Isolation, identification and activities of natural antioxidants from Callicarpa kwangtungensis Chun.

Hao Cai,Guanghui Liu,Guangtian Peng,Qiongfeng Liao,Baoqin Lin,Xiuman Sun,Zhiyong Xie,Gianfranco Pintus

doi:10.1371/journal.pone.0093000

Hao Cai, Guanghui Liu + Show 6 more

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https://doi.org/10.1371/journal.pone.0093000

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Abstract

Reactive oxygen species leads to some diseases associated with oxidative stress. Callicarpa kwangtungensis Chun (CK) is a common remedy in traditional Chinese medicine and possesses diverse biological activities involving antioxidant properties; its main compounds phenylethanoid glycosides (PG) and flavonoids are always reported as antioxidants. In order to develop CK as a safe and activated antioxidant, our investigation was performed to validate antioxidant properties and assess which types of compounds (similar polarity or similar structure), even which compounds, played the role of antioxidants. The extracted compounds of CK were analyzed qualitatively and quantitatively by HPLC-DAD-ESI-Trap MS and UV for their contents and antioxidant activities. The correlations between antioxidant activities and known contents were respectively counted and a semi-quantitative experiment was designed to screen antioxidant compounds of CK with HPLC-UV. The n-butanol fraction (BF) showed the highest total phenolic and flavonoid contents (TPC, TFC), and three PG (forsythiaside B, poliumoside and acteoside) contents. BF showed the significantly best (P<0.05) activities in most assays. There were significant correlations (P<0.05) between DPPH•, ABTS+•, •O2 − scavenging, Cu2+-chelating, anti-lipidperoxidation activities and TPC. BF also has significant antioxidant activities on CCl4-induced acute liver injury Mice and TBHP-reduced HepG2 cells. Nine PG (forsythiaside B, poliumoside, acteoside, alyssonoside, brandioside and their derivatives) and one flavone (rhamnazin) were screened out as antioxidants. BF in CK contained abundant polyphenolic, which reflected some definite antioxidant properties. The antioxidant compounds consisted at the least of nine PG and one flavone.

Highlights

Oxygen is critically important for most of the organisms on earth, it may be toxic and mutagenic for living organisms
ME and its four fractions obtained from CK were fractionated through solvent-solvent partitioning to obtain four fractions of petroleum ether fraction (PEF), ethyl acetate fraction (EAF), butanol fraction (BF), and AF
In the aspects of Total Phenolic Content Assay (TPC),BF was higher than EAF (P,0.05) and they showed significantly high (P,0.05) TPC compared to the other fraction and ME

Summary

Introduction

Oxygen is critically important for most of the organisms on earth, it may be toxic and mutagenic for living organisms. To protect the body from such effects, in addition to antioxidant enzymatic system, there are nonenzymatic biomolecules and proteins in living organisms, which act as antioxidant and free radical scavengers. A large dose of vitamin E has been proved to lower the antioxidant enzyme activity by signaling pathways to reduce the antioxidant defensive systems and act as pro-oxidant. Since the polyphenolic compounds, including flavonoids, contain a large amount of phenolic hydroxyl,they have a very strong effect on antioxidation and elimination of free radicals. For the purpose of a detailed investigation of the in vitro antioxidant potentials of CK, seven methods representing different mechanisms of antioxidant protection of organisms from oxidative stress, namely, DPPH?scavenging, ABTS+?scavenging, ?OH scavenging, ?O22 scavenging, Cu2+-chelating, Fe3+ reducing antioxidant power (FRAP), and anti-lipidperoxidation (anti-LP), were used to evaluate CK antioxidant activity. The correlations between antioxidant activity from seven methods and known contents were counted respectively, and a semi-quantitative experiment was designed to screen antioxidant compounds of CK

Materials and Methods

Results and Discussion

Brandioside

Conclusions