Three Kinds of Peony; Mu Dan, Bai Shao and Chi Shao

Paeon, doctor who killed by his teacher, Asclepius

Mu Dan (Peony) and Shao Yao (White Peony) are two plants that have been deeply ingrained in Chinese and Korean culture, both for their aesthetic appeal and their medicinal properties. Both Mu Dan and Shao Yao have been revered as valuable medicinal herbs since ancient times. The scientific name for Shao Yao, 'Paeonia lactiflora,' is derived from Paeon, the Greek god of healing.  Paeon was a student of Asclepius, the god of medicine and healing. He was once instructed by Leto (Apollo's mother and goddess of fertility) to obtain a magical root growing on Mount Olympus that would soothe the pain of women in childbirth. Asclepius became jealous and threatened to kill his pupil. Zeus saved Paeon from the wrath of Asclepius by turning him into the peony flower. However, peony seeds were actually used by pregnant women in ancient times. In Homer’s Illiad, Paean was brought to treat Ares, the god of war, when he was wounded by Diomedes, the hero of the epic. In Homer’s other epic, The Odyssey, Paean also treated HADES after he was wounded by HERACLES‘ arrow. The word “Paean” became a common name for the god Apollo and then for ASCLEPIUS, the god of healing.

Mu Dan and Shao Yao

Mu Dan, or the tree peony, is believed to have been first cultivated for ornamental purposes in Chinese households during the Southern and Northern Dynasties in the 5th century. The popularity of the peony surged during the Tang Dynasty, leading to the widespread creation of peony gardens. In Korea, the story of Queen Seondeok of Silla and the peony is well-known. The queen, upon seeing a painting of a peony without a butterfly, remarked that the flower must lack fragrance. This was a misunderstanding, as in Chinese culture, the peony symbolizes wealth, while the butterfly represents longevity. The omission of the butterfly in the painting was intentional, as it signifies a wish for eternal wealth.

Shao Yao, or Paeonia lactiflora, is native to Tibet, Siberia, and the Korean Peninsula. Unlike the peony, which has maintained its status as a noble flower, Shao Yao has been a flower loved by the common people. While the peony is referred to as the 'king of flowers,' Shao Yao is called the 'minister of flowers.'

Mu Dan tree (left) and Shao Yao plant(right)

Despite their similarities, Mu Dan and Shao Yao are distinctly different plants. Mu Dan is a tree, while Shao Yao is a herb. They differ in their places of origin and blooming periods. The size of the flowers, the shape of the petals, the way the flowers wilt, and the timing of their blooming are all different. Even their fragrances are distinct, with Shao Yao having a sweet and refreshing scent similar to a rose.

In traditional Chinese medicine, the bark of the Mu Dan tree is used as a medicinal herb called Mu Dan Pi, and the root of Shao Yao is used under the name Bai Shao and Chi Shao. Mu Dan Pi is known for its properties of clearing heat, cooling blood, invigorating blood, dispelling blood stasis, dissipating swelling, and expelling pus. On the other hand, Bai Shao is known for nourishing blood, regulating menstruation, calming the liver, relieving pain, preserving yin, and stopping perspiration.

Mu Dan flower (left) and Shao Yao flower (right), both colors can be varied

The therapeutic use of Paeonia lactiflora, commonly known as peony, dates back to ancient China. The earliest recorded use as a medicinal substance appears in the "Mawangdui Fifty-two Disease Prescriptions" (771-476 BC). 

White and Red Peony in Pharmacopoeia

In the 2002 edition of the South Korean Pharmacopoeia, the distinction between white and red peony was removed, and both were unified under the term "peony." It is defined as the root of Paeonia lactiflora Pallas or other closely related species, containing more than 2.0% of the compound paeoniflorin.

In the 2000 edition of the Chinese Pharmacopoeia, white peony is the root of Paeonia lactiflora Pallas, harvested in summer or autumn, cleaned, boiled, and dried in the sun, containing more than 1.8% paeoniflorin. Red peony is the dried root of either Paeoniflorin lactiflora Pall. or Paeoniflorin veitchii Lynch, containing more than 0.8% paeoniflorin.

대한민국의 약전 2002년판에서는 백작약과 적작약의 구분을 없애고 작약으로 통일하였으며, 작약 Paeonia lactiflora Pallas 또는 기타 동속 근연식물(작약과 Paeoniaceae)의 뿌리로 지표물질 paeoniflorin 이 2.0% 이상 함유한다 하였다.

중국약전 2000년판에서 백작약은 Paeonia lactiflora Pallas의 뿌리를 여름이나 가을에 캐내어 씻고 頭尾와 가는 뿌리를 없애고 끓는 물에 삶은 뒤 껍질을 벗기고 햇볕에 말리거나, 이를 다시 삶고 햇볕에 말리고, paeoniflorin은 1.8% 이상이다. 

적작약은 芍藥 Paeoniflorin lactiflora Pall.이나 川芍藥 Paeoniflorin veitchii Lynch의 뿌리를 말린 것으로, 봄·가을에 캐내어 뿌리줄기와 수염뿌리와 흙을 없애고 햇볕에 말리며, paeoniflorin은 0.8% 이상이다. 이전판에는 P. obovata Maxim.(草작약)도 실려있었으나 삭제되었는데 paeoniflorin이 매우 적다. 川芍藥은 열매에 黃色絨毛가 있으므로 毛果赤芍이라고도 한다. 잎은 일반작약보다 좁다.

paeoniflorin 함량만으로 본다면 한국의 작약은 적작약과 백작약을 모두 포함하면서도 중국의 적작약이나 백작약보다 기준치가 높다. 그렇지만 paeoniflorin 함량이 多多益善인 것은 아니고 작약의 약효를 모두 대변하는 것도 아니다. 관상용 중에는 무려 6.0% 이상인 것도 있기 때문이다. 

일부에서는 백작약을 만드는 과정에서 껍질벗기고 물로 씻으면 paeoniflorin이 줄어들기 때문에 작약은 그대로 건조해야 한다는 주장을 한다.

하지만 백작약의 제법은 이미 1,000년전의 본초서에 수록되어있고, 사용목적도 적작약과는 달랐다.  paeoniflorin 함량에 근거하여 작약을 껍질벗기지 말자는 주장은 틀리다. 지표성분이 유효성분은 아니기 때문이다. 

Notable ancient Chinese medical texts, like Shennong Bencao Jing and Shanghan Lun, also mention its use. However, the clear distinction between red peony (Chi Shao) and white peony (Bai Shao) was not made at this time. The Variorum of the Classic of Materia Medica (480–498 AD) provides a mixed perspective on peony, acknowledging the existence of both Chi Shao and Bai Shao but offering no further explanation of their differences in medicinal properties or applications. It was only in the Suidang period when the first official Chinese pharmacopeia was published, loosely defining both Chi Shao and Bai Shao under the umbrella of peony (PLP).

神農本草經(shen nong bencao jing)에는 작약이 上品藥으로 수록되었으며 적백구분은 없었다. 적작약과 백작약의 구분은 陶弘景의 本草經集注에서 ‘今出白山, 蔣山, 茅山最好, 白而長大. 餘處亦有而多赤, 赤者小利’라 한 것이 처음이며, 다른 판본에서는 약효를 구분하여 적작약은 利小便, 下氣하고, 백작약은 止痛, 散血한다 하였다. 神農本草經에서는 작약을 맛은 쓰고 기운은 평하다 하였는데, 名醫別綠에서는 맛은 시고 기운은 평하면서 조금 차다고 하였다. 생것을 맛보면 대단히 쓰므로 신농본초경의 기술과 일치한다. 본초경집주는 현재 판본이 남아 있지 않다. 그 내용이 《證類本草》를 비롯한 여러서적에 기록되어 있을 뿐이다.

	Mu Dan Pi	Bai Shao	Chi Shao
Name in Chinese	牧丹皮	白芍	赤芍
Latin Name	Moutan Cortex	Paeoniae Radix alba	Paeoniae Radix rubra
Definition	Moutan root bark	White peony root	Red peony root
Temperature and Taste	Cold, bitter, acrid	Cool, sour, bitter	Cold, sour, bitter
Channels Entered	Heart, Liver, Kidney	Liver, Spleen	Liver, Spleen
Dosage	6~12g	6~15g	6~15g
Actions in Traditional Chinese Medicine	Clears heat and cools blood, invigorates blood and dispels blood stasis, dissipates swelling and expels pus	Nourishes blood and regulates menstruation, calms the liver, relieves pain, preserves yin and stops perspiration	Invigorates blood and relieves pain, clears heat and cools blood

The distinction in therapeutic use and properties between Chi Shao and Bai Shao began during the Northern Song Dynasty, as noted in the Kaibao Bencao (973–934 AD) and Taiping Shenghui Fang (978–992 AD). The differences and varying applications had a significant impact on the medical practices of the Jin and Yuan dynasties.

In the Ming and Qing dynasties, the Materia Medica of South Yunnan and Introduction to Medicine described Chi Shao and Bai Shao as two different compounds. These works also specified the organs targeted by these drugs and the processing methods used. Subsequent physicians built specific prescriptions based on this knowledge, further developing their use based on clinical experience.

Bai Shao and Chi Shao

Raw Materials of Chi Shao and Bai Shao

Chi Shao and Bai Shao originate from the root of the peony plant, sharing many common characteristics on a biological level.

Chi Shao is the dried root of the peony, predominantly sourced from wild plants. It is primarily produced in regions like Inner Mongolia, Heilongjiang, Liaoning, and Sichuan.

Bai Shao, on the other hand, undergoes a process of boiling and peeling before drying. This root is mainly cultivated and produced in Anhui, Zhejiang, and Hangzhou.

Today, the two variants are differentiated based on processing methods, whether they are wild or cultivated, regions of production, and constituent content, according to the Chinese Pharmacopoeia Commission (2015). Chi Shao, primarily from wild sources, does not undergo processing, while Bai Shao, mostly cultivated, requires a series of processing steps.

During the processing, volatile constituents can easily be lost, and chemical transformations can occur. Both Chi Shao and Bai Shao contain paeoniflorin and polyphenolic components, but the levels are higher in Chi Shao. However, Bai Shao has higher levels of albiflorin, oxypaeoniflorin, monoterpene glycosides(excluding paeoniflorin).

[4],[1]

[4], [2]

Additionally, Bai Shao undergoes fumigation with sulfur to enhance its appearance and preservation, which alters its chemical composition. For example, paeoniflorin sulfonate, not naturally occurring, can be detected in sulfur-treated Bai Shao. However, this fumigation alters the drug's pharmacokinetics and can potentially reduce its safety and efficacy. Therefore, sulfur fumigation is not recommended.

My humble Opinion about Bai Shao and Chi Saho

In China, the origin plants are considered different, while in Korea, the same plant is used, differentiated only by the presence or absence of the peel. Modern Chinese medicine teaches that white peony tonifies blood, while red peony invigorates blood. However, according to ancient texts, it is actually the white peony that invigorates blood.

The complexity of traditional herbs has increased in modern times, often without sufficient textual or clinical evidence to support such distinctions.

Pharmacological Action

a. Chi Shao: liver and cardiovascular system

Evidence suggests Chi Shao has various pharmacological actions, particularly protective effects on the liver and cardiovascular circulation. These protective effects are attributed to the presence of paeoniflorin, ethyl palmitate, and ethyl linoleate. Studies suggest that paeoniflorin in Chi Shao regulates glutathione and shows anti-fibrotic activity in the liver. In the cardiovascular system, paeoniflorin suppresses inflammation and iNOS signaling pathways. It alleviates myocardial infarction, cardiac hypertrophy, fibrosis, inflammation, and improves left ventricular function. It also lowers blood pressure and suggests a role in the relaxation of vascular smooth muscles.

b. Bai Shao: nervous and immune systems, anti-cholinergic activity

Bai Shao has various pharmacological effects, notably on the nervous and immune systems. It offers therapeutic effects such as neuroprotection, anti-depressant properties, sedation, analgesia, and anticonvulsant activities. Albiflorin, a major constituent of Bai Shao, reduces neuronal nitric oxide synthase (nNOS) levels and shows anti-cholinergic activity. Experimental data suggest that albiflorin has potential as an anti-depressant drug.

Shared pharmacological actions: Both Chi Shao and Bai Shao contain similar constituents, offering anti-inflammatory and anti-tumor activities, mainly due to the presence of paeoniflorin and paeonol.

In Modern TCM

a. Bai Shao, 白芍, Paeoniae Radix alba 

① Definition/ Temperature and Taste/ Channels entered/ Dosage

White peony root/ cool, sour, bitter/ Liver, Spleen/ 6~15g

② Actions

Nourishes blood and regulates menstruation 

Calms the Liver and relieves pain 

Preserves yin and stops perspiration 

b. Chi Shao, 赤芍, Paeoniae Radix rubra 

① Definition/ Temperature and Taste/ Channels entered/ Dosage

Red peony root/ cold, sour, bitter/ Liver, Spleen/ 6~15g

② Actions

Invigorates blood and relieves pain 

Clears heat and cools blood

	Chi Shao	Bai Shao
Origin	Dried root of peony	Root of peony after boiling and peeling
Source	Predominantly wild plants	Cultivated
Production regions	Inner Mongolia, Heilongjiang, Liaoning, and Sichuan	Anhui, Zhejiang, and Hangzhou
Processing	No processing	Requires boiling, peeling, and drying
Constituents	Higher levels of paeoniflorin and polyphenolic components	Higher levels of albiflorin, oxypaeoniflorin, monoterpene glycosides(excluding paeoniflorin)
Pharmacological Action	Liver and cardiovascular system protection	Therapeutic effects on nervous and immune systems, anti-cholinergic activity
Temperature and Taste	Cold, sour, bitter	Cool, sour, bitter
Channels Entered	Liver, Spleen	Liver, Spleen
Dosage	6~15g	6~15g
Actions in TCM	Invigorates blood and relieves pain, clears heat and cools blood	Nourishes blood and regulates menstruation, calms the liver, relieves pain, preserves yin and stops perspiration

Summary and Implications

In China, Bai Shao (White Peony) and Chi Shao (Red Peony) are differentiated by species.

In Korea, they are considered the same plant, distinguished only by the presence or absence of the peel.

In modern traditional Chinese medicine, Bai Shao is commonly taught as a herb that 'tonifies blood', while Chi Shao is taught as a herb that 'invigorates blood'. However, according to the 'Ben Cao Jing Ji Zhu(本草經集注)', a classic Chinese medical text, Chi Shao is described as a herb that 'promotes urine and descends qi', while Bai Shao is described as a herb that 'invigorates blood and stops pain'. This suggests that Bai Shao is actually the herb that 'invigorates blood'.

중국- 기원식물이 다르다

한국- 동일한 것을 사용한다. 시중에서는 껍질의 유무에 따라 나눈다.

흔히 현대 중의학에서 백작은 보혈(tonify blood)하고, 적작은 산혈(invigorate blood)한다고 가르친다. 그러나, 本草經集注에 따르면, 적작약은 promote urine and desced qi, 백작약은 invigorate blood and stop pain한다고 하였으니, 백작약이야말로 산혈하는 것이다. 

References

[1] Tan YQ et al. Efficacy, Chemical Constituents, and Pharmacological Actions of Radix Paeoniae Rubra and Radix Paeoniae Alba. Front Pharmacol. 2020 Jul 10;11:1054. doi: 10.3389/fphar.2020.01054. PMID: 32754038; PMCID: PMC7365904.

[2] Feng C, Liu M, Shi X, et al. Pharmacokinetic properties of paeoniflorin, albiflorin and oxypaeoniflorin after oral gavage of extracts of Radix Paeoniae Rubra and Radix Paeoniae Alba in rats. J Ethnopharmacol. 2010;130(2):407-413. doi:10.1016/j.jep.2010.05.028

[3] https://tnknam.tistory.com/933

[4] https://blog.naver.com/lefhod0706/222104017531

[5] https://www.joongang.co.kr/article/21613804#home