Antioxidant Responses of Pomegranate Due To Oxidative Stress Caused by ROS
Antioxidant Responses of Pomegranate Due To Oxidative Stress Caused by ROS
Antioxidant Responses of Pomegranate Due To Oxidative Stress Caused by ROS
ISSN No:-2456-2165
Abstract:- Pomegranate plant has wide usage because of progression of numerous pathological disturbances, such as
its biologically active compounds with different atherosclerosis [8], brain dysfunctions [9] and cancer [10]. It
biological activities, being present in different parts of was found that polyphenols from peel of pomegranate
plants. In this review, the point of focus is on antioxidant inhibit the proliferation and induced apoptosis of human
responses of this plant under conditions of oxidative prostate cancer cells [11]. Anti-inflammatory activity of
stress due to reactive oxygen species. In pomegranate, pomegranate peel is due to gallagyldilacton, gallic acid,
ROS cause oxidative stress due to different biotic and granatin B [12], [13]. Antioxidant activities of peel are due
abiotic stresses, some of them causing elevation of to Tannins like punicalin, punicalagin, pedunculagin, gallic
antioxidant level and some stresses cause decline in acid and casuarinin [13]-[15]. It was found that the peel
antioxidant level. But plant has ROS scavenging extract has tannins that made it effective virucidal agent
mechanism that is antioxidant defense system which can [123] in opposition to genital herpes virus [16]. Numerous
be enzymatic and non-enzymatic preventing damage flavonoids in peel show antibacterial, antiviral, antioxidant,
caused by reactive oxygen species. By evaluating level of anti-inflammatory and antineoplastic bioactivities. These
antioxidants in different parts of plant, we can decide flavonoids are catechin, epicatechin, epigallocatechin-3-
about its therapeutic and commercial usage; this gallate, flavan-3-ol, kaempferol, kaempferolerol-3-O-
evaluation also acknowledges about its agricultural glucoside, kaempferol-3-O-rhamnoglycoside, luteolin,
plantation at specific areas under specific stress luteolin 7-O-glucoside, Naringin, pelargonidin,
conditions. Owing to more antioxidant activities in peel prodelphindin, quercetin and rutin [4], [17]-[19].
part, it can be used in prevention of food spoilage by
enhancing the shelf life. Hydroxyl, carbonyl, and aromatic groups are also
present in peel among significant amount of punicalagin
Keywords:- Biologically Active Constituents, Defense [29], punicalin [14], granatin A [20], maleic acid [21], gallic
mechanism, Oxidative, Stress Pomegranate, ROS. acid [122], ursolic acid [26], and antioxidant constituents [5]
and efficient constitutive chemical groups in the structure of
I. INTRODUCTION these constituents could exhibit corrosion inhibition
functioning. Phytochemicals are frequently mentioned to
A. Introduction to Pomegranate non-nutritive compounds assumed to be formed by plants,
Pomegranate plant belongs to botanical family providing defense against harmful ultraviolet radiation,
Punicaceae [1]. The worldwide production of pomegranate pathogens and herbivorous predators. Phytochemicals are of
is approximately 1,500,000 tons [2]. Pomegranate (Punica utmost significance for having prospective human health
granatum L.) is introduced from South East Asia. It is benefits and are valued for their biological and free radical
planted in Turkey, Iran, the USA, the Middle East, and scavenging actions. Peel of pomegranate has phenolic
Mediterranean and Arabic countries, as one of the compounds, including flavonoids, anthocyanins and tannins
significant fruits [3]. Pomegranate peel is taken into account that are the chief group of antioxidant phytochemicals [6].
as an agro-waste but it is a powerful source of compounds Pomegranate fruit peel can be used as natural dye source for
giving human health aids. Peel accounts for about 60 % of unmordanted fabrics. So, use of pomegranate peel in dyeing
weight of pomegranate fruit [4]. Total Phenolic contents and fabrics removes use of metallic mordants that have effect on
antioxidant activity of pomegranate peel is greater than pulp color efficiency in process of mordanting. Unmordanted
[5]. Antioxidant activity of peel is also higher than flower, fabrics when dyed with pomegranate peel, show
leaf and seed [6]. considerable antimicrobial activity [22]. One of the studies
conducted in rats whose liver was made damaged due to
B. Biological Activities of Pomegranate Peel CCl4 showed that pretreatment with PPE boosts or preserves
Peel contains substantial amounts of polyphenols such the action of hepatic enzymes superoxide dismutase,
as ellagic tannins, ellagic acid and gallic acid [7]. Recently, peroxidase and catalase. These enzymes have ability to
addition of polyphenols to foods and biological systems scavenge free radicals, preventing their deleterious effects.
remained point of focus. Polyphenols have ability to PPE decreases lipid peroxidation to 54%. PPE cause
scavenge free radicals, i. e. antioxidant power. The considerable hypoglycemic effect by increasing insulin
generation of free radicals plays an important role in the levels and renewal of pancreatic beta cells [23]. Blood
Table-I: Biological activity of major tannins owing to its particular biologically active compounds (Sushil et al., 2013)
Compound Bioactivity
Casuarinin Antiviral, antioxidant
Corilagin Antihypertensive, antineoplastic
Ellagic acid [EA] Antineoplastic, skin whitening
Gallic acid Antimutagenic, anti-inflammatory, antiviral, antioxidant
Methyl gallate Antioxidant
Granatin A Antioxidant, anti-inflammatory
Granatin B Antioxidant, anti-inflammatory
Pedunculagin Antineoplastic, antioxidant
Punicalagin Antioxidant, antihypertensive, anti-hyperglycemic
Punicalin Antioxidant, anti-HIV, anti-hyperglycemic
Table-II: Biological activities of major flavonoids and alkaloids owing to particular active constituents (Sushil et al., 2013)
Compound Bioactivity
Catechin Antineoplastic, antioxidant
Cyanidin Antioxidant
Epicatechin Antineoplastic
Epigallocatechin 3-gallate Antineoplastic
Flavan-3-ol Antineoplastic
Kaempferol Antioxidant, anti-inflammatory
Kaempferol-3-0-glucoside Antioxidant
Luteolin Antioxidant, antioxidant
Luteolin-7-0-glucoside Antioxidant
Quercetin Antiviral, antioxidant, antineoplastic
Naringin Antiviral, antibacterial
Major alkaloids of pomegranate peel
Pelletierine Antioxidant
Valoneic acid dilactone Antidiabetic
C. ROS Generation
These are produced in mitochondria, chloroplast and
peroxisomes of plant cells [30]. ROS are also produced in
other sites such as cytosol, cell wall and cytoplasm.
H2O2 has ability to cross plant membranes. During As a result of classification of SOD on basis of metal
photo respiratory oxidation, beta-oxidation of fatty acids and cofactor, there are three types: (1) Fe-SOD that is contained
other enzymatic systems for example an enzyme system in in chloroplast, (2) Mn-SOD being located in mitochondria,
which XOD coupled to SOD, H2O2 are generated and CAT (3) Third type is Cu-SOD contained in chloroplast,
scavenges these H2O2 [57], [58]. Cytosol, chloroplast and peroxisome and cytosol [67], [68]. Its structure differs from
mitochondria all contain CAT but substantial CAT activity others two on basis of structure. It means that SOD has three
is no more pronounced in these organelles [59]. Subcellular isozymes, each having its own sensitivity level to H2O.
localization of CAT is peroxisome, glyoxisome and Nucleus encodes all forms of SOD and then through an
mitochondria [28]. CAT is classified on basis of expression amino terminal targeting sequence, these isoforms target
profile of genes of tobacco [60]. Light regulates class I CAT specific subcellular compartments [212]. Cu/Zn-SOD exists
and expression of these CAT happens in photosynthetic as a dimer and is sensitive to cyanide in eukaryotes, but
tissues. Expression of class II CAT happens on vascular other two isoforms (Mn-SOD and Fe-SOD) are not sensitive
tissues with this expression occurring at high levels. to cyanide and existing as dimer or tetramer [66], [69].
Whereas in seedy and young seedlings, there is abundance Mechanism by which ROS are generated and prevented by
of class III CAT. It is shown in figure6 how ROS generation SOS is shown in figure 7 as follows:
is prevented. Equation (1) shows the function of CAT as
follows:
Type of non-enzymatic antioxidants with their particular function and subcellular localization are given in concise form in
Table-IV as follows:
Table-IV: Non-enzymatic antioxidants with their subcellular localization (Kaushik et al., 2014)
Non-enzymatic antioxidants Function Subcellular location
Ascorbic acid Detoxifies H2O2 via APX Cytosol, Chloroplast, Mitochondria,
Peroxisomes, Vacuole and apoplast
Glutathione Act as detoxifying co-substrate for enzyme like Cytosol, Chloroplast, Peroxisome,
peroxidases and GR Vacuole and Apoplast
Alpha tocopherols Guards against and detoxifies the products of Mostly in membrane
membrane LPO
Flavonoids Direct scavenge of H2O2, Vacuole
1
O2 and OH.
C. Tocopherols D. Phenolics
TOCs are lipophilic antioxidants that are effective in Are secondary metabolites that are abundant in tissues
trapping free radical as in lipid autoxidation there is a step- of plants with also having diversity and include flavonoids,
in which chain propagation happens, tocopherols prevent tannins, lignin and hydroxycinnamate esters. All of these
this step. All plants synthesize these antioxidants and also have properties of antioxidants [117]. Biological activity
biological membranes contain these antioxidants as their such as antioxidant activity of polyphenols is due to -OH or
vital constituents [120]. Oxidizing radicals are repaired OCH3 substituents that are present in aromatic rings of
directly by tocopherol, and prevent chain propagation steps, polyphenols. It has been shown in in vitro antioxidant assays
so are known as chain-breaking antioxidant. In their polar that polyphenols are highly capable of donating electrons or
head structure, phenolic rings present to which methyl hydrogen atoms, therefore are more effective antioxidants
groups are attached, due to pattern of attached methyl than AsA and alpha-tocopherol. Phenolics contain properties
groups. Only green parts of plants have tocopherols and also of antioxidants due to following factors such as phenolics
only photosynthetic organisms synthesize these are highly reactive as donating electrons. Unpaired electrons
antioxidants. Two compounds homogenetistic acid (HGA) are stabilized and delocalized due to ability of polyphenol-
and phytyl diphosphate (PDP) act as precursors in pathway derived radical; it means that they have role in chain-
synthesizing tocopherols. Five enzymes synthesizing breaking. Also transition metal ions are chelated by
tocopherols are as 4-hydroxyphenyl-pyruvate dioxygenase polyphenols. For scavenging of free radicals, polyphenols
(HPPD), homogentisate phytyl transferase (VTE2), have perfect chemistry of structure and active oxygen
tocopherol cyclase (VTE1), gamma-tocopherol species directly scavenged by polyphenols; these trap alkoxy
methyltransferase (VTE4), and 2-methyl-6- radical so inhibiting lipid peroxidation. Kinetics of