The stem bark of the Arjuna tree has been valued for heart health since 500 BC. This beautiful and amazing tree is native to central India and lives on average over fifty years. Ayurvedic physicians commonly prescribe the powdered tree bark for alleviating angina, hypertension and other cardiovascular conditions. In research, the bark extract has been shown to have diuretic and hypotensive properties.[1]
I often use Arjuna in my clinical practice, and combine it with hawthorn leaf, flower, and berry (Crataegus oxycantha); olive leaf (Olea europea); coleus (Coleus forskohli); grape seed extract; green coffee bean; celery seed (Apium graveolens) and rauwolfia (Rauwolfia serpentina). All of these botanicals have been found to have therapeutic benefit in cardiovascular health, and in particular for maintaining healthy blood pressure, tonifying the heart, and improving its function.
The stem bark of Arjuna contains bioactive compounds with medicinal benefits including glycosides, large quantities of flavonoids, tannins, and minerals. Flavonoids exert antioxidant, anti-inflammatory, and lipid lowering effects, while glycosides are cardiotonic. Arjuna is unique among currently used medicinal plants because of this dual action effect for the heart.[3]
In addition to the wide-ranging cardiovascular benefits of Arjuna, the herb could be an effective therapeutic against COVID-19 based on its demonstrated binding activity against SARS-CoV-2. In a recent study, Arjuna bark oleanane triterpenoid type compounds from oleanolic acid, arjunolic acid, arjunolitin, and arjunetin were isolated from ethanolic bark extract as bio-active compounds and their structures were elucidated using 1H, 13C NMR, HR-ESIMS, IR. Of the various compounds, arjunetin showed significant inhibition of catalase activity as compared to the other compounds. Based on the structural similarity between arjunetin and current antiviral drugs, arjunetin might exhibit antiviral activity.
Molecular docking and molecular dynamics studies showed that arjunetin binds to the key targets of SARS-CoV-2 (namely, 3CLpro, PLpro, and RdRp) with higher binding energy values than the FDA approved protease inhibitor drugs Lopinavir and Remdesivir.
To further investigate this, researchers performed 200-500 ns molecular dynamics simulation studies. The results showed that the binding affinity of arjunetin is higher than Remdesivir in the RNA binding cavity of RdRp. Based on structural similarity between arjunetin and saikosaponin (a known antiviral agent) and based on molecular docking and molecular dynamic simulation studies, the researchers proposed that arjunetin showed promise as a drug candidate against COVID-19.[4]
Cardiovascular Benefits
Arjuna is a cardio-tonic plant that is anti-ischemic, and a potent antioxidant, preventing LDL cholesterol oxidation and reperfusion ischemic injury to the heart. It also reduces atherogenic lipid levels, as demonstrated in various experimental and clinical studies.[5]
In short term studies, Arjuna has demonstrated effectiveness for numerous cardiac related health ailments with no major side effects. Patients reported a better sense of well-being and lesser intensity of chest discomfort when taking Arjuna in addition to conventional drugs.[6],[7]
An open human study of Arjuna’s effects on stable and unstable angina revealed a 50 percent reduction of anginal episodes in patients with stable angina (p < 0.01) after three months’ treatment. A statistically significant reduction was also noted in systolic blood pressure in these patients.[8]
Importantly, Arjuna taken together with conventional drugs such as aspirin, beta-blockers, ACE inhibitors and statins does not show any adverse effects on hematological, renal or hepatic parameters even after 4–5 years.[9]
Chronic Coronary Artery Disease
In a 2019 study, 35 patients with chronic CAD received Arjuna bark extract powder (500 mg three times daily) along with conventional drugs. The control group (35 patients) received conventional drugs alone. Hemogram, liver function tests and kidney function tests were done at baseline and then every 6 months until the end of the study. Electrocardiography was done every 6 months and echocardiography was done yearly for left ventricular ejection fraction and regional wall motion abnormalities. Any adverse drug reactions reported by the patients were also recorded.
The mean age of patients in test and control groups was 60.88 ± 9.02 and 58.51 ± 12.64 years, respectively. There was a predominance of male patients in both groups. The patients were observed for a duration ranging from 9 months to 4 years and 9 months. The results of the study concluded that Arjuna is safe and effective in patients with chronic coronary artery disease.[10]
Arjuna bark extract has multiple protective effects, including against doxorubicin-induced DNA damage and cardiotoxicity.[11],[12] Arjuna also protects the heart against myocardial changes induced by chronic β-adrenoceptor stimulation, caused by prolonged intense stress.[13]
Substantiating this, in a recent experiment Arjuna bark extract significantly attenuated cardiac dysfunction and myocardial injury in rats with congestive heart failure (CHF). Arjuna bark extract has significant prophylactic and therapeutic benefits in protecting the heart against catecholamine-induced CHF, possibly through maintaining endogenous antioxidant enzyme activities and inhibiting LPO and cytokine levels. The cardioprotective action of Arjuna is comparable to Fluvastatin.[14]
Triterpenoids derived from Arjuna bark extract containing arjunolic acid show cardioprotective activity by boosting the endogenous antioxidant defense system.[15]
Lipid Lowering Effects
Along with the many other cardioprotective benefits of Arjuna, animal experiments have demonstrated that Arjuna bark powder/extract reduces total cholesterol and triglyceride levels.[16],[17],[18],[19]
Researchers found an ethanol extract of Arjuna bark extract exerted significant lipid lowering effect as assessed by reversal of plasma levels of total cholesterol, triglyceride and phospholipids in rats in hyperlipidemic rats.[20]
The cholesterol lowering action is thought to be mediated through increased hepatic clearance of cholesterol, down-regulation of lipogenic enzymes, and inhibition of HMG-CoA reductase.[21] There is a possibility of involvement of thyroid hormones in the amelioration of cardiac and hepatic cholesterol in animals.[22]
Antihypertensive Activity
Oxidative stress is a major cause of hypertension. Researchers evaluated different extracts of Arjuna bark having variable marker yield for antihypertensive effects in a buthionine sulfoxamine (BSO) induced oxidative stress-based model. Soxhlet extraction (SE), room temperature extraction (RTE), microwave assisted extraction (MAE), and ultrasound assisted extraction (USAE) were quantitatively estimated for marker compounds arjunolic acid and arjunic acid through HPTLC.
Hypertension was induced using buthionine sulfoxamine (2 mmol/kg b.w. i.p.) and results suggested that the MAE and USAE showed better recovery of systolic blood pressure (110.33±0.10 and 118.33±0.10) and GSH level (3.62±0.07 nmoles/mL and 3.22±0.13 nmoles/mL) respectively as compared to the positive control group treated with ascorbic acid (systolic BP: 119.67±0.10, GSH level: 3.11±0.10 nmoles/mL). The RTE and SE also showed decrease in hypertension but were having moderate effects as compared with the standard positive control.[23]
Beneficial Effects in Pulmonary Hypertension
Pulmonary hypertension (PH) is a fatal disease which causes right ventricular hypertrophy and right heart failure. Pulmonary vascular smooth muscle hypertrophy and increased
oxidative stress are major pathological features of PH. As available limited therapeutic options fail to reduce the mortality associated with PH, alternative areas of therapy are worth exploring for potential drugs which might be beneficial.
Researchers investigated the effect of arjuna bark extract in preventing monocrotaline (MCT)-induced PH in rats. The study was approved by Institutional Animal Ethics Committee. Male Wistar rats (150-200g) were randomly distributed into five groups: Control, MCT (50mg/kg subcutaneously once), sildenafil (175µg/kg/day three days after MCT for 25 days), and Arjuna extract (TA125 and TA250 mg/kg/day orally after MCT for 25 days). PH was confirmed by right ventricular weight to left ventricular plus septum weight (Fulton index), right ventricular systolic pressure, echocardiography, percentage medial wall thickness of pulmonary arteries. Oxidative stress in lung was assessed by super oxide dismutase, catalase, reduced glutathione and thiobarbituric acid reactive substance. The protein expressions of nicotinamide adenine dinucleotide phosphate oxidase in lung and gene expression of Bcl2 and Bax in heart were analyzed by Western blot and RT PCR respectively.
Study results showed Arjuna bark extract prevented hypertrophy and right ventricular systolic pressure. Pulmonary artery acceleration time to ejection time ratio in echocardiography was decreased. Arjuna bark extract significantly increased expression of NOX1 in lung and gene expression of Bcl2/Bax ratio was significantly decreased in right ventricle in MCT-induced PH.
The researchers concluded that Arjuna bark extract prevented MCT-induced pulmonary hypertension which may be attributed to its antioxidant as well as its effects on pulmonary arteriolar wall thickening.[24]
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