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Open Access Research article

Enhanced DPPH radical scavenging activity and DNA protection effect of litchi pericarp extract by Aspergillus awamori bioconversion

Sen Lin12, Bao Yang1, Feng Chen3, Guoxiang Jiang12, Qing Li12, Xuewu Duan1 and Yueming Jiang1*

Author Affiliations

1 Key Laboratory of Plant Resource Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, People’s Republic of China

2 Graduate School of Chinese Academy of Sciences, Beijing, 100039, People’s Republic of China

3 Department of Food, Nutrition and Packaging Sciences, Clemson University, Clemson, SC, 29634, USA

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Chemistry Central Journal 2012, 6:108  doi:10.1186/1752-153X-6-108

Published: 27 September 2012

Abstract

Background

Litchi (Litchi chinensis Sonn.) pericarp is a major byproduct which contains a significant amount of polyphenol. This study was designed to biotransformation litchi pericarp extract (LPE) by Aspergillus awamori to produce more bioactive compounds with stronger antioxidant activities.

Results

The study exhibited that the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities significantly (p < 0.05) increased from 15.53% to 18.23% in the water-extracted fraction and from 25.41% to 36.82% in the ethyl acetate-extracted fraction. Application of DNA cleavage assay further demonstrated the enhanced protection effect of the fermented phenolics on DNA damage. It is also noted that the water-extracted fraction of the fermented LPE possessed a much stronger capacity than the ethyl acetate-extracted fraction to prevent from damage of supercoiled DNA. Interestingly, it was found that some new compounds such as catechin and quercetin appeared after of A. awamori fermentation of LPE, which could account for the enhanced antioxidant activity.

Conclusion

The DPPH radical scavenging activity and DNA protection effect of LPE were increased by Aspergillus awamori bioconversion while some compounds responsible for the enhanced antioxidant activity were identified. This study provided an effective way of utilizing fruit pericarp as a readily accessible source of the natural antioxidants in food industry and, thus, extended the application area such as fruit by-products.

Keywords:
Litchi pericarp; Phenolics; Aspergillus awamori; DPPH radical scavenging activity; DNA protection; HPLC