Pharma Voice

Fight diabetes the herbal way!

Edwin E, Sheeja E, Gupta VB and Jain DC give an insight into herbal remedies which can be used to fight diabetes.

Edwin E

The diabetic population has reached the 100 million mark. Decreased physical activity, increasing obesity, stress, and changes in food consumption are responsible for the increasing prevalence in the past two decades. As the incidence continues to grow, diabetes is being projected to be the world's primary killer in the next 25 years.

Diabetes and insulin

Insulin is a hormone secreted by the pancreas to transport glucose from blood to the body cells. If pancreas do not produce enough insulin or the produced insulin does not work properly, glucose cannot enter the body cells.

Hence, glucose stays in the blood cells, which makes the blood sugar level high causing diabetes. It is initially characterised by a loss of glucose homeostasis. Blood glucose levels of a healthy man are 80mg/dl on fasting and up to 160mg/dl in the post-prandial state. According to National Diabetes Data Group 1979, Non Insulin dependent diabetes (NIDDM) is diagnosed when a patient has random blood sugar level >200mg/dl on two occasions and has a fasting plasma glucose concentration>200mg/dl after an oral glucose load of 75gm at two hours and one other between 0-2 hours.

Types of Diabetes

Type I—Insulin dependent Diabetes mellitus (IDDM): Insulin dependent diabetes mellitus (IDDM) is characterised by auto-immune, cell mediated, selective destruction of insulin-secreting cells of pancreatic islets in genetically predisposed individuals. Genetic factors are believed to be a major component for the development of IDDM. As a result, patients are completely reliant upon exogenous insulin to prevent ketosis and thereby preserve life. This is common in children and in adults less than 30 years old, but may occur at any stage of life.

Type II—Non-Insulin dependent Diabetes mellitus (NIDDM): Non-insulin depe-ndent diabetes is caused by the loss of functional cells within islets of langerhans in the pancreas, resulting in insulin deficiency and thereby producing hyperglycemia. This high-level blood glucose for longer periods causes many complications to different systems of the body. Approximately 90 percent of diabetics suffer from Type II diabetes. This type is usually diagnosed in adults who are more than 30 years old, but may occur at any stage of life.

Gestational diabetes mellitus: Diabetes diagnosed in pregnancy, includes pre-existing diabetes and diabetes which develops during pregnancy. This condition occurs in approximately two to four percent of pregnant women, generally during the second or third trimester. In majority of cases, glucose regulation returns to normal post-pregnancy. It increases future risk for developing Type II diabetes.

Other specific forms: It is a broad term used to classify patients who have unusual causes of diabetes eg genetic defects in cell function, genetic defects in insulin action, diseases of the exocrine pancreas, secondary to endocrinopathies, drugs or chemical induced.

Need and scope of alternative remedy

Regardless of the type of diabetes, patients are required to control their blood glucose with medications and/or by adhering to an exercise program and a dietary plan. Insulin therapy by injection is given to those with Type I DM and to some patients with Type II DM. Due to modernisation of lifestyle, Non-Insulin Dependent Diabetes Mellitus is becoming a major health problem in developing countries. Even in the developed countries the rate of mortality due to diabetes is more alarming. It is the seventh leading cause of death in the USA.

In India every fourth man is susceptible to diabetes. Non-Insulin Dependent Diabetes Mellitus drastically reduces life expectancy in developing countries where its prevalence is increasing due to change in lifestyle. Patients with Type II diabetes are usually placed on a restricted diet and are instructed to exercise, the purpose of which is primarily to control weight. If diet and exercise fail to control blood glucose at the desired level, oral anti-diabetic medication is prescribed. In some cases, insulin injections are necessary.

Oral anti-diabetic agents exert their effects by various mechanisms:

• stimulation of beta cells in the pancreas to produce more insulin (sulfonylureas and meglitinides)
• increasing the sensitivity of muscles and other tissues to insulin (thiazolidinediones)
• decreasing gluconeogenesis by the liver (biguanides)
• delaying the absorption of carbohydrates from the gastrointestinal tract (alpha-glucosidase)

These treatments are associated with side effects, and some may produce toxic effects (e.g. thiazolidinediones may cause liver toxicity). With increasing incidence of diabetes in rural population, there is a clear need for development of indigenous, inexpensive botanical sources for anti-diabetic crude or purified drugs. Even though different types of oral hypoglycemic agents are available along with insulin, there is an increased demand from patients to use natural products with anti-diabetic activity.

Herbal remedies

As per Ayurveda and Hindu literatures like Charka Samhita, Madhav Nidan and Astang Sanghra, there are about 600 plants, which are supposed to have anti-diabetic property. Since times immemorial, medicinal plants have been used in virtually all cultures as a source of medicine. Ayurvedic anti-diabetic herbs improve digestive power, increasing one of the rasas (gastric secretions) laghu and ruksha, decreases output of overall body fluids eg urine, sweat.

Food items which are 'madhumehaghna' ie antidote is an important underlying principle of therapy for the prameha (diabetes) patient. Foods exhibiting rasa, katu, laghu, medaghna properties try to correct the metabolic imbalance by their action.

The foods which come under this category are roasted cereal, barley, jowar, ragi, mung dal, horsegram, tur dal, drumstick leaves, bittergourd, jamun, amla, fig, raw papaya, milk and meat of animals which live in dry region. Indigenous diet, all by itself, may not be useful in lowering the blood sugar to the same extent as insulin and other hypoglycaemic agents. But, it has some other properties, which may be useful for the management of the disease and its complications.

Developing countries have observed the increasing use of traditional medicines and medicinal plants. Furthermore, increasing reliance on the use of medicinal plants in industrialised societies have been traced to the extraction and development of several drugs and chemotherapeutics from these plants as well as from traditionally used herbal remedies. Among the 600 traditional plants used for diabetes, only a small number of these have received scientific and medical evaluation.

Of the small number, Gymmema sylvestre, Trigonella foenumgraecum, Pterocarpus marmipium, Aloe vera, Momordica charantia, Azadirachta indica, Panax sps, Syzigium cumini, Allium sps, Phyllanthus emblica, Coccinia cordifolia, Coccinia indica, Salacia oblonga and Cassia auri-culata are the important ones.

The way herbal anti-diabetics work

There are several mechanisms through which these herbs act to control the glucose level. They are more or less similar actions to the synthetic drugs. The mechanism of action of herbal anti-diabetics could be grouped as:

• Stimulation of insulin secretion (Teucrium polium, Allium sativum, Allium cepa, Panax ginseng)
• Inhibition in renal glucose reabsorption (Fraxinus excelsior)
• Stimulation of glycogenesis and hepatic glycolysis (Momordica charantia)
• Protective effect on the destruction of the beta-cells (Thea sinensis)
• Improvement of digestion and reduction of blood sugar and urea (Aegle marmelos)
• Prevents pathological conversion of starch to glucose (Eugenia jambolina and Pterocarpus marsupium)
• Inhibits b-galactocidase and a-glucocidase (Clitoria ternata)
• increasing the use of glucose by tissues and effect on adrenergic receptors (Panax ginseng, Allium sativum, Allium cepa)
• Potentiates the action of exogenously injected insulin
• cortisol lowering activities (Inula racemosa, Boerhaavia diffusa and Ocimum sanctum)

Wide range of plant constituents could have different site of action within the body and herbs exert similar mechanism of action like synthetic oral hypoglycemic drugs. Many of these herbs may have a direct or an indirect impact on blood glucose levels, thus interfering with the clinical management of diabetic patients.

The above mentioned plants have been considered for possible hypoglycaemic actions and some preliminary investigations have been carried out by the researchers. Scientific studies available on a good number of medicinal plants indicate that promising phytochemicals can be developed for diabetes too.

However, there are numerous other plants which are mentioned in the indigenous systems of health care but still await scientific inquiry.

There are many grey areas, which need substantial amount of work in the case of herbal antidiabetics. For a given dose of herbal medicine, its physiological effect will be governed by the effective tissue concentration of the remedy, which in turn is determined by pharmacokinetic parameters, absorption, distribution, metabolism and excretion of its various components. Only knowledge of herbal pharmacokinetics can provide valuable information to practitioners in prescribing herbs safely and effectively. Modern professionals in this equipped with proper standardisation will accept these drugs. Much more work should be done in this direction to make the herbs useful.

A holistic approach to the problem of diabetes is necessary, which should evenly proportionated by the combination of modern scientific knowledge and traditional folk knowledge to abolish the disease diabetes.

(The writers are the faculty of BR Nahata College of Pharmacy & Research Center, Mandsaur, Madhya Pradesh)