Huang Lian (黄连) – Coptis Chinensis Franch.

Huang Lian (黄连) – Coptis Chinensis Franch.

Botanical Characteristics:

  • Plant Description: Coptis chinensis, a perennial herb from the Ranunculaceae family, features a yellow root, often branched with numerous fibrous roots. The leaves are long-petioled, thinly leathery, and ovate or pentagonal, with a heart-shaped base. The leaflets are deeply divided, with the middle segment being diamond-shaped or ovate and finely serrate with pointed teeth. The involucral bracts are narrow and deeply divided, while the sepals are yellow-green and lanceolate. The petals are line-shaped or lanceolate, and the fruit is elongated-oval.
  • Flowers and Fruits: The flowers bloom from February to March and fruit from April to July. The flower stalks (peduncles) range from 12 to 25 cm in height, and the inflorescences are cymes with 3-8 flowers. The involucral bracts are lanceolate and deeply divided, while the sepals are yellow-green, elliptical, and 9-12.5 mm long. The petals are linear or lanceolate, with a central nectar groove. The plant has about 20 stamens and 8-12 carpels. The achenes are 6-8 mm long, with 7-8 seeds that are brown, elongated-oval, approximately 2 mm long and 0.8 mm wide.

Growth Environment:

  • Adaptation: Huang Lian prefers cool, moist, and shaded environments, thriving in high-altitude areas with low temperatures and high humidity. It cannot tolerate strong sunlight and prefers shaded conditions. The root system is shallow, and it grows best in loose, fertile, and humus-rich surface soil. It is commonly found in high mountain forests.

Distribution:

  • Native Range: Huang Lian is native to China, particularly in Sichuan, Guizhou, Hunan, Hubei, and southern Shaanxi.

Propagation Methods:

  • Seed Propagation: Seeds are generally sown in the spring or autumn. In moist conditions, sowing is done around the spring equinox; in arid conditions, sowing should occur before the rainy season. Seeds should be soaked in 30°C water for 24 hours and then dried before sowing. If soil is dry and irrigation is not feasible, seeds should not be soaked to avoid loss of germination ability. In early September, seeds can be sown without pre-soaking. Furrows should be made 50 cm apart, seeds sown, covered with 3-5 cm of soil, and lightly tamped down. The seeding rate is 0.7-1 kg per mu, and for point sowing, seeds are planted 15 cm apart with 3-5 seeds per hole.
  • Division: Huang Lian can also be propagated by dividing the rootstock.

Medicinal Value:

  • Traditional Uses: Huang Lian root is a commonly used herb in traditional Chinese medicine. It is known for its bitter taste and cold nature, entering the Heart, Pericardium, Spleen, and Stomach meridians. It is used to clear heart heat, reduce fire, alleviate restlessness, and is beneficial for conditions such as stomach discomfort, diarrhea, and irritability.
  • Precautions: Huang Lian should be used with caution in cases of stomach deficiency, nausea, or diarrhea, and should not be used excessively. It is considered non-toxic but is extremely bitter and should be used under medical guidance.
  • Historical Texts: In “Bencao Gangmu” (Compendium of Materia Medica), Huang Lian is noted for its medicinal properties and its use in treating various conditions. The “Pearl Bag” text describes its six primary uses: clearing heart fire, eliminating damp-heat from the middle burner, treating various types of sores, relieving wind-damp conditions, treating acute conjunctivitis, and stopping bleeding in the abdominal region.

Huang Lian is a valuable and highly regarded medicinal herb, listed as a national secondary key protected medicinal material in 2021.

Distribution and Growth Habits of Huang Lian (黄连)

Distribution Range:

  • Geographic Distribution: Huang Lian is found in several provinces in China, including Sichuan, Guizhou, Hunan, Hubei, and southern Shaanxi. It grows in mountainous regions or shady valleys at altitudes ranging from 500 to 2000 meters. The type specimen was collected from Chongqing Chengkou.

Growth Habits:

  • Preferred Environment: Huang Lian thrives in cool, moist, and shaded environments, preferring temperatures between 1200 and 1800 meters above sea level with high humidity. It is sensitive to high temperatures and drought conditions and cannot tolerate strong sunlight, thus requiring shade.
  • Soil Requirements: The plant has a shallow root system that grows in the top 5-10 cm of soil. It prefers loose, fertile, and humus-rich soil with a pH of 5.5 to 6.5, indicating a preference for slightly acidic soils. It is commonly found in the cold, wet, and shaded forests of high mountains.

Medicinal Value and Uses

Medicinal Properties:

  • Traditional Uses: Huang Lian is known for its ability to clear heat, dry dampness, purge fire, and detoxify. It is used for conditions such as:
    • Damp-Heat Disorders: To treat fullness and discomfort due to damp-heat, vomiting, diarrhea, jaundice, high fever, and agitation.
    • Heart Fire and Restlessness: To relieve symptoms related to excessive heart fire and restlessness.
    • Blood Heat: To address symptoms such as bleeding and redness in the eyes, toothache, and diabetes.
    • Skin and External Applications: For treating eczema, moist sores, and ear infections.
  • Specific Preparations:
    • Alcoholic Huang Lian: Clears heat from the upper body, used for eye redness and mouth sores.
    • Ginger Huang Lian: Clears the stomach and stops vomiting, useful for conditions where cold and heat are mixed and damp-heat obstructs the stomach.
    • Evodia Huang Lian: Soothes the liver and stomach, used for liver-stomach disharmony and vomiting with sour taste.

Pharmacological Actions:

  • Antibacterial Effects: Effective against a range of bacteria.
  • Antifungal Effects: Demonstrates activity against fungi.
  • Antiviral Effects: Provides protection against certain viruses.
  • Anti-Amoebic Effects: Useful in combating amoebic infections.
  • Anti-Inflammatory and Antidiarrheal Effects: Reduces inflammation and alleviates diarrhea.
  • Cardiovascular Effects: Influences cardiovascular health.
  • Antipyretic Effects: Helps reduce fever.
  • Hypoglycemic Effects: Lowers blood sugar levels.
  • Hypolipidemic Effects: Reduces blood lipid levels.
  • Antioxidant Effects: Provides protection against oxidative stress.
  • Anti-Ulcer Effects: Aids in ulcer treatment.

Precautions and Toxicity:

  • Contraindications: Huang Lian should be used cautiously in individuals with stomach deficiency, diarrhea, and those with cold and weak spleen-stomach conditions.
  • Toxicity Information: Berberine, the primary alkaloid in Huang Lian, has a high safety margin. However, large doses or prolonged use may cause adverse effects such as gastrointestinal discomfort and heart toxicity. In animals, berberine’s lethal dose is relatively high, but caution is advised. Allergic reactions and side effects like itching, urticaria, and hypotension have been reported with berberine injections.

Historical Use and Chemical Composition

Historical Background:

  • Historical Records: Huang Lian is first recorded in “Shennong Ben Cao Jing” as a top-grade herb. Historical texts, such as “Bencao Gangmu,” describe its use and identify Sichuan as a major producing region. Other historical records mention its use in areas east of the Yangtze River and in Hunan and Anhui provinces.

Chemical Components:

  • Key Alkaloids: The rhizome of Huang Lian contains several important alkaloids, including:
    • Berberine: 5.56%–7.25%
    • Coptisine
    • Epiberberine
    • Berberrubine
    • Palmatine
    • Columbamine
    • Jatrorrhizine
    • Worenine
    • Magnoflorine
    • Ferulic Acid
    • Obakunone
    • Obakulactone

These components contribute to Huang Lian’s effectiveness in treating various conditions and its pharmacological actions.

Drug Identification

Physical Identification

The rhizome is often clustered with branching, curving, and massive, resembling an inverted chicken claw, commonly referred to as “chicken claw Coptis.” The single branches are cylindrical, 3–6 cm long, and 2–8 mm in diameter. The surface is gray-yellow or yellow-brown, with red-brown exposed areas where the outer skin has peeled off, rough, with irregular nodular elevations, root hairs, and root hair remnants. Some segments have smooth surfaces like stems, known as “bridges.” The upper part often retains brownish scales, and the top often has residual stems or leaf stalks. It is hard, with an irregular break surface; the skin is orange-red or dark brown, the wood is bright yellow or orange-yellow, and the pith is red-brown, sometimes hollow. It has a faint odor and is extremely bitter. [2]

Microscopic Identification

Cross-section of Rhizome:

  • Scale leaf tissue is often shed. The cork layer consists of rows of cork cells. The cortex is broad, with visible root and leaf vascular bundles; stone cells are yellow, scattered singly or in groups. The paper tube bundles are external and tough, arranged in intermittent ring-like patterns with indistinct cambium between the bundles. The outer part of the phloem contains fiber bundles, varying in size from several to dozens or even hundreds of fibers; some also contain yellow stone cells. The wood is yellow and fully lignified; wood fibers are well-developed. The pith sometimes contains a few scattered or clustered stone cells. Parenchyma cells contain starch grains. [2]

Powder Characteristics

The powder is yellow-brown or yellow.

  1. Stone cells are bright yellow, round, square, polygonal, or slightly elongated, 25–64 μm in diameter, up to 102 μm in length, with walls 9–28 μm thick, and distinct or layered pores.
  2. Wood fibers are numerous, yellow, and elongated; diameter 10–13 μm, with slightly thick walls and sparse pores.
  3. Phloem fibers are bright yellow, spindle-shaped or long fusiform, 136–185 μm long, 25–40 μm in diameter, with thicker walls and sparse pores.
  4. Vessels are primarily perforated and spiral, with diameters of 8–20 μm.
  5. Starch grains are mostly single, oval, kidney-shaped, spherical, or elliptical, 1–10 μm in diameter; compound grains are few, consisting of 2–4 components. Scale leaf epidermal cells are green-yellow or yellow-brown, slightly rectangular, with wavy curved walls. [2]

Physicochemical Identification

The broken surface of the substance shows golden-yellow fluorescence under ultraviolet light, with the wood part being particularly notable. [2]

Take about 1 g of the powder, add 10 ml of ethanol, heat to boiling, cool, filter, take 5 drops of the filtrate, add 1 ml of dilute hydrochloric acid and a small amount of bleaching powder, which turns cherry red; another 5 drops of the filtrate, add 2–3 drops of 5% gallnut acid ethanol solution, evaporate, and while hot, add a few drops of sulfuric acid, which turns dark green. (Check for Berberine) [2]

Take the powder or slices, add 1 drop of dilute hydrochloric acid or 30% nitric acid, after a moment, observe under the microscope, yellow needle-like crystal clusters will appear; heating causes the crystals to turn red and disappear. (Check for Berberine)

Thin-Layer Chromatography

Take about 1 g of the powder, add 10 ml of methanol, heat to boiling, cool, and filter. The filtrate is used as the sample solution. For comparison, use hydrochloric berberine, hydrochloric phellodendrine, hydrochloric coptidine, and hydrochloric magnolia alkaloid as reference substances, preparing a mixture containing 2 mg per ml in methanol. Apply 1–2 μl of the sample solution and 5 μl of the reference solution on a silica gel TLC plate. Develop using chloroform-methanol-ammonia (15:4:1), remove, and air dry. The chromatogram shows berberine and phellodendrine as yellow under natural light, coptidine as red-brown in the presence of ammonia, and magnolia alkaloid as colorless. Under ultraviolet light (254 nm), berberine and phellodendrine show bright yellow-green, magnolia alkaloid shows bright blue-purple, and coptidine shows dark spots. [2]

Product Specifications

  • First-grade Coptis: Often clustered, with robust and solid branches, containing bridges, and not exceeding 2 cm in length. Free from fragments less than 1.5 cm, residual stems, scorched parts, impurities, and mold.
  • Second-grade Coptis: Strips are smaller and thinner than first-grade, with bridges. Contains fragments, debris, and scorched parts. Other characteristics are similar to first-grade. [2]

Conservation Status

  • Conservation Level: Listed in China’s “National Secondary Protected Plants List.”