WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
29.38 - Glycosides, natural or reproduced by synthesis, and their salts, ethers, esters and other derivatives. - Rutoside (rutin) and its derivatives 2938.90 - Other 2938.10 Glycosides occur mainly in the vegetable kingdom. Usually, under the action of acids, bases or enzymes, they are split into a sugar part and a non-sugar part (aglycone). These parts are bonded to each other via the anomeric carbon atom of the sugar. Thus, products such as vacciniin and hamamelitannin of heading 29.40 are not considered to be glycosides. The most common naturally-occurring glycosides are the 0-glycosides, in which the su ar moiety and aglycone normally are linked by an acetal function. However, there are a so naturally-occurnngN- lycosides, S-glycosides and C-glycosides, in which the sugar's anomeric carbon is linked to tfe aglycone via a nitrogen atom,, a sulphur atom or a carbon atom, res ectively Je-g., casimiroedine (an N- lycoside) sinigrin (an S-glycoside) and aloin (a 8-glycoside ). The aglymne is sometimes inked m the sugar by an ester group. f Glycosides are generally solid, colourless compounds; the form the reserve substances in vegetable organisms, or act as stimulants. Many are used fort erapeutic purposes. t (1) Rutoside (rutin), found in many plants, especially the buckwheat plant (Fagopyrwm esculentum Moench., Polygonaceae) which contains about 3 % (dry basis). (2) Digitalis glycosides, present in plants of the Digitalis genus (e.g., D. lanata, D. pulpurea). Certain are important in medicine as heart stimulants. The group includes digitoxin, white crystalline powder, odourless, very toxic; digoxin; and digitonin, a saponin of digitalis, used as a chemical reagent. (3) Glycyrrhidn and glycyrrhizates, present in liquorice root; colourless c stals. Ammonium glycyrrhizate is a reddish-brown mass used in the preparation of ';Knks. Glycyrrhizates are also used in medicine. (4) Strophanthin, glycosides found in many species of the Strophanthw genus; very efficacious heart stimulants. Several are known, including ouabain or Strophanthin-G, in colourless crystals; very toxic. (5) Saponins, amorphous glycosides fairly abundant in the vegetable kingdom; sternutatory properties. Their aqueous solutions froth when shaken. Used in medicine, in the manufacture of detergents and in foam fire extinguishers. (6) Aloin, present in the leaves of various species of aloe. (7) Amygdalin, contained in bitter almonds and various h i t stones. Used as expectorant. (8) Arbutin, contained in leaves of arbutus; used as a diuretic. (9) Sinigrin, present in black mustard seeds and horse radish root. Used in medicine. This heading also includes certain tannin derivatives of natural or synthetically-reproduced glycosides. This heading also covers natural mixtures of glycosides and of their derivatives (e.g., a natural mixture of digitalis 1 cosides containing purpurea glycosides A and B, digitoxin, gitoxin, gitaloxin, etc.); but de 1 erate intermixtures or preparations are excluded. 7-g This heading also excludes : (1) Nucleosides and nucleotides (heading 29.34). (2) Alkaloids (e.g., tomtine) (heading 29.39). (3) Non-natural glycosides (other than products of heading 29.37 or 29.39) in which the glycosidic linkage is an acetal fimction formed by etherification at the anomeric carbon (a-methylglucoside, tribenoside (INN)) (heading 29.40). (4) Antibiotics (e.g., toyocamycin) (heading 29.41). -
1.- Except where the context otherwise requires, the headings of this Chapter apply only to : (a) Separate chemically defined organic compounds, whether or not containing impurities; (b) Mixtures of two or more isomers of the same organic compound (whether or not containing impurities), except mixtures of acyclic hydrocarbon isomers (other than stereoisomers), whether or not saturated (Chapter 27); (c) The products of headings 29.36 to 29.39 or the sugar ethers, sugar acetals and sugar esters, and their salts, of heading 29.40, or the products of heading 29.41, whether or not chemically defined; (d) The products mentioned in (a), (b) or (c) above dissolved in water; (e) The products mentioned in (a), (b) or (c) above dissolved in other solvents provided that the solution constitutes a normal and necessary method of putting up these products adopted solely for reasons of safety or for transport and that the solvent does not render the product particularly suitable for specific use rather than for general use; (f) The products mentioned in (a), (b), (c), (d) or (e) above with an added stabiliser (including an anti- caking agent) necessary for their preservation or transport; (g) The products mentioned in (a), (b), (c), (d), (e) or (f) above with an added anti-dusting agent or a colouring or odoriferous substance or an emetic added to facilitate their identification or for safety reasons, provided that the additions do not render the product particularly suitable for specific use rather than for general use; (h) The following products, diluted to standard strengths, for the production of azo dyes : diazonium salts, couplers used for these salts and diazotisable amines and their salts. 2.- This Chapter does not cover : (a) Goods of heading 15.04 or crude glycerol of heading 15.20; (b) Ethyl alcohol (heading 22.07 or 22.08); (c) Methane or propane (heading 27.11); (d) The compounds of carbon mentioned in Note 2 to Chapter 28; (e) Immunological products of heading 30.02; (f) Urea (heading 31.02 or 31.05); (g) Colouring matter of vegetable or animal origin (heading 32.03), synthetic organic colouring matter, synthetic organic products of a kind used as fluorescent brightening agents or as luminophores (heading 32.04) or dyes or other colouring matter put up in forms or packings for retail sale (heading 32.12); (h) Enzymes (heading 35.07); (ij) Metaldehyde, hexamethylenetetramine or similar substances, put up in forms (for example, tablets, sticks or similar forms) for use as fuels, or liquid or liquefied-gas fuels in containers of a kind used for filling or refilling cigarette or similar lighters and of a capacity not exceeding 300 cm3 (heading 36.06); (k) Products put up as charges for fire-extinguishers or put up in fire-extinguishing grenades, of heading 38.13; ink removers put up in packings for retail sale, of heading 38.24; or (l) Optical elements, for example, of ethylenediamine tartrate (heading 90.01). 3.- Goods which could be included in two or more of the headings of this Chapter are to be classified in that one of those headings which occurs last in numerical order. 4.- In headings 29.04 to 29.06, 29.08 to 29.11 and 29.13 to 29.20, any reference to halogenated, sulphonated, nitrated or nitrosated derivatives includes a reference to compound derivatives, such as sulphohalogenated, nitrohalogenated, nitrosulphonated or nitrosulphohalogenated derivatives. Nitro or nitroso groups are not to be taken as “nitrogen-functions” for the purposes of heading 29.29. For the purposes of headings 29.11, 29.12, 29.14, 29.18 and 29.22, “oxygen function”, the characteristic organic oxygen-containing group of those respective headings, is restricted to the oxygen-functions referred to in headings 29.05 to 29.20.