Phenolic extracts from Acacia mangium bark and their antioxidant activities.

Jiahong Chen,Dongmei Wu,Liangliang Zhang,Man Xu,Yongmei Wang

doi:10.3390/molecules15053567

Abstract

Phenolic compounds are present at very high concentrations in the bark of Acacia mangium. These compounds are known to have strong antioxidant activity and thus different beneficial effects on human health. Phenolic compounds in bark of A. mangium were extracted and their antioxidant activities were investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging and ferric-reducing antioxidant power (FRAP) assays. A central composite design has been employed to optimize the experimental conditions for a high total phenolic content and antioxidant activity. The desirability function approach has been employed to simultaneously optimize the three responses: total phenols, antiradical activity and FRAP. An extraction time of 90 min, liquid-solid ratio of 5, and temperature of 50 °C was predicted for the optimum experimental conditions using the desirability function. A significant linear relationship between antioxidant potency, antiradical activity and the content of phenolic compounds of bark extracts was observed. The structures of condensed tannins isolated from A. mangium were characterized by MALDI-TOF MS analyses. Condensed tannin oligomers from A. mangium were shown to be heterogeneous mixtures consisting of procyanidin and prodelphinidin structural units with polymerization degrees up to 9.

Highlights

Phenolic compounds, which are secondary metabolites in plants, are known to be responsible for antioxidant effects
The Folin-Ciocalteu reagent is popularly used to obtain a crude estimate of the amount of phenolic compounds present in an extract [12,13]
This paper shows how an experimental design approach led us to obtain an effective extraction of total phenolic compounds with respect of a reduced number of experiments

Summary

Introduction

Phenolic compounds, which are secondary metabolites in plants, are known to be responsible for antioxidant effects. In the food industry, antioxidants are used to retard the oxidative degradation of fats by inhibiting the formation of free radicals. Synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and propyl gallate (PG) are widely used; the use of synthetic antioxidants in food products is being questioned [2,3]. Fruits and vegetables are the main sources of phenolic compounds in the human diet. Other sources, such as bark extracts from high plants, have received particular attention as sources of antioxidants [8]. Recent antioxidant studies have focused on the improvement of phenol extraction techniques from some natural products [9]

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