Curcuma longa (rhizome)

Nomenclature

Curcuma longa L.   Zingiberaceae  
Syn. Curcuma domestica Valeton  
Standardized common name (English): turmeric  
Ayurvedic name(s): haridra  
Pinyin name(s): jiang huang; jiang huang (rhizome); yu jin (root tuber)

Botanical Voucher Specimen

Source: Encyclopedia of Life (Smithsonian Institution, National Museum of Natural History, Department of Botany)

Organoleptic Characteristics

Flavor Characteristic pungent taste. Source: Winton, A. (1916) Microscopy of vegetable foods, 2nd ed.

Macroscopic Characteristics

The main rhizome (round turmeric) is ovate or pear-shaped, up to 4 cm. long and 3. cm thick (Fig. 515). The upper part is encircled by leaf-scars, the lower part is marked by scars of the secondary rhizomes and roots. It is sliced before drying. The secondary rhizomes (long turmeric) are 0.5-1.5 cm. thick, elongated, indistinctly ringed, simple or sparingly branched. The vitality of the rhizomes is destroyed by scalding previous to drying, thus converting the grains into lumps, to which the mixture of oil and curcumin liberated from the oil cells imparts a deep yellow color. As found on the market, the product is hard, tough, and sinks in water. The fractured surface is smooth, waxy, of an orange-yellow color. As appears in cross section, the rind is thicker than in ginger, constituting almost one-quarter of the thickness of the rhizome. It cannot be removed by scraping. Source: Winton, A. (1916) Microscopy of vegetable foods, 2nd ed. Source: PlantaPhile Source: PlantaPhile Winton Fig. 515. Primary (round) and secondary (long) rhizomes. Source: Winton, A. (1916) Microscopy of vegetable foods, 2nd ed.

Microscopic Characteristics

Curcuma Starch (Curcuma longa, +). Elliptic granules, flat, contracted at one end; layers numerous, delicate, hilum small, at narrow end. Source: Culbreth, D. (1917) A Manual of Materia Media and Pharmacology, 6th ed. Turmeric (Fig. 516) closely resembles ginger in structure, but is distinguished by the absence of bast fibers. The epidermis, which in parts is well preserved, resembles that of Curcuma Zedoaria, and like the latter bears thick-walled unicellular hairs. The yellow lumps (h) consisting largely of starch-paste, are colored blue by iodine. On addition of dilute alkali the yellow coloring substance (curcumin) with which they are impregnated becomes brown-red. Concentrated sulphuric acid imparts a crimson color. In addition to the starch lumps, perfect starch grains are often present. These resemble the grains of ginger, but are usually longer (65 uM) and narrower, although some are broader than long. The parencymatous ground tissue, as well as the oil cells, is colored deep yellow. Neither the vessels (g) nor the cork-cells (K) are characteristic. Source: Winton, A. (1916) Microscopy of vegetable foods, 2nd ed. Thin walled parenchyma cell showing bright red contents as a result of being heated with an acid observed at 400x with Acidified Chloral Hydrate Glycerol Solution. Source: Elan M. Sudberg, Alkemist Laboratories Large thick walled covering trichome observed at 400x with Acidified Chloral Hydrate Glycerol Solution. Source: Elan M. Sudberg, Alkemist Laboratories Winton Fig. 516 Cross section of rhizome, and 517 Cork cells in surface view. Source: Winton, A. (1916) Microscopy of vegetable foods, 2nd ed.

Ultra Performance Liquid Chromatographic Identification

Method Test Sample Preparation: 1 g of ground plant material into a Soxhlet thimble and extractovernight with about 90 ml of acetone, centrifuge and use the supernatant. Dilute the extract 1:10 in acetone and mix well. Before injection, filter through a 0.20 um PTFE membrane filter. Column: 100-mm x 2.1-mm, 1.7 um, Waters Acquity BEH C18 Mobile Phase: 0.1% formic acid in water (Solution A) and acetonitrile (Solution B) Elution: Gradient, see Table below Column Temperature: 70°C Flow rate: 0.6 mL/min Detection: Vis, 426 nm Injection volume: 1.0 uL, maintained at 10°C Needle wash: Acetonitrile System suitability: Curcumin peak, tailing 0.8 to 1.5 Source: Indena S.p.A.

Table: Gradient program

Time (min)	Solution A (%)	Solution B (%)
0.00-3.20	70-47	30-53
3.20-4.10	47-5	53-95
4.10-5.10	5	95
5.10-5.15	5-70	95-30
5.15-6.00	70	30

High Performance Liquid Chromatographic Identification

Method Test Sample Preparation: 1 g of ground plant material into a Soxhlet thimble and extract overnight with about 90 ml of acetone, centrifuge and use the supernatant. Dilute the extract 1:10 in acetone and mix well. Before injection, filter through a 0.20 um PTFE membrane filter. Column: 25-cm x 4.6-mm, 5 um, Waters Symmetry C18 Mobile Phase: 0.3% acetic acid in water (Solution A) and acetonitrile (Solution B) Elution: Gradient, see Table below Column Temperature: 35°C Flow rate: 1.0 mL/min Detection: Vis, 426 nm Injection volume: 10 uL System suitability: Curcumin peak, tailing 0.8 to 2.0; resolution between demethoxycurcumin and curcumin is ≥ 2.0 Source: Indena S.p.A.

Table: Gradient program

Time (min)	Solution A (%)	Solution B (%)
0-17	60-40	40-60
17-18	40-0.0	60-100
18-24	0.0	100
24-25	0.0-60	100-40
25-32	60	40

High Performance Thin Layer Chromatographic Identification

Turmeric (rhizome) HPTLC ID - White RT Turmeric (rhizome) (Curcuma longa) Lane Assignments Lanes, from left to right (Track, Volume, Sample): 2 µL Bisdesmethoxycurcumin 2 µL Desmethoxycurcumin 2 µL Curcumin 4 µL Curcuminoids 2 µL Turmeric (Curcuma longa) 2 µL Curcuma xanthorrhiza  Reference Sample(s) Reference: Dissolve 2 mg of USP Curcuminoids RS in 5 mL of methanol.  Stationary Phase Stationary phase, i.e. Silica gel 60, F254  Mobile Phase Toluene, acetic acid (4:1) (v/v)  Sample Preparation Method Sample: Mix 0.2 g of powdered sample with 3 mL of methanol, sonicate for 10 minutes, then centrifuge or filter the solution and use the supernatant/filtrate as test solution.  Detection Method Saturated chamber; developing distance 70 mm from lower edge; relative humidity 33%  Other Notes Images presented in this entry are examples and are not intended to be used as basis for setting specifications for quality control purposes. System suitability test (UV 366 nm): Curcuminoids: three yellowish-green zones at Rf ~ 0.21 (bisdesmethoxycurcumin), Rf ~ 0.32 (desmethoxycurcumin), and Rf ~ 0.42 (curcumin). Identification: Compare result with reference images. The fingerprint of the test solution is similar to that of the corresponding botanical reference sample. Additional weak zones may be present. The chromatogram of the test solution shows three yellowish-green zones at Rf ~ 0.21, Rf ~ 0.32, and Rf ~ 0.42 corresponding to the three zones of the curcuminoids reference. Test for other species: The chromatogram of Curcuma xanthorriza does not show an intense fluorescent zone at Rf ~ 0.21 (orange arrow). Turmeric (rhizome) HPTLC ID - White RT Turmeric (rhizome) HPTLC ID - UV 366 nm Source: HPTLC Association

Supplementary Information

Detection of adulteration of products of Curcuma longa rhizome with the anti-inflammatory drug nimesulide

Turmeric adulteration with nimesulide (rhizome) HPTLC ID - UV 254 nm Turmeric adulteration with nimesulide (rhizome) (Curcuma longa) Lane Assignments Lanes, from left to right (Track, Volume, Sample): 2 µL Curcuma longa rhizome 1 (not spiked) 2 µL Curcuma longa rhizome 1 (spiked w/ 1% nimesulide) 2 µL Curcuma longa rhizome 1 (w/ 2% nimesulide) 2 µL Curcuma longa rhizome 1 (w/ 5% nimesulide) 2 µL Curcuma longa rhizome 1 (w/ 10% nimesulide) 2 µL Curcuma longa rhizome 2 (not spiked) 2 µL Curcuma longa rhizome 2 (w/ 1% nimesulide) 2 µL Curcuma longa rhizome 2 (w/ 2% nimesulide) 2 µL Curcuma longa rhizome 2 (w/ 5% nimesulide) 2 µL Curcuma longa rhizome 2 (w/ 10% nimesulide) 2 µL Curcuma longa rhizome 3 (not spiked) 2 µL Curcuma longa rhizome 3 (w/ 1% nimesulide) 2 µL Curcuma longa rhizome 3 (w/ 2% nimesulide) 2 µL Curcuma longa rhizome 3 (w/ 5% nimesulide) 2 µL Curcuma longa rhizome 3 ( w/ 10% nimesulide)  Reference Sample(s) Reference: Dissolve 1.0 mg of nimesulide in 10 mL of methanol.  Stationary Phase Stationary phase, i.e. Silica gel 60, F254  Mobile Phase Toluene, acetic acid (4:1) (v/v)  Sample Preparation Method Sample: Mix 0.2 g of powdered sample with 3 mL of methanol, sonicate for 10 minutes, then centrifuge or filter the solution and use the supernatant/filtrate as test solution. Derivatization reagent: 2,5-Dichloro-1,4-benzoquinone reagent, Preparation: 0.50 g of 2,5-Dichloro-1,4-benzoquinone is dissolved in 80 mL of dimethyl sulfoxide and then diluted with 160 mL of tetrahydrofuran, Use: Dip (time 0, speed 5), dry in a stream of cold air for 3 min.  Detection Method Saturated chamber; developing distance 70 mm from lower edge; relative humidity 33%  Other Notes Images presented in this entry are examples and are not intended to be used as basis for setting specifications for quality control purposes. System suitability test: Nimesulide: Rf ~ 0.51 Test for adulteration: Compare result with reference images. The fingerprint of the test solution is similar to that of the corresponding botanical reference sample. Additional weak zones may be present. The chromatogram of the test solution shows no zone at Rf ~ 0.51 corresponding in color and position to that of the nimesulide reference standard. Turmeric adulteration with nimesulide (rhizome) HPTLC ID - UV 254 nm Turmeric adulteration with nimesulide (rhizome) HPTLC ID - 2,5-Dichloro-1,4-benzoquinone reagent, UV 366 nm Turmeric adulteration with nimesulide (rhizome) HPTLC ID - 2,5-Dichloro-1,4-benzoquinone reagent, white RT Source: HPTLC Association