Chestnut trees are a familiar pretty sight on the streets and in parks all over the world. Once they used to grow only in the Balkan Mountains, in the South East of Europe.
How chestnut trees spread all over the world is not quite clear, but today they are found in every country with moderate climate. Chestnut tree is now an official symbol of Kiev, capital of Ukraine.
Horse chestnut trees got their name because they look very similar to oak and beech trees of the Fagaceae family, whose Latin name is Castanea. Oaks and beeches thrive in moderate climate too and some types of them bear fruit that look a lot like chestnuts. All 30-something types of edible chestnuts belong to this genus. Horse chestnut, however, does not. This tree is a very distant relative of ‘real chestnuts’, it is one of the Aesculus Hippocastanacea genus, commonly referred to as ‘horse chestnut family’.
Despite the name, horse chestnut fruit, especially green, are poisonous for horses and people. Raw seeds contain poison, affecting nervous system. Horse chestnut poisoning causes nausea and vomiting, sometimes convulsions and coordination loss with horses and people. Deer, however, are immune to the poison and eat horse chestnut fruit without any consequences.
The horse chestnut fruit extract is used both in cosmetics and medicine, and the history of its medical application is actually quite interesting.
Traditionally horse chestnut fruit were used to repel spiders (and it is still unknown, why of all insects it is the spiders who can’t stand it), and since varicose veins visible under the skin are often called ‘spider veins’, English doctors started applying chestnut pulp onto the skin of their patients with varicose veins dilatation. And it worked. Both small and large veins would become less visible, swelling and pain subsided. Horse chestnut very soon became a primary folk remedy for varicose veins and venous insufficiency.
When pharmacologists began researching the horse chestnut fruit, they discovered that about 20% of the fruit is made up of escin (or aescin), which is in fact a complex of triterpenic saponins, a mixture of 30 agents, primarily beta-escin, afrodescin, argirescin, and kryptoescin. The escin complex, as it turned out, has a vein strengthening and anti-inflammatory effect. And it is escin that makes the fruit poisonous, which is why its concentration in medicine is usually very small.
Besides escin, horse chestnut fruit contain many proanthocyanidins with anti oxidant action, and flavonoids, notably quercetin, isoquercetin, and rutin, same as in green tea. Flavonoids strengthen the blood vessels and reduce inflammation, among other things.
Another class of ingredients found in abundance in horse chestnut fruit is coumarins, namely esculin and fraxin. This makes horse chestnut similar to tonka beans, that were the first source of coumarin. Coumarins are aromatic molecules, widely used in perfumery, and also anticoagulants — the agents reducing the viscosity and coagulation of blood and lymph.
In 2001 Cochrane confirmed that horse chestnut extract works, which officially makes it a pharmaceutical substance with objectively and reliably proven efficacy — an extremely rare case for herbal preparations, and a practically unique one for cosmetic ingredients.
What it means is that the use of any external medicine with a proper concentration of horse chestnut will not only improve the look of the skin, but also be therapeutical for blood vessels and surrounding tissues.
By now it has been scientifically confirmed that horse chestnut extract has anti inflammatory, anti edematic, and vein strengthening (venotonic) effect.
Escin reduces the permeability of vascular walls and decreases the enzyme activity that destroys the proteins of the capillary walls, thus stopping liquids and electrolytes from permeating through vascular walls into the surrounding protein tissues. Calcium, remaining in the capillaries, enhances the regeneration process, and the syntheses of harmful substances reduces in the first days of use. And on top of this aescin decreases the activity of the enzymes destroying hyaluronic acid, one of the primary structural molecules of the skin. Hyaluronic acid retains water in all skin layers, and when it is destroyed, the skin’s dehydration brings about wrinkles, dryness and flakiness. When the hyaluronidase enzymes’ activity is suppressed, the skin quickly restores its thickness and resilience and instantly looks much better. The proanthocyanidins of horse chestnut act as free radicals trap, simultaneously suppressing the activity of the enzymes that destroy collagen and elastin, thus allowing the vascular walls of small capillaries to regenerate—and in time they can even make spider veins disappear completely. Recently it was confirmed that horse chestnut has an anti sun effect as well. The extract itself does not reduce the harmful impact of sun rays, but it enhances the efficacy of other protective ingredients significantly and preserves the integrity of the cell membranes’ lipids. When added to sun screens horse chestnut extract reduces the skin’s redness caused by the sun and speeds up the regeneration process after sun tanning.