The measurement of antioxidant capacity in fruits differs from that of other biological samples due to their low pH and very low lipophilic antioxidant capacity. In this report, we present a modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method for fruits and compare its performance with the other commonly used antioxidant methods of 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The antioxidant capacity and reaction kinetics of four phenolic compounds, two antioxidant standards, and five fruits were also investigated. The modified ABTS method prepared at a pH of 4.5 with sodium acetate buffer is highly stable and easily applied to fruit samples as compared to the standard (pH 7.4) version. The measured antioxidant capacity of samples varied with the assay method used, pH, and time of reaction. Traditional antioxidant standards (trolox, ascorbic acid) displayed stable, simple reaction kinetics, which allowed end point analysis with all of assays. Of the phenolic compounds examined, chlorogenic and caffeic acids exhibited the most complex reaction kinetics and reaction rates that precluded end point analysis while gallic acid and quercetin reached stable end points. All fruit extracts exhibited complex and varied kinetics and required long reaction times to approach an end point. Because the antioxidant capacity of fruit extracts is a function of the array of individual antioxidants present, accurate comparisons among fruit samples require that reaction times be standardized and of sufficient length to reach steady state conditions and that more than one assay be used to describe the total antioxidant activity of fruit samples.

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Anthocyanin constituents in black raspberries (Rubus occidentalis L.) were investigated by HPLC-DAD, and their involvement as potent, significant antioxidants in black raspberries was demonstrated by three common antioxidant assays (FRAP, DPPH, ABTS) in this study. Five anthocyanins were present in black raspberries: cyanidin 3-sambubioside, cyanidin 3-glucoside, cyanidin 3-xylosylrutinoside, cyanidin 3-rutinoside, and pelargonidin 3-rutinoside. Their identities and structures, with particular emphasis on cyanidin 3-xylosylrutinoside, were confirmed by NMR spectroscopy. Two of these anthocyanins, cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside, predominated, comprising 24-40 and 49-58%, respectively, of the total anthocyanins in black raspberries. On the basis of both potency and concentration, cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside were found to be the significant contributors to the antioxidant systems of black raspberries. These findings indicate that these two anthocyanin compounds may function as the primary phenolic antioxidants in black raspberries. These two compounds exhibit potential biological activities that may be exploited in conjunction with other naturally occurring bioactive compounds in black raspberry fruit-based products used in clinical trials for the treatment of various types of cancer.

Fourteen purple-black American elderberry accessions (Sambucus canadensis L.) obtained from various sites in midwestern USA and then grown at a single Ohio production site in USA were analyzed for their total phenolic (TP) and total monomeric anthocyanin (TMA) contents and for their antioxidant capacity by the ferric reducing antioxidant power (FRAP) and DPPH radical scavenging assays. Total phenolic and anthocyanin contents were measured using the Folin-Ciocalteu reagent and the pH differential methods, respectively. Overall, the phytonutrient contents and antioxidant capacity of our elderberry accessions were similar to those typically reported for black raspberries, blackberries and other dark-fleshed small fruits. Variability among accessions was greatest for TMA content (CV 37.5%); individuals ranged nearly threefold from 1308 to 4004 μg cy3-GE/g on a fresh weight basis. Variation among accessions was also evident for TP, FRAP and DPPH values (CV 14.4, 21.7 and 26.8%, respectively). TP and TMA values were very highly correlated (r = 0.93), although individuals differed in the estimated proportion of total phenolics attributable to anthocyanins. Both TP and TMA also highly correlated to antioxidant capacity values (r = 0.70–0.85). Within this limited study of 14 accessions, variability for phytonutrient content and antioxidant capacity suggested the employment of wild germplasm within an elderberry improvement program to incorporate an array of superior horticultural, post-harvest or processing traits into new or existing cultivars with superior phytonutrient profiles.

Mitogen-activated protein kinase (MAPK) genes in eukaryotes regulate various developmental and physiological processes including those associated with biotic and abiotic stresses. Although MAPKs in some plant species including Arabidopsis have been identified, they are yet to be identified in soybean. Major objectives of this study were to identify GmMAPKs, assess their evolutionary relationships, and analyze their functional divergence. We identified a total of 38 MAPKs, eleven MAPKKs, and 150 MAPKKKs in soybean. Within the GmMAPK family, we also identified a new clade of six genes: four genes with TEY and two genes with TQY motifs requiring further investigation into possible legume-specific functions. The results indicated the expansion of the GmMAPK families attributable to the ancestral polyploidy events followed by chromosomal rearrangements. The GmMAPK and GmMAPKKK families were substantially larger than those in other plant species. The duplicated GmMAPK members presented complex evolutionary relationships and functional divergence when compared to their counterparts in Arabidopsis. We also highlighted existing nomenclatural issues, stressing the need for nomenclatural consistency. GmMAPK identification is vital to soybean crop improvement, and novel insights into the evolutionary relationships will enhance our understanding about plant genome evolution.