Peony - Paeonia SPP - Monograph - uses in natural medicine

Alternative Medicine Review, Oct, 2001

Introduction

Peonies have provided useful medicine and attractive ornamental flowers for over 3,000 years in China and at least 500 in Europe. (1) There are four species of this Ranunculaceae family plant that are utilized in traditional Chinese medicine (TCM) under the general rubric of peony: Paeonia suffruticosa (tree peony), Paeonia lactiflora (Chinese peony), Paeonia veitchii (Chinese peony), and Paeonia obovata (Chinese peony).

For millennia, peony root has been used to treat wounds, fungal infections, pain, and spasmodic conditions in TCM. (1) In recent times, peony root has received growing research attention, primarily in Japan and China. It has a long history of use in Europe as well, particularly for spasmodic conditions. (2)

Description and Constituents

All three Chinese peony species are perennial and achieve heights up to nine meters (the tree peony is somewhat larger). They have alternate, elliptical, smooth-edged leaves growing on smooth stems bearing two or more flowers. The large blossoms of the Chinese peony can have a range of color and are generally 4-6 cm in diameter. (1) The roots of all peonies are large, straight, and firm with easily peeled bark that reveals a powdery underlayer when removed.

There are three possible medicines that are produced from peony plants in TCM. (3) P. suffruticosa (tree peony) bark of root provides mu dan pi, referred to below as tree peony. P. lactiflora, P. veitchii and P. obovata root with bark attached provides chi shao, referred to below as red peony. The root without the bark of these same three plants provides bai shao (white peony), although most often this medicine is derived from P. lactiflora. The color designation does not refer to the flowers of these plants (which are most commonly pink, red, purple, or white) but to the color of the root after processing.

White, red, and tree peony contain glycosides (most notably paeoniflorin), flavonoids, proanthocyanidins, tannins, terpenoids, triterpenoids, and complex polysaccharides that may all contribute to its medicinal effects. (3) Paeoniflorin has received the most research attention.

Mechanisms of Action

The exact mechanisms of action of peony constituents have not been determined in their entirety. Paeoniflorin, monoterpenoids, and other constituents in white and red peony have been shown to be spasmolytic. This is in part achieved by interfering with acetylcholine release into neuromuscular junctions (NMJ) associated with gut smooth muscle tissue. (4)

There is a great deal of synergism of activity between white or red peony and licorice (Glycyrrhiza uralensis, for which G. glabra can be substituted) -- the two components of shakuyaku-kanzo-to, a formula commonly used in Japanese and Chinese herbal medicine. One animal study found that peony extracts interfere with acetylcholine release into the NMJ while licorice extracts interfere with acetylcholine's activity in the NMJ. (5) An in vitro study found concentrations of paeoniflorin and glycyrrhizin (a major active glycoside in licorice) that individually were too low to inhibit muscle contraction were very active when applied simultaneously. (4)

Other actions possessed by peony extracts and their constituents in preclinical studies include the following: (1) improvement of memory; (6,7) (2) antioxidant activity; (8,9) (3) hepatoprotection; (10) (4) anti-atherosclerotic effects associated with lipid peroxidation inhibition; (11) (5) inhibition of hydrochloric acid secretion; (12) (6) anti-epileptic activity; (13) (7) appetite suppressant and metabolism stimulating activity; (14) (8) antimutagenic properties; (15) (9) protection of endothelium from negative effects of hyperlipidemia; (16) (10) platelet aggregation inhibition; (17) and (11) anticoagulation and fibrinolysis. (18,19) The complex polysaccharides of peony exert immunomodulating effects in vitro. (20)

Clinical Indications

Muscle Cramps

The efficacy of white peony for relieving muscle cramps of various types, particularly combined with licorice in the formula shakuyaku-kanzo-to, is supported by several clinical trials. In a double-blind, placebo-controlled trial involving 101 patients with muscle cramps due to hepatic cirrhosis, dried extract of shakuyaku-kanzo-to was significantly superior to placebo in relieving symptoms over a two-week period. (21) The dose in this study -- 2.5 g three times daily before meals -- was sufficiently high to induce signs of pseudoaldosteronism (edema and weight gain) in five patients (9%) receiving shakuyaku-kanzo-to, due to the high intake of licorice. Other uncontrolled trials have shown that skakuyaku-kanzo-to can help relieve muscle cramps in people with diabetes mellitus, (22) those undergoing dialysis, (23) in alcoholics, (24) and in people with cerebrovascular disease. (25)

Women's Health

Both white and red peony are commonly used for various women's health problems in TCM. There is evidence from preliminary clinical trials supporting their use in dysmenorrhea and polycystic ovary syndrome (PCOS). The TCM formula toki-shakuyaku-san -- containing white peony, Atractylodes lancea (red atractylodes) rhizome, Alisma plantago-aquatica (alisma; water plantain) rhizome, Poria cocos (hoelen) sclerotium, Cnidium monnieri (cnidium) rhizome, and Angelica dahurica (Chinese angelica) radix -- has been reported to alleviate pain in patients with primary dysmenorrhea in one double-blind clinical trial. (26) Shakuyaku-kanzo-to reduced dysmenorrhea in 60 percent of women with uterine fibroids in an open trial. (27) Shakuyaku-kanzo-to helped increase fertility in women with PCOS in another open clinical trial. (28) More research is warranted to clarify the exact role and degree of efficacy of white peony by itself and in combination formulae for these and other women's health concerns, particularly luteal dysfunction and menopausal symptoms. (29)