Wilson, A.T.Ronaldson, John William2026-04-012026-04-011978https://hdl.handle.net/10289/18166This thesis was concerned with the chemistry of two fungal products, sporidesmin and crepidotine. The structure of sporidesmin was known but aspects of its chemistry, such as how it could be modified to function as an antigen, were not. The structure of crepidotine was unknown but was elucidated in the course of this work. Since only 50 mg of crepidotine was available, non-destructive methods were used to arrive at the structure, 2-phenyl-1,6-naphthyridin-4-one. Of these methods, ¹H nuclear magnetic resonance spectroscopy was the most important. This spectrum (¹H n.m.r.) of crepidotine was compared with known or expected spectra of possible isomers most of which were unknown. Sporidesmin is the toxin which causes Facial Eczema. One approach for combating the problem of Facial Eczema is to develop antibodies in the animals against sporidesmin. Sporidesmin is too small a molecule per se to induce antibody formation so one of the aims of this thesis was to produce derivatives of sporidesmin and to complex them to proteins. Proteins with many molecules of sporidesmin covalently bound to them were produced to be used as antigens. When animals were treated with these antigens, antibodies were detected in their sera. The titre was low for sporidesmin complexed to albumins but four times higher when sporidesmin was complexed to bovine thyroglobulin. The method of complexing sporidesmin to the proteins was to open the -S-S- bridge (in sporidesmin) and alkylate the sulphur atoms with iodoacetic esters. When protein was treated with these sporidesmin derivatives the ε-amino-groups of the lysyl residues (in the protein) were transacylated yielding modified sporidesmin covalently bound to the protein, synthetic or natural. The new compounds formed from sporidesmin in these syntheses were: diethyl and dimethyl secosporidesmin-S,S'-diacetate, ethyl and methyl 11a-mercaptosecosporidesmin-3-S-acetate, methyl 3-mercaptosecosporidesmin-11a-S-acetate; and one of the antigens was cross-linked poly(ethoxy)-poly(secosporidesmin-S,S'-diacetyl)poly-(L-lysine). Of other new derivatives of sporidesmin that were synthesized, 3,11a-dimercaptosecosporidesmin, S,S'-homosporidesmin, and sporidesmin 11-(methyl glutarate), the first was the most difficult to prepare. When attempted in the normal way (opening the -S-S- bridge as for the above esters) only sporidesmin was recovered. But the dimercapto-compound was obtained when oxygen was eliminated in the reaction. Because the toxicity of the sporidesmin molecule resides in the epidithiodioxopiperazine ring, means of covalently linking sporidesmin to protein without altering the -S-S- bridge were sought, e.g. acylation or diazonium coupling with suitable bridging groups. Having successfully acylated with the chloroacetyl group (forming sporidesmin di(chloroacetate) it may be possible to complex this ester to protein through the halogen atom. In the diazonium coupling reaction, the sole aromatic hydrogen resisted coupling. Diazonium salts eliminated the epidithiodioxopiperazine ring by rupturing the pyrrolidine ring: the products were the strongly coloured substituted indoleazobenzenes, 5-chloro-2-hydroxy-6,7- dimethoxy-1-methyl-4'-nitroindole-3-azobenzene and the 2'-chloro- and 2'-nitro-analogues. From anhydrodethiosporidesmin 5-chloro-6,7-dimethoxy-8-methyl-2' ,4'-dinitropyrrolo[2,3-b]indole-2-azobenzene was obtained. These indoleazobenzenes are new compounds. In the search for methods of diazonium coupling to o-dihydroxy-benzene, veratrole, the following new compounds were synthesized: 2-chloro-3', 4'-dimethoxy-4-nitrobiphenyl, 2-chloro-4'-hydroxy-3'-methoxy-4-nitroazobenzene, 4'-hydroxy-3'-methoxy-2, 4-dinitroazobenzene, 3', 4'-dimethoxy-2,4-dinitroazobenzene, 2-chloro-3', 4'-dimethoxy-4-nitroazobenzene and 2-chloro-4, 5-dimethoxy-2', 4'-dinitroazobenzene. In the ¹³C nuclear magnetic resonance spectra of sporidesmin and sporidesmin-D (dimethylthiosecosporidesmin) (decoupled and undecoupled) the peaks were assigned to the appropriate carbons. Where a resonance seemed anomalous, a reasonable explanation of the anomaly has been put forward. Comparison of the spectra of the two compounds indicated the resonances of those carbons which were involved in the strained epidithiodioxopiperazine ring system. Having assigned the peaks for sporidesmin, the structure of unknown analogues may now be more readily elucidated. An analogue of sporidesmin, sporidesmin-E, of comparable toxicity, having an -S-S-S- bridge was synthesized from sporidesmin for field studies. It was an unstable molecule readily decomposing to sporidesmin plus sulphur, e.g. pure sporidesmin-E always showed three spots in thin layer chromatography. The mixed melting point between these two compounds was undepressed (they melted within 3.5° of each other). That sporidesmin-E had been formed was confirmed by the M⁺ being 32 mass units greater than sporidesmin but this was still no criterion of purity. In the hydrogen-bonding investigation of the two compounds sporidesmin absorbed in the νOH region where sporidesmin-E did not so the degree that sporidesmin-E was contaminated with sporidesmin could be determined. Comparison of the infra-red spectra of sporidesmin and sporidesmin-E prepared in different ways (in KBr from MeOH or EtOEt, in nujol or in halocarbon oil) showed there were only minor differences between them. The hydrogen bonding analysis revealed that the C-S bonds of 3,11a-di-mercaptosecosporidesmin and sporidesmin-E were similarly orientated (i.e. diverging) and not more or less parallel as in sporidesmin-D. The mono-mercapto-derivative (methyl 11a-mercaptosecosporidesmin-3-S-acetate) showed no νSH peak: the elements of the thiol group are present (m.s.) but the hydrogen is ionic and with the adjacent amido-group is apparently in hyperconjugation.enAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.Thesis