoes, sweet potatoes, and cassava, are not yet fully explored for their nutritional and health benefits. In Asian countries, some edible tubers are also used as traditional medicinal. A variety of foods can be prepared using tubers and they may also be used in industrial applications. Processing may affect the bioactivities of constituent compounds. Tubers have an immense potential as functional foods and nutraceutical ingredients to be explored in disease risk reduction and wellness.

Etherified Insoluble bound Hydroxybenzoic acids Hydroxycinnamic acids Flavonoids A B S T R A C T Over 50 phenolic compounds belonging to several classes, namely, phenolic acids and their derivatives, dehydrodiferulates and dehydrotriferulates, flavan-3-ol monomers and dimers, flavonols, flavones and flavanonols in four phenolics fractions of several whole millet grains (kodo, finger (Ravi), finger (local), foxtail, proso, little and pearl millets) were positively or tentatively identified using high performance liquid chromatography (HPLC) and HPLC-tandem mass spectrometry (MS n ). Total phenolic content (TPC) was determined colourimetrically using Folin-Ciocalteu reagent. Antioxidant and antiradical activities of phenolic fractions were estimated using oxygen radical absorbance capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, and singlet oxygen scavenging activity. In addition, antioxidant activities of phenolic fractions were determined in a b-carotene linoleate emulsion system. Insoluble bound fraction of kodo millet showed the highest phenolic content as well as antioxidant activity in the in vitro test systems employed. In general, hydroxycinnamic acids and their derivatives were the main contributors (87-98%) to the TPC of insoluble bound phenolic fraction of millet varieties examined.Flavonoids were predominantly present in the free phenolic fractions of two finger millet varieties and included catechin, epicatechin, gallocatechin, epigallocatechin, and procyanidin dimers B1 and B2 among others. The degree of esterification or etherification of phenolics with sugar residues in the soluble fraction changed with the variety. Thus millet grains may serve as a viable functional food ingredient and a source of natural antioxidants.

Hydroxycinnamates are among the most widely distributed plant phenylpropanoids present in the free, conjugated-soluble and insoluble-bound forms. This review will focus on the occurrence, in vitro and in vivo antioxidant activities of ferulic, coumaric, caffeic and sinapic acids and their derivatives. Hydroxycinnamates are found in almost all food groups though they are abundant in cereals, legumes, oilseeds, fruits, vegetables and beverages and render antioxidant activity by scavenging hydroxyl radical, superoxide radical anion, several organic radicals, peroxyl radical, peroxinitrite and singlet oxygen, among others. Further, their antioxidant activity as chain breaking antioxidants and reducing agents is also notable. Ferulic acid and its derivatives such as ferulic acid ethyl ester, ferulic acid dehydrodimers, feruloyl glycosides and curcumin have demonstrated potent antioxidant activity in both in vitro and in vivo systems. Similarly, caffeic acid and some of its derivatives such as caffeic acid phenethyl ester, rosmarinic acid, and chlorogenic acid exhibit antioxidant activity. The highest antioxidant activity was observed for caffeic acid whereas p-coumaric acid had the least effect among major hydroxycinnamic acids. The importance of structural effects on the potency of antioxidant activity of hydroxycinnamates is discussed. While this review also shows the existence of substantial body of evidences for in vitro antioxidant activity of hydroxycinnamates, there is a clear gap for in vivo information, particularly for sinapic and p-coumaric acids and their derivatives. The role of grains, fruits, vegetables and red wine in disease risk reduction and health promotion could partly be attributed to their constituent hydroxycinnamates. KeywordsCaffeic Á Ferulic Á In vitro antioxidant activity Á In vivo studies Á Sinapic Abbreviations AAPH 2, 2 0 -Azobis-(2-methyl propionamidine) dihydrochloride diFA Dehydrodiferulic acid CAPE Caffeic acid phenethyl ester DPPH 1, 1-Diphenyl 2-picrylhydrazil DOPAC 3, 4-Dihydroxyphenylacetic acid FAEE Ferulic acid ethyl ester FRAP Ferric reducing antioxidant power IR Ischaemia-reperfusion LPS Lipopolysacchride LDL Low density lipoprotein NO Nitric oxide TPA 12-O-Tetradecanoylphorbol-13-acetate TEAC Trolox equivalent antioxidant capacity TBARS Thiobarbituric reactive substances

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