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         Caraway is the dried ripe fruit of Carum carvi L. (Family Umbelliferae), Herbarium Specimen Number:  see Additional information 1, Crude Drug Number:  DMSc 0434.

Constituents  Caraway contains volatile oil, of which (+)-carvone and (+)-limonene are its major components.  It also contains fixed oils, flavonoids, etc. 

Description of the plant  (Figs. 1a, 1b)  Perennial herb 15 to 100 cm tall; taproot cylindrical, up to 25 cm long; stem solitary, rarely 2 to 8, base without remnant sheaths, glabrous.  Leaves 2- to 3-pinnated, alternate, basal and lower leaves oblong-lanceolate in outline, 8 to 15 cm long, 3 to 8 cm wide, gradually reduced upwards, ultimate segments linear or linear-  lanceolate, 3 to 5 mm long, 1 to 2 mm wide; petiole sheathing, 5 to 8 cm long.  Inflorescence loose compound umbels, terminal.  Flower small; pedicel extremely unequal; sepal minute  or wanting; petals 5, pinkish or white, obovate with a narrower, inflexed apex; stamens 5, inserted around epigynous disk, alternating with the petals; ovary inferior, 2-loculed, ovule 1 per locule, stylopodium short conic, styles 2, short, spreading.  Fruit cremocarp, brown to dark brown, oblong to ovate, 3 to 4 mm long, consisting of 2 dry, 1-seeded, indehiscent mericarps, ridges prominent, carpophore 2-fid. 

Description  Odour and taste, aromatic and characteristic.

       Macroscopical  (Fig. 1a)  Cremocarp ovoid, 3 to 6 mm long, 1 to 2 mm wide; mericarp frequently separated, each being crescent shaped, slightly pubescent.  Dorsal side convex, brown, with 5 longitudinal ridges and at the summit with a short conical stylopodium; commissural side concave, brown, with persisting carpophore and pedicel. 

       Microscopical  (Figs. 2a, 2b)  Transverse section of the mericarp through the cotyledon shows epicarp, mesocarp, endocarp, spermoderm, endosperm, and cotyledon.  Epicarp, slightly elongated epidermal cells, covered with striated cuticle.  Mesocarp, several layers of elongated parenchyma cells with more or less collapsed cells; the ridge portions, small lignified fibrovascular bundles; vittae, large, elliptic, brown, lined by small epithelial secretory cells, 4 on dorsal side between the vascular bundles and 2 on commissural side. Endocarp, a layer of broad elongated cells.  Spermoderm, attached to the endocarp,  consisting of a layer of brownish, elongated cells with some collapsed cells.  Endosperm, thick-walled, polygonal cells containing oil globules, aleurone grains with rosette crystals. Cotyledon, small thin-walled cells containing oil globules and aleurone grains.

          Caraway in powder possesses the diagnostic microscopical characters of the unground drug.

Additional information

       1. Caraway plant is not native to nor commercially cultivated in Thailand. The plant yielding caraway fruit is here referred to the herbarium specimen, collector’s number J.F. Rock 14117, deposited at the Kew Herbarium (K), London, United Kingdom.  The  photographic illustration of the specimen can be seen at the Department of Medical Sciences Herbarium (DMSC), Nonthaburi, Thailand.

2. It is commonly used with other herbal drugs in Thai traditional herbal preparations. 

Packaging and storage  Caraway shall be kept in well-closed containers, preferably of metal or glass, protected from light and stored in a cool and dry place. 

Identification

       A. Add 5 mL of chloroform to 1 g of the sample, in powder, shake well, set aside for  30 minutes, and filter.  Allow 0.1 mL of the filtrate to dry and add a few drops of a 5 per cent w/v solution of vanillin in sulfuric acid:  a reddish brown colour develops and changes to red and to purple, consecutively.

       B. Mix 1 g of the sample, in powder, with 3 mL of ethanol, shake for 5 minutes and filter. To 1 mL of the filtrate, add 1 mL of dinitrophenylhydrazine TS1:  a turbid, orange-yellow solution is produced.

       C. Carry out the test as described in the “Thin-Layer Chromatography” (Appendix 3.1), using silica gel GF254 as the coating substance and a mixture of 90 volumes of toluene and  10 volumes of ethyl acetate as the mobile phase.  Apply separately to the plate, 2 μL each of solutions (A), (B) and (C).  Prepare solution (A) by shaking 500 mg of sample, in fine powder, with 5 mL of ethyl acetate for 3 minutes and filtering.  For solution (B), add 2 μL of carvone to  1 mL of ethyl acetate and mix.  For solution (C), add 40 μL of olive oil to 1 mL of ethyl acetate  and mix.  After removal of the plate, allow it to dry in air and examine under ultraviolet  light (254 nm), marking the quenching spots.  The chromatogram obtained from solution (A) shows a quenching spot (hR_f value 55 to 58) corresponding to the carvone spot from  solution (B).  Spray the plate with vanillin-sulfuric acid TS and heat at 110° for 10 minutes;  the spot due to carvone is purple.  One violet spot (hR_f value 83 to 85) corresponds to the triglycerides of olive oil from solution (C).  Other several spots are also observed  (Table 1); see also Fig. 3.

Water Not  more than 12.5 per cent v/w (Azeotropic Distillation Method, Appendix 4.12).

Foreign matter  Not more than 2.0 per cent w/w (Appendix 7.2).

Acid-insoluble ash  Not more than 1.5 per cent w/w (Appendix 7.6).

Total ash  Not more than 7.0 per cent w/w (Appendix 7.7).

Ethanol-soluble extractive  Not less than 5.5 per cent  w/w (Appendix 7.12).

Volatile oil Not less than 2.5 per cent v/w,  calculated on the anhydrous basis (Appendix 7.3H).  Use 20 g, in coarse powder, freshly prepared and accurately weighed.  Use 200 mL of water as the distillation liquid and a 500-mL round-bottomed flask.  Distil at a rate of 2 to 3 mL per minute for 4 hours.  Use 1.0 mL of xylene in the graduated tube.

Dose  0.5 to 2.0 g three times a day.