Bai Zhu

ATRACTYLODIS MACROCEPHALAE RHIZOMA (白术, Baizhu) Largehead Atractylodes Rhizome (Fam. Compositae) The drug is collected in winter when the lower leaves turn yellow and the upper leaves become withered and fragile. It is removed from the soil, dried in the sun or by baking, and the fibrous roots are then removed. Description Irregularly plump masses, 3–13 cm long and 1.5–7 cm in diameter. Externally greyish-yellow or greyish-brown, with wart-like protuberances, interrupted longitudinal wrinkles and grooves, and fibrous root scars. The apex usually bears remnants of stems and bud scars. Texture hard and not easily broken. Fracture uneven, yellowish-white to pale brown, scattered with numerous brownish-yellow oil cavities. Material dried by baking is horny, darker in colour, and often shows cracks on the cut surface. Odour faintly aromatic. Taste sweet, slightly pungent, and somewhat sticky on chewing. Identification (1) Powder Pale yellowish-brown. Minute needle crystals of calcium oxalate, 10–32 μm long, aggregated in parenchymatous cells; a few individual crystals up to 4 μm in diameter. Fibres yellow, mostly occurring in bundles, long fusiform, up to 40 μm in diameter, with fairly thick, lignified walls and distinct pit canals. Stone cells pale yellow, subrounded, polygonal, rectangular, rarely fusiform, 37–64 μm in diameter. Parenchymatous cells containing inulin with characteristic radial striations. Vessel elements short, reticulate or bordered-pitted, up to 48 μm in diameter. (2) To 0.5 g of the powder add 2 mL of n-hexane. Ultrasonicate for 15 minutes and filter. Use the filtrate as the test solution. Prepare a solution of 0.5 g of Atractylodis Macrocephalae Rhizoma Reference Drug in the same manner as the reference drug solution. Carry out the method for Thin-Layer Chromatography (0502), using silica gel G as the coating substance and a mixture of petroleum ether (60–90°C) and ethyl acetate (50:1) as the mobile phase. Apply separately 10 μL of each solution to the plate. After development, remove the plate, dry in air, spray with 5% vanillin in sulfuric acid solution, and heat until the spots become clearly visible. The spots in the chromatogram obtained with the test solution correspond in position and colour to those obtained with the reference drug solution. A characteristic pink principal spot (atractylone) appears in both chromatograms. Water Not more than 15.0% (0832, Method 2). Total Ash Not more than 5.0% (2302). Residual Sulfur Dioxide Carry out the method for determination of residual sulfur dioxide (2331). Not more than 400 mg/kg. Degree of Colouration Accurately weigh 1 g of the very coarse powder into a stoppered flask. Add 200 mL of 55% ethanol. Adjust to pH 2–3 with dilute hydrochloric acid. Shake continuously for 1 hour and filter. Transfer 10 mL of the filtrate into a colorimetric cylinder. Carry out the method for Determination of Solution Colour (0901, Method 1). The colour of the test solution shall not be darker than Standard No. 9 of the yellow colourimetric solution. Extractives Carry out the method for determination of ethanol-soluble extractives (2201, Hot Extraction Method) using 60% ethanol as the solvent. Not less than 35.0%. Assay Carry out the method for High-Performance Liquid Chromatography (0512). Protect the test solutions from light throughout the procedure. Chromatographic system and system suitability Use octadecylsilane-bonded silica gel as the stationary phase. Mobile phase: Methanol : Water = 79 : 21 Detection wavelength: 340 nm The number of theoretical plates shall be not less than 5000, calculated with reference to the atractylodin peak. Reference solution Accurately weigh Atractylodin CRS. Dissolve in methanol to prepare a solution containing 120 μg/mL. Test solution Accurately weigh 0.2 g of the powder (through No. 3 sieve) into a stoppered conical flask. Add accurately 50 mL of methanol. Weigh. Ultrasonicate (250 W, 40 kHz) for 1 hour. Cool and weigh again. Replace any loss in weight with methanol. Mix well and filter. Use the subsequent filtrate as the test solution. Procedure Inject accurately 10 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 atractylodin (C₁₃H₁₀O), calculated with reference to the dried drug. Prepared Slices Processing Atractylodis Macrocephalae Rhizoma Remove foreign matter. Wash clean. Soften thoroughly. Cut into thick slices. Dry. Description Irregular thick slices. Outer surface greyish-yellow or greyish-brown. Cut surface yellowish-white to pale brown, scattered with brownish-yellow oil cavities. Xylem shows distinct radial striations. Material dried by baking is horny, darker in colour, and often shows cracks. Odour faintly aromatic. Taste sweet, slightly pungent, and somewhat sticky on chewing. Identification As required for the crude drug, except for the powder. Water, Total Ash, Residual Sulfur Dioxide, Degree of Colouration, and Extractives As required for the crude drug. Atractylodis Macrocephalae Rhizoma (Processed with Bran) Place honey-fried bran into a hot pan. When smoke appears, add the slices of Atractylodis Macrocephalae Rhizoma. Stir-fry until the slices become yellowish-brown and emit a roasted aroma. Remove and sift off the bran. For every 100 kg of sliced Atractylodis Macrocephalae Rhizoma, use 10 kg of honey-fried bran. Description Similar in shape to the crude slices. Outer surface yellowish-brown. Scorched spots occasionally visible. Slight roasted aroma. Identification As required for the crude drug, except for the powder. Water, Total Ash, and Residual Sulfur Dioxide As required for the crude drug. Degree of Colouration The colour of the test solution shall not be darker than Standard No. 10 of the yellow colourimetric solution, following the method for the crude drug. Extractives As required for the crude drug. Property and Flavor Warm; bitter and sweet. Meridian Tropism Spleen and Stomach meridians. Actions To fortify the spleen, replenish qi, dry dampness, promote urination, stop sweating, and prevent miscarriage. Indications Spleen qi deficiency with poor appetite, abdominal distension, diarrhea, dizziness and palpitations due to retention of phlegm-fluid, edema, spontaneous sweating, and threatened miscarriage. Administration and Dosage 6–12 g. Storage Preserve in a cool, dry place, protected from insects.