Chai Hu

BUPLEURI RADIX (柴胡, Chaihu) Chinese Thorowax Root Bupleurum chinense DC. or Bupleurum scorzonerifolium Willd. (Fam. Umbelliferae). According to the botanical origin and morphological characteristics, the former is known as Beichaihu (Northern Chinese Thorowax Root) and the latter as Nanchaihu (Southern Chinese Thorowax Root). The drug is collected in spring or autumn, removed from the aerial parts and soil, and dried. Description Beichaihu Cylindrical or elongated conical, 6–15 cm long and 3–8 mm in diameter. Rootstock enlarged, apex bearing 3–15 stem bases or short fibrous leaf bases. Lower portion branched. Externally blackish-brown or pale brown, with longitudinal wrinkles, rootlet scars, and lenticel-like protuberances. Texture hard and tough, difficult to break. Fracture fibrous. Bark pale brown. Wood yellowish-white. Odour slightly aromatic. Taste slightly bitter. Nanchaihu More slender and conical. Apex bearing numerous hairy fibres from withered leaves. Usually unbranched or only slightly branched at the lower part. Externally reddish-brown or blackish-brown. Dense transverse annulations present near the rootstock. Texture somewhat soft. Easily broken. Fracture relatively even and non-fibrous. Odour rancid. Identification Beichaihu To 0.5 g of the powder add 20 mL of methanol. Ultrasonicate for 10 minutes. Filter. Concentrate the filtrate to about 5 mL as the test solution. Prepare a solution of 0.5 g of Beichaihu Reference Drug in the same manner as the reference drug solution. Dissolve Saikosaponin a CRS and Saikosaponin d CRS in ethanol to prepare a mixed solution containing 0.5 mg of each per mL as the reference solution. Carry out the method for Thin-Layer Chromatography (0502) using silica gel G as the coating substance and a mixture of ethyl acetate, ethanol, and water (8:2:1) as the mobile phase. Apply separately 5 μL of each of the three solutions to the plate. After development, remove the plate and dry in air. Spray with 2% p-dimethylaminobenzaldehyde in 40% sulfuric acid solution. Heat at 60°C until the spots become clearly visible. Examine in daylight and under ultraviolet light (365 nm). The spots and fluorescent spots obtained with the test solution correspond in position and colour to those obtained with the reference drug solution and the reference solution. Water Not more than 10.0% (0832, Method 2). Total Ash Not more than 8.0% (2302). Acid-insoluble Ash Not more than 3.0% (2302). Extractives Carry out the method for determination of ethanol-soluble extractives (2201, Hot Extraction Method) using ethanol as the solvent. Not less than 11.0%. Assay Beichaihu Carry out the method for High-Performance Liquid Chromatography (0512). Chromatographic system and system suitability Use octadecylsilane-bonded silica gel as the stationary phase. Mobile Phase A: Acetonitrile Mobile Phase B: Water Gradient elution: Time (min) Mobile Phase A (%) Mobile Phase B (%) 0–50 25 → 90 75 → 10 50–55 90 10 Detection wavelength: 210 nm. The number of theoretical plates shall be not less than 10,000, calculated with reference to the saikosaponin a peak. Reference solution Accurately weigh Saikosaponin a CRS and Saikosaponin d CRS. Dissolve in methanol to prepare a mixed solution containing: Saikosaponin a: 0.4 mg/mL Saikosaponin d: 0.5 mg/mL Test solution Accurately weigh 0.5 g of the powder (through No. 4 sieve) into a stoppered conical flask. Add accurately 25 mL of methanol containing 5% Strong Ammonia TS. Stopper tightly. Ultrasonicate (200 W, 40 kHz) at 30°C for 30 minutes. Filter. Wash the flask and residue twice with a total of 20 mL of water. Combine the filtrate and washings. Evaporate to dryness. Dissolve the residue in methanol. Transfer to a 5 mL volumetric flask. Dilute to volume with methanol. Mix well. Filter. Use the subsequent filtrate as the test solution. Procedure Inject accurately 20 μL of the reference solution and the test solution into the chromatograph. Determine and calculate the content. The drug contains not less than 0.30% of the total amount of Saikosaponin a (C₄₂H₆₈O₁₃) and Saikosaponin d (C₄₂H₆₈O₁₃), calculated with reference to the dried drug. Prepared Slices Beichaihu Processing Remove foreign matter and stem remnants. Wash clean. Soften thoroughly. Cut into thick slices. Dry. Description Irregular thick slices. Outer surface blackish-brown or pale brown with longitudinal wrinkles and rootlet scars. Cut surface pale yellowish-white and fibrous. Texture hard. Odour slightly aromatic. Taste slightly bitter. Identification As required for Beichaihu. Water, Total Ash, Acid-insoluble Ash, and Extractives As required for Beichaihu. Assay As required for Beichaihu. Beichaihu (Processed with Vinegar) Stir-bake the slices of Beichaihu according to the method for stir-baking with vinegar (0213) until dry. Description Similar in shape to the crude slices. Outer surface pale brownish-yellow. Slight vinegar-like aroma. Taste slightly bitter. Identification As required for Beichaihu. Water, Total Ash, and Acid-insoluble Ash As required for Beichaihu. Extractives Not less than 12.0%, following the method for Beichaihu. Assay As required for Beichaihu. Nanchaihu Processing Remove foreign matter. Wash clean. Soften thoroughly. Cut into thick slices. Dry. Description Subrounded or irregular thick slices. Outer surface reddish-brown or blackish-brown. Dense transverse annulations or hairy remnants of leaves sometimes present on the rootstock. Cut surface yellowish-white and even. Odour rancid. Nanchaihu (Processed with Vinegar) Stir-bake the slices of Nanchaihu according to the method for stir-baking with vinegar (0213) until dry. Description Similar in shape to the crude slices. Slight vinegar-like aroma. Property and Flavor Mildly cold; pungent and bitter. Meridian Tropism Liver, Gallbladder, and Lung meridians. Actions To release the exterior and reduce fever, soothe the liver and relieve constraint, and raise yang qi. Indications Common cold with fever, alternating chills and fever, distending pain in the chest and hypochondrium, irregular menstruation, uterine prolapse, and rectal prolapse. Administration and Dosage 3–10 g. Precautions and Warnings The dried rhizome of Bupleurum longiradiatum Turcz., characterized by numerous annular nodes on the outer surface, is poisonous and must not be used as Bupleuri Radix. Storage Preserve in a well-ventilated, dry place, protected from insects.