Tannin-containing herbs Witch hazel leaves

Tannin-containing herbs Witch hazel leaves

One of the most widely used herbs in this category is witch hazel leaves. Also known as hamamelis leaves, this herb consists of the dried leaves of Hamamelis virginiana L., a native American shrub or small tree of the

family Hamamelidaceae. The leaves contain 8–10 percent of a mixture of tannins consisting chiefly of gallotannins with some condensed catechins and proanthocyanins. 2

An aqueous or hydroalcoholic extract of witch hazel leaves contains large amounts of tannin and is an excellent astringent. Unfortunately, such preparations are not ordinarily available in the United States. The only common commercial product here is technically referred to as hamamelis water, witch hazel extract, or distilled witch hazel extract; however, in the vernacular it is known simply as witch hazel.

Distilled witch hazel extract is prepared by macerating in water and then steam distilling the recently cut, dormant twigs of the plant. Alcohol is then added to the distillate to obtain a final concentration of 14–15 per- cent. The FDA has declared this product, prepared according to the pro- cedure described in the National Formulary XI in 1960, under the colloquial designation “witch hazel,” to be a safe and effective astringent. Because the tannins are not carried over into the extract during the distillation process, the only plant constituent present is a trace of volatile oil too lim- ited in amount to exert any therapeutic influence. Whatever astringent activity is present—and that must be very limited indeed—can only be attributed to the 14–15 percent alcohol contained in the product.

Authentic (nondistilled) hydroalcoholic extracts of witch hazel leaves are, on the other hand, much more effective astringents and styptics. They are used as such or following incorporation into an ointment base to relieve local inflammation of the skin and mucous membranes and to treat hemorrhoids and varicose veins.

Witch hazel has a low toxicity profile, but internal use is not recom- mended. 3 A decoction can be prepared for external use as a poultice by using 5–10 heaping teaspoonfuls of finely chopped leaves to a cupful (240 mL) of water. Bring to a boil and simmer for five to ten minutes, and then strain.

Oak bark When this product was an official drug in the National Formulary, it was said to consist of the dried inner bark of the trunk and branches of the white oak, Quercus alba L., family Fagaceae. However, the barks of a num- ber of different oaks have been used medicinally, including Q. robur L., the British oak, and Q. petraea (Matt.) Liebl., the winter oak.

Oak bark has a highly variable total tannin content of 8–20 per- cent, which includes catechins, oligomeric proanthocyanidins, and

Chapter ten: Problems of the skin, mucous membranes, and gingiva 179 ellagitannins. For external use, a decoction is prepared from 2 teaspoon-

fuls of the coarsely powdered bark and 500 mL of water. After straining, this aqueous extract is applied directly to the affected skin, including the genital and anal regions of the body; it is also used as a mouthwash for inflammation of the mucous membranes of the oral cavity. 4

English walnut leaves The dried leaves of the English walnut, Juglans regia L., family Juglandaceae, contain about 10 percent of an ellagic acid–derived tannin and are there- fore utilized as a local astringent in a manner similar to that for the pre- ceding herbs. A decoction prepared by boiling 5 teaspoonfuls of the leaves in 200 mL of water and straining is applied to the affected skin three or four times a day. 5