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REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
Department of Biochemistry ISSN (online) 2347-2154
Available online: www.ijipsr.com July Issue 1606
ROLE OF PHYTOCHEMICALS IN COMBATING OBESITY
1Ramachandran. H. D*
Department of Biochemistry, Bangalore University, Bangalore-560 001, INDIA
Corresponding Author:
Dr. H. D. Ramachandran
Department of Biochemistry
Central College Campus,
Bangalore University,
Bangalore -560 001, INDIA
Email: [email protected]
Phone: +91-9448422287 / 080-22961248
International Journal of Innovative
Pharmaceutical Sciences and Research www.ijipsr.com
Abstract
Phytochemicals are plant chemicals possesing potential for inducing apoptosis, inhibiting
adipogenesis and are anti-obetic. Anti-obesity mechanisms of phytochemicals appear to involve
mediation of complex and interconnected cell signaling pathways. Phytochemicals like polyphenols,
carotenoids and organosulphurs have anti-obesity, anti-inflammatory and apoptotic effects
respectively. Obese individuals generally have high leptin levels. The regulation of adipocyte
lifecycle by regulating both size and number of adipocytes may provide a better approach for
treating obesity. Two different obesity treatment drugs currently in the market are Orlistat, which
reduces intestinal fat absorption via inhibition of pancreatic lipase and Sibutramine, which is an
anorectic or appetite suppressant. Both drugs have hazardous side-effects including increased blood
pressure, dry mouth, constipation, head ache and insomnia. The objective of this review is to
determine the dosages of phytochemicals in leptin regulation and its efficacy in reducing obesity.
Key words: Phytochemicals, leptin, adiposity, obesity, polyphenols, carotenoids, organosulphurs.
REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
Department of Biochemistry ISSN (online) 2347-2154
Available online: www.ijipsr.com July Issue 1607
INTRODUCTION
The World Health Organization (WHO) defines obesity as an abnormal or excessive fat
accumulation detrimental to human health. WHO defines overweight as a BMI (Body Mass
Index) greater than or equal to 25 and BMI greater than or equal to 30 as obese. Obesity and
obesity-related complications are rapidly increasing both in developed and developing countries,
presenting an increase in the risk of morbidity and mortality. Around 3.4 million adults die each
year as a result of being overweight or obese. (WHO, 2014) [1]. The United States is the most
obese country in the World with 34% of the adult population classified as obese, according to the
latest OECD (Organization for Economic Cooperation and Development) survey. In India the
prevalence of overweight rose from 2 to 17.1% from 1989 till 2012. In a total of 6940
subjects(3433 women and 3507 men) selected from various cities in India, the overall
prevalence of obesity was 6.8% (7.8 vs 6.2% P< 0.05) and of overweight was 33.5% ( 35vs 32%
P< 0.05) (Ambika et al., 2012) [2]. Obesity is a multifactorial complex disease influenced by life
style, behavioural, environmental as well as genetic factors. The development and continuation of
obesity is closely associated with a state of chronic, low grade inflammation characterized by
abnormal cytokine production and activation of inflammatory signaling pathways (Tsukomo et
al., 2007) [3]. Obese individuals generally have high leptin levels and a highly significant
correlation between body fat content and plasma leptin concentration has been observed. The
protein leptin regulates appetite and energy balance of the body. Adipose tissue growth involves
formation of new adipocytes from precursor cells, further leading to an increase in adipocyte size.
Preadipocytes can proliferate throughout life to increase fat mass. A number of natural products
were shown to inhibit preadipocyte proliferation and induce apoptosis. (Rayalam et al., 2008) [4].
Leptin is an adipocyte derived 167 amino acid protein hormone which is produced in proportion
to fat stores. The production of leptin by adipose tissue is regulated by energy balance. Regulation
of leptin secretion depends on the activation of mTOR, increase in ATP, adenosine, malonyl CoA
and the increase in cAMP and fatty acids decrease the secretion of leptin. Mutations in the leptin
gene (ob-gene) can result in low levels of functional leptin leading to obesity in individuals. So
the only way to increase leptin is to increase its expression on the genomic level. Phytochemicals
are natural chemical compounds formed during normal metabolic processes in plants (Okigbo et
al., 2009) [5]. These chemicals are often referred to as secondary metabolites of which there are
several classes including alkaloids, flavanoids, coumarins, glycosides, gums, polysaccharides,
REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
Department of Biochemistry ISSN (online) 2347-2154
Available online: www.ijipsr.com July Issue 1608
phenols, tannins, terpenes and terpenoids (Okwu, 2004) [6]. Phytochemicals were studied for
their weight loss, efficacy based on five broad mechanisms of actions, namely (1) decreased lipid
absorption (2) decreased energy intake (3) increased energy expenditure (4) decreased pre-
adipocyte differentiation and proliferation, or (5) decreased lipogenesis and increased lipolysis
(Yun, 2010) [7]. Phytochemicals have gained increased interest due to their anti-oxidant activity,
apoptotic, anti-adipogenic, cholesterol lowering properties, and other potential health benefits
(Awaika and Rooney, 2004) [8]. Furthermore, latest studies on phytochemicals suggest that they
are potential agents in the treatment of obesity. Various studies suggest that anti-obesity effects
could be achieved by consuming lower levels of phytochemicals but in specific combinations.
(Baile et al., 2011; Dooley et al., 2005) [9,10]. Phytochemical combinations that included
polyphenols such as stilbene, resveratrol, genistein and naringenin have proven the most effective.
1. Polyphenols are a class of phytochemicals that are likely anti-obesity agents, as several
studies have suggested they can modulate the adipocyte lifecycle. (Rayalam et al., 2008; Yun,
2010).4, 7
Polyphenols possessing at least two phenol subunits include the flavonoids and those
compounds possessing three or more phenol subunits are referred to as the tannins
(hydrolysable and non- hydrolysable). Polyphenols including their functional derivatives,
esters and glycosides have one or more phenol groups with one hydroxyl substituted aromatic
ring. (Dey and Harborne, 1989) [11]. The three main types of polyphenols are phenolic acids,
flavonoids and stilbenoids.
A. The flavonoid subclasses, flavonols eg. Quercetin, kaempferol, myricetin, and rhamnetin,
the flavones eg.luteolin and apigenin. (Williams et al., 2013) [12] Flavanols, flavanones,
proanthocyanidins and anthocyanins, isoflavones, chalcones and dihydrochalcones. (FGE.
3.2) [13].
B. Stilbenoids comprises the polyhydroxylated stilbenes, the main representative being
resveratrol.
C. The simple phenolic acids such as chlorogenic, coumaric, ferulic, gallic , gentisic and
caffeic acids.
Laboratory studies indicate that the anti-obesity effects of polyphenol rich diet may be
attributed to the ability of polyphenols to interact, directly or indirectly, with adipose tissues
(preadipocytes, adipose tissues and immune cells) (Wang et al., 2014) [14]. Many lines of
REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
Department of Biochemistry ISSN (online) 2347-2154
Available online: www.ijipsr.com July Issue 1609
research indicate that dietary polyphenols prevent obesity development through the following
possible mechanisms: a) Lowered food intake b) Decreased lipogenesis c) Increased lipolysis
d) Stimulated fatty acid β-oxidation e) Inhibition of adipocyte differentiation and growth, and
f) Attenuation of inflammatory responses and suppress oxidative stress.
Most dietary polyphenols have relatively short half lives once ingested due to rapid metabolism,
so it is important that their consumption is maintained throughout the life span. After eating
polyphenol-rich foods or taking dietary supplement, humans achieve peak plasma polyphenol
concentration at less than 10µM. (Lee et al., 2002; Anand et al., 2007; Baur et al., 2006; Conquer
et al., 1998) [15,16,17,18].
A. Flavonoids comprises of flavonols, flavones, flavanols, flavanones, isoflavones,
anthocyanins, chalcones. Both flavonols and flavones usually occur in plant as glycosides.
a) Flavonols: quercetin, isorhamnetin, kaempferol, myricetin:
(i) Quercetin (3, 3’, 4’, 5, 7-Pentahydroxyflavone): This compound has been shown to inhibit
adipogenesis (Strobel et al., 2005) [19] and induce apoptosis in mouse pre-adipocytes. (Fang et
al., 2008; Kuppusamy and Das, 1992) [20,21] It also provides some protective effects against
obesity-related inflammation. (Al Fayez et al., 2006; Chuang et al., 2010) [22,23]. A recent study
(Ahn et al., 2008) [24] provided useful insights into the molecular mechanisms by which
quercetin influences the regulation of fat cell differentiation and apoptosis. Combination of
quercetin and isoflavone, genistein and the stilbene, resveratrol to human adipocytes enhanced
inhibition of lipid accumulation in maturing human adipocytes than the individual compounds.
(Park et al., 2008) [25].
(ii)Isorhamnetin (3-Methylquercetin; 3’-Methoxy 3,4’,5,7tetrahydroxyflavone): Antiviral
agent, antioxidant. (Yokozawa et al., 2002), [26] antitumor compound (Ito et al., 1999) [27] and
apoptosis inducer (Ma et al., 2007) [28].
(iii) Kaempferol (3, 4’, 5, 7-Tetrahydroxyflavone): Antioxidant flavonoid (Evans et al., 1996)
[29] apoptosis inducer, reversible inhibitor of fatty acid synthase (FAS) (Li et al., 2003, Lupu et
al., 2006) [30, 31]
(iv)Myricetin (3, 3’, 4’, 5, 5’, 7- Hexahydroxyflavone): Antioxidant flavonoid, posseses
antitumor and chemopreventive properties (Lee et al., 2007) [32] anti-inflammatory, inhibits NF-
κB activation (Ong and Khoo, 1997) [33].
REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
Department of Biochemistry ISSN (online) 2347-2154
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b) Flavones : luteolin, apigenin, baicalein.
(i) Luteolin: Anti-adipogenic effect of luteolin on murine 3T3-L1 pre-adipocytes is mediated
through decreased lipid accumulation and inhibition of differentiation (Park et al., 2009) [34].
(ii) Apigenin (4’, 5, 7-Trihydroxyflavone): Apigenin induces apoptosis (Shukla and Gupta,
2007) [35].
(iii) Baicalein (5, 6, 7- Trihydroxyflavone): Induces cell cycle arrest and apoptosis (Lee et al.,
2005) [36].
c) Flavanols: Catechins [(±)-Catechin, (-)- Epigallocatechin gallate]
(i) (±)-Catechin ((±)-3, 3’, 4’, 5, 7-Flavanpentol): Antioxidant flavonoid, Free radical scavenger
(Williamson, et al., 2005) [37] and has chemopreventive and antitumor properties. (Lazaro, 2002)
[38].
(ii) (-)-Epigallocatechin gallate: Antitumor reagent, antioxidant, protects cells from lipid
peroxidation and DNA damage, inhibits inducible nitric oxide synthase (iNOS; NOS II),
chemopreventive anticancer agent (Chen and Zhang, 2007) [39], inhibits - MAP kinase signaling,
angiogenesis, inhibits telomerase and DNA methyltransferase and is also anti-inflammatory
(Khan et al., 2006) [40].
d) Flavanones: Bavachin and related compounds
(i) Bavachin: Weak antioxidant, antimutagenic, stimulates bone formation and has potential
activity against osteoporosis. Also exhibits inhibitory activity against the antigen-induced
degranulation and weak estrogen-like activity. (Wang et al., 2001) [41].
e) Isoflavones: Genistein and related compounds
(i) Genistein (Genistein-7-O-glucoside):
Selective inhibitor of terminal deoxyribonucleotidyltransferase (TdT). (Uchiyama et al., 2005)
[42] and displays antioxidant and anticarcinogenic properties (Choi et al., 2007) [43].
f) Anthocyanins:
Anthocyanins have potential for anti-obesity related effects which is responsible for the red, blue
and purple colours in vegetables (Clifford, 2000) [44]. Cyanidin, the most common anthocyanin
foods, reduced blood glucose level as well as downregulating inflammatory protein cytokines
REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
Department of Biochemistry ISSN (online) 2347-2154
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such as monocyte chemoattractant protein-1(MCP-1) in the adipose tissue of mice. (Sasaki et al.,
2007) [45].
g) Chalcones:
(i)Curcumin(1,7-bis(4-Hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione;
Diferuloylmethane: Plays an important role in inflammation, apoptosis, angiogenesis,
autoimmune diseases and cancer. (Rayalam et al., 2008) [6]
B: Stilbenoids are polyhydroxy stilbenes.
(i) Resveratrol (trans-3,4´,5- Trihydroxy stilbene): It is a polyphenol from red wine possessing
anti-oxidant, anti-inflammatory, anti-thrombogenic, cardioprotective, neuroprotective, cancer
preventive and therapeutic activities.(Rayalam et al., 2008) [6].
C. Phenolic acids are substances containing a phenolic ring and an organic carboxylic acid
function (C6-C1 skeleton). Hydroxycinnamates and hydroxybenzoic acids are the naturally
occurring phenolic acids, in which hydroxybenzoic acid derivatives are mainly present as
glycosides (Williams et al., 2013) [46]. Common hydroxycinnamic acids, comprising nine carbon
atoms, derivatives are coumaric, caffeic and ferulic acids. Hydroxybenzoic acids contain seven
carbon atoms. Gentisic acid and gallic acids are hydroxybenzoic acids. Administration of
phenolic acids at a dose of 10 mg/kg p.o (per os) daily for 4 weeks to ovariectomized or non-
ovariectomized rats slowed their body mass gain. (Zych et al., 2009) [47].
(I) Caffeic acid (3- (3, 4- dihydroxyphenyl) – 2 - propenoic acid): It exhibits anti tumor,
antiviral, antioxidant and anti-inflammatory effects. Also inhibits 5- and 12- lipoxygenase.
(Oztruk et al., 2012) [48].
(ii) Chlorogenic acid (3-O-caffeoylquinic acid): This is an analog of caffeic acid, which exhibits
antioxidant, analgesic, antipyretic and chemopreventive activity. (Rayalam et al., 2008) [6]
(iii)Ferulic acid ((E)-3-(4-hydroxy-3-methoxy-phenyl) prop-2-enoic acid): Recent studies
evaluated that the dietary phenolic acid, ferulic acid, suppressed the weight gain due to the high
fat diet and inhibited fatty acid biosynthesis. (Son et al., 2010) [49].
(iv)p-coumaric acid ((E)-3-(4-hydroxyphenyl)-2-propenoic acid): is a hydroxycinnamic acid
with antioxidant properties. p-coumaric acid protects the myocardial infarcted rat's heart against
apoptosis by inhibiting oxidative stress. (Prince et al., 2013) [50].
REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
Department of Biochemistry ISSN (online) 2347-2154
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(v)Gallic acid (3, 4, 5- trihydroxybenzoic acid): This is an organic acid which exists in two
forms as free molecule and as part of tannins (gallotanins). (Nasr et al., 2012) [51]. It exhibits
cytotoxicity against cancer cells, without harming healthy cells (Elvira et al., 2006) [52] and also
has antifungal and antiviral properties (Kinjo et al., 2002) [53] which is used as an antioxidant
and helps to protect human cells against oxidative damage (Jittawan, 2008) [54], it can be used as
a remote astringent in cases of internal hemorrhage (Hurrell et al., 1999) [55] and can also used
to treat psoriasis (Cook et al., 1995) [56].
(vi) Gentisic acid (2, 5 - dihydroxybenzoic acid): Possesses greater anti-radical activities
(Williams et al., 1995) [12].
2. Carotenoids:
Carotenoids are a subclass of terpenoids possessing anti-obesity and anti-inflammatory abilities.
(Castejon et al., 2011) [57]. Carotenoids are classified into hydrocarbons (carotenes) and their
oxygenated derivatives (xanthophylls).
α-carotenes and β- carotenes possess the anti-obesity effects. Carotenoids containing an allene
bond, such as fucoxanthin and fucoxanthinol, showed anti-obesity effects. Carotenoids with an
allene bond and an additional hydroxyl substituent on the side group show suppressive effects on
adipocyte differentiation in 3T3-L1 cells. These findings show a great potential for application in
the field of therapeutics for the development of novel anti-obesity compounds. (Miyashita et al.,
2007) [58].
3. Organosulphurs:
Glucosinolate hydrolysis products found in Brassica vegetables are anti-obesity organosulphurs
(Castejon et al., 2011) [57]. Organosulphur compounds isolated from Allium vegetables (Ajoene)
have induced apoptosis of human tumour cells. (Nishikawa et al., 2002, Siegers et al., 1999) [59,
60]. Several garlic derived organosulphur compounds have shown inhibitory effect on
adipogenesis. (Ambati et al., 2009) [61]. Ajoene is more potent on adipocytes when compared to
several other garlic organosulphur compounds, in addition ajoene significantly suppresses cell
viability, adipogenesis and increases apoptosis in different stages of 3T3- L1 adipocytes. Zinc
complexes with garlic components serve as insulin mimetic (Banos et al., 2008) [62], a new
therapeutic approach to treat diabetes, leptin resistance and to suppress progression of obesity in
rodent models.(Adachi et al., 2004) [63].
REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
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Fig. 1: Adipocyte life cycle [64].
Fig. 2: Flow diagram of biological response to differing leptin levels [65].
NPY: Neuropeptide Y; ART: Agouti- related transcript;
MSH: Melanocyte Stimulating Hormone; CRH:Corticotropin Releasing Hormone; GnRH:
Gonadotropin Releasing Hormone; PNS: Parasympathetic Nervous System.
Fig. 3: Leptin is secreted by adipocytes as a signal of fat storage [66].
LRb: Leptin Receptor B.
REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
Department of Biochemistry ISSN (online) 2347-2154
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Fig. 4: Effect of natural products and their combinations on different stages of Adipocyte
life cycle [4].
GSPE: Grape Seed Proanthocyanidin Extract; DHA: Docosahexaenoic Acid
CLA: Conjugated Linoleic Acid; EGCG: Epigallocatechin gallate
1, 25(OH) 2D3: 1,25 dihydroxy Vitamin D3 (Calcitriol)
Quercetin Isorhamnetin Kaempferol
Myricetin Luteolin Apigenin
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Baicalein Catechin Epigallocatechin gallate
Anthocyanins Curcumin Bavachin
Genistein Resveratrol Caffeic acid
Chlorogenic acid Ferulic acid p-coumaric acid
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Gallic acid Gentisic acid Carotene
Table 1: Effect of reviewed phytochemicals on adipogenesis in vivo and in vitro. 67
Phytochem
ical
Proliferatio
n
of
Adipocytes
Apoptosis
of
pre-
adipocytes
Lipid
accumu-
lation
Adipogeni
c
gene
expression
Apoptosi
s
of
adipocyte
s
Lipolysis
of
adipocyte
s
BW
of
rodents
Adipose
tissue
mass
in
rodents
Effect
In
Clinical
studies
EGCG M NE ↓ ↓ ↑ NE ↓ ↓ M
Genistein ↓ NE ↓ ↓ ↑ ↑ HD HD NE
Resveratrol ↓ ↓ ↓ ↑ ↑ HD HD
Xanthohum
ol NE ↓ ↓ ↑ ↑ NE ↓
Quercetin ↓ ↓ M ↑ ↑
Rutin ↓ ↓ ↓ ↓
Curcumin ↓ NE ↑ ↓ ↓
Capsaicin ↓ ↓ ↑ M M Small
o- coumaric
acid ↓ ↓ ↓ ↓
Berberine NE ↓ ↓ ↓ ↓
Evodiamine ↓ ↓ M ↓ ↓
Retinol ↓ ↓ ↑ M ↓
Negative
correlatio
n with
BMI
1.25(OH)2D
3 ↓ ↓ ↓ ↑ ↑
Associatio
n with
adiposity
Guggulstero
ne NE NE ↓ ↓ ↑ ↑
Ajoene ↓ ↓ ↓ ↑
Esculetin ↓ NE ↓ ↑
Withaferin
A ↓ ↓ ↓ ↓ ↑
NE- No Effect, HD- High Dose, M- Mixed Effects, BW- Body Weight
REVIEW ARTICLE H.D.Ramachandran et.al / IJIPSR / 2 (7), 2014, 1606-1624
Department of Biochemistry ISSN (online) 2347-2154
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OVERVIEW
Table 2: Modified from “Quercetin: A Versatile Flavonoid” [68]
Groups Compounds Rich sources
Flavonols
Quercetin
Isorhamnetin
Kaempferol
Myricetin
Yellow onion, leek, cherry tomato, broccoli, apple,
green and black tea, black grapes, blueberry.
Flavones
Luteolin
Apigenin
Baicalein
Parsley, celery, capsicum, pepper.
Flavanols
(±)- Catechin
(-)- epigallo
catechin gallate
Chocolate, beans, apricot, cherry, grapes, peach, red
wine, cider, green tea, black tea, black berry.
Flavanones Bavachin Psoralea corylifolia (Babchi plant)
Isoflavones Genistein Soy cheese, soy flour, soy bean
Anthocyanins Cyanidin Black berry, black grapes, cherry, plum, strawberry,
red wine, red cabbage.
Chalcones Curcumin Turmeric
Stilbenoids Resveratrol Red grapes, blue berries.
Hydroxycinnamic
acids
Caffeic acid
Chlorogenic acid,
ferulic acid,
p-coumaric acid
Blue berries, kiwis, plums, cherries, apples.
Hydroxybenzoic acids Gallic acid, gentisic acid. Black radish, onion, tea
Carotenoids Carotene
Xanthophyll
Carrot.
Green plants.
Organosulphurs Ajoene Garlic
Table 3: Mechanism of action of some phytochemicals [69,70,71]
Name of phytochemical Mechanism of action
Quercetin Inhibiting NO production and iNOS protein expression.
Inhibits both cyclooxygenase and lipoxygenase activities.
Isorhamnetin Anti oxidant activity, shows anti adipogenic activity mediated by the
stabilization of β- catenin.
Kaempferol Induces apoptosis, induced apoptosis in glioma cells by elevating
intracellular oxidative stress.
Myricetin Inhibits NO production.
Luteolin
Inhibiting the upregulation of THP-1 adhesion and VCAM-1
expression.
Inhibiting the activity of NF-κB.
Apigenin
Blocking the expression of intercellular adhesion molecule-1(ICAM
1), VCAM 1and E- selectin.
Inhibiting prostaglandin synthesis and IL- 6,8 production.
Baicalein Modulation of angiogenic processes.
(±)-Catechin Shows anti oxidative, anti mutagenic, anti carcinogenic and free radical
scavenging effects
(-)-Epigallo
catechin gallate
Inhibits the expression of iNOS
Reducing the activity of NF-κB and AP -1
Bavachin Induction of NO production which stimulates angiogenesis.
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Genistein
Inhibits the activity of ATP utilizing enzymes. Induces apoptosis,
exerts antioxidant effects, inhibits angiogenesis, suppress osteoclast
and lymphocyte functions.
Anthocyanins &
Hydroxycinnamic acids
Localizes into endothelial cells.
Reduces upregulation of IL-8, MCP -1 and ICAM-1.
Curcumin
Decreasing MPO activity and TNF-α on chronic colitis.
Reducing nitrites levels and the activation of p38 MAPK.
Downregulating COX-2 and iNOS expression.
Resveratrol
Inhibiting stimulation of caspase-3 and cleavage of PARP induced IL-
1β.
Suppressing the expression of iNOS mRNA and protein by inhibiting
the activation of NF-κB inhibiting NO generation.
Upregulating MAP kinase phosphatase -5.
Carotenoids Act as anti oxidants by reducing the toxic effects of reactive oxygen
species.
Organosulfurs
Modulates the activity of several metabolizing enzymes that activate
(cytochrome P450s) or detoxify (glutathione S-transferases)
carcinogens and inhibit the formation of DNA adducts in several target
tissues.
CONCLUSION AND FUTURE PROSPECTS
Obesity, a global health problem, is associated with increase in the size and mass of the adipose
tissue. Adipose tissue growth involves formation of new adipocytes from precursor cells, further
leading to an increase in adipocyte size. Thus, adipose mass can be decreased by removing
adipocytes, inturn aiding the reduction and control of obesity. Inhibiting adipogenesis at various
stages of adipocyte life cycle, inducing apoptosis and lipolysis are the processes that can be
employed to decrease the adipose mass. Although two main drugs - orlistat and sibutramine are
being currently used for the treatment, both have shown deleterious side effects. Hence, the
spotlight shifts to natural products or phytochemicals. Therefore, screening of indigenous plants
for the various phytochemicals found in them, which specifically target adipogenesis and
adipocyte apoptosis pathways possess better potential for treatment and prevention of obesity.
These phytochemicals can be explored for safer and more effective pharmacological treatment of
obesity, either individually or in combination. Thus, identification, isolation and characterization
of the effective phytochemical components, the target site of these phytochemicals in adipocyte
life cycle individually and in combination and dosage determination in regulating leptin levels
promise great scope in this direction and have to be undertaken.
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