Cao Wu (Zhi)

ACONITI KUSNEZOFFII RADIX (草乌, Caowu) Kusnezoff Monkshood Root (Fam. Ranunculaceae) The drug is collected in autumn when the aerial parts have withered, removed from the rootlets and soil, and dried. Description Irregularly long-conical, slightly curved, 2–7 cm long and 0.6–1.8 cm in diameter. The apex usually bears the remains of the stem and a few adventitious root bases. Sometimes the apex bears a withered bud on one side and a circular or oblate adventitious root scar on the other. Externally greyish-brown to blackish-brown, shrivelled, with longitudinal wrinkles, dotted rootlet scars, and several tubercular lateral roots. Texture hard. Fracture greyish-white to dark grey, often with fissures. Cambium ring polygonal or subrounded. Pith relatively large or hollow. Odour slight; taste pungent and numbing. Identification (1) Transverse section Metaderm consists of 7–8 layers of brownish-yellow suberized cells. Cortex contains stone cells, occurring singly or in groups of 2–5; cells subrectangular, square or oblong, with large lumina. Endodermis distinct. Phloem broad, usually with irregular clefts; groups of sieve tubes abundant. Cambium ring irregularly polygonal or subrounded. Xylem vessels arranged in 1–4 rows or several in groups, located inside each angle of the cambium, some containing brownish-yellow contents. Pith relatively large. Parenchymatous cells filled with starch granules. Powder Greyish-brown. Simple starch granules subrounded, 2–23 μm in diameter. Compound starch granules composed of 2–16 components. Stone cells colourless, but appearing brown when attached to fragments of the metaderm; subsquare, subrectangular, subrounded, fusiform, or elongated rectangular; 20–133 (234) μm in diameter and up to 465 μm long. Walls vary in thickness. The thicker-walled cells show distinct striations and fine pits. Some stone cells contain brown contents. Metaderm cells brown, subsquare or elongate-polygonal in surface view, with unevenly thickened walls; some are tuberculate and project into the lumen. (2) Macerate 1 g of the powder with 2 mL of Ammonia TS. Add 20 mL of ether, ultrasonicate for 30 minutes, and filter. Evaporate the filtrate to dryness. Dissolve the residue in 1 mL of a mixture of isopropanol and chloroform (1:1) as the test solution. Dissolve Aconite Diester-Alkaloids Reference Extract in a mixture of isopropanol and chloroform (1:1) to prepare a solution containing 3 mg of each alkaloid per mL as the reference extract solution. Carry out the method for Thin-Layer Chromatography (0502), using silica gel G as the coating substance and a mixture of n-hexane, ethyl acetate and methanol (6.4:3.6:1) as the mobile phase. Apply separately 5 μL of the test solution and 10 μL of the reference extract solution to the plate. Develop the plate in a chamber pre-equilibrated with ammonia vapour for 20 minutes. Remove the plate, dry in air, and spray with dilute potassium iodobismuthate TS. Examine in daylight. The spots in the chromatogram obtained with the test solution correspond in position and colour to those obtained with the reference extract solution. Foreign Matter Not more than 5.0% (2301). Water Not more than 12.0% (0832, Method 2). Total Ash Not more than 6.0% (2302). Assay 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: 0.2% glacial acetic acid solution, adjusted to pH 6.20 with triethylamine. Gradient elution: Time (min) Mobile Phase A (%) Mobile Phase B (%) 0–44 21 → 31 79 → 69 44–65 31 → 35 69 → 65 65–70 35 65 Detection wavelength: 235 nm. Theoretical plates: not less than 2000, calculated with reference to the mesaconitine peak. Reference extract solution Accurately weigh 20 mg of Aconite Diester-Alkaloids Reference Extract (labelled with the contents of mesaconitine CRS, hypaconitine CRS, and aconitine CRS). Transfer to a 10 mL volumetric flask. Dissolve with 0.01% hydrochloric acid in ethanol, dilute to volume, and mix well. Calibration standards Transfer accurately 1 mL of the reference extract solution into 2, 5, 10, and 25 mL volumetric flasks, respectively. Dilute each to volume with 0.01% hydrochloric acid in ethanol and mix well. Inject 10 μL of each solution. Plot calibration curves using the concentrations of mesaconitine, hypaconitine, and aconitine as the abscissa and their corresponding peak areas as the ordinate. Procedure Accurately weigh 2 g of the powder (through No. 3 sieve) into a stoppered conical flask. Add accurately 3 mL Ammonia TS and 50 mL of isopropanol–ethyl acetate (1:1). Weigh. Ultrasonicate (300 W, 40 kHz) for 30 minutes, maintaining the water temperature below 25°C. Cool and weigh again. Replace any lost solvent with the same solvent mixture. Mix well and filter. Measure accurately 25 mL of the filtrate and evaporate under reduced pressure below 40°C. Dissolve the residue with 0.01% hydrochloric acid in ethanol. Transfer to a 5 mL volumetric flask, dilute to volume, mix well, and filter. Inject 10 μL of the filtrate. Calculate the contents from the calibration curves. The drug should contain 0.15–0.75% of the total alkaloids consisting of aconitine (C₃₄H₄₇NO₁₁), hypaconitine (C₃₃H₄₅NO₁₀), and mesaconitine (C₃₃H₄₅NO₁₁), calculated with reference to the dried drug. Prepared Slices Aconiti Kusnezoffii Radix Cocta Processing Aconiti Kusnezoffii Radix (Unprepared) Remove foreign matter, wash clean, and dry. Description As required for the crude drug. Identification As required for the crude drug. Foreign Matter, Water, and Total Ash As required for the crude drug. Assay As required for the crude drug. Property and Flavor Hot; pungent and bitter; highly toxic. Meridian Tropism Heart, Liver, Kidney, and Spleen meridians. Actions To dispel wind, eliminate dampness, warm the meridians, and relieve pain. Indications Wind-cold-damp Bi syndrome, arthralgia, cold pain in the heart and abdomen, abdominal pain due to cold colic, and as an anesthetic for pain relief. Administration and Dosage Generally processed products should be used for oral administration. Precautions and Warnings The unprocessed drug should be used with extreme caution for oral administration. Contraindicated during pregnancy. Incompatible with: Pinelliae Rhizoma Trichosanthis Fructus Trichosanthis Semen Trichosanthis Pericarpium Trichosanthis Radix Fritillariae Cirrhosae Bulbus Fritillariae Thunbergii Bulbus Fritillariae Ussuriensis Bulbus Fritillariae Pallidiflorae Bulbus Fritillariae Hupehensis Bulbus Ampelopsis Radix Bletillae Rhizoma Storage Preserve in a well-ventilated, dry place, protected from insects.