Terminalia Arjuna - An Ancient Cardioprotective Plant

Terminalia Arjuna, commonly known as Arjuna or Arjun, belongs to the family Combretaceae. Arjuna is a potential cardioprotective agent mentioned in many ancient Indian medicinal texts, including Charaka Samhita, Sushruta Samhita, and Astanga Hridayam. Vagabhatta was the first to advocate using Arjuna stem bark in heart ailments. The bark has been described as cardiotonic, astringent, expectorant, styptic, and antidysenteric. It is useful in cardiomyopathy, cirrhosis, fractures, ulcers, leucorrhoea, diabetes, and anaemia.

For centuries Arjuna has been used in the Indian subcontinent for many cardiovascular disorders, including angina pain, congestive heart failure, hypertension, and dyslipidemia. Studies have suggested that Arjuna possesses antioxidant, hypolipidemic, anti-ischemic, and antiatherogenic activities. Arjuna contains several phytochemicals, including triterpenoids, β-sitosterol, flavonoids, and glycosides. Triterpenoids and flavonoids are responsible for their antioxidant and cardiovascular properties. Arjuna has shown a promising effect on ischemic cardiomyopathy.

In recent years, Arjuna has been screened for its various pharmacological properties, mainly cardioprotective, and is effective in both experimental and clinical studies.

Experimental Studies of Arjuna

1. Effect of Arjuna on Cardiac Haemodynamics, Coronary Flow, and Blood Pressure

The bark of Arjuna possesses diuretic, inotropic (strengthen the force of heartbeat), and chronotropic (alter heart rate and rhythm) properties. The inotropic effect is mediated through the high concentration of calcium ions present in the plant. Studies show that the aqueous extract of Arjuna bark increases the force of cardiac muscle contraction, thus increasing coronary flow, and Arjuna bark also decreases heart rate and blood pressure. The hypotensive effect is mediated by direct action on the heart muscle, cholinergic mechanisms, or adrenergic β2-receptor agonist.

2. Antioxidant and Cardioprotective Properties of Arjuna

Extract of Arjuna provides cardioprotection against oxidative stress due to its antioxidant properties. The bark extract significantly prevents increased oxidative stress. The antioxidant property of Arjuna is due to its phenolic content. In myocardial ischemia (MI), Arjuna has prostaglandin-like activity with coronary vasodilatation and hypotension. Further, the bark extract protects against doxorubicin-induced DNA damage and cardiotoxicity. Arjuna bark extract has a significant prophylactic and therapeutic beneficial effect. It protects the heart against congestive heart failure (CHF) by maintaining endogenous antioxidant enzyme activities and inhibiting lipid peroxide and cytokine levels.

3. Hypolipidemic and Antiatherogenic Effect of Arjuna

Experiments have demonstrated that Arjuna bark reduces the total cholesterol (TC) and triglyceride (TG) levels, exerting a significant lipid-lowering effect. Arjun bark possesses potent antioxidant and hypolipidemic properties. Subsequent work also substantiates Arjuna's hypolipidemic and antioxidant effect on elevated lipids and oxidative stress levels. The hypolipidemic action of Arjun is mediated through increased hepatic clearance of cholesterol, down-regulation of lipogenic enzymes, and inhibition of the enzyme 3-hydroxy-3-methylglutaryl coenzyme (HMG-CoA) reductase.

Clinical Uses Of Arjuna

1. Role of Arjuna in Angina and Myocardial Infarction

Arjuna bark has an anti-ischaemic effect. Regular use of Arjuna bark extract reduces the frequency of angina significantly, along with improvement in ECG changes, a decrease in systolic blood pressure (SBP), and a reduction in serum cholesterol levels. Arjuna bark also reduces the positivity grade of treadmill test (TMT) response in coronary artery disease (CAD). It improves exercise tolerance and reduces the frequency of angina attacks and the use of sublingual nitrates. It reduces angina episodes along with a significant delay in the time of onset of angina on TMT and changes in ECG of stable angina patients. Studies prove that Arjuna bark is also helpful in post-myocardial infarction angina. Arjuna significantly lowers systolic blood pressure and body mass index, with a marginal improvement in left ventricular ejection fraction (LVEF) and a slight increase in high-density lipoprotein (HDL) levels.

2. Arjuna for Congestive Heart Failure and Hypertension

Studies show improvement in breathlessness and overall well-being with significant diuresis and a fall in systolic and diastolic blood pressure in congestive heart failure after regular use of Arjuna bark powder. It also shows a substantial reduction in inter-ventricular septal thickness, posterior wall thickness, and an increase in left ventricular stroke volume and LV ejection fraction. In addition to continued betterment in symptoms and signs, improved quality of life is also observed. Arjuna is also helpful in improving cardiovascular function in normal healthy persons.

3. Role of Arjuna in Rheumatic Heart Disease

Arjuna is effective in rheumatic heart disease associated with congestive heart failure. The results reveal a significant improvement in left ventricular ejection fraction (LVEF), exercise duration, and a significant reduction in heart size.

4. Role of Arjuna in Ischemic Mitral Regurgitation

Studies show that Arjuna significantly decreases ischemic mitral regurgitation (IMR) and angina frequency following acute myocardial infarction. It also offers a significant improvement in diastolic dysfunction.

5. Effect of Arjuna in Cardiomyopathy

In addition to its anti-ischemic property, Arjuna also reduces Left ventricular mass (LVM) and improves left ventricular ejection fraction (LVEF). Studies conducted on dilated cardiomyopathy with reduced LVEF show a significant improvement in left ventricular parameters and functional capacity after using Arjuna.

6. Effect of Arjuna on Platelet Aggregation

The Arjuna bark extract possesses antithrombotic properties. Studies show that Arjuna causes a significant increase in mean cardiac output, reduces mean systemic vascular resistance, and inhibits platelet aggregation. It decreases platelet activation in Coronary artery disease (CAD). The mechanism involves desensitizing platelets by competing with platelet receptors or interfering with signal transduction.

7. Role of Arjuna in Oxidative Stress and Dyslipidemia

In coronary heart disease, regular use of Arjuna bark improves lipid profile and symptomatic relief. The antioxidant effect of bark is comparable to vitamin E. There is a significant decrease in total cholesterol (TC), high-density lipoprotein (LDL), and lipid peroxide levels. The hypocholesterolemic effect of Arjuna is due to the soluble fibres and sitostanol content, while the antioxidant effect can be attributed to the flavonoids.

8. Effect of Arjuna on Lipoprotein, Endothelial Dysfunction, and Thrombotic condition

The use of Arjuna shows a significant reduction in lipoprotein levels in β-thalassemia associated with hyperlipoproteinemia and metabolic syndrome. The hydroalcoholic extract of bark leads to substantial regression of the endothelial abnormality amongst smokers. Studies show that Arjuna extract possesses significant thrombolytic activity and also significantly inhibits the haemolysis of RBCs.

Conclusion

The perpetual interest in medicinal plants has led to discovering new chemical constituents and pharmacological actions of Arjuna. It is widely used to treat cardiovascular diseases, including heart diseases and related chest pain, high blood pressure, and high cholesterol. The effectiveness of Arjuna as an anti-ischemic agent and as an antioxidant preventing LDL and its potential to reduce atherogenic lipid levels have been sufficiently demonstrated in different experimental and clinical studies. Increasing the awareness regarding the medicinal usage of Arjuna can give direction to the physicians to respond to the challenges in treating cardiovascular diseases.