Phenolic Composition and Related Antioxidant Properties in Differently Colored Lettuces: A Study by Electron Paramagnetic Resonance (EPR) Kinetics

Abstract

Differently colored lettuce (Lactuca sativa L.) cultivars (green, green/red, and red) were studied to correlate their phenolic composition with their antioxidant kinetic behavior. Electron paramagnetic resonance (EPR) was employed to monitor decay kinetics of 1,1-diphenyl-2-picrylhydrazyl (DPPH(•)), which allowed the identification of three differently paced antioxidants. The results showed that as long as lettuce had higher red pigmentation, the hydrophilic antioxidant capacity increased together with the contents in free and conjugated phenolic acids, free and conjugated flavonoids, and anthocyanins. EPR allowed the identification of slow-rate antioxidants in green and green/red cultivars, intermediate-rate antioxidants in green, green/red, and red cultivars, and fast-rate antioxidants in green/red and red cultivars. At present, the different kinetic behaviors cannot be attributed to a specific antioxidant, but it is suggested that the flavonoid quercetin accounted for the majority of the intermediate-rate antioxidants, whereas the anthocyanins accounted for the majority of the fast-rate antioxidants.

Elicitation effect of Saccharomyces cerevisiae yeast extract on main health‐promoting compounds and antioxidant and anti‐inflammatory potential of butter lettuce (Lactuca sativa L.)

“…This has been confirmed by others studies on various lettuce cultivars in which caffeic acid derivatives were identified . Our results correspond with those of Mulabagal et al and Pérez‐López et al , who noted that the most representative phenolic acid for lettuce cultivars was chicoric acid. As several previous studies indicate, the content of phenolics may be correlated with some pro‐health activity of plant food.…”

“…Our results correspond with those of Mulabagal et al and Pérez‐López et al , who noted that the most representative phenolic acid for lettuce cultivars was chicoric acid. As several previous studies indicate, the content of phenolics may be correlated with some pro‐health activity of plant food. Our research suggests that the phenolics (especially chicoric and chlorogenic acids) induced after elicitation with yeast extracts are most likely responsible for the plant's antioxidant capacity (Table ).…”

“…Some studies indicate that, unlike of DPPH, the ABTS method has additional flexibility and can be used at different pH levels. The accumulation of various caffeic acid derivatives in response to some stress treatment correlated with the enhanced antioxidant capacity of lettuce in the study conducted by Oh et al The increase in chlorogenic acid in lettuce leaves was significantly and positively correlated with the antioxidant activity of this vegetable in the works of Złotek et al and Pérez‐López et al Additionally, some previous studies have shown that chicoric acid has antioxidant and anti‐inflammatory activities . This was confirmed in the present study, where the correlation between chicoric acid content and the ability for LOX inhibition was positive and statistically significant (Table ).…”

Estimation of cotyledon isoflavone abundance by a grey luminance-based model in variously hilum-coloured soybean varieties

“…The relationship between colour and antioxidant compound accumulation in plant organs has recently been documented in leaves of variously coloured lettuce varieties. 29 As long as lettuce had higher red pigmentation, contents of free and conjugated phenolic acids, free and conjugated flavonoids and anthocyanins increased, suggesting that relationships among pigments and isoflavones may occur in other plant species and organs.…”

Reduced nitrogen supply enhances the cellular antioxidant potential of phenolic extracts through alteration of the phenolic composition in lettuce (Lactuca sativa L.)

“…Nitrogen, which is a vital nutrient, is an extremely important factor affecting the production of phenolic compounds in plants, and a reduction in nitrogen availability generally increases the level of phenolic compounds in plants . Chemical assays, such as ABTS, DPPH and FRAP assays, are some of the most widely used methods for the evaluation of antioxidant activity in vegetables because of advantages such as low cost, as well as simple and rapid operation . Our previous study showed that lettuce cultivated with low nitrate levels exhibits a higher phenolic content, and thus, a higher DPPH radical‐scavenging capacity and FRAP value .…”