Evaluation of chlorogenic acid accumulation in cultivated and wild apples

Bioassay-guided preparation of antioxidant, anti-inflammatory active fraction from crabapples (Malus prunifolia (Willd.) Borkh.)

The aim of current study was to optimize the extraction process and purification of main components (MC) to obtain high antioxidant, anti-inflammatory effective fractions from crabapple (Malus prunifolia (Willd.) Borkh.). The effects of three variables including ethanol concentration A₁, solid-liquid ratio A₂, extraction temperature A₃ were investigated and optimized by response surface methodology (RSM) coupled with Box-Behnken design (BBD). The adsorption/desorption characteristics of MC on the five types of macroporous resins were investigated. According to batch adsorption test, HPD-300 resins were selected for kinetics. The adsorption mechanism showed that the process was appropriate by pseudo-second-order kinetics model, and purification parameters of MC were optimized through adsorption/desorption experiments with the column packed by HPD-300 resin. The effective fractions were obviously superior to other fractions according to DPPH, ABTS, COX-2 and 15-LOX radical scavenging. This work implies that the purified active fraction with high contents of antioxidants and anti-inflammatory compounds from crabapple might be potential source for natural products and food industries.

A New Strategy Based on LC-Q TRAP-MS for Determining the Distribution of Polyphenols in Different Apple Varieties

Apples are a rich source of polyphenols in the human diet. However, the distribution of polyphenols in different apple varieties and tissues is still largely unclear. In this study, a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) strategy was developed to reveal the spatial distribution of polyphenols in different apple tissues and varieties. A method based on multiple reaction monitoring (MRM)-enhanced product ion (EPI) was established in the information-dependent acquisition (IDA) mode for pseudo-target screening of major apple polyphenols. A total of 39 apple polyphenolic metabolites were finally identified. Qualitative and quantitative results showed that the variety and content of polyphenols in apple peels were higher than those of other tissues. In apple roots, stems, and leaves, the highest polyphenol variety and content were found in wild species, followed by cultivars and elite varieties. Dihydrochalcone substances, one kind of major apple polyphenols, were more abundant in apple roots, stems, and leaves. This strategy can be applied as a model for other agricultural products, in addition to revealing the distribution of polyphenols in different tissues of apples, which provides a theoretical basis for the utilization of polyphenol resources and variety selection.

Integrative analysis of the metabolome and transcriptome reveals the molecular mechanism of chlorogenic acid synthesis in peach fruit

As the most abundant phenolic acid in peach fruit, chlorogenic acid (CGA) is an important entry point for the development of natural dietary supplements and functional foods. However, the metabolic and regulation mechanisms underlying its accumulation in peach fruits remain unclear. In this study, we evaluated the composition and content of CGAs in mature fruits of 205 peach cultivars. In peach fruits, three forms of CGA (52.57%), neochlorogenic acid (NCGA, 47.13%), and cryptochlorogenic acid (CCGA, 0.30%) were identified. During the growth and development of peach fruits, the content of CGAs generally showed a trend of rising first and then decreasing. Notably, the contents of quinic acid, shikimic acid, p-coumaroyl quinic acid, and caffeoyl shikimic acid all showed similar dynamic patterns to that of CGA, which might provide the precursor material basis for the accumulation of CGA in the later stage. Moreover, CGA, lignin, and anthocyanins might have a certain correlation and these compounds work together to maintain a dynamic balance. By the comparative transcriptome analysis, 8 structural genes (Pp4CL, PpCYP98A, and PpHCT) and 15 regulatory genes (PpMYB, PpWRKY, PpERF, PpbHLH, and PpWD40) were initially screened as candidate genes of CGA biosynthesis. Our findings preliminarily analyzed the metabolic and molecular regulation mechanisms of CGA biosynthesis in peach fruit, which provided a theoretical basis for developing high-CGA content peaches in future breeding programs.