Antifungal activity of isothiocyanates and related compounds. 3. Derivatives of biphenyl, stilbene, azobenzene, and several polycondensed aromatic hydrocarbons

This paper presents the results of a study on the antifungal activity of isothiocyanates-derivatives of biphenyl (group "A"), of stilbene ("B"), of azobenzene and benzeneazonaphthalene ("C"), of naphthalene ("D"), and of further polycondensed aromatic hydrocarbons ("E"). From a total of 48 investigated compounds, antifungal activity was observed only in A and D group compounds. B, C, and E group derivatives are extremely insoluble in water, and the molecules are very large; as a result, they probably cannot pass into spores or mycelium of fungi. Thus, the -NCS group cannot manifest its reactivity.

Antifungal activity of isothiocyanates and related compounds. II. Mononuclear aromatic isothiocyanates

Antifungal activity on Aspergillus niger, Penicillium cyclopium, and Rhizopus oryzae, as well as on additional saprophytic and parasitic fungi, was determined in 57 substituted derivatives of phenylisothiocyanate. Most of the investigated compounds displayed rather equal activity against the three mentioned fungi, in contradistinction to the analogues of natural benzyl- and beta-phenylethylisothiocyanate with their characteristic low activity against R. oryzae. Differences occurred in the type of activity of compounds in which the -NCS group is directly bound on the aromatic moiety, as compared with those compounds in which this group is bound to the aliphatic radical or to the aromatic moiety indirectly by means of the methyl group or by a longer aliphatic chain. The results obtained confirm the negative influence of ionized substituents on the aromatic moiety, i.e., of -COOH, -CH(2)- COOH, and -SO(3)H groups, as well as of substituents which cause an extreme increase in reactivity of the -NCS group resulting in a high instability of the entire isothiocyanate molecule.

Antifungal activity of isothiocyanates and related compounds. I. Naturally occurring isothiocyanates and their analogues

Data are presented concerning the antifungal activity of 11 natural isothiocyanates and 27 synthetized analogues in Aspergillus niger, Penicillium cyclopium, and Rhizopus oryzae, as well as in 13 additional saprophytic and parasitic fungi. A remarkable antifungal activity was observed in some analogues of benzylisothiocyanate and beta-phenylethylisothiocyanate. The latter-mentioned compounds have not been described previously. In the group of benzylisothiocyanates, a correlation, which was inversely proportional, was detected between ed(100) values for A. niger and R. oryzae and the corresponding molar solubilities of compounds in water. In contradistinction, no relationship was observed between antifungal activity and chemical reactivity of investigated derivatives.