Black Walnut Bark

SCIENTIFIC NAME : Juglans Nigra

COMMON NAME : Black walnut

BOTANY

There are about 15 species of Juglans. "Wal­nuf' refers to several varieties, most commonly the En­glish or Persian walnut and the black walnut. Walnut trees have short trunks with round-topped crowns, and can grow to 45 m in height.

The black walnut is native to the deciduous forests of the eastern United States (c and Canada. Its wood is valued for its rich beauty and yields valuable lumber, prized for furniture, cabinets, and gun stocks. The fruit is an elongated drupe, containing a 4-ribbed edible nut within a thick, hard, black shell

HISTORY

Walnuts have been found in prehistoric de­posits dating from the Iron Age in Europe. They are mentioned in the Bible; King Solomon's nut garden dates back to 940 BC.4 Black walnuts were an important food for American Indians and early settlers. The genus name, "Juglans," comes from the Latin "Jovis glans," meaning "nut of Jupiter" or nut of the gods. Many legends have been associated with the walnut. Greeks and Ro­mans regarded it as a symbol of fertility. In the Middle Ages, walnuts were thought to ward off witchcraft, the evil eye, and epileptic fits, from evil spirits lurking in the walnut branches. Medicinal uses of walnuts included treatments for swollen glands, shingles, and sores. The oil was used for intestinal discomfort.

CHEMISTRY

Black walnuts contain juglone (5-hydroxy­1,4-naphthagulone) alpha hydro-juglone and its glycoside beta-hydrojuglone, caffeic acid, hyperin, kaempferol, and tannin.3 Ellagic acid is also present.3,5 Black walnuts contain 15 to 20 g of protein/100 g. Trace minerals present include 3 mg of iron and zinc, 2 mg of sodium, phosphorus, and magnesium.2,3,6 Black walnuts contain 678 to 694 calories/100 g. Fat (oil) content is 60%.2 Methyl 2-benzimidazolylcarbamate has been reported in black walnut fruit?

PHARMACOLOGY

Aside from the use of its wood as a valuable lumber, black walnut has been employed in other ways; extract of black walnut was used to dye the hairY skin, and clothing. Black walnut as a food is common, including its presence in baked goods, candies, and frozen foods.2,4 Even its shells, after hulling, have been used as fillers in glues, roofing materials, and tiles. They are also employed as stuffing for toys and as abrasives. Walnut shells are even burned for energy.

The black walnut is important for its nutritional value (see Chemistry). The nuts are high in calories, a good protein source, and rich in dietary fiber and essential fatty acids (EFAs), which protect against heart disease and reduce cholesterol. EFAs reduce platelet adhesion and may also playa role in reducing arrhythmias and cardiac arrest.8-11 Dietary fiber content not only helps reduce cholesterol but aids in relieving constipation.

Black walnut is beneficial in certain skin problems, includ­ing eczema, pruritus, psoriasis, and blistering.3,12 It has been used as an astrigent to shrink tissues and as a tonic restorative.3 Black walnut has been shown to kill skin parasites due to its disinfectant qualities. Constituent juglone is antimicrobial and antiparasitic.3,13 Black walnut has been used for warts. Eye irritations and styes have been relieved by black walnut as well? Internally, black walnut is beneficial for these same conditions. It is mentioned by many sources as a vermifuge. The anthel­mintic properties are said to be due to high tannin content. The bark (including kernel and green hull) has been used by Asians and certain American Indian tribes to expel worms. Other fungal and parasitic infections including ringworm and tapeworm have been eliminated by black walnut.1,12 Other uses for black walnut include reduction of fluid secretion in glandular disturbances, treatment of gout and rheumatism, and for purported anti-cancer ef­fects.3,14 The toxic nature of juglone makes it a possible candidate for chemotherapy.

No major human clinical trials regarding black walnut and its claimed uses have been found through a search of medical literature.

TOXICOLOGY

Juglone, the naphthaquinone found in black walnut and many others in the family Juglandaceae, is regarded as a toxin. Induced toxicosis in horses has been studied. Juglone 1 g orally administered in horses caused inconsistent mild signs of laminitis, in which inflammation of the feet around the hooves occurs, result­ing in lameness from the pain. Other studies have confirmed this type of toxicosis from black walnut,17,18 including a detailed description in a case report.19 In contrast, 1 report confirms the laminitis to be from black walnut but not from the constituent juglone, because the heartwood of black walnut, which is devoid of this com­ponent, was used 2O Black walnut's effects on equine