1

1. INTRODUCTION

1.1 DIABETES MELLITUS:

Diabetes mellitus (DM) is a chronic disease caused by inherited and/or

acquired deficiency in production of insulin by the pancreas, or by the

ineffectiveness of the insulin produced. Such a deficiency results in increased

concentrations of glucose in the blood, which in turn damage many of the body’s

systems, in particular the blood vessels and nerves. Diabetes is a chronic incurable

disorder.

Diabetes is associated with premature mortality, predominantly through

atherosclerotic vascular disease and micro vascular complications which affect the

small blood vessels in the eye, kidney and nerves, are associated with considerable

morbidity which leads to complications like diabetic retinopathy, diabetic

neuropathy, kidney failure, heart disease, stroke etc1.

As the number of people with diabetes multiplies worldwide, the disease

takes an ever-increasing proportion of national and international health care

budgets.it is projected to become one of the world’s main disables and killers

within the next 25 years. Regions with greatest potentials are Asia and Africa,

where DM rates could rise to two to three-fold than the present rates2.

In view of the side effects associated with the treatment by Insulin and

synthetic drugs which are available at present, searching for an effective and safer

anti hyperglycemic plant drugs is going on all over the world. Herbal medicines

play a vital role in this part to prevent side effects 3.

2

Our ancient Hindu physicians had mastered the managing of diabetes with

effective balance of ‘Ashuda’ (some herbs or plant food sources), as medicine ‘Ahar’

(Pathyam) in modern terms ‘therapeutic diets’ and ‘vihar’ (exercise). While

management of diabetes mellitus (DM) includes diet, exercise, oral hypoglycemic

agents and insulin treatment do not effectively prevent the complications of diabetes

like neuropathy, nephropathy and hypertension. Therefore, it has become necessary

to look for an economical as well as therapeutically effective treatment for usage in

developing and undeveloped countries.

In the traditional system of Ayurvedic treatment, medicines consist of plant

products, either single drug or in combination with others which are considered to be

less toxic and free from side effects compared to synthetic drugs. Since the time of

Charaka and Sushruta many herbal medicines have been recommended for the

treatment of diabetes mellitus4.

Diabetes is the world’s largest disease with deranged carbohydrate, fat and

protein metabolism. As per a WHO report, approximately 150 million people have

diabetes worldwide, and this number may well double by 2025. Statistical

projections suggest that the number of diabetics will rise from 15 million in the year

1995 to 57 million in 2025, making India the country with the largest number of

diabetics5.

1.1.1 Types of Diabetes

Etiologic classification of diabetic mellitus6

I. Type 1 diabetes (beta-cell destruction, usually leading to absolute insulin deficiency.

A. Immune mediated

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B. Idiopathic

II. Type 2 diabetes (may range from predominantly insulin resistance with

relative insulin deficiency to a predominantly secretory defect with insulin

resistance).

III. Gestational diabetesmellitus(GDM)

IV. Other specific types

a) Genetic defects of -cell function

b) Genetic defects in insulin action

c) Diseases of the exocrine pancreas

d) Endocrinopathies

e) Drug or Chemical-induced

f) Infections

g) Uncommon forms of immune-

i. Anti-insulin receptor antibodies

ii. Others

h) Other genetic syndromes sometimes associated with diabetes

Type I diabetes:

Type I Diabetes is an autoimmune disease that affects 0.3% population on an

average. It is due to result of destruction of beta cells due to aggressive nature of

cells present in the body. Researchers believe that some of the etiology and risk

factors which may trigger type 1 diabetes may be genetic, poor diet (malnutrition)

and environment (virus affecting pancreas). Secondly, in most of the cases, diabetes

occurs because there is abnormal secretion of some hormones in blood which act as

antagonists to insulin. Example – Adrenocortical hormone, Adrenaline hormone and

4

Thyroid hormone. 7 Type 1 DM is associated with specific human leukocyte antigen

(HLA) alleles, especially at the B and DR loci .Approximately 90% of patients

with type-1DM are positive for HLA-DR3 or -DR4, as compared with only 40%

of the general population. Compound heterozygotes appear to be at particular risk.

In contrast, the haplotype HLA-DR2 appears to be negatively associated with the

occurrence of the disease.

A polymorphism of the HLA-DQb chain at position 57 correlates even more

closely with susceptibility to diabetes. These findings implicate both humoral

and cell-mediated immune mechanisms in the etiology of type 1 DM8.

Type II Diabetes:

It is also called as NIDDM or adult onset diabetes. It occurs when the body

produces enough insulin but cannot utilize it effectively. This type of diabetes

usually occurs in middle age. A general observation says that 90-95% of people

suffering with this type of diabetes are of type 2; about 80% are overweight. It is

more common among people who are older; obese; have a family history of

diabetes; have had gestational diabetes. The situation in type 2 DM is not so clear-

cut. Most studies indicate that there is reduced cell mass in type 2 DM patients.

Obesity, duration of diabetes, and prevailing hyperglycemia potentially can confound

interpretation of data, but studies that have controlled for these variables have

reported an approximately 50% reduction in cell volume in type 2 DM patients

compared with nondiabetic control subjects. Owing to the heterogeneous nature of

type 2 DM, mean 24-hour plasma concentrations of insulin in patients have been

reported to vary from low to even normal relative to values in control subjects.

of note, standard insulin radioimmunoassay detects proinsulin and processing

5

intermediates. Studies in which specific insulin and proinsulin assays have been used

have revealed that "true" insulin values in "hyperinsulinemic" type 2 DM patients are

either no greater or distinctly less than values in control subjects. Therefore,

increased amounts of proinsulin have confounded the appreciation of subnormal

insulin levels in type 2 DM patients. Furthermore, even apparently "normal" values

of plasma insulin in a hyperglycemic type 2 DM patient are considerably reduced

relative to the insulin levels that would be observed in a similarly hyperglycemic

nondiabetic individual8.

Gestational diabetes is a form of glucose intolerance that is diagnosed in some

women during pregnancy. It is also more common among obese women and women

with a family history of diabetes. During pregnancy, gestational diabetes requires

treatment to normalize maternal blood glucose levels to avoid complications in the

infant. GDM prevalence by NDDG and Carpenter and Coustan criteria, was 5.0

and 7.4% in Asians, 3.9 and 5.6% in Hispanics, 3.0 and 4.0% in African-Americans,

and 2.4 and 3.8% in whites9.

Other specific types of diabetes do not fit into type-1, type-2, or gestational diabetes.

These results from specific genetic conditions (such as maturity-onset diabetes of

youth), surgery, drugs, malnutrition, infections, and other illnesses10.

1.1.2 Etiology of Diabetes 8, 9

Hereditary or Inherited Traits : It is strongly believed that due to some genes

which passes from one generation to another, a person can inherit diabetes. It

depends upon closeness of blood relationship as mother is diabetic, the risk is

2 to 3%, father is diabetic, the risk is more than the previous case and if both

the parents are diabetic, the child has much greater risk for diabetes.

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Age: Increased age is a factor which gives more possibility than in younger age. This

disease may occur at any age, but 80% of cases occur after 50 year, incidences

increase with the age factor.

Poor Diet (Malnutrition Related Diabetes): Improper nutrition, low protein and

fibre intake, high intake of refined products are the expected reasons for

developing diabetes.

Obesity and Fat Distribution: Being overweight means increased insulin

resistance that is if body fat is more than 30%, BMI 25+, waist grith 35 inches in

women or 40 inches in males.

Sedentary Lifestyle: People with sedentary lifestyle are more prone to diabetes,

when compared to those who exercise thrice a week, are at low risk of falling prey

to diabetes.

Stress: Either physical injury or emotional disturbance is frequently blamed as the

initial cause of the disease. Any disturbance in Corticosteroid or ACTH therapy

may lead to clinical signs of the disease.

Drug induced: Clozapine (Clozaril), Olanzapine (Zyprexa), Risperidone (Risperdal),

Quetiapine (Seroquel) and ziprasidone (Geodon) are known to induce this lethal

disease.

Infection: Some of the staphylococci are supposed to be a responsible factor for

infection in pancreas.

Sex: Diabetes is commonly seen in elderly especially males but, strongly in

women and those females with multiple pregnancy or suffering from (PCOS)

Polycystic Ovarian Syndrome.

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Hypertension: It had been reported in many studies that there is direct relation

between high systolic pressure and diabetes.

Serum lipids and lipoproteins: High triglyceride and cholesterol level in the blood

is related to high blood sugars, in some cases it has been studied that risk is

involved even with low HDL levels in circulating blood1, 9

.

1.1.3 Signs and Symptoms of Diabetes9, 10:

In both types of diabetes, signs and symptoms are more likely to be similar as

the blood sugar is high, either due to less or no production of insulin, or

insulin resistance. In any case, if there is inadequate glucose in the cells, it is

identifiable through certain signs and symptoms. These symptoms are quickly

relieved once the diabetes is treated and also reduces the chances of developing

serious health problems.

Type-I Diabetes:

In Type- I, the pancreas stops producing insulin due to autoimmune

response or possibly viral attack on pancreas. In absence of insulin, body cells don’t

get the required glucose for producing ATP (Adenosine Triphosphate) units which

results into primary symptom in the form of nausea and vomiting. In later stage,

which leads to ketoacidosis, the body starts breaking down the muscle tissue and fat

for producing energy hence, causing fast weight loss. Dehydration is also usually

observed due to electrolyte disturbance. In advanced stages, coma and death is

witnessed.

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Type-II Diabetes:

Increased fatigue, Polydypsia, Polyuria, Polyphagia, Weight fluctuation, Blurry

vision, Irritability, Infections, Poor wound healing

1.1.4 Chronic Complications of Diabetes8, 9

.

Diabetic retinopathy is a type of micro vascular disease in which the micro vessel,

supplying blood to the retina of our eye is affected. Retinopathy is related to high

blood sugar level and obstructs the flow of oxygen to the cells of the retina. Retina is

an ultra thin layer of blood vessel made up of rods and cones. As soon as the retina

receives signals of light, it is sent to the brain and a three dimensional figure is formed

and identified, this is sent back to the eye by which we can recognize the

things around us.

Retinal detachment is the cause behind blindness among diabetics in middle

age. The other two types of eye problems usually seen earlier in the people suffering

from diabetes are:

Cataract: A thin cloudy layer appears in front of your eye leading to unclear vision.

In cataract surgery this thin layer is removed and setting of a plastic layer in front of

the lens is done, thus gives you a clear vision again.

Glaucoma: Due to high pressure on the optic nerve, it gets damaged. The damaged

optic nerve creates disturbance in clear vision. Laser surgery or simple eye drops may

help in regaining the normal vision10.

A diabetic must go for the regular eye checkups so that the early stages of

diabetic retinopathy can be detected and treated in initial stages itself, with less harm

to the eyes. Blood sugar levels should also be monitored and maintained to prevent

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blood vessel damage. Nerves depend on multiple tiny vessels which carry

nutrients and oxygen to keep intact all the segments of these very long nerves.

Damage to one small segment can result in loss of feeling, pain or burning

sensations that bother the foot and leg12.

Feet: Diabetes can decrease the blood supply to the foot and gradually damages the

nerves which carry sensation. A second micro vascular disease is diabetic foot or

diabetic peripheral neuropathy or distal symmetric neuropathy. Neuropathy is the

common complication of diabetes, and due to high blood sugar, chemical changes

occur in the nerves. It always starts in the feet as they are the longest nerves and fed

with longest blood vessels of the body. Generally it is seen in the obese people with

high blood sugar levels and age more than 40 years. Neuropathy can develop within

a span of first few years and it affects approximately 60% of diabetics.

Signs and symptoms of Diabetic Neuropathy14

Decrease or no sweating i.e. dry scaly skin with callus formation.

Numbness, tingling, and some sort of burning sensation.

Weakness and loss of reflexes.

Decreased sensation to the slight change in temperature.

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1.2 Insulin11

The failure to make insulin or insufficiency of insulin is termed as Diabetes

mellitus. Insulin is a natural hormone which controls the level of the sugar glucose in

the blood. Insulin allows cells to use glucose for energy15

. Cells cannot utilize

glucose without insulin. Excess glucose builds up in the bloodstream, increasing the

risk of diabetes.

Glucose is the body's primary source of fuel. Insulin enables the body cells to

take glucose from the bloodstream. The cells might use glucose for production of

energy if required, or it is sent to the liver to preserve it, in the form of glycogen16

.

1.2.1 Functions of Insulin -

In addition to its role of regulating glucose metabolism, insulin also -

Stimulates lipogenesis-

Diminishes lipolysis-

Increases amino acid transport into cells

Modulates transcription

Altering the cell content of numerous mRNAs

Stimulates growth

DNA synthesis

Cell replication

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1.2.2 Structure of insulin14 –

Insulin is composed of 2 peptide chains i.e. A chain and B chain. Both the

chains are linked together by two disulfide bonds, and one disulfide is formed within

the A chain. In most species, the A chain consists of 21 amino acids and the B

chain of 30 amino acids that means it is composed of 51 amino acids in two peptide

chains (A and B). The three-dimensional structure of insulin molecule (insulin

monomer) exists in two main conformations. These differ in the extent of helix in

the B chain due to phenol or its derivatives. In acid solutions, the insulin

monomer assembles as dimmers (diffuses in the blood) neutral pH and in the

presence of zinc ions, as hexamers. The intermediate and long acting insulin has high

proportion of hexamers, to delay its action. The sequence of amino acid in insulin

varies among species, certain segments are conserved, like positions of the three

disulfide bonds, both ends of the A chain and the C-terminal residues of the B chain.

These similarities in the amino acid sequence of insulin lead to a three

dimensional conformation of insulin that is very similar among species, and insulin

from one animal is very likely biologically active in other species. Indeed, pig insulin

has been widely used for human.

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Fig.No.1.1 - Structure of Insulin

1.2.3 MECHANISMS OF INSULIN RELEASE14

:

The secretion of insulin from pancreatic beta cells is a complex process

involving the integration and interaction of multiple external and internal stimuli.

Thus, nutrients, hormones, neurotransmitters, and drugs all activate –- or inhibit --

insulin release. The primary stimulus for insulin secretion is the beta-cell response to

changes in ambient glucose. Normally, glucose induces a biphasic pattern of insulin

release. First-phase insulin release occurs within the first few minutes after

exposure to an elevated glucose level; this is followed by a more enduring second

phase of insulin release. Of particular importance is the observation that first-phase

insulin secretion is lost in patients with type 2 diabetes. Thus, molecular mechanisms

involved in phasic insulin secretion are important.

A widely accepted sequence of events involved in glucose-induced insulin secretion is

as follows:

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1. Glucose is transported into beta cells through facilitated diffusion of GLUT2

glucose transporters.

2. Intracellular glucose is metabolized to ATP.

3. Elevation in the ATP/ADP ratio induces closure of cell-surface ATP-sensitive K+

(KATP) channels, leading to cell membrane depolarization.

4. Cell-surface voltage-dependent Ca2+ channels (VDCC) are opened, facilitating

extra cellular Ca2+ influx into the beta cell.

5. A rise in free cytosolic Ca2+

triggers the exocytosis of insulin.

A widely accepted sequence of events involved in glucose-induced insulin

secretion is as follows:

1. Glucose is transported into beta cells through facilitated diffusion of GLUT2

glucose transporters.

2. Intracellular glucose is metabolized to ATP.

3. Elevation in the ATP/ADP ratio induces closure of cell-surface ATP-sensitive K+

(KATP) channels, leading to cell membrane depolarization.

4. Cell-surface voltage-dependent Ca2+ channels (VDCC) are opened, facilitating

extra cellular Ca2+ influx into the beta cell.

5. A rise in free cytosolic Ca2+

triggers the exocytosis of insulin.

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Fig No -1.2 - Mechanisms of insulin release

Insulin receptor substrates and glucose transporters:

Insulin receptor substrate (IRS) proteins are key mediators in insulin

signaling from the insulin receptor. It takes place through receptor-mediated tyrosine

phosphorylation of IRS proteins. IRS-1, IRS-2, GLUT 1, GLUT 2, GLUT 3, and

SIRP1α were strongly expressed in the Sertoli cells (except GLUT 1), early

spermatocytes, peritubular myoid cells, macrophage-like interstitial cells, and

testicular endothelial cells in all the testes investigated by immunohistochemistry15.

Insulin stimulation of glucose transport in muscle and adipose cells is

essential for maintenance of glucose homeostasis. This is mediated by sodium-

independent, facilitated-diffusion glucose transporters (GLUTs). In tissues with

insulin-sensitive glucose transport (i.e. skeletal and cardiac muscle and adipose

cells), GLUT4 is the predominant glucose transporter and GLUT1 plays a minor

role. The large stimulatory effect of insulin in these tissues results from the

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translocation of GLUT4-containing vesicles from intracellular storage sites to the

plasma membrane where they dock and fuse with the membrane, markedly

augmenting glucose transport into the cell16. In human muscle training induces a

local contraction-dependent increase in GLUT 4 protein, which enhances the effect of

insulin on glucose uptake17.

Insulin receptor (IR) and GLUT2 form a receptor-transporter complex in

hepatocytes, which forms a mechanism of insulin-mediated hepatic glucose

regulation18.

Fig No- 1.3- Regulation of glucose on glucose uptake by GLUT2 receptor19:

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Fig No-1.4- Regulation of glucose on glucose uptake by GLUT4 receptor20

:

1.3 Therapy for Diabetes mellitus:

1.3.1 Drugs that Promote the Body’s Production of Insulin (Insulin

Secretagogues )

SULFONYLUREA’S9, 11:

Ex: Tolbutamide, Glipizide, Glyburide, Glimeperide, Glibenclamide.

BENZOIC ACID DERIVATIVES 11, 12

Ex: Repaglinide

1.3.2 Drugs that Reduce Glucose Production by the Liver-9, 11

BIGUANIDES:

Ex: Metformin

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1.3.3 Drugs that Help the Body Respond to Insulin

(Insulin Sensitizers) – THIAZOLIDINEDIONES9, 11, 12

:

Ex: Troglitazone, Rosiglitazone, Pioglitazone.

1.3.4 Drugs that Reduce Postprandial Glucose Concentrations9, 11

:

GLUCOSIDASE INHIBITORS

Ex: Acarbose, Miglitol

DPP-4 INHIBITORS 9 (Dipeptidyl peptidase-4)

Advantages of DPP IV inhibitors 9

Oral Therapy

Maintain Euglycemia

Stimulates glucose dependent insulin secretion

Increase insulin mRNA stability

Prevent β cell loss & improves β cell function & β cell mass

Inhibits glucagon secretion

Delays gastric emptying

Inhibits apoptosis of islets

Beneficial cardiovascular effects

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Table: 1.1 Activity, advantages and disadvantages of oral hypoglycemic agents

Repaglinide

Increases endogenous

insulin secretion in the

presence of glucose; well

tolerated; can be used by

patients with renal

impairment

Similar incidence of

hypoglycaemia and similar

efficacy to sulphonylureas;

drug interactions with

enzyme inhibitors or

inducers; relatively

expensive; bodyweight gain

Acarbose,

Miglitol

Inhibit carbohydrate

absorption from the

gastrointestinal tract; serious

adverse effects are rare;

hypoglycaemia is not a risk;

no effects on body weight

Gastrointestinal adverse

effects; hepatic toxicity

(acarbose); less effective

than sulphonylureas or

metformin; contraindicated in

patients with

inflammatory bowel disease

or renal or hepatic

impairment.

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1.4 SCREENING METHODS FOR ANTI-DIABETIC ACTIVITY24

:

I. Most commonly used Animal models to test drugs with potential

antidiabetic activity-

1. In vivo animal models of diabetes mellitus -

1) Pharmacological induction of diabetes.

2) Surgical models of diabetes.

3) Genetic models of diabetes.

a. Animal strains that spontaneously develop diabetes.

b. Genetically engineered diabetic mice.

4) Other models to evaluate the reduction of pancreatic β-cell mass.

2. In vitro studies -

1) In vitro studies on insulin secretion.

a. Studies using isolated pancreatic islet cell lines.

b. Studies using insulin-secreting cell lines.

2) In vitro studies on glucose uptake.

3) In vitro Insulin sensitizing activity-

3. Models of diabetes accelerated atherosclerosis-

II. Animal models most commonly used as prototype of type-2 diabetes-

1. Spontaneous or transgenic animal models of reduced β-cell mass.

1) Transgenic mice deficient in factors involved in pancreas development.

2) Transgenic mice deficient in factors involved in β-cell growth and/or

survival.

3) Animal models with increased β-cell apoptosis due to endoplasmic

reticulum (ER) stress.

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4) Animal models with increased β-cell apoptosis due to islet amyloid

production.

5) Animal models with increased β-cell apoptosis due to gluco- and/or

lipotoxicity.

6) Spontaneous animal syndrome of non-obese type 2 diabetes with reduction

of β- cell mass.

2. Animal models of type 2 diabetes with experimentally induced reduction

of β-cell mass.

1) Models with reduction of β-cell mass induced by foetal growth retardation.

2) Models with surgically induced reduction of β-cell mass.

III. Diet-induced models for obesity and type 2 diabetes –

IV. Other models-

1) Alfa-glucosidase inhibiting activity used in the treatment of type-2

diabetes.

2) Glucagon-like peptide-1activity.

3) Antidiabetic activity through PPAR-γ expression.

1.4.1 Alloxan Induced Diabetes:

Alloxan (mesoxalylurea) produces hyperglycemia and glycosuria in most of the

experimental animals except the guinea pig. Free radicals are involved in the

production of DNA lesions by alloxan25.

Chemical structure of alloxan:

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Diabetes results from irreversible damage of insulin-producing β-cells. In

laboratory animals, diabetes can be induced with alloxan (ALX), a 2,4,5,6-

tetraoxopyrimidine. ALX is a potent generator of reactive oxygen species (ROS),

which can mediate β-cell toxicity. Glucose transporter 2 (GLUT2) and glucokinase

(GK) are target molecules for ALX25.

The diabetogenic action of alloxan is mediated by hydroxyl radicals generated

in an iron-catalysed reaction. Protection against alloxan in vivo depends both on

the chemical reactivity of protector with radicals or radical-generating systems

and on the stereospecific requirement of some strategic site in the β-cell27.

Though alloxan can produce very good diabetes in animals, it has some

drawbacks High mortality rates in rats, causes ketosis in animals due to free fatty acid

generation, Diabetes induced is reversible28.

Alloxan has been almost completely replaced by Streptozotocin for inducing

diabetes because of these drawbacks.

1.4.2 Streptozotocin Induced Diabetes:

STZ [2-deoxy-2-(3-methyl-3-nitrosourea) 1-D-glucopyranose] is a broad-spectrum

antibiotic.

Chemical structure of STZ:

22

STZ, a glucose analogue, was originally isolated from the cultures of

Streptomyces achromogenes by Herr et al. in 1960. The glucose transporter2

(GLUT2), which mediates glucose uptake into β-cells of pancreas also mediates the

cellular uptake of STZ. Reaching the pancreatic β-cells STZ causes fragmentation of

DNA through formation of free alkylating radicals leading to reduction in the cellular

levels of nucleotides and related compounds, particularly NAD+

, which causes a

rapid necrosis of β-cells25

.

Streptozotocin has almost completely replaced alloxan for inducing diabetes

because of greater selectivity towards β-cells, lower mortality rate, longer or

irreversible diabetes induction. But guinea pigs and rabbits are resistant to its

diabetogenic action28.

Two possible mechanisms underlying dexamethasone-induced insulin

resistance have been suggested. One possibility is the down regulation of insulin

receptor substrate (IRS)-1 expression by dexamethasone, because IRS-1 plays a

major role in the activation of phosphatidylinositol 3-kinase (PI3-K), which is

essential for GLUT4 translocation.

On the other hand, in the liver, dexamethasone treatment reportedly decreased

IRS-1 phosphorylation and IRS-1–associated PI3-K levels despite an increased

IRS-1 protein content. When taking these reports into consideration, impaired PI3-K

activation may be regarded as a cause of insulin resistance in both liver and muscle.

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The other possibility is that dexamethasone impairs the GLUT4 translocation

step independently of insulin signaling. This possibility may be supported by

evidence that glucocorticoids inhibit not only insulin- induced but also hypoxia

induced GLUT4 translocation to the cell surface in skeletal muscle. Thus, whether the

step in early insulin signaling in which IRS-1 is involved or whether the impairment

of GLUT4 translocation machinery is the main cause of insulin resistance or

adipose tissue remain unclear30

.

1.4.3 Dexamethasone Induced Diabetes:

Chemical structure of Dexamethasone29

:

Metformin can ameliorate dexamethasone-induced hyperglycemia and insulin

resistance in part by increasing glucose disposal into skeletal muscle31.

1.5 PHARMACOLOGICAL IMPORTANCE OF PLANT PRODUCTS:

Traditional antidiabetic plants might provide new oral hypoglycaemic

compounds, which can counter the high cost and poor availability of the current

medicine .Present day drugs for many rural populations in developing countries32.

Diabetes mellitus and obesity remain the most common disorders of carbohydrate

metabolism. The WHO Expert Committee on diabetes recommended further

evaluation of the folkloric methods of managing this disease because of the high

mortality and morbidity arising from its attendant complications and problems

associated with the use of conventional antidiabetic agents33.

Diabetes is still not

completely curable by the present anti diabetic agents. Insulin therapy is the only

satisfactory approach in diabetic mellitus, even though it has several drawbacks like

insulin resistance, anorexia, brain atrophy and fatty liver in chronic treatment. Herbal

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drugs are gaining popularity in the treatment of diabetic mellitus. The major

advantages of herbal medicine seem to be their efficacy, low incidence of side effects,

and low cost34.

Several indigenous medicinal plants are employed in the traditional

management of diabetes mellitus but there is a need to conduct pharmacognostic and

pharmacological studies to ascertain their therapeutic values35.

A multitude of herbs,

species and other plant materials have been described for the treatment of diabetes

throughout the world36.

The medicinal plants might a useful source for the

management of diabetes and its complications for development of new pharmaceutical

entities or as a dietary adjunct to existing therapies. Few of the plants used for the

treatment of diabetes have received scientific or medical scrutiny even the WHO

expert committee on diabetes recommends that this area warrant further

attention37.

Indian Medicinal Plants with Antidiabetic and related beneficial effects38, 39:

Though there are various approaches to reduce the ill effects of diabetes and

its secondary complications are available, herbal formulations and use of Indian

medicinal plants are preferred by many mainly due to lesser side effects and economic

reasons.

Table No.1. 2. Anti-diabetic effects of traditional medicine.

Plant name Common

name

Anti-diabetic and other beneficial

effects in traditional medicine

Acacia arabica Babul Initiates insulin release from

pancreatic beta cells.

Aegle marmelos Bael Hypoglycemic, chemopreventive

Allium cepa Pyaj Hypoglycemic, Hypolipidemic

Allium sativum Lahasun Hypoglycemic, Hypolipidemic,

Antibacterial, Cardio protective.

Aloe vera Kumar panthu Hypoglycemic, Anti inflammatory

wound healing effects.

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Artemisia pallens Davana Hypoglycemic, increases peripheral

glucose utilization or inhibits glucose

reabsorption. Areca catechu Supari Hypoglycemic

Azadirachta indica Neem Hypoglycemic antibacterial.

Beta vulgaris Chukkander Increases glucose tolerance in OGTT

Bombax ceiba Semul Hypoglycemic.

Butea monosperma Palash Anti-diabetic.

Caesalpinia bonducella Kantikaranja Anti-hyperglycemic, Hypolipidemic.

Camellia sinensis Tea Anti-hyperglycemic, antioxidant.

Capparis deciduas Karir / pinju Hypoglycemic, antioxidant,

hypolipidemic

Cassia auriculata Mature tea tree Anti-diabetic.

Coccinia indica Bimb/ kanturi Hypoglycemic

Emblica officinalis Amla Decrease lipid peroxidation, anti oxidant.

Eugenia uniflora Pitnga Hypoglycemic, inhibit lipase activity.

Ficus bengalenesis Bur Hypoglycemic antioxidant.

Gymnema sylvestre Gudmar Anti-hyperglycemic, Hypolipidemic.

Hibiscus rosasinensis Gudhal Initiate insulin release from pancreatic

β-cell.

Lpomoea batatas Sakkargand Reduce insulin resistance.

Mangifera indica Aam / Amb Hypoglycemic, anti-oxidant.

Momardica

Cymbalaria

Kadavanchi Hypoglycemic, Hypolipidemic.

Momardica charantia Karela Hypoglycemic, anti-atherogenic,

hypocholesterolemic

Murraya koeingii Kurry patta Hypoglycemic, increases glycogenesis

and decreases gluconeogenesis and

glucogenolysis.

Ocimum sanctum Tulsi Hypoglycemic, antioxidant,

hypolipidemic, antimutagenic,

immunostimulant.

Phyllanthus amarus Bhui amla Hypoglycemic, antioxidant.

Swertia chirayita Chirata Stimulates insulin release from islets.

Trigonella foenum Methi Hypoglycemic, antioxidant,

hypocholesterolemic activity

Terminalia belerica Behada Hypoglycemic, antibacterial

Tinospora cardifolia Gluchi Hypoglycemic, antioxidant,

antibacterial, stimulates macrophages

Vinca rosea Sadabahar Anti-hyperglycemic.

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1.6 Lipids and their role in the body:

Major lipids found in blood stream are triglycerides, phospholipids,

cholesterol and cholesterol esters and free fatty acids. The function of cholesterol is to

help carry fat in the body, because fat being insoluble in the water cannot travel on its

own in the blood stream. Cholesterol associates with fat and protein and comes out of

the liver as lipoprotein. There are several types of lipoproteins for the transport of

fatty material in the body such as chylomicrons, very low density

lipoproteins(VLDL), Low density lipoproteins (LDL), intermediate density

lipoproteins(IDL),High density lipoproteins (HDL). Each has a different function in

the transport system. VLDL is responsible to carry endogenous triglycerides from the

liver in to the blood stream and to other part of the body. Lipoprotein lipase catalyzes

triglycerides degradation to generate VLDL remnants which are further degraded by

Hepatic glyceride hydrolase to generate LDL. It easily adheres along the walls of the

arteries and therefore called as bad cholesterol. There are different types of HDL like

HDL1, HDL2 and HDL3. It is called as good cholesterol as it finds and removes stuck

LDL of peripheral cell and bring them back to liver. The normal range for total blood

cholesterol is between 140 and 200mg/deciliter (mg/dl) of blood40

.

1.6.1 Hyperlipidemia

Hyperlipidemia, the elevation of lipid concentration in plasma, is the

manifestation of a disorder in the synthesis and degradation of plasma lipoprotein.

Primary type hyperlipidemia can be treated with drugs but the secondary type

originating from diabetes, renal lipid necrosis or hypothyroidism demands the

treatment of original disease rather than hyperlipidemia40

. Levels between 200 and

240mg/dl indicate moderate risk and levels surpassing 240mg/dl indicate high risk.

27

While their role in heart disease is not entirely clear, it appears that as triglyceride

levels rise, levels of good cholesterol fall. It is the complex interaction of these three

types of lipids that is thrown off when a person has hyperlipidemia. High cholesterol

is characterized by elevated levels of LDL cholesterol, normal or low levels of HDL

cholesterol and normal or elevated levels of triglycerides. According to world health

organization (WHO) 2002, almost one fifth (18%) of global stroke events (mostly non

fatal events) And about 56% of global heart diseases are attributable to total

cholesterol levels above 3.2m mmol/l. This amounts to about 4.4 million deaths (7.9%

of the total) and 2.8%of the global disease burden.

1.6.2 Classification of hyperlipidemia40

Type 1 hyperlipidemia : It is characterized by high concentration of blood

chylomicrons. Currently there are no drugs available for treating this type.

Type 2 hyperlipidemia: it is sub divided in to type IIA hyperlipidemia and type IIB

hyperlipidemia.

Type IIA:

Hyperlipidemia is characterized by high LDL and cholesterol levels with a slight

increase in Blood triglycerides.

Type II B:

Hyperlipidemia is characterized by the elevation of triglycerides, serum cholesterol

LDL and VLDL.

Type III Hyperlipidemia: it shows elevated levels of triglycerides and LDL.A

blockade in the normal conversion of VLDL to LDL results in the accumulation of

IDL. Controlled diet is the treatment of this type of hyperlipidemia.

28

Type IV hyperlipidemia: it is due to high concentration of triglycerides and VLDL

and often faulty carbohydrate metabolism. Both diet and drug therapy is

recommended for this type of Hyperlipidemia.

Type V hyperlipidemia: It shows elevated levels of chylomicrons, VLDL and

triglycerides resulting from faulty carbohydrate metabolism. A major concern in

patients with hyperlipidemia is the increase risk of atherosclerosis resulting in heart

diseases. The aim of treating the patients with hyperlipidemia is to reduce serum

cholesterol and / or improve the HDL cholesterol by maintaining a high ratio of HDL

to LDL cholesterol level there by reducing the risk of developing heart disease or the

occurrence of further cardiovascular or cerebrovascular events.

1.6.3 Signs and symptoms41

In its primary stage, high cholesterol generally occurs without any symptoms. For this

reason, screening through routine blood tests is crucial for early detection. In its

advanced stage, however, high cholesterol may result in any of the following:

Fat deposits in the tendons and skin(called Xanthomas).

Enlarged liver and spleen (which the health care provider may feel on exam).

Severe abdominal pain as a result of pancreatic (happens if

triglyceride deposit level in the pancreas is 800 mg/dl or higher)

Chest pain and even a heart attack (may occur when enough cholesterol has built

up in blood vessel walls to block the flow of blood in the heart)

29

1.6.4 CAUSES:

Causes of high total and LDL cholesterol levels include:

Hereditary hyperilipidemia (types IIA or IIB)

Diets high in saturated fats and cholesterol

Liver disease.

Active under thyroid

Poorly controlled diabetes

Overactive pituitary gland

A kidney disorder called nephric syndrome characterized by elevated

cholesterol ,loss of protein in the urine leading to low levels of protein in the

blood and excessive fluid retention Causing swelling.

Anorexia nervosa

Medications such as progestogens, cyclosporins and thiazide diuretics.

Causes of low HDL cholesterol include:

Malnutrition

Obesity

Cigarette smoking

Certain medications such as beta blockers and anabolic steroids.

Low level of physical activity

Polycystic ovarian syndrome

Causes of high triglyceride levels include:

Hereditary hyperlipidemia

Diets high in calories, especially from sugar and refined carbohydrates

Obesity

30

Poorly controlled diabetes

Insulin resistance

Alcohol use

Kidney failure

Stress

Pregnancy

Polycystic ovarian syndrome

Hepatitis

Multiple myeloma

Lymphoma

Certain medications such as estrogens (available in either oral contraceptives or as

part of hormone replacement therapy for menopausal women), corticosteroids, a class

of cholesterol lowering medications know as bile acid binding resins and isotretinoin.

1.6.5 Current Management of Hyperlipidemia42

Diet:

Diet modification is always being encouraged in a patient with hyperlipidemia but it

alone is rarely successful in bringing about a significant improvement in lipid profile.

Randomized control trails of dietary fat reduction or modification have shown that

variables on cardiovascular morbidity and mortality. There is a common

misconception that a healthy diet is one that is low in cholesterol. However, it is the

saturated fat contents that are important, although many components of a healthy diet

are not related to fat content. For example, the low incidences of coronary heart

disease in those who consume Mediterranean diet suggest that increase intake of fruits

and vegetables are also important. The typical Mediterranean diet has an abundance

31

of plant food minimally processed, seasonally fresh, and locally grown; fresh fruits as

the typical diet dessert, with sweets containing concentrated sugars or honey

consumed a few times per week: olive oil as the principle source of fat: dairy products

such as cheese and yoghurt, consumed daily in low to moderate amounts :zero to four

eggs consumed weekly and red meat consumed in a low to moderate amounts.

Salt:

Dietary salt (sodium) has an adverse effect on blood pressure and thereby a

potential impact on coronary heart disease and stroke. As part of dietary advice the

average adult intake of sodium should be reduced from approximately 150 mmol(9 g)

to 100 mmol(6 g) of salt. This intake can be reduced by consuming fewer processed

food, avoiding many ready meals and not adding salt at the table.

Lipid Lowering Therapy43

Statins:

These agents block the rate limiting enzyme for endogenous cholesterol

synthesis, Hydroxyl-methyl glutaryl coenzyme A reductase (HMG CoA). This results

in up – regulation of LDL-receptors in the liver and increased clearance of LDL from

the circulation; plasma total cholesterol and LDL-cholesterol fall to attain a maximum

effect in 1 month after commencing therapy.

Fibric acid derivatives:

This class include benzofibrate, ciprofibrate, fenofibrate and gemfibrozil. The

drug clorfibrate partly resemble short chain fatty acids and increases the oxidation of

these acids in both liver and muscle. In liver, the secretion of triglyceride rich

32

lipoproteins falls, and in muscle the activity of lipoprotein lipase and fatty acid uptake

from the plasma are both increased.

Anion – Exchange Resins:

Cholestyramine is an oral anionic resin which binds bile acids in the intestine.

Bile acids are formed from cholesterol in the liver, pass into the gut in the bile and are

largely reabsorbed at the terminal ileum.

Nicotinic Acid Derivatives:

Nicotinic acid acts as an antipolytic agent in adipose tissue, reducing the

supply of free fatty acids and hence the availability of substrate for hepatic

triglyceride synthesis and the secretion of VLDL. Nicotinic acid lowers plasma

triglyceride and cholesterol concentrations an rises HDL-cholesterol.

Acipimox is better tolerated than nicotinic acid, has longer duration of action but is

less effective. Unlike nicotinic acid, it does not reduce levels of lipoproteins, the

modest reduction of which may contribute to overall protection against the

complications of atheroma.

Other Drugs:

Alpha – tocopherol acetate(Vitamin E), Omega-3-marine triglycerides (maxepa)

Orlistat, Ezetimibe44

, is the first compound approved for lowering total and LDL-C

levels that inhibits cholesterol absorption by enterocytes in the small intestine.

33

1.7 Plant remedies for hyperlipidemia 45

A number of plant preparations such as Allium sativum, Cicer arientinum,

Inula racemosa, Terminalis arjuna , Trigonella foenum graecum,Commiphora mukul,

green tea and curcumin have been reported to have hyperlipidemic action. Few of

these also possess certain other beneficial properties like anti angina and anti platelet

actions. Plant preparations contain many compounds that work synergistically on

multiple parts of the body. For example, garlic is not only anti bacterial, but anti

fungal and helps to lower cholesterol. This synergy of chemicals helps to balance the

overall activity of the herb. Since the chemicals in the herb are non specific and un

concentrated, there are generally fewer side effects from the herbs than from

manufactured drugs. Further according to a study published in the April 15, 1998

issue of the Journal of American medical Association, the fifty leading cause of death

in the United states in 1994 was adverse drug reactions of modern medicine, an

excess of 100,000 deaths. By contrast, there has been less than 100 adverse reactions

and only one death attributed to herbs in Canada science 1990.Most reactions to herbs

have to do with an individual allergic reaction to the herb or to an interaction with

prescription drugs.

Table No:1.3 List of plants with antihyperlipidemic activities45

Sl.

No.

Name of the plant Family Vernacular

Name

Plant Part

1. Aegle marmelos Rutaceae Bael fruit,

Bilwa

Fruits

2. Agrave veracruz Amryllidaceae American aloe,

barakhawar

Root, leaves,

gums

3. Allium cepa Liliaceae Onion, piyaj,

palandu

Bulbs

4. Aloe barbadensis Liliaceae Ghee kumar,

gwarpatha

Leaves

5. Bambusa Graminae Bamboo

vamsha

Leaves

34

6. Boswellia serrata Burseraceae Salai guggul Gum

7. Brassica vercapitata Cruciferae Cabbage Oil

8. Cajanus cajan Fabaceae Red Gram Seeds

9. Capparis decidua Capparaceae Karli, tint Leaves, fruits

and stem

10. Capsicum capacapitum Solanaceae Chillies Fruits

11. Carpum capaticum Umbelliferae Jawan, ajowan Fruits, roots

12. Celastrus paniculatus Celestraceae Khunjri, Kusur Seed oil, barks,

roots and fruits.

13. Curcuma amada Zingiberaceae Turmeric,

haridra

Rhizomes

14. Cyamopsis

tetragonoloba

Euphorbiaceae Guar Seeds

15. Embellica officinalis Euphorbiaceae Amla, amalaki Dried fruits,

seeds, leave.

16. Eugenia cumini Myrtaceae Jamun Seeds

17. Inula racemosa Compositae Pushkarmul Roots

18. Juglans regia Juglandaceae Walnut, akhrot Kernel oil

19. Medicago sativa Papilionaceae Alfa alfa Seeds

20. Momordica charantia Cucurbitaceae Bitter ground Fruits

21. Musa saspientum Musaceae Banana, Kela Roots, stems,

flowers, fruits.

22. Nepeta hindostana Libiateae Billiola,

badranj, boya

Whole plant

23. Phaseolus aureus Fabaceae Green gram Seeds

24. Phaseolus mungo Fabaceae Black gram Seeds

25. Picrorhiza kurroa Scrophularaceae Kulki, kataki Roots

26. Piper nigrum Piperaceae Golmirch,

kalilmirch

Leaves

27. Pisum sativum Papillionaceae Garden pea,

Matar

Seeds

28. Pterocarpus marsupium Papillionaceae Indian

malabarkino

Gum and leaves

29. Saussuraea lappa Asteraceae Kustha, kut Roots

30. Terminalia arjuna Combrettaceae Arjun Barks

35

Diabetes and hyperlipidemia are among the important disorders affecting

mankind and remain one of the serious health problems. No permanent remedy is

available to majority of these. In the absence of suitable protective drugs in allopathic

medical practices, herbs plays important role in the management of various disorders.

A number of medicinal plants have been advocated in traditional system of medicine,

especially in Ayurveda for treating diabetes and hyperlipidemia. This usage is in

vogue since centuries and are quite often claimed to offer significant relief.

Based on the ethnomedical claims,The need for the development of newer

plant based antidiabetic and anticholesterolemic drugs, hence in the present study an

attempt has been made to investigate the antidiabetic and anticholesterolemic

activities of leaves of Amaranthus caudatus, Amaranthus spinosus and Amaranthus

viridis (Amaranthaceae)