Citrinin structure

Representative Compounds Aflatoxins Citrinin Ergot alkaloids Fumonisins Ochratoxin A Patulin Trichothecenes Zearalenone Stachybotrys toxin Chemical Formula C17H12O6 (Aflatoxin Bi) Chemical Structure Aflatoxin Bi... 

FIGURE 2 Chemical structures of selected second metabolites from Monascus. (A) Monascus pigments, (B) monacolins, (C) citrinin. 

Citrinin (4.41) is a mycotoxin that is formed in quite large amounts by Penicillium citrinum, where it co-occurs with related metabolites such as the isocoumarins 4.42 and 4.43, the phenols 4.44 and 4.45, and decarboxycitrinin. Some dimers have also been isolated. Citrinin was first isolated by Raistrick in 1931 and its structure was proposed by Robertson in 1948. Although it exists as a quinone-methide in the crystalline state, it forms a hydrate rather rapidly. Much of the chemistry of citrinin can be understood in terms of the ready formation of this hydrate. The lactol of citrinin hydrate is readily oxidized to a... 

Citrinin (9.22) is a widespread mycotoxin that is formed by many Penicillium and Aspergillus species, particularly P. citrinum, P. expansum and P. roqueforti. It was first isolated in 1931 by the Raistrick group and described as an antibiotic. It has been shown to have carcinogenic effects and to produce kidney damage. Evidence for its structure and biosynthesis is discussed in Chapter 4. 

The specificity of the inhibition by mevinolin through its high affinity for HlK-CoA reductase may also serve as a model to develop highly effective and specific artificial biocides and to stinulate research in this topic. For example, citrinin, another antibiotic having a bicyclic structure produced by Pentctllium citrinum has been shown to inhibit sterol biosynthesis (143) at the site of acetoacetyl-CoA thiolase (EC 2.3.2.9) and HMG-CoA... 

Brown IP, Cartwright NJ, Robertson A, Whalley WB (1948) Structure of Citrinin. Nature 162 72... 

Rodig OR, Shiro M, Fernando Q (1971) Crystal and Molecular Structure of Citrinin. J Chem Soc Chem Commun 1553... 

Further, in the C-NMR spectrum of [1- C, 02]-ace-tate-enriched citrinin, isotopically shifted signals are observed for the resonances due to C-3, C-6, and C-8. This indicates that oxygen atoms attached to each of these carbons come from acetate. The quinone-methide structure (as in compounds 9 and 10) must be formed by the elimination of hydroxyl (as water ) from the hemiacetal (11). Compound... 

The biosynthesis of ascochitine (16), a phytotoxic hexake-tide from the fungus Ascochyta fabae, has been investigated by means of C-labeled acetates and methionine and Relabeled precursors (Ballio, 1981 Stoessl, 1981) (Fig. 5.12). Ascochitine is derived from a single hexaketide precursor with introduction of three methyl groups from methionine via a quinone-methide structure (17) similar to that involved in the biosynthesis of citrinin. The aldehyde (18) and quinone-methide (17) were specifically incorporated. 

Roquefortine C was often accompanied by a structurally related mycotoxin isofumigaclavine A (12-98). P. roqueforti molds may occasionally produce patulin, citrinin (12-99), penicillic acid (12-100), the so-called PR-toxin (12-101) and certain other toxins that have been implicated in incidents of mycotoxicoses. However, PR toxin is not stable in cheese and breaks down to the less toxic PR imine (12-101). Other secondary metabolites ofP. roqueforti found in blue cheeses are andrastins A-D with skeletons of ent-5a,lA -androstane. In European blue cheeses, the content of andrastin A (12-102) ranged from 0.1 to 3.7 mg/kg and contents of andrastins B, C and D were on average five times lower. The most significant biological activity of adrastins is the ability to inhibit the enzyme farnesyltransferase, an enzyme that catalyses the transfer of farnesyl residue from farnesyl diphosphate to proteins. It is a part of the apparatus carrying post-translational modification of proteins in... 

Citrinin is a quinone similar in structure to unsubstituted ochratoxin. 

Several chemical properties of the antibacterial substances have been assembled in Table III. The division into the groups of acidic substances, neutral substances, and basic substances has been maintained. The empirical formulas are those given by one of the authors cited in the references and represent usually results of analysis of the pure substance. A few of the structures, and, hence, the empirical formulas, also, have been proved by synthesis. Several formulas, citrinin, gliotoxin, and patulin, for example, are based upon analytical results and a consideration of degradation products. Probably several of these formulas will be revised after more work has been done with the compounds. The approximate stability of the compounds in acid, neutral, and alkaline solutions are given. Many of... 

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