Phytochemical profiles and antioxidant activities in six species of ramie leaves.

Yongsheng Chen,Xinbo Guo,Rui Hai Liu,Gonggu Zang,Chaohua Cheng,Hong Wang,Gaoyan Wang,Gianfranco Pintus

doi:10.1371/journal.pone.0108140

Abstract

Increased consumption of vegetables or plant food has been associated with decreased risk of developing major chronic diseases, such as cancers, diabetes, cardiovascular diseases, and age-related functional decline. Ramie leaves are rich in phenolics and flavonoids, which have been suggested for human health benefits. Phenolic contents, flavonoid contents, phenolic compounds, and anti-cancer properties in six species of ramie leaves were analyzed by Folin-reagent method, sodium borohydride/chloranil-based assay (SBC), HPLC method and antiproliferation, cytoxicity, respectively. Antioxidant activities were measured through peroxyl radical scavenging capacity (PSC) method, oxygen radical absorbance capacity (ORAC) method, and cellular antioxidant activity (CAA). Research indicated that Boehmeria penduliflora contained the highest total phenolic content (2313.7±27.28 mg GAE/100 g FW), and flavonoid content (1682.4±27.70 mg CAE/100 g FW). Boehmeria tricuspis showed the highest PSC value (9574.8±117.63 µM vit. C equiv./100 g FW), while Boehmeria penduliflora indicated the highest ORAC value (330.44±16.88 µmol Trolox equiv./g FW). The antioxidant activities were correlated with phenolic contents and flavonoid contents. Boehmeria tricuspis had the highest antiproliferative capacity with the lowest EC50 (4.11±0.19 mg/mL). The results for the analyzed ramie for CAA were significantly different from each other (p<0.05), Boehmeria tricuspis had the highest CAA value (133.63±7.10 µmol QE/100 g). Benzoic acid, 4-coumaric acid, caffeic acid, and ferulic acid were the dominant phenolic ingredients in the ramie leaves according to HPLC analysis. Our research is the first report to study the phytochemical profiles and antioxidant activities in different species of ramie leaves for their health benefit.

Highlights

Phytochemicals are a class of bioactive non-nutrient compounds which usually exist in fruits, vegetables, grains, and other basedplant foods
Phenolics and flavonoids are the secondary metabolites of plants, which is very important in maintaining essential functions in the reproduction and growth of the plants [6], and flavonoids are a kind of phenolics
Ramie leaves as food and traditional medicine has a long history

Summary

Introduction

Phytochemicals are a class of bioactive non-nutrient compounds which usually exist in fruits, vegetables, grains, and other basedplant foods. Free radicals and other reactive oxygen species are constantly generated in human cells and organisms as a result of aerobic metabolism, some of which are necessary for life. Their pivotal role is to maintain balance between oxidants and antioxidants to maintain optimal physiological conditions [1]. Oxidative stress could cause oxidative damages to large bio-molecules (lipids, proteins, and DNA), eventually resulting in development of many chronic diseases, such as cancer, cardiovascular, and neurodegenerative diseases [5]. Phenolics and flavonoids are biologically active plant compounds, widely spread in fruits, vegetables, teas, and corns, and have attracted extensive research interests due to their strong antioxidant activities. Phenolics and flavonoids are the secondary metabolites of plants, which is very important in maintaining essential functions in the reproduction and growth of the plants [6], and flavonoids are a kind of phenolics

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Conclusion