Clove is the dried flower bud of Eugenia caryophyllata Thunb. (Fam. Myrtaceae). The drug is collected when it turns from green to brick-red, and dried in the sun.
Description Pestle-shaped, 1-2 cm long. Corolla globular, 0.3-0.5 cm in diameter, petals 4, imbricated, dark brown to brownish-yellow, enclosing stamens and style. After rubbing into pieces, numerous yellow and granular anthers visible. Calyx tube cylindrical, slightly flattened, sometimes slightly curved, 0.7-1.4 cm long, 0.3-0.6 cm in diameter, reddish-brown or dark brown, sepals 4, triangular, occurring at the upper part, separating in cruciform. Texture hard, oily. Odour, strongly aromatic; taste, pungent and numb.
Identification (1) Transverse section of the middle of calyx tube: Epidermal cells 1 row, with relatively thick cuticle. Oil cavities 2-3 rows, longitudinally elongated-elliptical, 150-200 mm long, scattered in the outer part of cortex. 20-50 small bicollateral vascular bundles underneath, arranged in an interrupted ring and surrounded by few pericyclic fibres, with thickened and lignified walls. Aerenchyma consisting of several layers of parenchymatous cells, occurring in the inner part, with large intercellular space. Numerous small vascular bundles scattered in the stele parenchyma. Parenchymatous cells consisting of numerous fine clusters of calcium oxalate.
Powder: Dark reddish-brown. Fibres spindle-shaped, apex obtusely rounded, with thickened walls. Pollen grains numerous, triangular in polar view and two convex lenseshaped in equatorial surface view, with 3 furrows. Clusters of calcium oxalate numerous, 4-26 mm in diameter, occurring in relatively small parenchymatous cells. Oil cavities frequently broken, dividing lines of secretory cells indistinct, containing yellow oil.
(2) To 0.5 g of the powder add 5 ml of ether, shake for several minutes, filter, the filtrate is used as the test solution. Dissolve eugenol CRS in ether to produce a solution containing 16 ml per ml as the reference solution. Carry out the method for thin layer chromatography (Appendix VI B), using silica G as the coating substance and a mixture of petroleum ether (60-90oC)-ethyl acetate (9:1) as the mobile phase. Apply 5 ml of each of the two solutions to the plate. After developing and removal of the plate, dry it in air, spray with 5% solutions of vanillin in sulfuric acid and heat at 105oC. The spot in the chromatogram obtained with the test solution corresponds in position and colour to the spot obtained with the reference solution.
Foreign matter Not more than 4% (Appendix IX A).
Water Carry out the method for determination of water (Appendix IX H, method 2), not more than 12.0%.
Assay Carry out the method for gas chromatography (Appendix VI E), using a column packed with 10% polyethylene glycol (PEG)-20M as the stationary phase and maintain the column temperature at 190oC. The number of theoretical plates of the column is not less than 1 500, calculated with reference to the peak of eugonol.
Reference Preparation Dissolve a quantity of eugenol CRS, accurately weighed, in hexane to produce a solution of 2 mg per ml.
Test Preparation To about 0.3 g of the powder (through No.2 sieve), accurately weighed, add 20 ml of hexane, accurately measured, weigh and sonicate for 15 minutes, allow to cool to room temperature and weigh again, make up the loss in weight with hexane to the initial weight and mix well, filter.
Procedure Inject separately 1 ml of each of the two solutions, accurately measured, into the column. Calculate the content of C10H12O2.
It contains not less than 11.0% of eugenol (C10H12O2).
Processing Eliminate foreign matter and sift the dust. Pound to pieces before use.
Action To warm the spleen and stomach, to regulate the adverse flow of the stomach qi, and to restore the kidney yang.
Indications Hiccup, vomiting, anorexia, diarrhea and epigastric and abdominal pain with cold sensation in deficiency-cold syndromes of the spleen and stomach; impotence due to deficiency of the kidney.
Usage and dosage 1-3 g
Precaution Incompatible with Radix Curcumae.
Storage Preserve in a cool and dry place.