Phenolic Acid Content and Composition of Eggplant Fruit in a Germplasm Core Subset

Abstract

<jats:p>Eggplant (<jats:italic>Solanum melongena</jats:italic> L.) is ranked among the top ten vegetables in terms of oxygen radical absorbance capacity due to its fruit's phenolic constituents. Several potential health promoting effects have been ascribed to plant phenolic phytochemicals. We report here a first evaluation of phenolic acid constituents in eggplant fruit from accessions in the USDA eggplant core subset. The core subset includes 101 accessions of the cultivated eggplant, <jats:italic>S. melongena,</jats:italic> and 14 accessions representing four related eggplant species, <jats:italic>S</jats:italic>. <jats:italic>aethiopicum</jats:italic> L., <jats:italic>S</jats:italic>. <jats:italic>anguivi</jats:italic> Lam., <jats:italic>S</jats:italic>. <jats:italic>incanum</jats:italic> L., and <jats:italic>S</jats:italic>. <jats:italic>macrocarpon</jats:italic> L. Significant differences in phenolic acid content and composition were evident among the five eggplant species and among genotypes within species. Fourteen compounds separated by HPLC, that were present in many but not all accessions, were identified or tentatively identified as hydroxycinnamic acid (HCA) derivatives based on HPLC elution times, UV absorbance spectra, ES-—MS mass spectra, and in some cases proton NMR data. These phenolics were grouped into five classes: chlorogenic acid isomers, isochlorogenic acid isomers, hydroxycinnamic acid amide conjugates, unidentified caffeic acid conjugates, and acetylated chlorogenic acid isomers. Among <jats:italic>S. melongena</jats:italic> accessions, there was a nearly 20-fold range in total HCA content. Total HCA content in <jats:italic>S. aethiopicum</jats:italic> and <jats:italic>S. macrocarpon</jats:italic> was low relative to <jats:italic>S. melongena</jats:italic>. A <jats:italic>S. anguivi</jats:italic> accession had the highest HCA content among core subset accessions. Chlorogenic acid isomers ranged from 63.4% to 96% of total HCAs in most core accessions. Two atypical accessions, <jats:italic>S. anguivi</jats:italic> PI 319855 and <jats:italic>S. incanum</jats:italic> PI500922, exhibited strikingly different HCA conjugate profiles, which differed from those of all other core subset accessions by the presence of several unique phenolic compounds. Our findings on eggplant fruit phenolic content provide opportunities to improve eggplant fruit quality and nutritive value.</jats:p>

Characterization of interspecific hybrids and first backcross generations from crosses between two cultivated eggplants (Solanum melongena and S. aethiopicum Kumba group) and implications for eggplant breeding

“…Measurements of fruit phenolics content in the parental lines confirms the occurrence of low total fruit phenolics in S. aethiopicum relative to S. melongena (Stommel and Whitaker 2003;Prohens et al 2007;Mennella et al 2010) and denote that S. melongena could be utilized for improving the phenolics content of S. aethiopicum. Low fruit phenolics in interspecific hybrids suggests dominance of the S. aethiopicum alleles.…”

“…Lester (1986) suggested that these three species together serve mutually as secondary genepools. For example, S. melongena could be a source of variation for fruit size and shape in the gboma and scarlet eggplants and might also be useful to increase fruit phenolic antioxidant content of S. aethiopicum, which usually presents concentrations much lower than those of S. melongena (Stommel and Whitaker 2003;Prohens et al 2007).…”

Diversity in eggplant (Solanum melongena) for superoxide scavenging activity, total phenolics, and ascorbic acid

“…This result was expected given the strong association between high antioxidant activity and phenolics content previously shown for eggplant (Sudheesh et al, 1999;Kaneyuki et al, 1999;Noda et al, 2000;Huang et al, 2004) as well as other crops such as blueberry (Connor et al, 2002), tomato (Hanson et al, 2004a) and pepper (Hanson et al, 2004b). Eggplant genotypes are highly diverse both in the number of phenolic compounds as well as the proportions of phenolic compounds contained in individual accessions (Stommel and Whitaker, 2003). Chlorogenic acid and its isomers make up the major class of phenolics in eggplant fruit (Stommel and Whitaker, 2003).…”

“…Eggplant genotypes are highly diverse both in the number of phenolic compounds as well as the proportions of phenolic compounds contained in individual accessions (Stommel and Whitaker, 2003). Chlorogenic acid and its isomers make up the major class of phenolics in eggplant fruit (Stommel and Whitaker, 2003). Isolation of phenolics other than nasunin from eggplant that confer high SOS activity is likely.…”

“…Varieties of purple, green, or white fruit colour in a wide range of colour intensities are common (Nothmann et al, 1976). Stommel and Whitaker (2003) distinguished at least 14 phenolic compounds among accessions in an eggplant core collection. Given the diversity of phenolic compounds in eggplant, it is possible that compounds other than anthocyanins contribute to high SOS activity.…”