Antidiabetic and Cardioprotective Effects of Amla (Emblica Officinalis Gaertn) and its Phytochemicals: Preclinical Observations

45CHAPTER

Antidiabetic and Cardioprotective
Effects of Amla (Emblica officinalis
Gaertn) and its Phytochemicals:
Preclinical Observations

M.S. Baliga*, A.N. Prabhu*, D.A. Prabhu†, A.R. Shivashankara*, A. Abraham‡,

P.L. Palatty*

ÃFather Muller Medical College, Mangalore, Karnataka, India
†Manipal University, Manipal, Karnataka, India
‡Clemson University, Clemson, SC, USA

ABBREVIATIONS # 2013 Elsevier Inc.

AGE Advanced glycation end products All rights reserved. 583
ALT Alanaine aminotransferase
AST Aspartate aminotransferase
BAX bcl2 associated X protein
bcl2 B cell lymphoma 2
CAT Catalase
CHOL Cholesterol
CHY Chylomicrons
CHY-r Chylomicron remnants
COX-2 Cyclooxygenase-2
CVB-3 Coxsackie virus B3
ECV-304 Endothelial cell lines
FFA Free fatty acid
GR Glutathione reductase
GSH Glutathione
GPx Glutathione peroxidase
HbA1c Glycated hemoglobin
HDL-C High density lipoprotein-cholesterol
IL Interleukin
LCAT Lecithin cholesterol acyl transferase
LDL-C Low density lipoprotein-cholesterol
MVA Mevalonic acid
NF-kB Nuclear factor kappaB
Ox-LDL Oxidized LDL
PL Phospholipid
PPAR Peroxisome proliferator-activated receptor

Bioactive Food as Dietary Interventions for Diabetes
http://dx.doi.org/10.1016/B978-0-12-397153-1.00039-1

584 M.S. Baliga et al.
SOD Superoxide dismutase
TBARS Thiobarbituric acid-reactive substances
TC Total cholesterol
TG Triglycerides
TGFb1 Transforming growth factor-beta
TNF Tumor necrosis factor
VLDL Very low density lipoprotein
VSMC Vascular smooth muscle cells

1. INTRODUCTION
Phyllanthus emblica (syn. Emblica officinalis) colloquially known as the Indian gooseberry
(English), amalaka (Sanskrit), and amla (Hindi) is an important deciduous tree. This plant
belongs to the Euphorbiaceae family and was originally native to India but is today found
growing in Pakistan, Uzbekistan, Srilanka, Southeast Asia China, and Malaysia
(Krishnaveni and Mirunalini, 2010). The tree is small to medium in size and grows up to
5.5 m. The barks are greenish-gray in color and peel off in scales. The fruits are the most
commonly used plant part and are of both dietary and medicinal use (Figure 45.1). The
raw fruits are green while; the ripe fruits are yellowish-green in color. The fruits are globular
in shape, fleshy and smooth striated with an obovate-obtusely triangular six-celled nut. The
seeds are centrally placed and are 4–5 mm long and 2–3 mm wide. The fruits are of culinary
use and are widely used to make murabbah, juice, pickle, chutneys, and as a vegetable in
various dishes (Krishnaveni and Mirunalini, 2010).

Figure 45.1 Photograph of amla.

Antidiabetic and Cardioprotective Effects of Amla (Emblica officinalis Gaertn) and its Phytochemicals 585

2. PHYTOCHEMICALS

Phytochemical studies have shown that amla contains tannins, alkaloids, and phenolic
compounds. It is a rich source of vitamin C and the levels are more than that in the or-
anges, tangerins or lemon. Amla also contains gallic acid, ellagic acid, chebulinic acid,
chebulagic acid, emblicanin-A, emblicanin-B, punigluconin, pedunculagin, citric acid,
ellagotannin, trigallayl glucose, pectin, 1-O-galloyl-beta-D-glucose, 3,6-di-O-galloyl-D-
glucose, chebulagic acid, corilagin, 1,6-di-O-galloyl beta-D-glucose, 3-ethylgallic acid
(3 ethoxy-4,5-dihydroxy benzoic acid), and isostrictinin. It also contains flavonoids like
quercetin, kaempferol 3 O-alpha L (600 methyl) rhamnopyranoside, and kaempferol 3
O-alpha L (600 ethyl) rhamnopyranoside (Krishnaveni and Mirunalini, 2010). Some of
the phytochemical structures are depicted in Figure 45.2.

3. TRADITIONAL USES

Amla is a very important medicinal plant and has been widely used by Ayurvedic prac-
titioners for more than 3000 years. In Ayurveda, amla is regarded as a very powerful

OH O
HO OH HO O

HO OH

O OH
O
HO O
Gallic acid Ellagic acid
OH

OH OH

HO O HO O

OH OH O OH
OH O Kaempferol
Continued
Quercetin

Figure 45.2 Some important phytochemicals of amla.

586 M.S. Baliga et al.

HO

HO COOCH2

HO HO R OH
HO R OH
O OOC
HO OH
CO O

O O COO
HO H

O OH
HO

O OH
O

Chebulic acid

OH
HO

HO O OH

HO O O O OH
HO O O OH
O
Figure 45.2—Cont’d OH O O O
O
O
HO HO
OH
O OH
O

Chebulinic acid

rejuvenating herb and its regular consumption is also considered to be useful in stalling
degenerative and senescence process, to promote longevity, enhance digestion, to treat
constipation, reduce fever, purify the blood, reduce cough, alleviate asthma, strengthen
the heart, benefit the eyes, stimulate hair growth, enliven the body, and to enhance
intellect. The fruit is also used for making hair oils and its regular application is supposed
to prevent graying of hair, increase the hair growth, and impart luster and gloss to the
mane (Krishnaveni and Mirunalini, 2010).

Antidiabetic and Cardioprotective Effects of Amla (Emblica officinalis Gaertn) and its Phytochemicals 587

OH OH
OH
HO OH
O
OH
O OH
HO
OH
O
HO O O

O

HO O OH

OH OH

OH Corilagin
HO

O

HO
HO O

O OO

HO OO O O

OH O O

HO OH

HO OHO OH
Pedunculagin

Figure 45.2—Cont’d

Amla is useful in the treatment of diabetes, cough, asthma, bronchitis, cephalalgia,
ophthalmopathy, dyspepsia, colic, flatulence, hyperacidity, peptic ulcer, erysipelas, skin
disease, leprosy, hematemesis, inflammations, anemia, emaciation, hepatopathy, jaun-
dice, strangury, diarrhea, dysentery, hemorrhages, leucorrhoea, menorrhagia, cardiac
disorders, and intermittent fevers. Because of all these properties, amla is an integral com-
ponent of many preparations like Amlakadi Gritha, Amlakadi Tailya, Amlakyadi churna,
Aamalaki Rasayanam, Asokarista, Avipatikar churna, Chyavananaprasa Leham, Dasamular-
ishta, Dhatri lauha, Dhatryarista, Kumaryasava, Panchatika guggulu Ghritam, Thriphala Lepam,
Thriphala Guggulu, Thriphala Ghritam, and Thriphala Churnam, that are commonly used to
treat various ailments (Krishnaveni and Mirunalini, 2010).

Amla is also of use in Siddha, Unani, Tibetan, Srilankan, and Chinese systems of med-
icine (Krishnaveni and Mirunalini, 2010). In the various folk systems of medicine, this fruit
is used as an astringent, expectorant, antiasthmatic, laxative, diuretic, spasmolytic, antacid,
antipyretic, anti-inflammatory, antidiarrheal, antidiabetic, and reduces premature graying
of hair. It is commonly used to treat a variety of ailments such as hemorrhoids, nervine

588 M.S. Baliga et al.

debility, anemia, jaundice, liver complaints, menorrhagia, leucorrhea, hematuria, osteo-
porosis, weak vision, and inflammation of the eyes (Krishnaveni and Mirunalini, 2010).

4. SCIENTIFICALLY VALIDATED STUDIES

Preclinical studies have shown that amla possesses antibacterial, antifungal, antiviral,
antidiabetic, hypolipidemic, antiulcerogenic, free radical scavenging, antioxidant, anti-
mutagenic, anti-inflammatory, immunomodulatory, antipyretic, analgesic, antitussive,
antiatherogenic, adaptogenic, snake venom neutralizing, gastroprotective, antianemic,
antihypercholesterolemic, wound healing, antidiarrheal, antiatherosclerotic, nephropro-
tective, and neuroprotective properties (Krishnaveni and Mirunalini, 2010). In Ayurveda
amla has been used either alone or in combination with other plants to treat diabetes and
cardiac ailments. In the following sections the antidiabetic and cardioprotective effects of
amla and some of its phytochemicals are addressed with emphasis on the mechanism
of action.

5. AMLA AS AN ANTIDIABETIC AND CARDIOPROTECTIVE AGENT

Globally, diabetes mellitus, hypertension, and hyperlipidemia are some of the leading
causes of mortality and morbidity and are gaining epidemic proportions both in devel-
oped and developing countries. Although medicines are available for these metabolic
diseases they do not offer complete cure and are associated with side effects. Hence, there
is a search for herbal medicines that are efficacious and are of dietary origin (Tilak-Jain
and Devasagayam, 2006). Studies by Mastan et al. (2009) have shown that the aqueous
extract of amla exhibited a cardiotonic activity and its possible mechanism of action
is through calcium channels. Preclinical studies have shown that amla and some of its
phytochemicals like gallic acid, ellagic acid, quercetin, and corillagin possess beneficial
effects (Krishnaveni and Mirunalini, 2010). Here an attempt is made to analyze the role
of amla and some of its phytochemicals as antidiabetic and cardioprotective agents.

6. AMLA POSSESSES HYPOGLYCEMIC EFFECTS AND AMELIORATES
THE DIABETIC COMPLICATIONS

Diabetes, the world’s leading endocrine disease, is caused by inherited and/or acquired
deficiency or inadequate secretion of hormone insulin (type I or insulin-dependent
diabetes mellitus) or due to an inadequate response of target cells to insulin (type II
or noninsulin-dependent diabetes mellitus), or by a combination of these factors that
ultimately culminates in hyperglycemia. The currently available medications are useful in
controlling hyperglycemia, but are ineffective in stalling the complications affecting the
heart, kidney, retina, peripheral nerves, and skin. Therefore, search still continues for an
agent that is both effective in preventing the hyperglycemia and the secondary complications.

Antidiabetic and Cardioprotective Effects of Amla (Emblica officinalis Gaertn) and its Phytochemicals 589

With regard to amla, multiple studies have shown it to be effective in ameliorating the
allaxon, streptozotocin, and high-fat diet-fed/low dose streptozotocin-induced diabetes
in rats (Pitchai et al., 2009; Punithavathi et al., 2011; Rao et al., 2005; Sabu and Kuttan,
2002). Sabu and Kuttan (2002) observed for the first time that the oral administration
of the methanolic extract of amla (100 mg kgÀ1 body weight) reduced the blood
sugar level in both normal and alloxan-induced diabetic rats when evaluated at 4 h
post-administration. Continued, daily administration of the extract was observed to be
better than single administration in causing antihyperglycemic effects indicating that
the prolonged administration was more beneficial (Sabu and Kuttan, 2002). Preclinical
studies have also shown that oral administration of aqueous extract of amla (350 mg kgÀ1)
over a period of 84 days reduced the serum glucose, glycosylated hemoglobin (HbA1c),
and the activity of gluconeogenic enzyme glucose-6-phosphatase, but increased serum
insulin, liver and skeletal muscle glycogen and the activity of glycolytic enzyme gluco-
kinase in alloxan-induced type I diabetic rats (Pitchai et al., 2009).

Recently, Krishnaveni et al. (2010) have also observed that amla possesses antidiabetic
effects in the streptozotocin-induced diabetic rats. The authors observed that administra-
tion of the ethanolic extract of amla (200 mg kgÀ1 body weight) for 45 consecutive days
was effective as antihyperglycemic and antihyperlipidemic agent. When compared to the
diabetic controls treated with the placebo, administering the amla extract caused a
significant reduction in the total cholesterol (TC), very low density lipoprotein
(VLDL)-C, low density lipoprotein-cholesterol (LDL-C), FFA, PL, TG, and increased
the levels of high density lipoprotein-cholesterol. Together these observations clearly
indicate that the usefulness of amla as an antihyperglycemic and an antihyperlipidemic
agent and also to reduce the diabetes-induced atherogenesis and possible cardiac
problems commonly seen in diabetics (Krishnaveni et al., 2010). Amla is effective in
ameliorating diabetes-induced (streptozotocin-induced) oxidative stress in rats. Oral
administration of the standardized extract (20 or 40 mg kgÀ1 of body weight per day)
or a polyphenol-rich fraction of ethyl acetate extract (10 or 20 mg kgÀ1 of body weight
per day) for 20 consecutive days was observed to be extremely effective in reducing
hyperglycemia and induced body weight gain in the diabetic rats (Rao et al., 2005).
Amla extracts showed strong free radical scavenging activity and significantly allevi-
ated various oxidative stress indices in the serum of the diabetic rats. Amla was also
effective in inhibiting/reducing the production of advanced glycosylated end products
and thiobarbituric acid-reactive substances (TBARS). Amla also decreased the
serum creatinine levels and increased the serum albumin and adiponectin levels (Rao
et al., 2005).

With regard to phytochemicals, studies have shown that feeding ellagic acid contain-
ing diet (5%) for 12 consecutive weeks to diabetic mice decreased the diabetes-induced
weight loss, increase plasma insulin and decrease the blood glucose levels and HbA1c at
weeks 6 and 12 (Chao et al., 2010). Additionally, oral administration of gallic acid (10 and
20 mg kgÀ1) daily for a period of 21 days to the streptozotocin-induced diabetic rats is

590 M.S. Baliga et al.

also shown to impart antihyperglycemic, antilipid peroxidative, and antioxidant effects in
a concentration dependent manner (Punithavathi et al., 2011). Mechanistic studies have
shown that when compared to the diabetic controls, administering gallic acid decreased
the blood glucose, glycosylated hemoglobin, total hemoglobin, and plasma insulin. It also
increased the body weight, increased the activity of hepatic hexokinase, and concomi-
tantly decreased the levels of glucose-6-phosphatase and fructose-1, 6-bisphosphatase
(Punithavathi et al., 2011).

Studies with the pancreatic tissues have shown that gallic acid decreased the levels of
TBARS and lipid hydroperoxides and increased the activities of superoxide dismutase
(SOD), catalase (CAT), and glutathione peroxidase (GPx). The histopathological obser-
vations of the pancreas confirmed the protective effects of gallic acid in diabetic rats
(Punithavathi et al., 2011). Gallic acid is also shown to possess antiapoptotic effects against
the glucose and palmitate-induce toxicity and to stimulate insulin-secretagog actions in
RINm5F beta cells in vitro (Sameermahmood et al., 2010).

Experimental studies with allaxon-induced diabetic rats have shown that the admin-
istration of quercetin (10 and 50 mg kgÀ1), an important flavanoid found in amla reduces
hyperglycemia and blood coagulation, increases liver glycogen content, reduces high
blood serum concentrations of TC and low density lipoprotein (LDL-C) and was as
effective as chlorpropamide in its action (Nuraliev and Avezov, 1992). Studies have also
shown that quercetin was effective in the in streptozocin-induced diabetes. Intraperito-
neal injection of quercetin was effective in decreasing the plasma glucose level and in-
creases the activity of hepatic glucokinase in the diabetic rats (Vessal et al., 2003).
Histopathological observations showed that quercetin preserves the islet cells (Coskun
et al., 2005) and helps in the regeneration of the pancreatic islets (Adewole et al.,
2006; Vessal et al., 2003) as observed from the immunohistochemical studies, where a
clear increase in the levels of insulin was observed (Coskun et al., 2005).

Preclinical studies have shown that the flavonoid-rich fruit extract (ethyl acetate:
methanol fraction) of amla was effective in ameliorating the type II (high-fat diet-fed/
low dose streptozotocin)-induced neuropathy in rats. When compared to the diabetic
animals, administering the amla extract and the phytochemical quercetin decreased
the hyperalgesia (nociception), increased tail flick latency in hot immersion test, pain
threshold level in hot plate test, and attenuated diabetic induced axonal degeneration.
Both amla and quercetin decreased the lipid peroxidation status and increased the activ-
ities of the antioxidant enzymes, SOD, and CAT (Kumar et al., 2009). Gallic acid, the
principal constituent of amla is also shown to impart neuroprotective effects in diabetic
rats and to mediate these effects by reducing the lipid peroxidation and enhancing the
activities antioxidants (Mainzen Prince et al., 2010).

Chronic hyperglycemia causes renotoxicity and studies with diabetic rats/mice have
shown that intraperitoneal administration of gallotannin (20 mg kgÀ1 dayÀ1, i.p.) for
four consecutive weeks decreased the levels of plasma creatinine and to reduce apoptosis

Antidiabetic and Cardioprotective Effects of Amla (Emblica officinalis Gaertn) and its Phytochemicals 591

by inhibiting poly-(ADP ribose) glycohydrolase cleavage (Chandak et al., 2009). Addi-
tionally, the polyphenol ellagic acid is reported to impart renoprotective effects and to
decrease the urine output, urinary glycated albumin, renal carboxymethyllysine, pento-
sidine, sorbitol, and fructose. It also decreased the activity of aldose reductase and sorbitol
dehydrogenase, and suppressed the mRNA expression of aldose reductase in the kidneys.
Ellagic acid caused a concentration dependent decrease in the levels of interleukin (IL)-6,
IL-1b, tumor necrosis factor (TNF)-a, and monocyte chemoattractant protein 1; and to
down-regulate the TNF-a and monocyte chemoattractant protein-1 mRNA expression
in the kidneys (Chao et al., 2010).

Studies have also shown that amla extract and the tannoid enriched fraction are potent
inhibitors of aldose reductase (Suryanarayana et al., 2004), prevented hyperglycemia-
induced aggregation and insolubilization of lens proteins and to delay the cataract pro-
gression in streptozotocin-induced diabetic rats (Suryanarayana et al., 2007). Ellagic acid,
an important constituent of amla is also reported to be an inhibitor of aldose reductase and
to inhibit the accumulation of sorbitol in erythrocytes, lens, and sciatic nerve (Ueda et al.,
2004). Quercetin is also reported to ameliorate diabetes-induced secondary complica-
tions like renal dysfunction and oxidative stress (Anjaneyulu and Chopra, 2004), alleviate
activities of intestinal and renal disaccharidases (Ramachandra et al., 2005), ameliorate
galactose-induced hyperglycemic oxidative stress in hepatic and neuronal tissues
(Ramana et al., 2006), decrease diabetes-induced memory dysfunction (Bhutada et al.,
2010), increase the sperm viability, motility, and serum total testosterone, thereby help-
ing in maintaining healthy sperm parameters and male reproductive function (Khaki
et al., 2010), and to improve vascular responsiveness in blood vessels by enhancing
the bioavailability of endothelial nitric oxide (Ajay et al., 2006). Together all these ob-
servations clearly indicate that amla was effective in reducing the diabetes-induced ox-
idative stress, improving glucose metabolism and ameliorating/decreasing the secondary
complications (Figure 45.3).

7. AMLA POSSESSES ANTIHYPERLIPIDEMIC EFFECTS

Dyslipidemia characterized by increased levels of TG, TC, and LDL, and decreased level
of high density lipoprotein (HDL), is the major risk factor for atherosclerosis. In diabetic
patients, due to the major abnormalities existing in the fatty acid metabolism and asso-
ciated lipoprotein, cardiovascular disease is a primary complication and a major cause
of death (Mathur et al., 1996). Seminal studies by Thakur and Mandal (1984) and Thakur
et al. (1988) have shown that feeding amla was effective in decreasing cholesterol-
induced hypercholesteolaemia and atherosclerosis in rabbits. When compared to
cholesterol alone fed cohorts, the coadministering of amla is shown to reduce the cho-
lesterolaemia, aortic sudanophilia and to decrease the levels of TC in the liver and aorta
(Thakur et al., 1988). Similar findings were also observed when fresh juice of amla was

592 M.S. Baliga et al.

Kidney Diabetic nephropathy
Neuron Oxidative stress, apoptosis
Heart Inflammation
Oxidative stress
Neuropathy

Atherogenesis

Liver Insulin sensitivity
Blood vessel Lipid peroxidation
Gluconeogenesis
Glycolysis, glycogenesis

Atherogenesis

Blood Blood glucose, HbA1C
Insulin, HDL
TG, cholesterol, LDL

Amla Testis Sperm viability
Sperm motility

Testosterone levels

Eyes Cataractogenesis
Age formation
Aldol reductase

Pancreas Apoptosis
Preserve β-cellls
Regenerate β-cellls
Insulin secretion

Muscle Glycolysis
Glycogenesis

Figure 45.3 Antidiabetic and beneficial effects of amla and its constituents (arrows up ¼ increase;
arrows down ¼ decrease).

administered to rabbits feeding on atherogenic diet and cholesterol feeding. Oral feeding
of fresh amla juice (5 ml kgÀ1 body weight per rabbit per day for 60 days) reduced the
serum TC, TG, phospholipid (PL), LDL levels, and also in the levels of tissue lipid.
Histopathological studies showed regression in the aortic plaques. Amla juice-treated
rabbits were observed to excrete more cholesterol and PLs, suggesting that amla affected
the absorption of cholesterol and mediate its hypolipidemic effects at least in part through
this mechanism (Mathur et al., 1996).

Antidiabetic and Cardioprotective Effects of Amla (Emblica officinalis Gaertn) and its Phytochemicals 593

Studies have also shown that amla was effective in ameliorating the butter fat
and beef diet-induced hyperlipidemia in rats, thereby clearly indicating that the
antihyperlipidemic effects of amla extended to other models of hyperlipidemia. Butter
fat and beef diet are standard models of hyperlipidemia and atherogenesis, and the
process of pathogenesis resembles that of humans. Coadministering amla (5%) incor-
porated diet caused hypolipidemic effects and decreased the serum levels of TG, TC,
VLDL, LDL cholesterol, the enzymes aspartate aminotransferase (AST) and alanine
aminotransferase (ALT) and concomitantly increased the levels of HDL. Studies also
showed that amla was effective in decreasing the levels of TG, TC, and lipid peroxides
in the liver, kidneys, and heart and decreasing the levels of AST and alkaline
phosphatase in liver and heart, and HMGCoA reductase in the liver and kidneys
(Augusti et al., 2001).

Amla is also shown to be effective in another model of hyperlipidemia and metabolic
syndrome (fructose-induced) in rats. Administration of ethyl acetate extract of amla that is
rich in polyphenol-rich fraction (10 or 20 mg kgÀ1 body weight per day for 2 weeks) to
rats feeding on high-fructose (65%) diet decreased the hypertriacylglycerolemia, hyper-
cholesterolemia and the levels of TG and TC in the liver in a concentration dependent
manner. Further, amla (20 mg kgÀ1) was effective in decreasing the increased levels of
serum and hepatic mitochondrial TBARS, and inhibited the increase of cyclooxygen-
ase-2 (COX-2) and the levels of Nuclear Factor kappaB (NF-kb). Additionally the
bcl-2 proteins were increased while bax was concomitantly decreased indicating
protective effects against apoptosis (Kim et al., 2010).

Administering amla (20 or 40 mg kgÀ1 body weight per day) or ethylacetate extract of
amla (10 or 20 mg kgÀ1 body weight per day) for 20 days to rats feeding on 1% choles-
terol diet significantly caused a dose-dependent decrease in the levels of TC, free and
LDL-cholesterol with better effects being observed with the ethylacetate extract (Kim
et al., 2005). Additionally studies have also shown that administering the polyphenol-rich
ethyl acetate extract of amla at 40 or 10 mg kgÀ1 body weight per day for 100 days to
young rats (2 months) and aged rats (10 months) is also reported to be effective in ame-
lioarating hyperlipidemia, especially in the older rats (Yokozawa et al., 2007). When
compared to the non amla treated controls, administering amla reduced the levels of
TC and TG in serum and liver (Yokozawa et al., 2007).

Mechanistic studies showed that amla increased the hepatic levels of PPARa protein
known to regulate the transcription of genes involved in lipid and cholesterol metabolism
and was also effective in inhibiting the serum and hepatic mitochondrial TBARS levels in
aged rats. The level of bax was decreased and a concomitant increase in the bcl-2 levels
were observed in the amla treated rats. Additionally, amla decreased the expressions of he-
patic NF-kB, inducible NO synthase, and COX-2 protein levels in aged rats, clearly in-
dicating its efficacy in preventing age-related hyperlipidemia through attenuation of
oxidative stress in the aging process (Yokozawa et al., 2007).

594 M.S. Baliga et al.

With regard to phytochemicals, studies have shown that the flavonoids from amla possess
hypolipidemic and hypoglycemic activities (Anila and Vijayalakshmi, 2000), increase the he-
moglobin levels (Anila and Vijayalakshmi, 2000) and to be effective in reducing the lipid levels
in serum and tissues of hyperlipidemic rats (Anila and Vijayalakshmi, 2002). The flavonoids of
Amla were effective in reducing the activity of hepatic HMG CoA reductase, an enzyme im-
portant in cholesterol biosynthesis and increased the levels of lecithin cholesterol acyl trans-
ferase (LCAT) which is known to promote esterification of cholesterol in HDL and thus
promoting uptake and catabolism of cholesterol in liver (Anila and Vijayalakshmi, 2002).

Preclinical studies by Duan et al. (2005) have shown that corilagin, an important con-
stituent of amla was effective as an antiatherosclerosis agent and to inhibit the progress of
atherosclerosis by decreasing the oxidation injury or by inhibiting oxidized LDL
(ox-LDL)-induced vascular smooth muscular cell proliferation. The authors observed
that incubation of the rat vascular smooth muscular cells with or without ox-LDL
(50 mg lÀ1) and with corilagin decreased the malondialdehyde levels and prevented endothe-
lial cell lines (ECV-304) from being adhering to by monocytes, and also inhibited the prolif-
eration of vascular smooth muscle cells (VSMC) activated by ox-LDL (Duan et al., 2005).

Studies have also shown that quercetin was effective in reducing the plasma CHOL
and TG in diabetic animals (Vessal et al., 2003). Quercetin also decreased the serum TG
and cholesterol levels elevated by high-fat diet and reduced the formation of atheroscle-
rotic plaques, both in the aorta as well as within injured carotid artery in the high-fat diet-
fed animals. Feeding quercetin reduced the intima and also atherosclerotic plaques in
high-fat diet-fed rabbits indicating its antiatherogenic properties (Juzwiak et al., 2005).
Together, all these observations clearly indicate the usefulness of amla in reducing both
experimental and age-related hyperlipidemia (Figure 45.4) in rats and suggest its useful-
ness in preventing and treating metabolic syndrome.

8. AMLA IS EFFECTIVE IN PREVENTING DOXORUBICIN-INDUCED
CARDIOTOXICITY

The anthracycline antibiotic adriamycin (doxorubicin), a topoisomerase II inhibitor is one of
the most effective chemotherapeutic agents against ovarian, breast, lung, uterine and cervical
cancers, Hodgkin’s disease, soft tissue and primary bone sarcomas, as well as against several
other cancer types. Unfortunately use of doxorubicin is associated with severe side effects
like myelosupression, anemia, nausea, alopecia, gastrointestinal toxicity, and cardiotoxicity.
As doxorubicin is a useful chemotherapeutic agent, several strategies have been tried to pre-
vent/attenuate their side effects with both synthetic and natural products. In vitro studies with
cultured cardiac myoblasts H9c2 cells have shown that the ethanolic extract of amla was ef-
fective in ameliorating the doxorubicin-induced cytotoxicity. Amla (100 mg mlÀ1) was ob-
served to possess cardioprotective effect and the IC50 was approximately 12-fold more than
that for doxorubicin alone (Wattanapitayakul et al., 2005).

Antidiabetic and Cardioprotective Effects of Amla (Emblica officinalis Gaertn) and its Phytochemicals 595

AcetylCoA Liver
TG
HMG CoA CHOL
MVA
FFA

Cholesterol Vascular smooth
muscle cells and

macrophages

Bile acids

Intestine CHY-r HDL LDL Ox-LDL
LCAT VLDL Blood vessel
Dietary lipids
Bile acids CHY FFA

Lipoprotein
lipase

FFA FFA Peripheral tissue

Figure 45.4 Biochemical mechanisms of antihyperlipidemic effects of amla (þ ¼ activates/increases;
⊝ ¼ inhibits/decreases). Amla inhibits cholesterol biosynthesis; TG synthesis; CHOL absorption;
decreases serum levels of CHOL, TG, LDL, VLDL; decreases oxidation of LDL and uptake of ox-LDL
by VSMC and macrophages. Amla increases serum HDL and activates LCAT.

9. PHYLLAEMBLICIN B, A CONSTITUENT OF AMLA IS EFFECTIVE
IN INHIBITING COXSACKIE VIRUS B3-INDUCED APOPTOSIS
AND MYOCARDITIS

Myocarditis often follows viral and/or bacterial infections, usually of acute onset with
chest pain, dyspnea, fever, and irregular pulse. This usually leads to diverse complications
depending on damage to muscle or conduction tissue resulting in cardiac failure, arrhyth-
mias, and syncope (Wang et al., 2009). Studies have shown that phyllaemblicin B, the
principal ellagitannin compound isolated from Phyllanthus emblica was effective in inhi-
biting the Coxsackie virus B3 (CVB3)-induced cytopathic effects on HeLa cells. Similar
observations were observed in the animal model of study. On administering phyllaem-
blicin B (12 mg kgÀ1 dayÀ1) reduced the cardiac CVB3 titers, decreased the serum levels
of LDH and creatine kinase and alleviated pathological damages to cardiac muscle in
myocarditic mice. Together both these observations clearly indicate that phyllaemblicin
B is effective and could be a novel therapeutic molecule in preventing the viral myocar-
ditis (Wang et al., 2009).

596 M.S. Baliga et al.

10. AMLA IS EFFECTIVE IN PREVENTING ISCHEMIC–REPERFUSION
INJURY

Ischemic–reperfusion injury, which refers to the cell and tissue damage, caused when
blood supply returns to the tissue after a period of ischemia causes local and remote
tissue destruction, and at times even death. Mechanistically, the reperfusion injury is me-
diated mainly by generation of oxygen free radicals from infiltrating leucocytes during
reperfusion. These oxygen free radicals may result in depression of contractile function,
arrhythmias, depletion of endogenous antioxidant enzymes, and membrane permeability
changes resulting in an increase in myocardial lipid peroxidation. In addition, activation
of phospholipases during reperfusion releases membrane fatty acids including arachidonic
acid, thereby modulating the inflammatory response leading to free radical-mediated
tissue damage. The reperfusion-associated pathologies and complications include
reperfusion-induced arrhythmia like ventricular tachycardia/fibrillation, myocardial
hemorrhage, irreversible cell damage distinct from an additional to injury due to original
ischemic event, micro vascular injury and prolonged ischemic muscle dysfunction (myo-
cardial stunning; Bhattacharya et al., 2002; Rajak et al., 2004).

Preclinical studies have shown that amla is effective in enhancing the myocardial
antioxidant system and to reduce the oxidative stress induced by ischemic–reperfusion in-
jury in rats. When compared to the placebo treated cohorts, the oral administration of the
fresh amla fruit homogenate (250, 500, and 750 mg kgÀ1) to rats daily for 30 days decreased
the basal myocardial lipid peroxidation and increased the myocardial antioxidants like
SOD, CAT, and GPx in the treated rats. Amla was also effective in preventing the
ischemic–reperfusion injury to the heart in the in vitro model of study. When compared
to the control (nonamla treated rats) the heart of rats treated with amla had reduced levels
of myocardial TBARS and halted the decrease in antioxidant GSH and the enzymes SOD,
CAT, and GPx (Rajak et al., 2004). Studies have also shown that the tannoids (emblicanin-
A and -B enriched) fraction of fresh juice of amla was also effective in reducing the
ischemia–reperfusion-induced oxidative stress in rat heart. The oral administration of tann-
poid, principles at 50 and 100 mg kgÀ1 body weight, twice daily for 14 consecutive days
before initiation of the perfusion experiments was observed to be effective in increasing the
activities of cardiac SOD, CAT and GPx and concomitantly decreased the lipid peroxida-
tion, thereby confirming the efficacy of tannoid principles in protecting against the ische-
mia–reperfusion-induced oxidative stress (Bhattacharya et al., 2002).

11. QUERCETIN AND GALLIC ACID ARE EFFECTIVE IN PREVENTING
ISOPROTERENOL-INDUCED MYOCARDIAL INFARCTION IN RATS

Globally, myocardial infarction (or acute myocardial infarction) commonly known
as heart attack is a leading cause of cardiac death and results from ischemia. It is

Antidiabetic and Cardioprotective Effects of Amla (Emblica officinalis Gaertn) and its Phytochemicals 597

the most important form of ischemic heart disease and is almost always due to for-
mation of occlusive thrombus in an atheromatous plaque in coronary arteries. At the
cellular level due to the interruption of blood supply the cardiac cells undergo death
and this affects the functional, biochemical and morphological functioning of the
heart. Anginal chest pain is the important symptom and the management includes
the uses of antianginal drugs (nitrates, morphine), antiplatelet, anticoagulants, and
beta blockers.

Preclinical studies have shown that quercetin was effective in preventing the
isoproterenol-induced myocardial infarction in rats. Administering quercetin
(10 mg kgÀ1) for 14 consecutive days was effective in reducing the mitochondrial lipid
peroxides and concomitantly increased the mitochondrial antioxidants and the
activities of isocitrate, succinate, malate, and a-ketoglutarate and NADH dehydroge-
nases and cytochrome-c-oxidase. Amla also increased the levels of calcium and
adenosine triphosphate (Punithavathi and Mainzen Prince, 2010). Quercetin lowered
the ST-segment elevation and decreased the levels of LPx, TC, TG, and FFA in serum,
heart and heart mitochondria and serum PLs in isoproterenol treated rats. Quercetin
also decreased the activity of HMG CoA reductase in plasma and liver and increased
the activity of LCAT in isoproterenol treated cardiotoxic rats (Prince and Sathya,
2010).

Studies have also shown that gallic acid (15 mg kgÀ1 daily for a period of 10 days) was
also effective in preventing the isoproterenol-induced cardiotoxicity. When compared to
the isoproteranol alone cohorts, the administration of gallic acid decreased the activities of
creatine kinase, creatine kinase-MB, aspartate transaminase, alanine transaminase and lac-
tate dehydrogenase in serum and the levels of troponin-T in the serum, reduced the levels
of lipid peroxidation and concomitantly increased the level of reduced glutathione. Gallic
acid also decreased the activities of the lysosomal enzymes the beta-glucuronidase, beta-
N-acetylglucosaminidase, beta-galactosidase, cathepsin-B and -D in both serum and
heart of isoproterenol treated rats (Priscilla and Prince, 2009; Stanely et al., 2009). Gallic
acid pretreatment increased the activities of enzymic antioxidants such as SOD, CAT,
GPx, GR, and glutathione S-transferase in the heart and the nonenzymatic antioxidants
such as glutathione, vitamin C and E in both plasma and the heart (Priscilla and Prince,
2009). Histopathological observations showed that gallic acid reduced the myocardial
damage and confirmed the cardioprotective observations seen in the various biochemical
endpoints (Priscilla and Prince, 2009).

12. CONCLUSIONS

Preclinical studies have shown that amla and some of its phytochemicals like gallic acid,
ellagic acid, quercetin and corillagin possess antidiabetic, antihyperlipidemic, and cardi-
oprotective effects. Amla improves glucose tolerance, increases glucose utilization, and

598 M.S. Baliga et al.

inhibits gluconeogenesis and prevents and/or reverses the diabetic complications. Amla
corrects dyslipidemia, inhibits TC biosynthesis and promotes uptake and catabolism of
TC in liver. Its potent antioxidant action scavenges free radicals, inhibits LDL
oxidation, atherogenesis and progression of cardiovascular diseases. However although
considerable work has been done to exploit the antidiabetic and cardioprotective effects,
countless possibilities for investigation still remain. Further in-depth mechanistic in vitro
studies, relevant animal studies and rationally designed clinical trials are required. Study
should also be aimed to assess for the possible adverse effects of amla at higher concen-
trations and when consumed over longer periods. The outcome of such studies may be
useful for the clinical applications of amla in humans and may open up a new therapeutic
avenue.

ACKNOWLEDGMENTS

The authors are grateful to Rev. Fr. Patrick Rodrigus (Director), Rev. Fr. Denis D’Sa (Administrator), and
Dr. Jaya Prakash Alva (Dean) of Father Muller Medical College for their unstinted support.

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