Lin Sen, Yang Bao, Chen Feng, Jiang Guoxiang, Li Qing, Duan Xuewu, Jiang Yueming
Key Laboratory of Plant Resource Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, People's Republic of China.
Chem Cent J. 2012 Sep 27;6(1):108. doi: 10.1186/1752-153X-6-108.
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.
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.
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.
荔枝（Litchi chinensis Sonn.）果皮是一种主要的副产品，含有大量多酚。本研究旨在通过泡盛曲霉对荔枝果皮提取物（LPE）进行生物转化，以产生更多具有更强抗氧化活性的生物活性化合物。
研究表明，水提物部分的2,2-二苯基-1-苦基肼自由基清除活性显著（p < 0.05）提高，从15.53%提高到18.23%，乙酸乙酯提取物部分从25.41%提高到36.82%。DNA裂解试验的应用进一步证明了发酵酚类物质对DNA损伤的增强保护作用。还注意到，发酵LPE的水提物部分比乙酸乙酯提取物部分具有更强的防止超螺旋DNA损伤的能力。有趣的是，发现荔枝果皮提取物经泡盛曲霉发酵后出现了一些新化合物，如儿茶素和槲皮素，这可能是抗氧化活性增强的原因。
泡盛曲霉生物转化提高了荔枝果皮提取物的DPPH自由基清除活性和DNA保护作用，同时鉴定了一些导致抗氧化活性增强的化合物。本研究为食品工业中利用水果果皮作为天然抗氧化剂的便捷来源提供了一种有效方法，从而扩展了水果副产品等应用领域。
