Chinese gall, also referred to as Chinese gallnuts (or nutgalls), is a plant excretion produced when irritants are released by the larvae of gall insects, such as those of the Cynipidae family, the gall wphps. A major commercial source of medicinal gallnuts is oak trees, which yield the Chinese herb moshizi, but a similar material is found on Chinese sumac (Rhus species), produced by the activities of a type of aphid; these galls are called wubeizi by Chinese herbalists.
The plant secretes the liquid gall, comprised mainly of tannins, that hardens to become the “nut.” Gallnuts are a native product of China and Southeast Asia, but are also produced in small amounts in Turkey, India, Japan, and Korea.
The annual yield of gallnuts in China is about 95% of the total world yield. Guizhou is the biggest gallnut-producing areas in China. hydrolyzable tannins are readily degraded into smaller molecules. Hydrolyzable tannins are present in many different plant species but are found in particularly high concentrations in nutgalls growing on Chinese.
The hydrolyzable tannins react with proteins to produce the typical tanning effect; medicinally, this is important for treatment of inflamed or ulcerated tissues. They also contribute to most of the astringent symptom noted when drinking tannin-containing beverages.
Tannin have been used to treat diseases in traditional medicine, the hydrolyzable tannins have long been considered official medicinal agents in Europe and North America. They have been included in many pharmacopoeias, in the older editions in particular, and are specifically referred to as tannic acid. These were recommended for treatment of inflammation and ulceration, including topical application for skin diseases and internal use for intestinal ulceration and diarrhea. Now, the condensed tannins also have important medicinal roles, such as stable and potent antioxidants. In China, tannin-containing substances, such as galls, pomegranate rinds, and terminalia fruits, are used in several medicinal preparations.
Chinese Herbal use of tannin-containing herbs that have tannins as their main component are astringent in nature and most such medicinals are listed in the Materia Medica category of astringents.
The most common applications are treating:
Intestinal disorders, such as diarrhea and dysentery, intestinal parasites, rectal prolapse, hemorrhoids; Bleeding, including functional bleeding, hematochezia (blood in the stool), bleeding hemorrhoids, and topically for bleeding wounds and ulcerations; and Excessive discharge, such as enuresis and frequent urination; leucorrhea; hyperhidrosis (excessive sweating) and night sweating; involuntary seminal emission.