Pericarpium Citri Reticulatae
Dried Tangerine Peel
Dried Tangerine Peel is the dried pericarp of the ripe fruit of Citrus reticulata Blanco or its cultivars (Fam. Rutaceae). The drug is subdivided into two classes, known respectively as “Chenpi”, and “Guang Chenpi”. The pericarp is peeled off when the fruit is ripe and dried in the sun or at a low temperature.
Description Chenpi often peeled in several lobes connecting at the base, or in irregular slices, 1-4 mm thick. Outer surface orange-red to reddish-brown, with fine wrinkles and sunken oil cavity spots; inner surface pale yellowish-white, rough, bearing yellowish-white or yellowish-brown vein-like vascular bundles. Texture slightly hard and fragile. Odour, aromatic; taste, pungent and bitter.
Guang Chenpi often in three lobes connected at the base, regular in shape and even in thickness, about 1 mm thick. The sunken oil cavity spots relatively large, transparent when observed against light. Texture slightly soft.
Identification (1) Powder: Yellowish-white to yellowish-brown. Parenchymatous cells of mesocarp numerous, cells irregular, with unevenly thickened walls, sometimes beaded. Epidermal cells of pericarp polygonal, subsquare or rectangular in surface view, anticlinal walls thickened, stomata subrounded, 18-26 mm in diameter, subsidiary cells indistinct; covered with cuticle in lateral view and the outer radial wall thickened. Numerous prisms of calcium oxalate containing in parenchymatous cells of the mesocarp, polygonal, rhombic or biconical, 3-34 mm in diameter, 5-53 mm long; sometimes two parallel polygonal crystals or 3-5 prisms occurring in one cell. Crystals of hesperidin mostly present in parenchymatous cells, yellow or colourless, in spheroid or amorphous masses, some crystals with radial striations. Spiral, pitted and reticulated vessels and tracheids small.
(2) To 0.3 g of the powder add 10 ml of methanol, heat under reflux for 20 minutes, filter. Condense 5 ml of the filtrate, to about 1 ml as the test solution. Dissolve hesperidin CRS in methanol to produce a saturated solution as the reference solution. Carry out the method for thin layer chromatography (Appendix VI B), using silica gel G containing 0.5% solution of sodium hydroxide as the coating substance and a mixture of ethyl acetate-methanol-water (100:17:13) as the mobile phase. Apply separately 2ml each of the two solutions to the plate. After developing about 3 cm and removal of the plate, dry it in air, and then use toluene-ethyl acetate-formic acid-water (20:10:1:1) as the mobile phase, after developing 8 cm and removal of the plate, dry it in air. Spray with a solution of aluminum chloride TS. The fluorescent spot in the chromatogram obtained with the test solution corresponds in position and colour to the spot in the chromatogram obtained with reference solution under ultraviolet light (365 nm).
Water Carry out the method for the determination of water (Appendix IX H method 2), not more than 13.0%.
Assay Carry out the method for high performance liquid chromatography (Appendix VI D).
Chromatographic system and system suitability Use octadecylsilane bonded silica gel as the stationary phase and a mixture of methanol-acetic acid-water (35:4:61) as the mobile phase. The wavelength of the detector is 283 nm. The number of theoretic plates of the column is not less than 2 000, calculated with the reference to the peak of hesperidin.
Preparation of reference solution Dissolve a quantity of hesperidin, accurately weight, in methanol to produce a solution containing 0.4 mg per ml and mix well.
Preparation of test solution Weight accurately 1 g of the coarse powder in a Soxhlet’s extractor, add 80 ml of petroleum ether (boiling range 60-90oC), heat under reflux on a water bath for 2-3 hour. Discard the petroleum ether extract and evaporate the residue to dryness, add 80 ml of methanol, further heat under reflux until the extract solution is colourless, cool and filter. Transfer the filtrate to a 100 ml of a volumetric flask, wash the container with a small quantity of methanol for several times, filter the washings to the same flask, dilute with methanol to volume, and mix well.
Procedure Inject accurately 5 ml of each of the reference solution and the test solution, separately into the column, determine and calculate the content.
It contains not less than 3.5% hesperidin (C28H34O15) on the dried basis.
Processing Eliminate foreign matter, spray with water, soften thoroughly, cut into slivers, dry in the shade.
Action To regulate the flow of qi, to invigorate the spleen function, to eliminate damp, and to resolve phlegm.
Indications Distension and fullness sensation in the chest and epigastrium with anorexia, vomiting and diarrhea; cough with copious phlegm.
Usage and dosage 3-9 g.
Storage Preserve in a cool and dry place, protected from mould and moth.
Note: The main cultivars are Citrus reticulata “Chachi” (Guang Chenpi), Citrus reticulata “Dahongpao”, Citrus reticulata “Unshiu” and Citrus reticulata “Tangerina”.