Spasmolytic, Analgesic, Blood-Nourishing, Hepatoprotective and Antitumor Effects of Baishao (White Peony Root)

Baishao (White Peony Root) is the dried root of Paeonia lactiflora of the Ranunculaceae family, produced mainly in Zhejiang and Anhui; that from Zhejiang is considered the most authentic, and it is one of the famous "Eight Herbs of Zhejiang" (Baizhu, Baishao, Zhebeimu, Hangjuhua, Yuanhu, Xuanshen, Maidong, Yujin).

In materia medica textbooks, Baishao is classified among the blood-tonifying herbs of the tonifying category. It is bitter and sour in flavor, slightly cold in nature, and enters the Liver and Spleen meridians. It nourishes blood and softens the liver, astringes yin to stop sweating, softens the liver to stop pain, and anchors liver yang. It is used for sallow complexion from blood deficiency, irregular menstruation, flooding and spotting, spontaneous sweating, night sweating, distending pain in the chest and hypochondria, epigastric and abdominal pain, spasmodic pain of the limbs, and headache and dizziness due to liver yang ascending.

Before the Tang dynasty, Baishao and Chishao (Red Peony Root) were not distinguished and were together called Shaoyao. After the Tang and Song, they came to be regarded as two medicines. Although both are the dried root of Paeonia lactiflora of the Ranunculaceae, because their colors differ their effects also differ slightly, so they are subdivided. Baishao is white in color and chiefly tonifies and astringes; Chishao is red and chiefly drains and disperses. Chishao's main actions are to clear heat and cool the blood, and dissipate stasis to stop pain, entering the Liver meridian. Baishao is used when there is yin-blood deficiency, hyperactive liver yang, or hypochondriac pain due to liver-yin insufficiency; Chishao is used for heat in the blood with blood stasis and exuberant liver fire.

Baishao's spasmolytic and analgesic effects are remarkable. I once treated a cervical-cancer patient in Shanghai who, after radiotherapy, could not walk for five years and suffered leg pain; numerous methods failed to relieve it. I used Shaoyao Gancao Tang (Peony and Licorice Decoction), heavily dosing Baishao, and within a week the patient's spasms and pain were markedly relieved. This treatment left a deep impression on me; it made me personally understand why this formula was in antiquity called "the Staff-Casting Decoction" (describing how patients who walked with a staff could cast it aside after taking it). Thereafter, when treating spasmodic abdominal and leg pain, I often use Baishao at 30 g or more.

The TCM expression "softening the liver to stop pain," viewed from modern medicine, refers to Baishao's spasmolytic action. Animal experiments also show that Paeonia inhibits or relieves spasm of smooth muscle, markedly inhibits gastrointestinal bioelectricity, suppresses the spontaneous contraction of isolated guinea-pig small intestine and lowers its tone, and counteracts the contraction of isolated guinea-pig and rabbit small intestine induced by barium chloride; the effect is even more pronounced when Gancao (Licorice) is added. Baishao's analgesic effect is also marked; intragastric administration of Baishao decoction significantly inhibits the acetic-acid writhing response in mice.

Baishao's treatment of stomach pain has also been confirmed by modern pharmacological research. Baishao has anti-inflammatory and anti-ulcer effects and prevents stress ulcers in rats. It protects the liver and detoxifies: Baishao extract inhibits the liver injury and ALT elevation induced by D-galactosamine and aflatoxin B1 in rats, and the elevation of lactate dehydrogenase (LDH) caused by aflatoxin. Baishao also destroys aflatoxin, an important carcinogen that greatly damages the liver.

Baishao also has antimutagenic and antitumor effects. Its extract interferes with the enzyme activity of the S9 mix and inactivates the metabolites of benzo(a)pyrene (BAP), thereby inhibiting BAP mutagenesis. The gallic acid (GA) and pentagalloyl glucose (PGG) contained in Baishao inactivate BAP metabolism. Experiments on mouse P-388 leukemia cells show that Baishao enhances the antitumor effect of mitomycin C.

Baishao also inhibits the leukopenia caused by mitomycin, raises the platelet count, improves anemia from acute blood loss, dilates blood vessels and increases organ blood flow. Thus Baishao is indeed beneficial for improving the patient's hemogram; the traditional TCM claim that Baishao nourishes blood is scientifically sound.

Baishao has some side effects. Intraperitoneal injection of Baishao methanol extract at 6 g/kg caused suppression of spontaneous movement, piloerection, diarrhea and respiratory depression in rats and mice, with half the rats dying; however, intragastric doses above 2500 mg/kg produced no obvious toxic reaction, showing that Baishao taken orally as traditionally decocted is safe. Long-term intragastric administration to normal mice showed only the side effect of raised platelets.

According to the TCM eighteen-incompatibility mnemonic, "all shen, xin and shao rebel against Lilu," Baishao must not be used together with Veratrum (Lilu). But Veratrum is an emetic, unsafe in clinical use; now almost no doctor uses it, and many pharmacies simply do not sell it, so Baishao has essentially no opportunity to be combined with Veratrum. The Bencao Jing Jizhu (Collected Commentaries on the Materia Medica Classic) also records that Baishao "abominate Dendrobium and mirabilite, and fear nitrum, turtle shell and thistle," so it should not be combined with these. Because Baishao is slightly cold, patients with yang deficiency should not use it.

Baishao is one of the herbs in the famous blood-tonifying formula Siwu Tang (Four Substances Decoction: Shudi, Baishao, Danggui, Chuanxiong); when tonifying blood, stir-fried Baishao or wine-fried Baishao is usually preferable. When Baishao is combined with Cebai tan (Biota charcoal) in a 1:6 ratio, it can also treat abdominal pain from metrorrhagia in women; this formula both stops bleeding and stops pain, and when used for this purpose Baishao is best charred to enhance hemostasis. Baishao is also one of the chief herbs in Guizhi Tang, known as the number-one TCM formula; in Guizhi Tang the doses of Baishao and Guizhi are equal, and the formula chiefly uses Baishao's yin-astringing, sweat-stopping action to treat spontaneous sweating in taiyang wind-stroke syndrome. The aforementioned Shaoyao Gancao Tang is also a formula centered on Baishao; it not only softens the liver to stop pain, but later generations also use it to treat the excessive thirst caused by diabetes.