Hawthorn

Hawthorn (Crataegus) is a shrub commonly found in Europe, western Asia, North America, and North Africa. Medicinal extracts primarily use the leaves and flowers. It has been used for many years for congestive heart failure and to relieve other cardiac problems including angina, cardiac arrhythmia, hypertension and atherosclerosis. Traditionally, it has also been used as a sore throat astringent and a diuretic for kidney disorders and edema. The leaves, flowers, and berries of hawthorn contain a variety of bioflavonoids that appear to be primarily responsible for the cardiac actions of the plant. These compounds are often standardized in leaf and flower extracts, which are widely used in Europe.

Clinical Applications

• • Increased coronary blood flow
  • Decreased arterial blood pressure Increased skeletal muscle blood flow
  • Decreased heart rate in vivo; increased heart rate in vitro.
• Hyperlipidemia and atherosclerosis
  • After one month of hawthorn treatment, hyperglycemic patients displayed significant reductions in serum cholesterol, triglycerides, LDL-C, and apo-B (a major component of LDL-C).
• Congestive heart failure (New York Heart Association Stages 1 and II)
  • A 6-week double-blind, placebo-controlled trial involving multi-morbid patients (64-82 years) with declining cardiac performance demonstrated the following benefits of standardized Crataegus extract:
    • Significantly decreased pressure heart rate product during exercise and recovery.
    • Decreased blood pressure.
    • Decreased heart rate.
    • Increased exercise tolerance.
    • Improved patient sense of well being.
  • An 8-week randomized, double-blind, placebo-controlled trial for Crataegus extract, involving patients with NYHA II cardiac insufficiency, revealed a significant advantage over placebo relative to pressure-rate product, exercise tolerance, blood pressure reduction, reduction in heart rate, and subjective improvement.

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How Hawthorne Works

Overall Cardiovascular Effects

Hawthorn flavonoid polymers have been found to have low toxicity, profound hypotensive activity, strong and prolonged cardiotonic effects, and some detoxifying properties.

Inotropic Effects

Crataegus has displayed a significant positive inotropic effect on the contraction of cardiac myocytes in vitro. This effect does not seem to be associated with the constituent anthocyanidin flavonoids. Concurrently, Crataegus increases myocyte energy turnover for mechanical activity and ionic cycling. Thus the increase in contractile activity is accomplished in an energy-economical fashion. The inotropic effect may be attributed to increased Ca++ sensitivity. Unlike sympathomimetic drugs, whose positive inotropic effects increase arrhymias by shortening the refractory period, Crataegus reduces the risk of arrhthmias by lengthening the refractory period. Unlike conventional anti-arrhymia drugs, that have negative inotropic effect, Crataegus reduces arrhymia risk with a concurrent positive inotropic effect.

Cardioprotective and Anti-Arrhythmic Effects

• The cardiotonic effects of hawthorn are believed to be due to the following benefits:
  • Increased cellular permeability to calcium ions.
  • Inhibition of the enzyme phosphodiesterase, that inactivates.cyclic AMP, thus increasing intracellular cAMP.
  • The overall enhancement of heart function by Crataegus may be explained by flavonoid inhibition of phosphodieaterases, thus increasing intracellular cyclic AMP.
• Monoacetyl-vitexinrhamnoside, a flavonoid constituent of Crataegus species, has demonstrated, during in vitro studies, the ability to:
  • Dilate peripheral and coronary arteries in a concentration-dependent manner that involves endothelium-derived relaxing factor (EDRF) and the inhibition of phosphodiesterase.
  • Enhance functional parameters of the heart – contractility (left ventricular pressure), velocity of contraction, and coronary flow – in a concentration-dependent fashion.
  • Reduce the tendency toward myocardial infarction in regional ischemia of heart tissue induced by coronary artery occlusion. This effect suggests an improvement in heart perfusion.
• Hawthorn has demonstrated the ability to protect the heart from the permanent loss of mechanical function that can result from temporary ischemia. This specific protection does not seem to involve an increase in blood flow to the myocardium.
• Crataegus increases blood flow into the myocardium of the left ventricle in dogs in a dose-dependent manner. Continued administration causes blood flow to rise toward a maximum level.
• Crataegus monogyna has exhibited a prophylactic anti-arrhythmic effect in studies involving rabbits.

Anti-Hyperlipidemia Effects

• Hawthorn has been used to lower significantly body weight, body fat, serum cholesterol, triglycerides, and LDL-C in rats.
• Crataegus oxyacantha extract has demonstrated, during in vitro and rat studies, the ability to reduce plasma and LDL –cholesterol by up-regulating hepatic plasma membrane LDL –receptors, thus increasing the influx of plasma cholesterol into the liver. Crataegus prevents the accumulation of cholesterol in the liver by increasing hepatic degradation of cholesterol into bile acids, increasing bile acid excretion, and reducing hepatic synthesis of new cholesterol. It is believed that these effects are the result of the synergistic interaction of a number of the major constituents of the plant.

Anti-Hypertensive Effects

• Hawthorn reduces resistance to blood flow in the peripheral vasculature.
• The hypotensive effects have been documented in vivo in dogs and in clinical trials.

Anti-Viral Effects

Crataegus extracts have demonstrated in vitro anti-viral effects against HIV.

Antioxidant

Phenolic proanthocyanidins and flavonoid constituents from the fresh young leaves, fresh floral buds, and pharmaceutical dried flowers have exhibited significant in vitro scavenging activity against reactive oxygen species.

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Dosage

Crataegus extract standardized to 1.8-2.0% vitexin, 450 mg three times a day.

Hawthorn Side Effects

• The oral acute toxicity dose has been determined to be 18-34 ml/kg and 50-2600 mg/kg respectively in rats. There is no clear information concerning chronic toxicity. No evidence of toxicity has been forthcoming at recommended doses in clinical experience.
• Overdosing symptoms and signs include hypotension, cardiac arrhythmias, sedation, dizziness, and tremor.
• Hawthorn is contraindicated in children under age 12 years and during pregnancy (at least during the first trimester).
• Heart rate and blood pressure should be monitored on a regular basis.

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Hawthorn Drug Interactions

• Crataegus extracts may potentate the effects of cardioactive glycosides. If hawthorn is used concurrently, the dosage of conventional drugs in this category (e.g., digoxin), as well as botanical medicines (e.g., Convallaria, Digitalis, and Cactus grandiflorus), will have to be reduced.
• Crataegus may have a hypertensive effect when used with beta-blockers.
• The use of anti-arrhythmia drugs concurrently with hawthorn is not prudent due to hawthorn’s own anti-arrhymic effects.
• Hawthorn inhibits the cellular influx of potassium. The simultaneous use of drugs having similar effects (potassium channel blockers) should be avoided.

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