สารบัญ

Gambier; Gambir

Thai name  สีเสียดเทศ  (SISIAT THET)

Category   Intestinal astringent.

       Pale Catechu is a dried aqueous extract prepared from the leaves and young shoots of Uncaria gambier (Hunter) Roxb. (Family Rubiaceae).

Constituents  Pale Catechu contains polyphenolic compounds mainly tannins and catechins.  It also contains indole alkaloids such as gambirine, flavonoids and gambirtannin.

Description  Odourless; taste, bitter and very astringent at first with sweetish aftertaste.
Macroscopical  Usually occurs as cubes or brick-shaped pieces, about 2.5 cm long and wide, the brick-shaped ones up to 4 cm long, externally dull pale greyish brown to dark reddish brown, internally pale brown, friable and porous.
Microscopical  Powdered drug of Pale Catechu shows yellowish brown masses of acicular catechin crystals, unicellular covering trichomes, epidermal cells of the leaves, corolla fragments, parenchyma, pollen grains, and fragments of cork.  Acicular catechin crystals abundant. Unicellular covering trichomes lignified-walled, pitted at base, some with one or two thin transverse septa; fewer, smaller trichomes conical, with warty, unlignified walls. Epidermal cells of the leaves thin-walled with finely striated cuticle and paracytic stomata on the lower epidermis. Corolla fragment reddish brown with numerous covering trichomes and characteristic pitted and lignified cicatrices in the epidermis.  Parenchyma containing calcium oxalate as cluster crystals and crystal sand.  Pollen grain subspherical with three pores, three furrows and minutely pitted exine.  Fragment of cork occasionally found.

Other relevant information  The plant yielding pale catechu is native to Indonesia and Malaysia.

Packaging and storage  Pale Catechu shall be kept in well-closed containers, protected from light and stored in a dry place.

Identification
A. To 200 mg of the powdered drug add 10 mL of water, warm in water-bath for 5 minutes with occasional shaking, and filter.  To the filtrate, after cooling, add 2 to 3 drops of gelatin TS:  a white turbidity or precipitate is produced.
B. Shake 100 mg of the powdered drug with 20 mL of ethanol (50 per cent) for 2 minutes, and filter.  Mix 1 mL of the filtrate with 9 mL of ethanol (50 per cent), and to the solution add 1 mL of vanillin-hydrochloric acid TS:  a light red to red-brown colour develops.
C. Warm 300 mg of the powdered drug with 2 mL of ethanol, cool, and filter; to the filtrate add 2 mL of 5 M sodium hydroxide; shake, add 2 mL of petroleum ether (boiling range, 40° to 60°), shake and allow to separate:  a brilliant greenish fluorescence is produced in the upper layer.

Ethanol-insoluble matter  Not more than 34.0 per cent w/w, calculated on the dried basis, determined by the following method.  Macerate 5 g, accurately weighed, in coarse powder, with 100 mL of ethanol, shaking frequently during 6 hours and allowing to stand for 18 hours; filter, wash the residue with ethanol, and dry to constant weight at 100°.

Starch  The residue obtained in the test for Ethanol-insoluble matter contains not more than an occasional starch granule.

Water-insoluble matter  Not more than 33.0 per cent  w/w, calculated on the dried basis, determined by the method for Ethanol-insoluble matter, using water in place of ethanol.

Loss on drying  Not more than 15.0 per cent w/w after drying at 105° to constant weight (Appendix 4.15).

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

Total ash  Not more than 8.0 per cent w/w (Appendix 7.7).