Characterization of Free, Conjugated, and Bound Phenolic Acids in Seven Commonly Consumed Vegetables.

Yuan Gao,Xiao-Yuan Feng,Shuai Ma,Meng Wang

doi:10.3390/molecules22111878

Yuan Gao, Xiao-Yuan Feng + Show 2 more

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https://doi.org/10.3390/molecules22111878

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Abstract

Phenolic acids are thought to be beneficial for human health and responsible for vegetables’ health-promoting properties. Free, conjugated, and bound phenolic acids of seven commonly consumed vegetables, including kidney bean, cow pea, snow pea, hyacinth bean, green soy bean, soybean sprouts and daylily, from the regions of Beijing, Hangzhou, and Guangzhou, were identified and quantified by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Three vegetables, namely green soy bean, soybean sprouts, and daylily (Hemerocallis fulva L.), from the Beijing region contained higher concentrations of total phenolic acids than those from the Hangzhou and Guangzhou regions. The results indicated that the phenolic acid content in the seven vegetables appeared to be species-dependent. The highest content of phenolic acids was found in daylily, followed by green soy bean, while the least amounts were identified in kidney bean and hyacinth bean. Typically, phenolic acids are predominantly found in conjugated forms. Principle component analysis (PCA) revealed some key compounds that differentiated the seven vegetables. Green soy bean, compared to the other six vegetables, was characterized by higher levels of syringic acid, ferulic acid, vanillic acid, and sinapic acid. Other compounds, particularly p-coumaric acid, neochlorogenic acid, and caffeic acid, exhibited significantly higher concentrations in daylily. In addition, p-coumaric acid was the characteristic substance in cow pea. Results from this study can contribute to the development of vegetables with specific phytochemicals and health benefits.

Highlights

As basic consumable food products in people’s daily lives, vegetables constitute an increasing amount of the diet, especially in China, reaching up to 33.7% of the total dietary consumption [1].Epidemiological studies have provided evidence to prove that the frequent consumption of fruits and vegetables is associated with a reduced risk for some chronic and cardiovascular diseases [2].In particular, phenolic compounds are one of the most important natural antioxidants responsible for these health promoting properties due to their bioactivities [3,4]
Phenolic acids are divided into hydroxybenzoic and hydroycinnamic acids according to their structural features
Our results indicate that among the three groups, the free-form phenolic acids accounted for the lowest proportional concentration in these vegetables

Summary

Introduction

As basic consumable food products in people’s daily lives, vegetables constitute an increasing amount of the diet, especially in China, reaching up to 33.7% of the total dietary consumption [1].Epidemiological studies have provided evidence to prove that the frequent consumption of fruits and vegetables is associated with a reduced risk for some chronic and cardiovascular diseases [2].In particular, phenolic compounds are one of the most important natural antioxidants responsible for these health promoting properties due to their bioactivities [3,4]. As basic consumable food products in people’s daily lives, vegetables constitute an increasing amount of the diet, especially in China, reaching up to 33.7% of the total dietary consumption [1]. Epidemiological studies have provided evidence to prove that the frequent consumption of fruits and vegetables is associated with a reduced risk for some chronic and cardiovascular diseases [2]. Phenolic compounds are one of the most important natural antioxidants responsible for these health promoting properties due to their bioactivities [3,4]. As a product of secondary metabolism, are considered to deliver health benefits by free radical scavenging, antioxidant, anticarcinogenic, anti-inflammatory, or antimicrobial effects [5,6,7]. The main dietary sources of phenolic acids are fruits, vegetables, cereals, Molecules 2017, 22, 1878; doi:10.3390/molecules22111878 www.mdpi.com/journal/molecules

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