Ochratoxins
Title: Ochratoxins
Literature References: Toxic metabolites from Aspergillus ochraceus Wilh.: Scott, Mycopathol. Mycol. Appl. 25, 213 (1965); A. sulphureus and A. melleus: Lai et al., Appl. Microbiol. 19, 542 (1970); and Penicillium viridicatum Westling: van Walbeek et al., Can. J. Microbiol. 15, 1281 (1969). As these molds occur widely, some toxins have been found as natural contaminants on corn, peanuts, storage grains, cottonseed and other decaying vegetation. Isolns: van Walbeek et al., ibid. 14, 131 (1968); Shotwell et al., Appl. Microbiol. 17, 765 (1969); Nesheim, J. Assoc. Off. Anal. Chem. 52, 975 (1969); Natori et al., Chem. Pharm. Bull. 18, 2259 (1970). Structure and stereochemistry: van der Merwe et al., J. Chem. Soc. 1965, 7083; Nature 205, 1112 (1965). Synthesis of ochratoxins A, B and ester deriv: Steyn, Holzapfel, Tetrahedron 23, 4449 (1967); Nesheim, loc. cit.; Roberts, Woolven, J. Chem. Soc. C 1970, 278. Facile synthesis of A: G. A. Kraus, J. Org. Chem. 46, 201 (1981). Toxicity study: Purchase, Theron, Food Cosmet. Toxicol. 6, 479 (1968). Physicochemical data: A. E. Pohland et al., Pure Appl. Chem. 54, 2220 (1982). Comprehensive reviews: Steyn, "Ochratoxin and other Dihydroisocoumarins" in Microbial Toxins vol. VI, A. Ciegler, et al., Eds. (Academic Press, New York, 1971) p 179-205; F. S. Chu, Crit. Rev. Toxicol. 2, 499-524 (1974); P. Krogh in Natural Toxins, D. Eaker, P. Wadström, Eds. (Pergamon, New York, 1980) pp 673-680; A. E. Pohland et al., Pure Appl. Chem. 64, 1029-1046 (1992).
 
Derivative Type: Ochratoxin A
CAS Registry Number: 303-47-9
CAS Name: (R)-N-[(5-Chloro-3,4-dihydro-8-hydroxy-3-methyl-1-oxo-1H-2-benzopyran-7-yl)carbonyl]-L-phenylalanine
Molecular Formula: C20H18ClNO6
Molecular Weight: 403.81
Percent Composition: C 59.49%, H 4.49%, Cl 8.78%, N 3.47%, O 23.77%
Properties: The major ochratoxin component. Crystals from xylene, mp 169°. Exhibits green fluorescence. [a]D -118° (c = 1.1 in CHCl3). uv max (ethanol): 215, 333 nm (e 34000; 2400) (van der Merwe). Also frequently reported as mp 90° from benzene (one mole of benzene of crystallization). uv max: 213, 332 nm (e 36800; 6400) (Steyn, Holzapfel). LD50 orally in rats: 20-22 mg/kg (Purchase, Theron).
Melting point: mp 169°; mp 90° from benzene (one mole of benzene of crystallization)
Optical Rotation: [a]D -118° (c = 1.1 in CHCl3)
Absorption maximum: uv max (ethanol): 215, 333 nm (e 34000; 2400) (van der Merwe); uv max: 213, 332 nm (e 36800; 6400) (Steyn, Holzapfel)
Toxicity data: LD50 orally in rats: 20-22 mg/kg (Purchase, Theron)
 
Derivative Type: Ochratoxin B
CAS Registry Number: 4825-86-9
CAS Name: (R)-N-[(3,4-Dihydro-8-hydroxy-3-methyl-1-oxo-1H-2-benzopyran-7-yl)carbonyl]-L-phenylalanine
Molecular Formula: C20H19NO6
Molecular Weight: 369.37
Percent Composition: C 65.03%, H 5.18%, N 3.79%, O 25.99%
Properties: The less toxic dechloro deriv of ochratoxin A. Crystals from methanol, mp 221° (van der Merwe); also reported as 208-209° (Nesheim). Exhibits blue fluorescence. [a]D -35° (c = 0.15 in ethanol). uv max: 218, 318 nm (e 37200, 6900).
Melting point: mp 221° (van der Merwe)
Optical Rotation: [a]D -35° (c = 0.15 in ethanol)
Absorption maximum: uv max: 218, 318 nm (e 37200, 6900)
 
Derivative Type: Ochratoxin C
CAS Registry Number: 4865-85-4
CAS Name: (R)-N-[(5-Chloro-3,4-dihydro-8-hydroxy-3-methyl-1-oxo-1H-2-benzopyran-7-yl)carbonyl]-L-phenylalanine ethyl ester
Molecular Formula: C22H22ClNO6
Molecular Weight: 431.87
Percent Composition: C 61.18%, H 5.13%, Cl 8.21%, N 3.24%, O 22.23%
Properties: The equally toxic amorphous ethyl ester of ochratoxin A: Steyn, Holzapfel, J. S. Afr. Chem. Inst. 20, 186 (1967), C.A. 69, 2797p (1968). uv max (ethanol): 333 nm (e 6500).
Absorption maximum: uv max (ethanol): 333 nm (e 6500)
 
CAUTION: Ochratoxin A is reasonably anticipated to be a human carcinogen: Report on Carcinogens, Eleventh Edition (PB2005-104914, 2004) p III-209.
Use: Exptlly as teratogen and carcinogen.

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