Isolation of polyphenol compounds from olive waste and inhibition of their derivatives for α-glucosidase and α-amylase

Article abstract of DOI:10.1080/14786419.2018.1538217

Olive waste was used as a sustainable resource because it contained a variety of valuable compounds. The polyphenols active fraction from enrichment by microporous resin and extraction with ethyl acetate were analysed by different chromatographic methods.

Full text of DOI:10.1080/14786419.2018.1538217

Natural Product Research
Formerly Natural Product Letters
ISSN: 1478-6419 (Print) 1478-6427 (Online) Journal homepage: http://www.tandfonline.com/loi/gnpl20
Isolation of polyphenol compounds from olive
waste and inhibition of their derivatives for α-
glucosidase and α-amylase
Zhihong Wang, Sheng Peng, Mijun Peng & Chengzhang Wang
To cite this article: Zhihong Wang, Sheng Peng, Mijun Peng & Chengzhang Wang (2019):
Isolation of polyphenol compounds from olive waste and inhibition of their derivatives for α-
glucosidase and α-amylase, Natural Product Research, DOI: 10.1080/14786419.2018.1538217
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NATURAL PRODUCT RESEARCH
https://doi.org/10.1080/14786419.2018.1538217
SHORT COMMUNICATION
Isolation of polyphenol compounds from olive waste
and inhibition of their derivatives for a-glucosidase
and a-amylase
a
b
a
c
Zhihong Wang , Sheng Peng , Mijun Peng and Chengzhang Wang
a
Guangdong Provincial Public Laboratory of Analysis and Testing Technology, Guangdong Institute
b
of Analysis, Guangzhou, China; National & local United Engineering Laboratory of Integrative
Utilization Technology of Eucommia ulmoides, Jishou University, Zhangjiajie, China; Institute of
c
Chemical Industry of Forest Products, CAF, Nanjing, China
ABSTRACT
ARTICLE HISTORY
Olive waste was used as a sustainable resource because it con-
tained a variety of valuable compounds. The polyphenols active
fraction from enrichment by microporous resin and extraction
with ethyl acetate were analysed by different chromatographic
methods. A total of 14 polyphenolic compounds were isolated
and identified by structure elucidation. Based on the above
obtained compounds, tyrosol was selected as a characteristic
polyphenol and participated in transesterification reaction to syn-
Received 27 July 2018
Accepted 16 October 2018
KEYWORDS
Olive waste; polyphenol;
isolation; derivative; enzyme
activity inhibition
3
thesise b-ketoester using Yb(OTf) . Then the Biginelli reaction with
benzaldehyde, urea and ketoester (1:1.2:1.2) was performed at
ꢀ
9
0 C for 3.0 h under the acidic condition. In addition, the
b-ketoester prepared using tyrosol with benzyl had a greater
inhibitory effect on a-glucosidase and a-amylase, and the inhib-
ition of enzyme activity for 3, 4-dihydropyrimidinone derivatives
prepared using abovementioned b-ketoester was improved sig-
nificantly. Meanwhile, fluorine-containing dihydropyrimidinone
derivatives were considerable inhibitors for both enzymes.
CONTACT Mijun Peng
pengmj163@163.com
Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2018.1538217.
ß 2018 Informa UK Limited, trading as Taylor & Francis Group

2
Z. WANG ET AL.
1. Introduction
Olive oil has natural health functions due to its multiple active ingredients, and which
is obtained from olive fruit by different extraction methods. It is worth nothing that
9
8% of the phenolic compounds from olive fruit were found in olive waste (Obied
et al. 2005). Therefore, polyphenol compounds can be utilised efficiently and further
derivatised due to the special hydroxyl structure by transesterification (Otera 1993).
The b-ketoester from transesterification is a multi-coupling reagent with electrophilic
and nucleophilic sites, and can be used to the preparation of dihydropyrimidinones,
which is also an important pharmaceutical intermediate and has widely application
prospects in biology and pharmacology (Chavan et al. 2003). Diabetes is a disease
caused by endocrine disorders, especially type II diabetics, controlling postprandial
hyperglycemia is one of the very significant treatments for relieving symptoms (Zhang
et al. 2014). At present, the development of new drugs with inhibition of a-amylase
and a-glucosidase and safe, efficient and no side effects has been widely concerned
(
Cust oꢀ dio et al. 2015). In this study, some active compounds were isolated from the
active fraction of olive waste, and tyrosol as a characteristic compound was selected
for the preparation of target derivatives. Meanwhile, the inhibitory effect of these
target products on a-glucosidase and a-amylase have been investigated.
2. Results and discussion
2.1. Isolation and identification of polyphenol compounds
Based on previous research results (Wang et al. 2017; Wang and Wang 2018), olive
pomace extracted by ethyl acetate (OPE) was considered to be the active fraction and
further investigated. The separation methods were considered using different chroma-
1
13
tography technology (Figure S1). The structure was identified by H NMR and C NMR
spectrum data (Figure S2). SciFinder database and Spectral Database for Organic
Compounds (SDBS) were used for the NMR spectra analysis. Due to differences in sam-
ple preparation methods, detection techniques and selected elution conditions, a total
of 14 compounds (mainly phenolics or flavonoids group) were obtained (Figure S3),
including ferulic acid (OPE-1), catechin (OPE-2), vanillin (OPE-3), protocatechuate (OPE-
4), ethyl gallate (OPE-5), coumalic acid (OPE-6), tyrosol (OPE-7), hydroxytyrosol (OPE-8),
eugenol (OPE-9), 4-hydroxybenzoic acid (OPE-10), quercetin (OPE-11), luteolin (OPE-12),
apigenin (OPE-13), chlorogenic acid (OPE-14).
2.2. Transesterification reaction
Because the tyrosol structure contained phenolic hydroxyl and alcohol hydroxyl, the
product of transesterification might be divided into two types. On the one hand, tyro-
sol was directly involved in transesterification (compound 1), on the other hand, the
phenolic hydroxyl group of tyrosol was protected by the benzyl group, then the
ketoester was obtained from above product through transesterification reaction (com-
pound 2) (Figure S4). Compared to the yield (34.6%) of compound 1, the transesterifi-
cation reaction of tyrosol protected for phenolic hydroxyl was more favorable for the

NATURAL PRODUCT RESEARCH
3
preparation of compound 2, and the b-ketoester yield reached to 75.7%. Ytterbium
III) trifluoromethanesulfonate (Yb(OTf) ) was a mild Lewis acid catalyst and used in
(
3
the transesterification (Hanamoto et al. 1996). The yield of product was higher with
.3 equivalent of Yb(OTf) compared with other amount of catalyst (Table S1). The spe-
0
3
3
þ
cial complex formed with methyl acetoacetate and Yb was critical to the reaction
Dharma Rao and Kaushik 2011).
(
2.3. Preparation of dihydropyrimidinone derivatives
According to the results from above experiment, the ketoesters selected (Methyl ace-
toacetate and compound 2) were used in the preparation of dihydropyrimidinones
derivatives through Biginelli reaction (Heravi et al. 2018; Kaur et al. 2017). Ethanol was
chosen as ideal reaction solvent in the experiment (Zumpe et al. 2007). Considering
the yield of the product and the cost of experiment, the ratio of reaction substrate
was chosen as n (benzaldehyde):n (urea):n (b-ketoesters) ¼ 1:1.2:1.2, and the result
ꢀ
showed that the yield of target compound was more satisfactory at 90 C (Table S2).
Based on the reaction condition obtained, the Biginelli reactions of the b-ketoesters
selected, urea and benzaldehyde with different substituent groups were performed.
Subsequently, compounds 2a, 2b, 2c, 2d, 2a’, 2b’, 2c’ and 2d’ were obtained
(Figure S5). The yield of product was affected by benzaldehyde containing different
substituents, but their values were higher than 60% (Table S3). It was worth noting
that the electrophilicity of carbonyl oxygen was increased and intermediate might be
generated under acidic conditions. Furthermore, the nucleophilic addition reaction of
N-acylimine ions with carbonyl isomerization was considered to be the critical step
(Kaur et al. 2017).
2.4. Enzyme inhibitory activity of target products
The inhibitory effects of different derivatives obtained from above reactions on a-glu-
cosidase and a-amylase activity were investigated (Hamid et al. 2015; Tan et al. 2017)
(Table S4). The ketoester prepared from tyrosol, whose phenolic hydroxyl group was
protected with benzyl group, had better inhibitory effect on the both enzyme activ-
ities, and the yield was also higher. Therefore, it was chosen as one of the reactants to
participate in the preparation of dihydropyrimidinones derivatives. The inhibitory effect
of the derivatives on these two enzyme activities had been significantly improved, and
these compounds contained b-amino ketone structure. Fluorine-containing com-
pounds have better inhibition on the a-glucosidase and a-amylase activities than other
substituents. Because fluorine had strong electronegativity, relatively small size, lipo-
philicity and notable leaving group ability from anionic intermediates, it could achieve
better inhibition of enzyme activity by replacing hydrogen atoms and induction effects
(Robert 1992). Furthermore, dihydropyrimidinones prepared from the above selected
b-ketoesters (compound 2) exhibited better inhibition to the both enzymes than other
corresponding derivatives. The transesterification and Biginelli reactions with enzyme
catalysis have been reported, but the reaction are often limited by the characteristic
group of the compounds, the reaction condition and the reaction time. In future

4
Z. WANG ET AL.
research, in addition to further focusing on the activity evaluation of new compounds,
it is very necessary to optimize the preparation process of the target compound by
using green technology and novel catalyst.
4. Conclusions
In summary, a total of 14 compounds were isolated and identified from the olive
waste active fraction, which was obtained by microporous resin enrichment and ethyl
acetate extraction. Based on the obtained compounds, as a characteristic compound,
tyrosol was chosen with a simple and effective transesterification reaction to synthe-
size b-ketoester using a catalyst of Yb(OTf) and the reaction mechanism might be
3
3þ
related to the formation of a complex system between Yb and reactants. Then the
Biginelli reaction with benzaldehyde, urea and ester (1:1.2:1.2) was performed at 90 C
ꢀ
for 3.0 h under the acidic condition using b-ketoester derived from tyrosol. And the
nucleophilic addition reaction of N-acylimine ions with carbonyl isomerization was cru-
cial in this process. In addition, compared to the product of direct transesterification,
the b-ketoester derivatives prepared using tyrosol, whose phenolic hydroxyl group
was preferentially protected, had a greater inhibitory effect on a-glucosidase and
a-amylase, and the inhibition of enzyme activity for 3, 4-dihydropyrimidinone deriva-
tives prepared using this b-ketoester was improved significantly. Meanwhile, fluorine-
containing derivatives were considerable inhibitors for both enzymes.
Acknowledgements
The authors acknowledge the Guangdong Academy of Sciences and National Natural Science
Foundation of China for financial support.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by GDAS’ Project of Science and Technology Development (grant
number 2017GDASCX-0702); National Natural Science Foundation of China (grant num-
ber 31660181).
References
Cust oꢀ dio L, Patarra J, Alber ꢀı cio F, Neng NR, Flor e^ ncio Nogueira JM, Romano A. 2015. In vitro
antioxidant and inhibitory activity of water decoctions of carob tree (Ceratonia siliqua L.) on
cholinesterases, a-amylase and a-glucosidase. Nat Prod Res. 29(22):2155–2159.
Chavan SP, Kale RR, Shivasankar K, Chandake SI, Benjamin SB. 2003. A simple and efficient
method for transesterification of b-ketoesters catalysed by iodine. Synthesis. 17:2695–2698.
Dharma Rao GB, Kaushik MP. 2011. Efficient trans-acetoacylation mediated by ytterbium (III) tri-
flate as a catalyst under solvent-free condition. Tetrahedron Lett. 52(39):5104–5106.

NATURAL PRODUCT RESEARCH
5
Hanamoto T, Sugimoto Y, Yokoyama Y, Inanaga J. 1996. Ytterbium (III) triflate–catalyzed selective
methanolysis of methoxyacetates: a new deprotective method. J Org Chem. 61(13):
4491–4492.
Hamid HA, Yusoff MM, Liu M, Karim MR. 2015. a-Glucosidase and a-amylase inhibitory constitu-
ents of Tinospora crispa: Isolation and chemical profile confirmation by ultra-high perform-
ance liquid chromatography-quadrupole time-of-flight/mass spectrometry. J Funct Foods. 16:
74–80.
Heravi MM, Moradi R, Mohammadkhani L, Moradi B. 2018. Current progress in asymmetric
Biginelli reaction: an update. Mol Divers. 22:751–767.
Kaur R, Chaudhary S, Kumar K, Gupta MK, Rawal RK. 2017. Recent synthetic and medicinal per-
spectives of dihydropyrimidinones: A review. Eur J Med Chem. 132:108–134.
Obied HK, Allen MS, Bedgood DR, Prenzler PD, Robards K, Stockmann R. 2005. Bioactivity and
analysis of biophenols recovered from olive mill waste. J Agric Food Chem. 53(4):823–837.
Otera J. 1993. Transesterification. Chem Rev. 93(4):1449–1470.
Robert H. 1992. Inhibitory effect of fluoride on enzyme activity. J Med Mol Biol. 14:40–42.
Tan YQ, Chang SKC, Zhang Y. 2017. Comparison of a-amylase, a-glucosidase and lipase inhibi-
tory activity of the phenolic substances in two black legumes of different genera. Food
Chem. 214:259–268.
Wang ZH, Wang CZ, Zhang CW, Li WJ. 2017. Ultrasound-assisted enzyme catalyzed hydrolysis of
olive waste and recovery of antioxidant phenolic compounds. Innov Food Sci Emerg. 44:
224–234.
Wang ZH, Wang CZ. 2018. Preliminary characterization of the composition and phenolic frag-
mentation of olive byproduct by gas chromatography-mass spectrometry and high perform-
ance liquid chromatography-tandem mass spectrometry. Anal Lett. 51(9):1335–1357.
Zhang J, Huang XY, Sun XM, Pei D, Di DL. 2014. Efficient method for the screening and identifi-
cation of anti-diabetic components in the leaves of Olea europaea L. New J Chem. 38(8):
3796–3802.
Zumpe FL, Fl u€ ß M, Schmitz K, Lender A. 2007. Propane phosphonic acid anhydride, a new pro-
moter for the one-pot Biginelli synthesis of 3, 4-dihydropyrimidin-2(1H)-ones. Tetrahedron
Lett. 48:1421–1423.