Sulfur-containing secondary

The general metabolism of sulfur, extensively described in many texts of biological sciences, is not considered in this article some topics (e.g. metallo-enzymes) are discussed elsewhere in this volume (Chapter 11.2). Our focus is on sulfur-containing secondary metabolites in microorganisms and plants. In view of the vast literature, we can only provide an eclectic account citing recent work where possible. 

Overview of Structural Types for Sulfur-Containing Secondary Metabolites... 

Plants of the genus Allium, e.g. garlic Allium sativum), leek Allium amp-eloprasum), and onion Allium cepa), produce a bewildering variety of sulfur compounds. Selenium analogs for some of these have also been found (Section 11.1.3.6). Much work has focused on garlic (contains more than 100 such materials) and onion.56,66,67 Key compounds for formation of the Allium sulfur-containing secondary metabolites are sulfoxides of cysteine derivatives,... 

A similar mechanism was proposed for sulfur containing secondary antioxidants ... 

Another half hindered phenolic antioxidant (PAO-4) showed a large synergism with a sulfur-containing secondary antioxidant [85,182]. 

Few sulfur-containing secondary metabolites have been isolated from green algae. As well as the sulfated triter-penic alcohols mentioned previously, two biologically active atypical compounds were characterized. The first compound is a bis-alkykanthate, whose function is very rare in the natural environment and is toxic to mosquito larvae. The second compound is a cyclic disulfide inhibitor... 

In 1977, a survey of low molecular weight sulphur-containing compounds in Nature ,4 noted that these secondary metabolites had little more in common than the possession of one or more sulfur atoms. The reader was left with a kaleidoscopic impression of almost 80 chemical structures. A comprehensive review today would require many hundreds of sulfur-containing chemical structures. 

While many sulfur-containing fungal secondary metabolites are known, they are found less frequently than in plants. There is a structural range from CH2S6, 1,2,3,4,5,6-hexathiapane, from Lentinus edodes, to C82Hii4N2oOi7S, a 13-unit peptide containing methionine from Saccharomyces cerevesiae,13... 

Complexes of both selenium(IV) and tellurium(IV) with sulfur-containing ligands are known although the structural properties appear to have been determined only for the tellurium(IV) species. However, due to the smaller size of selenium(IV) and its poorer acceptor properties, as compared with tellurium(IV), its maximum coordination number appears to be six whilst it has been found to be eight for tellurium.78 Furthermore, the greater tendency of tellurium to form secondary bonds may cause the structures of similar selenium(IV) and tellurium(IV) compounds to be different. 9 It is also pertinent to note that the reduction of tellurium(IV) to... 

In the case of 4,6-DMDBT, it was possible to determine the rate constants for direct extraction of sulfur from the fully saturated sulfur-containing ring system (k0l) and for the secondary hydrogenation of the tetrahydro-dibenzothiophene intermediate (fcHs2)- As might be expected, the rate constants for direct sulfur extraction follow a clear trend in which A Dq < < d2 The reverse trend is observed in the aromatic ring hydrogenation rates, /cHs, > kHS, and kHPl > kw , which is consistent with the literature (see Fig. 10) (5, 35). 

ABSTRACT This chapter provides a comprehensive overview of the sulfur-containing natural products that are non-sulfated and have been isolated from marine organisms. The overview covers the published literature from 1985 to 1999. A total of 482 compounds and 371 references are recorded. These secondary metabolites are organized in sections according to structural classifications by sulfur functional groups and by structural families of compounds. Comments on structural characterization, biogenesis, and biological activity have also been included. 

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