Penolic Compose

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ANALYTICAL CHEMISTRY AND MICROCHEMISTRY

PHENOLIC COMPOUNDS
TYPES, EFFECTS AND RESEARCH

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ANALYTICAL CHEMISTRY AND MICROCHEMISTRY

PHENOLIC COMPOUNDS
TYPES, EFFECTS AND RESEARCH

TERESA GARDE-CERDÁN,
ANA GONZALO-DIAGO
AND

EVA P. PÉREZ-ÁLVAREZ
EDITORS


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Copyright © 2017 by Nova Science Publishers, Inc.
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CONTENTS
Preface

vii

Chapter 1

Natural Phenolic Compounds and Parkinson’s Disease
Elena Alañon, Amani Taamalli, Mokhtar Zarrouk,
Antonio Segura Carretero and David Arráez Román

Chapter 2

Understanding the Relationship between Wine Phenolic
Compounds and Sensory Properties: Bitterness and Astringency
Ana Gonzalo-Diago, Yong-Sheng Tao,
Marta Dizy and Purificación Fernández-Zurbano

Chapter 3

Chapter 4

Chapter 5

Chapter 6

Chapter 7

1

29

Bioactive Phenolic Compounds:
Extraction Procedures and Methods of Analysis

Raquel de Pinho Ferreira Guiné

57

Metabolite Profiling of Chlorogenic Acid
Derivatives after the Ingestion of Coffee
Malgorzata Gwiazdon and Magdalena Biesaga

91

Phenolic Compounds in Plant Materials:
Problems and New Analytical Solutions
Malgorzata Gwiazdon and Magdalena Biesaga

105

Phenolic Compounds in Wine:
Types, Color Effects and Research
Jesús Heras-Roger, Carlos Díaz-Romero and
Jacinto Darias-Martín
Cover Crops in Viticulture: A Strategy to
Modify Grape and Wine Phenolic Composition
Eva P. Pérez-Álvarez

133

179


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vi
Chapter 8

Index

Contents
Biological Properties of Phenolic Compounds from
Industrial Wastes
María José Rodríguez-Vaquero and
Claudia Verónica Vallejo

213

231


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PREFACE
Phenolic compounds are a large family of metabolites that result from the secondary
metabolism of plants. Novel insights about phenolic chemical structure, analytical
methods, therapeutic effects, sensory properties, viticultural practices to modify their
content and the re-use of natural compounds from agro-industrial wastes have been
gathered in this book. A comprehensive overview on phenolic compounds and
neurodegenerative disorders, highlighting their antioxidant, anti-inflammatory properties
and their effects on Parkinson’s disease have been compiled. In relation to antioxidant
properties, the metabolism and bioavailability of several hydroxycinnamic acids present
in coffee have been studied in detail, and also the methods to determine antioxidant
capacity have been included. Different strategies in order to improve the extraction and

determination of phenolic compounds in a complex matrix by analytical techniques are
provided, reporting problems and new analytical solutions. The role of these compounds
in color stabilization and also in bitterness and astringency perception has been reported.
Moreover, the interactions that take place among wine non-volatile and volatile
compounds have been briefly introduced. Furthermore, the use of cover crops in
vineyards and their effects on agronomical and enological behavior – particularly, their
impact on phenolic compounds – have been highlighted. Finally, the biological properties
of phenolic compounds from industrial wastes have been tackled, since they are a
promising alternative to transform agro-industrial wastes into a source of natural and
healthy compounds.
Chapter 1 - There is a lot of scientific evidence that phenolic compounds have effects
on human health. Both parent compounds and their metabolites might explain the effects
on health of phenolic compounds. For instance, several studies have demonstrated the
emerging and promising role of these compounds and their beneficial properties against
neurodegenerative diseases.
Parkinson’s disease is the second most common form of neurodegenerative diseases
after Alzheimer’s. It affects approximately 1% of the population over the age of 50.


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viii

T. Garde-Cerdán, A. Gonzalo-Diago and E. P. Pérez-Álvarez

Currently, there is no known cure for Parkinson’s disease, but certain drugs, namely
levodopa and carbidopa, have been proved to be effective in relieving its symptoms in a
large number of persons suffering from such disease. Some environmental-, dietary- and
life-style- related factors have been found to influence its incidence. In this sense, many
studies have demonstrated the protective effects of plant phenolic compounds against

brain damage in Parkinson’s disease.
This chapter provides a comprehensive overview on phenolic compounds and
neurodegenerative disorders, their antioxidant and anti-inflammatory properties.
Furthermore, the effects of phenolic compounds on Parkinson’s disease were compiled.
Finally, possible mechanisms of action of these compounds are also discussed.
Chapter 2 - Polyphenols are a large family of metabolites that result from the
secondary metabolism of plants. It is known the multiple healthy properties of
polyphenols and their use as nutraceutical compounds. Furthermore, in grapes and wines,
these compounds are able to modulate quality perception. To search reliable relationships
between wine fractions composition and sensory description it is necessary to train tasters
specifically and to perform chemical and statistical analysis. The work with these
procedures in parallel allows obtaining key information towards a better understanding of
how interactions between chemical components may affect flavor perception. The aim of
this review was to gather the current knowledge of the effect of non-volatile low and high
molecular weight phenolic compounds on bitter taste and in-mouth feeling perceptions,
especially astringency and to highlight the recent research on wine interactions.
Chapter 3 - Phenolic compounds are very important to the physiology of plants as
well as humans because once ingested they have a protective role on the human body
against oxidative stress, acting as antioxidants. Phenolic compounds have thousands of
different structures and they are classified into families according to some characteristics.
The evaluation of phenolic compounds is very much influenced by the methodologies
used for their extraction from the source materials as well as those used for their
quantification. Hence, this chapter aims to introduce briefly some knowledge about
phenolic compounds and the different categories, then to review some important aspects
about the extraction methodologies reported in literature and the methods of analysis,
namely the spectrophotometric technics, the chromatographic methods and some other
recent methods. Furthermore, the antioxidant capacity is also addressed and the methods
for its evaluation are also reviewed, namely those using Hydrogen Atom Transfer (HAT)
or Single Electron Transfer (SET) reaction mechanisms.
Chapter 4 - Coffee is the main source of chlorogenic acids in humans diet. These

phenolic compounds contain an ester bond between quinic acid and different
hydroxycinnamic acids, such as ferulic acid (feruloylquinic acids, FQAs) and caffeic acid
(caffeoylquinic acids CQAs). Some studies indicate potential health benefits linked to
coffee consumption due to its antioxidant activity. However, the biological properties of
antioxidants such as phenolic acids depend on their bioavailability and metabolism in


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Preface

ix

human body. Chlorogenic acids are extensively metabolized during their passage through
the digestive tract and their metabolites are present in human circulatory system in
greater quantity than parent compounds. Modifications of chlorogenic acids in human
body could result in a decrease or even in an inhibition of the antioxidant properties in
relation to their initial precursors. The aim of proposed studies was to describe the
metabolism and bioavailability of coffee CQAs in healthy human volunteers through the
identification of metabolites in urine samples and examination of their pharmacokinetic
profiles using high performance liquid chromatography tandem mass spectrometry (LCMS/MS). For that purpose, the volunteers were on polyphenol-restricted diet for 24 h to
wash-out. Then, a cup of espresso coffee (Jacobs®), containing 27.5 mg of 5-CQA (77.7
μmol) was consumed by the volunteers and urine samples were collected after different
times from coffee consumption for a total period of 24 h and analyzed. A total of 13
metabolites were identified in urine samples after coffee ingestion. The main compounds
identified were sulfate and glucuronide conjugates of ferulic acid, caffeic acid,
dihydroferulic acid, and dihydrocaffeic acid. Only trace amounts of unchanged 5-CQA
acid were detected during the analysis. Collection of urine samples during a total period
of 24 h from polyphenol-rich food consumption allowed the creation of pharmacokinetic
profiles. Sulfate derivatives of ferulic acid and caffeic acid were absorbed in the small

intestine due to the fact that their maximum concentrations (Cmax) were observed in a
short time. Dihydroferulic and dihydrocaffeic acids and their derivatives formed via the
reduction of carbon-carbon double bond could be detected after longer time than others
metabolites indicating their transformation in the large intestine. A significant increase in
the excretion of the studied acids after coffee consumption was observed. This indicates
that chlorogenic acids are intensively metabolized in human digestive tract.
Chapter 5 - One of the main challenges analytical chemistry faces is selective
identification of compounds present at low concentrations in complex matrix. Despite the
development of modern research equipment, in terms of analysis of natural samples of
unknown composition, it is necessary to develop new methods. The ones currently
available and commonly used, often, are based on multi-stage procedures, which make
them not suitable for universal application.
The matrix effect, its influence on analyte’s form and its extraction modes, is one of
the biggest challenges modern analytical chemistry faces. Its elimination or reduction
would simplify process of selective identification of compounds. The successful and
useful method should: i) indicate a sample preparation process, preferably without
changing the form of the analyte, and ii) provide assurance that the received signal comes
from a determined analyte.
In general, the methods to determine phenolic compounds require extraction and preconcentration processes of the analytes, due to the low concentrations of major of these
compounds in natural samples. The number of commercially available standards is
limited, and frequently, an additional step, especially hydrolysis of esters or glycosides


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x

T. Garde-Cerdán, A. Gonzalo-Diago and E. P. Pérez-Álvarez

has to be performed. Another problem is the reactivity of these compounds, in particular

their redox properties, which cause their transformation during extraction and preconcentration of the samples. For these reasons, the validation of the methods for
determining phenolic compounds is complex. Moreover, many of phenolic compounds
are structural isomers; therefore, the use of mass spectrometry is not always enough to
their correct identification. The use of the high performance liquid chromatography
combined with different detectors, enables the correct separation and identification of the
isomers. Modern stationary phases with small particle size can increase the efficiency of
the separation and can help in a more effective identification of these compounds. The
lack of standards and certified reference materials for phenolic compounds, as well as a
great variation in the composition of the matrix result in difficulties in the validation of
the methods.
The first part of this chapter is focused on the developing of a new separation method
using high performance liquid chromatography (HPLC). The typical stationary phases C18 with different geometry: monolithic phase, fully porous phase, and with core-shell
particles have been applied for phenolic acids determination. In the next part of this
chapter, the possibility of using different detectors: UV-VIS, fluorescence, MS, and
MS/MS for the identification and detection of the phenolic compounds is presented. The
influence of different factors that might occur during the extraction process of these
compounds from plants, fruits and honey samples has been examined. Finally, the
correlation between the stability of phenolic compounds and the extraction method used,
the type of matrix as well as the structure of the compounds has been described.
Chapter 6 - Wine is one of the most researched beverages due to its outstanding
phenolic content. Phenolic compounds are responsible for the sensory attributes of wine,
such as color and structure, and for health benefits derived from its consumption. The
most studied substances are anthocyanins and flavones (related to color), tannins (causing
astringency) and stilbenes (antioxidants and cardiovascular protectors). Wine’s phenolic
compounds are important not only because of their high levels, but also their variability
and heterogeneity, since they depend on geographic origin, grape variety and
winemaking techniques. The different types of wine (white, red, rosé, naturally sweet,
fortified, etc.) show different phenolic profiles in constant change during wine aging. Due
to the various chemical equilibriums involved, even differences between vintages, oak or
bottle storage can be observed in the phenolic content. In this chapter the main phenolic

compounds present in wines are reviewed, in addition to their interactions and related
effects, such as color stabilization, antioxidant capacity and wine structure.
Chapter 7 - This chapter discusses the repercussion of cover crops use in vineyard on
grapes and wines phenolic compounds. Cover crops are not often used in Mediterranean
vineyards but they are extended in humid climate zones. They can be mixed or pure
vegetal species, from different families and they can be sown in alternating or continuous
vineyard alleyways; moreover, cover crops can be used throughout the whole grapevine


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Preface

xi

vegetative cycle or during part of it. Usually, their use is related to the soil water and
nutritive competition that they exert on the grapevine. However, cover crops are also able
to provoke important agronomic changes in the plot such as soil structure and quality
improvement, avoiding soil erosion and reducing its compaction thus favoring the water
infiltration rate and the machinery transitability, … Cover crops also affect the
grapevines vegetative development, controlling the excessive vigor, which could
influence the grapes health and quality, favoring some compounds synthesis, including
phenolic compounds. These compounds are mainly responsible for the wines color, taste
and tactile sensations and also contribute to their longevity and stability. Besides,
phenolic compounds are important for human health due to their cardioprotective, antiinflammatory, anti-carcinogenic, and anti-microbial activities.
Chapter 8 - The increase of residue production in modern society is an unavoidable
fact, and society requires different waste management than in past decades. The industrial
waste production increases with population so it is necessary to manage it or contract
qualified industrial treatment companies. In order to reduce environmental loading and
effectively use resources, promotion of reuse of industrial wastes is now one of the most

important environmental tasks. Natural compounds found in wastes, such as phenolic
compounds, could be an alternative to transform them in a source of natural compounds
with beneficial properties. Polyphenols exhibit a huge variety of structures. Numerous
studies relate the ingestion of polyphenols on diet to a lower risk of cardiovascular
diseases and development of cancers. Besides, some investigations have conferred to
them a relevant role in foods as nutraceuticals. Polyphenols are chemotaxonomic markers
due to their specificity and ubiquity, and they have been tested to be chemical markers for
food authentication. Phenolic compounds have received considerable attention for their
biological effects, such as antioxidant, antiglycative, antiatherogenic, and
cardioprotective activities. During olive oil elaboration, a high amount of black olive mill
wastewater is produced. This liquid effluent has a high polluting organic load. Some
authors reported that phenolic compounds found in this waste, possess strong antioxidant
properties, which may turn the olive oil residues into a cheap source of natural
antioxidants. Otherwise, grapes used for the wine industry constitute around 80% of the
worldwide grape production; the largest fraction of winery waste consisting of the skins,
seeds, and stems left after juice or wine is pressed. Grapes are particularly rich in
bioactive polyphenols, especially flavonoids, stilbenes, and phenolic acids. Some authors
proposed using winery waste in the development of antibacterial agent. The possible
reuse of natural compounds from wastes with beneficial biological activities could be a
promising alternative to transform a waste in a source of natural compounds.


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In: Phenolic Compounds
ISBN: 978-1-53612-033-2
Editors: Teresa Garde-Cerdán et al. © 2017 Nova Science Publishers, Inc.

Chapter 1

NATURAL PHENOLIC COMPOUNDS
AND PARKINSON’S DISEASE
Elena Alañon1,2, Amani Taamalli3,*,
Mokhtar Zarrouk3, Antonio Segura Carretero1,2
and David Arráez Román1,2
1

Research and Development Functional Food Center, Granada, Spain
2
Department of Analytical Chemistry, Faculty of Sciences,
University of Granada, Granada, Spain
3
Laboratory of olive Biotechnology, Centre of Biotechnology
of BorjCédria, Hammam-Lif, Tunisia

ABSTRACT
There is a lot of scientific evidence that phenolic compounds have effects on human
health. Both parent compounds and their metabolites might explain the effects on health
of phenolic compounds. For instance, several studies have demonstrated the emerging
and promising role of these compounds and their beneficial properties against
neurodegenerative diseases.
Parkinson’s disease is the second most common form of neurodegenerative diseases
after Alzheimer’s. It affects approximately 1% of the population over the age of 50.
Currently, there is no known cure for Parkinson’s disease, but certain drugs, namely
levodopa and carbidopa, have been proved to be effective in relieving its symptoms in a
large number of persons suffering from such disease. Some environmental-, dietary- and
life-style- related factors have been found to influence its incidence. In this sense, many

studies have demonstrated the protective effects of plant phenolic compounds against
brain damage in Parkinson’s disease.

*

Corresponding Author:


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2

Elena Alañon, Amani Taamalli, Mokhtar Zarrouk et al.
This chapter provides a comprehensive overview on phenolic compounds and
neurodegenerative disorders, their antioxidant and anti-inflammatory properties.
Furthermore, the effects of phenolic compounds on Parkinson’s disease were compiled.
Finally, possible mechanisms of action of these compounds are also discussed.

1. INTRODUCTION
Phenolic compounds are secondary metabolites that are broadly distributed in higher
plants, which possess aromatic ring with one or more hydroxyl substituents. These
metabolites include flavonoids, tannins, stilbenes, coumarins and phenolic acids. The
health effects of natural phenolics have received the most attention among researchers in
the last decades. Phenolic compounds are perhaps the largest group of phytochemicals
that have shown disease preventing and health promoting effects (Tsao & Akhtar, 2005).
As antioxidants, phenolics compounds may protect cell constituents against oxidative
damage and, therefore, limit the risk of various degenerative diseases associated to
oxidative stress (Scalbert et al., 2002). Such compounds have been found to be strong
antioxidants able to neutralize free radicals by donating an electron or hydrogen atom
(Balasundram et al., 2006). They act as direct radical scavengers of the lipid peroxidation

chain reactions (Tsao, 2010). Moreover, they are also known as metal chelators (Shahidi
& Ambigaipalan, 2015). In addition, phenolic compounds may also act by increasing the
expression or activity of endogenous antioxidant enzymes such as glutathione peroxidase,
catalase and superoxide dismutase and inhibit the expression of enzymes such as xanthine
oxidase (Tsao, 2010). In fact, there is a considerable body of evidence that phenolic
compounds play beneficial role in the prevention of cardiovascular diseases (Arts et al.,
2001; Knekt et al., 1996; Hertong et al., 1995; Peters et al., 2001), cancers (Galati &
O’Brien, 2004; Paluszczak et al., 2010), and osteoporosis (Coxam et al., 2010) and
support their contribution in the prevention of neurodegenerative diseases (Commenges
et al., 2000; Letenneur et al., 2007) and diabetes mellitus (Dam & Feskens, 2002).
Neurodegenerative diseases are considered a worldwide problem. The main causes of
the neuronal degeneration along with environmental factors, genetic mutations and brain
aging, are several cellular and molecular events such as increase in oxidative stress,
impaired mitochondrial functions, deposition of aggregated proteins, inflammatory
response, activation of neuronal apoptosis, altered cell signaling and gene expression
(Jellinger, 2001; Parihar et al., 2008). However, there are clinical evidences that
neurodegenerations can be ameliorated upon dietary intake or supplementary intake of
natural antioxidants. The latter could prevent proteins oxidation, lipid peroxidation and
prevent generation of reactive oxygen species (ROS), and thus acting as a barrier to
oxidative stress (Uttara et al., 2009).


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Natural Phenolic Compounds and Parkinson’s Disease

3

In this sense, the aim of this chapter is to briefly summarize the evidence regarding
the role of phenolic compounds in one of the most common neurodegenerative disease

such as Parkinson, used test modes, bioavailability and mechanisms of action with a
particular focus on flavonoids.

2. PARKINSON'S DISEASE (PD)
Parkinson disease is the second most common neurodegenerative disease recognized
by resting tremor, rigidity, bradykinesia and postural instability.
Parkinson`s disease patients show a significant and continual degeneration of neurons
responsible for controlling and coordinating movements and muscle tone. Specifically,
these neurons reside in a core called substantia nigra due to their dark color. In the
Parkinson´s disease, as pigmented neurons of the substantia nigra disappear, it fails to
produce dopamine, an amino acid which acts as a neurotransmitter capable of
transporting information from a group of neurons to another through chemical and
electrical mechanisms (Dauer & Przedborski, 2003). Furthermore, the formation of
endogenous neurotoxins such as 5-S-cysteinyl-dopamine and 5-S-cysteinyl-catecholamine conjugates have been pointed out as endogenous nigral toxins which initiate a
sustained increase in intracellular ROS in neurons leading to DNA oxidation, caspase-3
activation and neuronal death in Parkinson`s diseases (Hastings, 1995; Spencer et al.,
1995, 2002).
Current treatments include drugs such as levodopa, which replaces endogenous
dopamine, dopamine agonists and catechol-o-methyl-transferase (COMT) inhibitors to
prolong the duration of levodopa action (Jankovic, 2002; Kaakkola et al., 1994).
However, the current treatments only ameliorate the symptoms derived from the neuronal
death (Solanki et al., 2016). Due to this fact and since Parkinson´s disease involve
multiple factors, numerous efforts have been made in recent years to elucidate the
mechanism of neurodegenerative diseases with the aim to look for therapies that can help
to slow down and prevent this disease (Costa et al., 2016; Moosavi et al., 2016; Solanki et
al., 2016; Vauzour et al., 2008).

3. IN VITRO AND IN VIVO NEUROTOXIC-BASED MODELS
In vitro and animal in vivo studies have been carried out to obtain greater insights on
the pathogenesis and the effects of phenolic compounds on PD. A wide range of

pharmacological agents or neurotoxins is capable to induce alterations in dopaminergic
structures, alterations that are similar with those observed in human PD (Tudorancea et


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4

Elena Alañon, Amani Taamalli, Mokhtar Zarrouk et al.

al., 2013). As summarized in Table 1, commonly used neurotoxins, applied to evaluate
the protective effects of phenolic compounds in isolated cells or animals in various mimic
aspects of Parkinson’s disease, were 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenyl1,2,3,6-tetrahydropyridine (MPTP) and rotenone. 6-OHDA is a structural analog of
dopamine that is highly electroactive and oxidizes to form reactive oxygen species. The
use of 6-OHDA, as an experimental dopaminergic neurotoxin, is one of the oldest and
most utilized models of PD. The 6-OHDA, which cannot cross the blood- brain barrier, is
often unilaterally infused into the medial forebrain bundle or striatum of rat or mouse to
model behavioral, neurochemical, and pathological features associated with severe
injuries of the nigrostriatal dopamine system. Currently, the MPTP model is one of the
most widely used models of PD. MPTP is typically administered systemically because it
is able to cross the blood–brain barrier (Cannon & Greenamyre, 2010). In other hand,
rotenone is a naturally occurring compound derived from plants, which has been used as
an insecticide in vegetable gardens, and to kill fish(Sengupta et al., 2016). Rotenone is
highly lipophilic and it is able to cross the blood–brain barrier rapidly (Cannon &
Greenamyre, 2010). This neurotoxin which produces systemic complex I inhibition, is
often chronically systemic administered in rats (Cannon & Greenamyre, 2010).
Animal models are important in such research studies and obviously the best model
for a better understanding of the human PD (Cannon & Greenamyre, 2010). The use of
neurotoxin animal models is the most widespread. Mice and rats are the most used
animals to establish the models for in vivo PD studies.

Different cell types have been used in the in vitro models among which
pheochromocytoma PC12 cell line, which is derived from a pheochromocytoma of the rat
adrenal medulla. These cells line are commonly used as alternative sources of
dopaminergic neurons because they share many properties of dopaminergic neurons, such
as expression of tyrosine hydroxylase (TH) and synthesis of dopamine (DA) (Song et al.,
2012).

4. BIOAVAILABILITY OF PHENOLIC COMPOUNDS
AND METABOLITES IN BRAIN
Our diet contains complex mixtures of phenolic compounds from several sources
such as fruits, vegetables and beverages. After absorption, these compounds are subjected
to conjugation such as methylation, sulfation, and glucuronidation. It is important to note
that the composition of the diet components and the bioavailability of the phenolic
compounds influence the health benefits of the latter (Shahidi & Ambigaipalan, 2015).


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Table 1. Neuroprotective polyphenols in Parkinson’s disease models
Test mode
In vivo

MPTP mice

In vivo

MPTP mice

Compounds/plant
extracts

Green tea extract,
EGCG
Green tea

In vitro

PC12 cells

EGCG

In vivo

OHDA-rats

Curcumin,
Naringenin

In vivo

6-OHDA rats

Green tea polyphenols

In vivo

MPTP mice

Curcumin,
Ttrahydrocurcumin

Ex vivo

MPTP mice

Curcumin,
Tetrahydrocurcumin

Observations/ Mechanisms

Reference

Neuroprotective effect
Antioxidant and iron chelating properties
Protective effects of dopaminergic neurons,TH
activity, and DA, DOPAC and HVA levels in the
brain
Inhibition of nNOS in the substantia nigra.
Neuroprotective effect
Rescue of PC12 cellsfrom death induced by
deprivation of trophic factor support
Induction of cell differentiation.
Neuroprotective effect
Antioxidant prperties and capability to penetrate
into the brain
Dose-dependently protection of dopaminergic
neurons through ROS-NO pathway.
Dose-dependently preservation of the free radical
scavenging capability of both the midbrain and the
striatum.
Neuroprotective effect

Reversation of the MPTP induced depletion of
DA and DOPAC
Neuroprotective effect
Significant decrease in MAO- B activity
Tetrahydrocurcumin showed greater inhibition of
MAO-B compared with that of curcumin

(Levites et al.,
2001)
(Choi et al., 2002)

(Reznichenko et al.,
2005)

(Zbarsky et al.,
2005)
(Guo et al., 2007)

(Rajeswari &
Sabesan, 2008)
(Rajeswari &
Sabesan, 2008)


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Table 1. (Continued)
Test mode

Compounds/

plant extracts

Observations/
Mechanisms

Reference

Test mode

In vitro

PC12 cells
LPS-induced N9
inflammation

Resveratrol,
quercetin

(Bureau et al.,
2008)

in vivo

MPTP mice

Morin

in vitro

PC12 cells

Morin

In vitro

Mouse brain
mitochondria

Glutamoyl diester of
curcumin

N27 dopaminergic
neuronal cells

Di-glutamoyl curcumin

MPTP mice

Thea flavin

Antiinflammatory effect
Reduction of IL-1α and TNFα gene expression in
N9 microglial cells
Decrease in microglial-induced neuronal death
Neuroprotective action
Attenuation of behavioral deficits, dopaminergic
neuronal death and striatal dopamine depletion
Neuroprotective action
Attenuation of MPP+
Inducion of loss of cell viability

Attenuation of MPP+ -induced apoptosis
Attenuation of MPP+ -induced ROS formation
Neuroprotective effect
Improving protection against PN-dependent CI
inhibition and protein nitration.
Protection of dopaminergic neurons against 1methyl-4- phenylpyridinium (MPP+)-mediated
neuronal death
Neuroprotective effect
Attenuation of MPTP/p induced apoptosis and
neurodegeneration
Increase in TH-positive cells

In vivo

(Zhang et al., 2010)

(Zhang et al., 2010)

(Mythri et al.,
2011)

(Anandhan et al.,
2012)


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Table 1. (Continued)
Test mode
In vivo

In vitro

Compounds/
plant extracts
6-OHDA rats

Observations/
Mechanisms
Camellia sinensis
(green tea),
Epicatechin,
EGCG

Human study

Green tea

SNCA (LB509)

EGCG

Test mode
In vitro
and in vivo

LRRK2

In vivo

Rotenone rats

In vivo

MPTP mice

Compounds/
plant extracts
Piceatannol,
Thymoquinone,
Esculetin
Schinus
terebinthifoliusstem
bark extract
Mulberry fruit extract

Reference

Test mode

Neuroprotective effect
Increase in locomotor activity, antidepressive
effects, and improvement of cognitive
dysfunction.
Reverse of the striatal oxidative stress and
immunohistochemistry alterations.
Antioxidant and anti inflammatory properties
Improvement of antioxidant status
Less oxidative stress
EGCG might inhibit dose-dependently the SNCA

aggregation byintermolecular hydrophobic
interactions.

(Bitu Pinto et al.,
2015)

Observations/ Mechanisms

Reference

Reduction of loss in dopaminergic neurons,
oxidative dysfunction, and locomotor defects.
Antioxidant and kinase inhibitor properties
Prevention of rotenone-induced dysfunctional
behavior
Antioxidant activity
Improvement of PD-related nonmotor symptoms
as well as motor impairment.
Protective effects against dopaminergic neuronal
damage induced by MPTP/p in the substantia
nigra and striatum.
Inhibition of the up-regulation of α-synuclein and
ubiquitin

(Angeles et al.,
2016)

(Chen et al., 2015)
(Xu et al., 2016)

(Sereniki et al.,
2016)
(Gu et al., 2017)


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The most important factors that dictate bioavailability and bio-efficacy are i)
physicochemical properties, ii) interaction with food matrix, and iii) response to
physiological conditions of the gastrointestinal tract (Reglodi et al., 2015). A key
requisite to be considered when studying the biological effects that a chemical compound
may exert in vivo is its pharmacokinetic properties (Rodriguez-Morato et al., 2015). The
effectiveness of phenolic compounds depends on preserving the stability, bioactivity and
bioavailability of the active ingredients and constitutes a crucial issue with respect to
therapeutic administration. Thus, it is important to determine the form and amount of a
compound that enters the brain since compounds need to reach effective concentrations in
the central nervous system to exert their neuroprotective effects.
Phenolics have evidenced their neuroprotective properties (see Table 1).
Nevertheless, their selective permeability across the blood-brain barrier (BBB), poor
absorption, rapid metabolism and systemic elimination limit their bioavailability and
therapeutic efficacy (Pandareesh et al., 2015). The BBB is a dynamic and complex
interface between the blood and the central nervous system regulating brain homeostasis.
Major functions of the BBB include the transport of nutrients and protection of the brain
from toxic compounds (Campos-Bedolla et al., 2014).
The entry of phenolics into the brain is complicated and it is important to consider
their capability to enter into it. The entry is dependent upon their stereochemistry and

interactions with efflux transporters. For instance, in vitro BBB models serve to study
uptake/efflux activities of phenolics compounds (Pandareesh et al., 2015).
It has been revealed that several bioactive phenolic compounds can penetrate the
BBB including curcumin administered (7.5 mg/kg/day) intravenously through tail vein
for a week (Lee et al., 2013), caffeic acid (Pinheiro Fernandes et al., 2014), resveratrol
(Vingtdeux et al., 2010), fistein (Lapchak, 2013), hesperetin (Youdim et al., 2003),
catechin, and cyanidin-3-glucoside (Faria et al., 2010), cyanidin (Andres-Lacueva et al.,
2005), apigenin and kaempferol (Yang et al., 2014), tangeretin (Datla et al., 2001) and
quercetin (Youdim et al., 2004a). It has been also found that native blackberry
anthocyanins and their methylated forms reached the brain (Talavéra et al., 2005). In
addition, anthocyanins including cyanidin-3-O-β-galactoside, cyanidin-3-O-β-glucoside,
cyanidin-3-O-β-arabinose,
malvidin-3-O-β-galactoside,
malvidin-3-O-β-glucoside,
malvidin-3-O-β-arabinose, peonidin-3-O-β-arabinose, and delphinidin-3-O-β-galactoside
were detected in the cerebellum, cortex, hippocampus or striatum of rats after a blueberry
supplemented diet (Andres-Lacueva et al., 2005). In another study, epicatechin
glucuronide and 3'-O-methyl epicatechin glucuronide formed after oral ingestion were
detected in the rat brain tissue (Abd El Mohsen et al., 2002). Besides, quercetin and
isorhamnetin/tamarixetin were also detected in rat brain after feeding a Hypericum
perforatum extract (Paulke et al., 2006).


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Natural Phenolic Compounds and Parkinson’s Disease

9

In other hand, it has been reported that conjugation and deconjugation may regulate

the biological activities of flavonoids. In this sense, glucuronidated flavonoids may be
concentrated in their more active aglycone form by cells responsible for inflammatory
damage (Jones et al., 2012). In other hand, phenolic compounds have also been used
together or with other PD-relevant drugs as multidrug treatments and new interesting
synergistic actions have emerged (Reglodi et al., 2015).

5. RELATIONSHIP BETWEEN FLAVONOIDS
AND PARKINSON’S DISEASE
Based on several animal and human trials, the consumption of fruits and vegetables
seems to reduce risk of neurodegenerative diseases caused by neuronal impairment
(Checkoway et al., 2002). Flavonoids, amongst the most abundant group of these natural
sources, which are divided into six subclasses based on their molecular structures
(flavonols, flavanols, isoflavones, anthocyanidins, flavanones and flavones) have been
regarded as plausible compounds responsible of the prevention and amelioration of
various neurodegenerative diseases (Costa et al., 2016).
For example, the inhibition of the formation of the neurotoxin 5-S-cysteinyldopamine by certain flavonoids such as pelargonidin, quercetin, hesperetin, caffeic acid,
4-O-mehtyl derivatives of catechin and epicatechin, epigallocatechin-3-gallate (EGCG)
or hesperetin among others have been reported in the literature (Vauzour et al., 2008;
Vauzour et al., 2007a). Thus, Ginkgo Biloba extract has been found to protect
dopaminergic neurons in an animal model of PD by reducing oxidative damage,
neuroinflammation and microglial activation (Rojas et al., 2012). Acacetin, an Omethylated flavone (5,7-dihydroxy-4-methoxy-flavone) found in acacia (Robinia
pseudoacacia) seems to inhibit the degeneration of dopaminergic neurons and depletion
of dopamine level induced by the action of the neurotoxin MPTP in Parkinson´s diseases
(Kim et al., 2012). The motor imbalance and coordination induced by the MPTP was also
improved by certain flavonoids such as quercetin increasing as well, the activities of
various antioxidants such as glutathione peroxidase, superoxide dismutase and an enzyme
Na+/K+APTase (Lv et al., 2012). Motor imbalance and coordination induced by the
MPTP was found to be improve by flavonoids such as quercetin along with the increase
in activities of various antioxidants such as glutathione peroxidase, superoxide dismutase
and enzyme Na+/K+ ATPase (Lv et al., 2012). Rutin and EGCG have also demonstrated

their prevent action againstneurotoxins such as 6-hydroxydopamine in animal and
cellular models (Moshahid Khan et al., 2012; Nie et al., 2002). Meanwhile, myricetin has
the capability to alleviate MPP+ induced mitochondrial dysfunction in PD (Cai et al.,
2015).


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On the other hand, baicalin has shown to inhibit the aggregation of amyloid beta
protein fibrils (Aβ) and reduce the production of hydrogen peroxide (H2O2) and oxidative
damage in SH-SY5Y cells (Yin et al., 2011) and curcumin has been used as potent antioxidative and anti-inflammatory agent. It also exhibits anti-amyloidogenic effects
(Hirohata et al., 2007), binds amyloid directly, inhibits Aβ aggregation preventing fibril
and oligomer formation (Yang et al., 2005) and increases the neuroprotective effects by
means of NF-E2-related factor 2 (Nrf2) expression (Yang et al., 2009).
Therefore, flavonoids perform neuroprotective function via the enhancement of
existing neuronal function or by stimulating neuronal regeneration. In addition,
flavonoids protect neuronal cells by reducing oxidation of proteins, lipid peroxidation and
prevent generation of ROS thus act as upstream therapy to neurogeneration (Vauzour et
al., 2008). This capability of flavonoids to target multiple sites in the brain makes them a
great alternative therapeutic promise in prevention and treatment of the age-associated
neurodegenerative diseases.

6. MECHANISM OF PROTECTIVE EFFECTS OF FLAVONOIDS IN
NEURODEGENERATION DISEASES
The neuroprotective mechanism of flavonoids has become a topic of interest in the
last years to set up an alternative medicine based on their potential beneficial effects in

the aging and diseased brain. The neuroprotective action of flavonoids relies on: i) their
antioxidant properties, which protect neurons against oxidative stress, ii) their capacity to
modulate cell signaling, and iii) their ability to suppress neuroinflammation via reduction
of the release of cytokines and down regulation of the pro-inflammatory transcription
factors and pathways (Solanki, et al., 2016).

6.1. Antioxidant Properties
The flavonoids are well known to be antioxidants as they are hydrogen-donating as
well as scavengers of reactive oxygen and nitrogen species (Rice-Evans, 2001). For that
reason, the neuroprotective mechanisms of flavonoids such as apigenin and quercetin
against oxidative stress via scavenging free radicals produced from impaired metabolism
have been deeply studied (Lv et al., 2012; Zhao et al., 2013). It was also demonstrated the
protection cell constituent against neurotoxins, which is associated with the stimulation of
oxidative stress and subsequently cell death. In PD, the effect of neurotoxins such as 6hydroxydopamine (6-OHDA), N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)
and 1-methyl-4-phenylpyridinium (MPP+) seem to be mitigated by some flavonoids such


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Natural Phenolic Compounds and Parkinson’s Disease

11

genistein, rutin, epigallocatechin 3-gallate, myricitrin, nobiletin, and tangeretin
(Baluchnejadmojarad et al., 2009; Cai et al., 2015; Datla et al., 2001; Jeong et al., 2015;
Kim et al., 2012; Levites et al., 2001; Lv et al., 2012; Moshahid Khan et al., 2012; Nie et
al., 2002). Meanwhile, the action 5-S-cysteinyl-dopamine is counteracted by various
flavonoids including pelargonidin, quercetin, hesperetin, caffec acid, the 4’-O-methyl
derivatives of catechin and epicatechin (Vauzour et al., 2008).
However, their potential in blocking oxidant-induced neuronal injury seems not to

rely on direct radical or oxidant scavenging due to strong evidences that should be taken
into account. On the one hand, the antioxidant effect of flavonoids in vivo is limited in
comparison with that observe in vitro as consequence of biotransformation and
conjugation processes (Spencer et al., 2001). It is well known that after their ingestion,
flavonoids are metabolized and converted to glucuronides, sulphates and conjugated Omethylated whose forms circulate for bloodstream. However, despite being involved in
antioxidant reactions, several studies have been demonstrated their less effectiveness
against reactive oxygen and nitrogen species (da Silva et al., 1998; Miyake et al., 2000;
Terao et al., 2001; Yamamoto et al., 1999). On the other hand, flavonoid metabolites
have been localized in different regions of brain (Williams et al., 2008) which is
explained by their ability to cross the blood brain barrier (BBB) by trans-membrane
diffusion to the brain (Schaffer & Halliwell, 2012). The entrance of the metabolites,
which do not exhibit an accumulative effect overtime (Bieger et al., 2008), is governed
by the degree of lipophilicity of each compound (Youdim et al., 2004b) and by the
interactions with specific efflux transporters such as P-glycoproteins (Lin & Yamazaki,
2003).
These facts have suggested that flavonoids seem to be implied in direct
neuroprotective and neuromodulatory actions. Consequently, there is an emerging view
that flavonoids, and their metabolites, do not act as conventional hydrogen-donating
antioxidants but they also modulate directly various signaling pathways (Mansuri et al.,
2014; Solanki et al., 2015, 2016; Spencer, 2001, 2007; Spencer et al., 2001).

6.2. Modulation of Cell Signaling Pathways
Flavonoids and some metabolites are believed to modulate protein kinase and lipid
kinase signaling pathways in neuronal cells. These pathways are likely to affect neuronal
function by altering the phosphorylation state of target molecules and/or by modulation
gene expression (Williams et al., 2004). Cell signaling pathways includes both cell
survival and cell death signaling pathways such as phosphatidylinositol-3-kinase / protein
kinase B (PI3K/Akt), extracellular signal-regulated protein kinase (ERK1/2), protein
kinase C (PKC), the protein p38 and c-Jun N-terminal kinase (JNK) (Spencer, 2007;
Williams et al., 2004).