title: Enzymatic hydrolysis of oleuropein from Olea europea (olive) leaf extract and antioxidant activities.
abstract: Oleuropein (OE), the main polyphenol in olive leaf extract, is likely to decompose into hydroxytyrosol (HT) and elenolic acid under the action of light, acid, base, high temperature. In the enzymatic process, the content of OE in olive leaf extract and enzyme are key factors that affect the yield of HT. A selective enzyme was screened from among 10 enzymes with a high OE degradation rate. A single factor (pH, temperature, time, enzyme quantity) optimization process and a Box-Behnken design were studied for the enzymatic hydrolysis of 81.04% OE olive leaf extract. Additionally, enzymatic hydrolysis results with different substrates (38.6% and 81.04% OE) were compared and the DPPH antioxidant properties were also evaluated. The result showed that the performance of hydrolysis treatments was best using hemicellulase as a bio-catalyst, and the high purity of OE in olive extract was beneficial to biotransform OE into HT. The optimal enzymatic conditions for achieving a maximal yield of HT content obtained by the regression were as follows: pH 5, temperature 55 °C and enzyme quantity 55 mg. The experimental result was 11.31% ± 0.15%, and the degradation rate of OE was 98.54%. From the present investigation of the antioxidant activity determined by the DPPH method, the phenol content and radical scavenging effect were both decreased after enzymatic hydrolysis by hemicellulase. However, a high antioxidant activity of the ethyl acetate extract enzymatic hydrolysate (IC50 = 41.82 μg/mL) was demonstated. The results presented in this work suggested that hemicellulase has promising and attractive properties for industrial production of HT, and indicated that HT might be a valuable biological component for use in pharmaceutical products and functional foods.
authors: Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, China. yejianzhong@163.com.|Key and Open Laboratory on Forest Chemical Engineering, SFA, Nanjing 210042, China. yejianzhong@163.com.|Key Laboratory of Biomass Energy and Matetial, Nanjing 210042, China. yejianzhong@163.com.|Institute of New Technology of Forestry, CAF, Beijing 100091, China. yejianzhong@163.com.
authors: Jiao-Jiao
authors: JJ
authors: Yuan
authors: Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, China. wangczlhs@sina.com.|Key and Open Laboratory on Forest Chemical Engineering, SFA, Nanjing 210042, China. wangczlhs@sina.com.|Key Laboratory of Biomass Energy and Matetial, Nanjing 210042, China. wangczlhs@sina.com.|Institute of New Technology of Forestry, CAF, Beijing 100091, China. wangczlhs@sina.com.
authors: Cheng-Zhang
authors: CZ
authors: Wang
authors: Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, China. yejianzhong@163.com.|Key and Open Laboratory on Forest Chemical Engineering, SFA, Nanjing 210042, China. yejianzhong@163.com.|Key Laboratory of Biomass Energy and Matetial, Nanjing 210042, China. yejianzhong@163.com.|Institute of New Technology of Forestry, CAF, Beijing 100091, China. yejianzhong@163.com.
authors: Jian-Zhong
authors: JZ
authors: Ye
authors: Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, China. trmoon1949@126.com.|Key and Open Laboratory on Forest Chemical Engineering, SFA, Nanjing 210042, China. trmoon1949@126.com.|Key Laboratory of Biomass Energy and Matetial, Nanjing 210042, China. trmoon1949@126.com.|Institute of New Technology of Forestry, CAF, Beijing 100091, China. trmoon1949@126.com.
authors: Ran
authors: R
authors: Tao
authors: Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, China. nmczhang@126.com.|Key and Open Laboratory on Forest Chemical Engineering, SFA, Nanjing 210042, China. nmczhang@126.com.|Key Laboratory of Biomass Energy and Matetial, Nanjing 210042, China. nmczhang@126.com.|Institute of New Technology of Forestry, CAF, Beijing 100091, China. nmczhang@126.com.
authors: Yu-Si
authors: YS
authors: Zhang
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000494:pharmacology; D001711:Biotransformation; D006868:Hydrolysis; D057888:Iridoid Glucosides; D039823:Iridoids / Q000737:chemistry* / Q000494:pharmacology; D031658:Olea / Q000737:chemistry*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D011714:Pyrans / Q000378:metabolism
chemical_list: D000975:Antioxidants; D057888:Iridoid Glucosides; D039823:Iridoids; D010936:Plant Extracts; D011714:Pyrans; C005975:3,4-dihydroxyphenylethanol; C002769:oleuropein; C000352:elenolic acid; D010626:Phenylethyl Alcohol