Isothiocyanates

General structure of isothiocyanates. The functional group is marked in blue .

Isothiocyanates are chemical compounds that are derived from the unstable isothiocyanic acid (also isorhodanic acid, HN = C = S). Organic isothiocyanates are also called mustard oils according to their natural occurrence (see also mustard oil glycosides ).

A distinction is made between salt-like inorganic compounds M ⁺ NCS ^- and covalent organic compounds with the general structure RN = C = S, such as B. methyl isothiocyanate , allyl isothiocyanate and sulforaphane .

Organic isothiocyanates are very reactive compounds that react quickly with numerous nucleophiles. With amines z. B. substituted thioureas . Volatile isothiocyanates have a pungent odor, are irritating to tears and are toxic.

Applications

Isothiocyanates produce thiourethanes when reacted with alcohols . In biochemistry , isothiocyanates are used in the course of Edman degradation to break down peptides and proteins step by step into their constituent parts, the amino acids , and thus to determine the amino acid sequence (order of the amino acids in the peptide or protein). Here z. B. phenyl isothiocyanate (PITC), 4- N , N -dimethylaminoazobenzene-4'-isothiocyanate ( DABITC ) or 4- (1'-cyanoisoindolyl) -phenyl isothiocyanate are used. Isothiocyanates are used to label and cross-link proteins and peptides, e.g. B. fluorescein isothiocyanate (FITC) and TRITC in fluorescent labeling .

Occurrence

In nature, they are mainly chemically bound as mustard oil glycosides in cruciferous vegetables , such as mustard (see above), white cabbage , red cabbage , broccoli , cauliflower , Brussels sprouts , pak choi , kohlrabi , in turnips , in radishes , rape , horseradish , rocket and in the garden cress and in the Great nasturtiums from the family of nasturtiums , and call there after the spin-off from the glucosinolates the pungent taste produced.

Physiological effect

In various animal models it could be shown that isothiocyanates are able to inhibit the chemically induced carcinogenesis of a number of carcinogens . The cancer preventive properties of some cruciferous vegetables are attributed to the isothiocyanates they contain.

Individual evidence

1. ^ Siegfried Hauptmann : Organic Chemistry, VEB Deutscher Verlag für Grundstoffindindustrie, Leipzig, 1985, p. 325. ISBN 3-342-00280-8 .
2. ↑ X. Wu et al: Isothiocyanates induce oxidative stress and suppress the metastasis potential of human non-small cell lung cancer cells. (PDF; 1.4 MB) In: BMC Cancer 10, 2010, 269. doi : 10.1186 / 1471-2407-10-269 ( Open Access ).