Horse Chestnut

Scientific Name(s): Aesculus hippocastanum L. (horse chestnut), A. californica Nutt. (California buckeye), A. glabra Willd. (Ohio buckeye), A. turbinata Blume. Family: Hippocastanaceae.

Common Name(s): Buckeye , castanea equine , chestnut , California buckeye , horse chestnut , Japanese horse chestnut , Ohio buckeye , Semen hippocastani . Commercial preparations containing aescin include Aesculaforce and Essaven gel.

Uses

Oral horse chestnut seed extract is effective in the short-term treatment of mild to moderate long-term venous insufficiency. Other investigations focus on the role of the major component aescin in antiobesity and anti-inflammatory effects, as well as potential cancer treatment. Aescin gel has been evaluated for use in bruising.

Dosing

Aescin 20 to 120 mg taken orally has been used for venous insufficiency and is available in tablet form. Oral tinctures and topical gels containing aescin 2% are also available.

Contraindications

Renal or hepatic impairment may be relative contraindications to the use of aescin or horse chestnut derivatives.

Pregnancy/Lactation

Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

The most commonly cited adverse effects include nausea and stomach discomfort, which may be minimized by the use of film-coated tablets. Other mild and infrequent complaints include headache, dizziness, and pruritus. Rare cases of allergy and anaphylaxis have been reported.

Toxicology

All parts of plants in the Aesculus family are potentially toxic, especially the seeds (nuts). Horse chestnut has been classified by the Food and Drug Administration (FDA) as an unsafe herb.

Botany

Members of the genus Aesculus grow as trees and shrubs, often attaining heights of 23 meters. The fruit is a capsule with a thick, leathery husk that contains 1 to 6 dark seeds (nuts). As the husk dries, the nuts are released. The pink and white flowers of the plant grow in clusters. The tree is native to the woods of the Balkan region of southeastern Europe and to western Asia, but is now cultivated worldwide. The dried ripe seeds of the plant are of most medicinal interest. 1 , 2 , 3

History

Because of their prevalence, chestnuts have been used in traditional medicine and in a variety of commercial applications for centuries. Extracts of the bark have been used as a yellow dye, and the wood has been used for furniture and packing cases. In the western United States, the crushed, unripe seeds of the California buckeye were scattered into streams to stupefy fish, and leaves were steeped as tea to remedy congestion. The horse chestnut has been used as a traditional remedy for arthritis and rheumatism, as well as for gynecological bleeding and as a tonic.

Even though the seeds are toxic, several traditional methods were employed to rid them of their toxicity. Seeds were buried in swampy, cold ground during the winter to free them of toxic, bitter components, and then eaten in the spring after boiling. American Indians roasted the poisonous nuts, peeled and mashed them, and then leached the meal in lime water for several days, creating a meal used to make bread. 3 , 4 , 5 , 6

Chemistry

The seeds of Aesculus contain a variety of complex constituents. The seed oil contains 65% to 70% oleic acid. The seeds contain protein, ash, and 74% carbohydrate, and triterpene oligoglycosides from horse chestnut seeds have been isolated.

The main active constituents isolated from horse chestnut are aescin (10%) and prosapogenin. Aescin (escin) is a mix of the triterpene saponins alpha- and beta-aescin and cryptoaescin.

Bioflavonoids present include quercetin and kaepferol, and their derivatives. Antioxidants, such as proanthocyanidin, and coumarins, including the toxic esculin, as well as fraxin and pavietin, are also found in the Aesculus genus.

Specific assays have been described to quantify the aescin content of preparations, including high-pressure liquid chromatography, thin-layer chromatography, and mass spectroscopy. 3 , 7 , 8 , 9 , 10

Uses and Pharmacology

Circulation

Meta-analyses and systematic reviews have consistently concluded that oral horse chestnut seed extract is safe and effective for the short-term treatment (up to 16 weeks) of mild to moderate long-term venous insufficiency. 7 , 11 , 12 , 13

Leg pain was significantly reduced ( P < 0.05) in 6 of 7 trials (N = 543) for the extract versus placebo, and in the seventh trial improvement versus baseline was reported. In 4 of 6 trials (N = 461) edema was reduced compared with placebo, reduced from baseline in another trial, and not different from compression in the final study. 11

In vitro and animal studies, as well as leg elevation studies, have demonstrated the antiedematous and venotonic effect of the extract. Suggested mechanisms of action include inhibition of the enzymes elastase and hyaluronidase, prevention of leukocyte activation, and influence on capillary filtration. 3 , 7 , 11 , 14 , 15

Horse chestnut seed extract has been shown to be effective in reducing symptoms in hemorrhoids (bleeding and swelling), bruising (pain and swelling), and postoperative edema in limited clinical trials. 3 , 7 , 16 Beta-aescin may have a potential antiedematous role in the management of Bell palsy; however, clinical studies are lacking. 17

Other uses
Anti-inflammatory

Inhibition of cyclooxygenase activity of Japanese horse chestnut seed extract has been demonstrated in animal experiments. 15 , 18 , 19 The bark of Aesculus is also reported to possess the anti-inflammatory steroids stigmasterol, alpha-spinasterol, and beta-sitosterol. 20 , 21

Cancer

Beta-aescin has been evaluated in a number of in vitro studies and animal experiments for antiproliferative, apoptotic, and growth-inhibiting activities. 22 , 23 , 24 Reductions in the number of aberrant crypt foci, as well as deceased tumor growth, has been demonstrated in rats with induced colon cancer. 22 , 24 The presence of an acyl group on other chemical constituents of horse chestnut seed extract may be important. 25 Antioxidant and antimutagenic effects have also been described. 26 However, an article from one of these research groups has been withdrawn. 27

Obesity

Seed extract of Japanese horse chestnut has been evaluated by a limited number of researchers for antiobesity effects. Inhibition of pancreatic lipase in vitro has been demonstrated, leading to suggestions of an antiobesity mechanism of delayed intestinal absorption of dietary fat. Studies have shown the extract to prevent weight gain in high-fat diet mice, as well as decreased adipose tissue content and plasma triglycerol. 28 , 29 , 30 In one of the animal experiments, blood glucose was reduced following a single dose of extract. 28

Dosage

Horse chestnut extracts typically are standardized on content of triterpene glycosides, calculated as the major component aescin.

Oral doses of standardized powdered extract 250 to 312.5 mg (equivalent to aescin 100 mg) twice a day have been cited in the Complete German Commission E Monographs . 3

Aescin 20 and 50 mg tablets are available. Doses of aescin 20 to 120 mg taken orally have been used for venous insufficiency. 11 , 31

Duration of use for the seed extract in clinical trials has been from 2 to 16 weeks, with steady state being attained after 8 twice-daily dosing intervals. 11 , 32 , 33

Intravenous aescin (5 to 10 mg) has been used in trials of postoperative edema. 7 Oral tinctures and topical gels containing aescin 2% are also available. 3 , 31

Pregnancy/Lactation

Horse chestnut seed extract has been used in clinical trials including pregnant women with no apparent ill effects; however, in the absence of specific safety data, use in pregnancy or lactation is not recommended. 3

Interactions

Because case reports of toxic nephropathy with high-dose aescin exist, horse chestnut extracts should not be coadministered with other nephrotoxic drugs such as gentamicin. 3

The coumarin derivatives found in horse chestnut extracts may potentiate warfarin, as well as interfere with highly plasma-bound drugs. 12 , 34 , 35

The possibility of interference with CYP34A metabolism and P-glycoprotein transport mechanisms of other drugs exists. 36

Adverse Reactions

Renal or hepatic impairment may be relative contraindications to the use of aescin or horse chestnut derivatives. 12 The issue of renal toxicity is uncertain. Trials conducted in the 1970s suggest aescin from whole horse chestnut extract is not toxic to the renal system; however, caution is still recommended. 7

The most commonly cited adverse effects include nausea and stomach discomfort, which may be minimized by the use of film-coated tablets. 3 , 11 , 31 , 33 Other mild and infrequent complaints include headache, dizziness, and pruritus. 7 , 11 Rare cases of allergy and anaphylaxis have been reported. 3 , 7

Because hypoglycemic effects have been reported, asecin preparations should be used with caution in persons with diabetes. 12 , 28 , 37

Toxicology

Because Aesculus (horse chestnut) is classified by the FDA as an unsafe herb, all members of this genus should be considered potentially toxic. 6

Toxic properties have been attributed to a number of components, including glycosides and saponins. Potential toxins identified in the genus include nicotine, quercitin, quercitrin, rutin, saponin, and shikimic acid. The most important toxic principle is esculin. The nut is the most toxic part of the plant. Poisoning is characterized by muscle twitching, weakness, lack of coordination, pupil dilation, vomiting, diarrhea, depression, paralysis, and stupor. Children have been poisoned by drinking tea made from the leaves and twigs, and by eating the seeds; deaths have been reported following such ingestion. Amounts as little as 1% of a child's weight may be poisonous. Gastric lavage and symptomatic treatment have been suggested. 6 , 38

A 30% ethanol extract of the seed was not mutagenic in the Salmonella test, and a 40% extract was not teratogenic or embryotoxic in rats or rabbits. Decreased birth weight has been observed in rabbits, while sodium aescinate had no effect on the fertility of male rats. 3 High lead levels are found in horse chestnut plants of Brazilian origin. 39

Bibliography

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