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        Cumin is the dried ripe fruit of Cuminum cyminum L. (Family Umbelliferae), Crude Drug Number:  DMSc 330.

Constituents  Cumin contains volatile oil, of which cuminaldehyde and p-cymene are its major components.  It also contains proteins, lipids, flavonoid glycosides, mucilage, etc.

Description of the plant  (Fig. 1)  Annual herb slender, erect, herbaceous, caulescent,  glabrous, 20 to 40 cm tall.  Basal leaves ovate in general outline, excluding the petioles 5 to 10 cm long, ternately dissected, the ultimate divisions linear-filiform, entire, 1 to 5 cm long; petioles sheathing, 1 to 2 cm long.  Inflorescence loose compound umbels; peduncle 2 to  10 cm long; involucre of 5 to 7 linear and entire or ternate bracts with linear divisions, unequal, 1 to 5 cm long; rays 2 to 6, 5 to 25 mm long, unequal; pedicel 2 to 8 mm long.  Flower small; sepal minute or wanting; petals 5, oblong with a narrower inflexed apex or emarginate, white or rose; stamens 5, alternating with the petals, inserted around an epigynous disc; ovary inferior, 2-celled, each cell 1-ovuled, styles 2, short stylopodium conic, attenuate into the rigid styles; carpophore 2-cleft to the base.  Fruit mericarp, ovoid- oblong, 4 to 5 mm long, glabrous or setulose  

Description  Odour, aromatic; taste, spicy.

      Macroscopical  (Fig. 1)  Entire cremocarp with pedicels attached, 4.5 to 7 mm long, 1.2 to 1.8 mm wide, oblong; mericarp, narrowly elliptical but slightly curved, covered with tiny bristly hair.  Dorsal surface convex, brown, with 5 lighter-coloured filiform  primary ridges, and at the summit with an acute conical stylopodium; secondary ridges occurred between each pair of primary ridges, covered with prominent bristles; commissural surface concave, brown. 

     Microscopical (Figs. 2a, 2b)  Transverse section of the mericarp through the cotyledon shows epicarp covered with striated cuticle; a layer of sinuous-walled epidermal cells; trichomes, multicellular, multiseriate, rounded at the apex.  Mesocarp, several layers of more or less collapsed, tangentially elongated parenchyma cells; each of the ridge,  sclerenchymatous cells and a lignified fibrovascular bundle; the dorsal side, 4 large  vittae located between the vascular bundles; the commissural side, 2 large vittae; each vitta, elliptical, brown, lined by small epithelial secretory cells.  Endocarp, a layer of tangentially elongated cells.  Spermoderm, a layer of brownish, tangentially elongated cells united with the endocarp except in the region of the raphe along the commissural side where separated by collapsed thin-walled cells.  Endosperm, thick-walled polygonal cells containing oil globules and aleurone grains with microcrystals.  Cotyledons, thin-walled cells containing aleurone grains and oil globules.

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

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

Packaging and storage  Cumin 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. 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.

       B. 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 95 volumes of toluene and  5 volumes of ethyl acetate as the mobile phase.  Apply separately to the plate, 10 μL each of solution (A) and solution (B).  Prepare solution (A) by shaking 1 g of the sample, in powder, with 5 mL of ethyl acetate for 2 to 3 minutes and filtering through 2 g of anhydrous sodium sulfate.  For solution (B), dissolve 2 μL of cuminaldehyde and 30 μL of olive oil in 5 mL of ethyl acetate.  After removal of the plate, allow it to dry in air and examine under ultraviolet light (254 nm).  The main quenching spot (hR_f value 49 to 52) obtained from solution (A)  corresponds to that of cuminaldehyde from solution (B).  Three other quenching spots,  one above and two below the main spot, are also observed.  Spray the plate with  dinitrophenylhydrazine TS1; the spot corresponding to cuminaldehyde appears orange while the others appear yellow (Table 1); see also Fig. 3. 

          Repeat the same procedure on another plate but spray with anisaldehyde TS and heat at 110° for 10 minutes. The chromatogram obtained from solution (A) shows a main violet spot (hR_f value 58 to 63) corresponding to triglycerides of olive oil from solution (B); other violet spots are also observed (Table 1); see also Fig. 3. 

Water  Not more than 10.0 per cent v/w (Azeotropic Distillation Method, Appendix 4.12).

Foreign matter  Not more than 3.0 per cent w/w of foreign matter including separated pedicels (Appendix 7.2).

Acid-insoluble ash  Not more than 1.0 per cent w/w (Appendix 7.6).

Total ash  Not more than 9.0 per cent w/w (Appendix 7.7).

Volatile oil  Not less than 2.5 per cent v/w (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 5 hours.  Use  2.0 mL of xylene in the graduated tube.

Dose  0.5 to 2 g.