Antifungal properties of new quaternary ammonium compounds in relation to their surface activity

The biological activity of 17 potential wood preservatives—quaternary ammonium and imidazolium compounds—was determined employing screening agar-plate and agar-block methods. Experiments were carried out on Scots pine (Pinus sylvestris L.) wood. The fungicidal value of new compounds with cycloalkyl substituents for Coniophora puteana ranged from 0.64 kg/m³ to 2.2 kg/m³. Aspergillus niger turned out to be the most resistant fungus to the action of modified ICs, whereas Sclerophoma pityophila was effectively inhibited by the examined salts. It was stated that the antifungal and surface active properties of new compounds depend upon the alkyl chain and the size of the cycloalkyl ring in the molecule. The presented results demonstrate the relationship between the effective dose (ED) and the lethal dose (LD) and critical micelle concentration of new QACs and ICs as well as the relation between inhibition of fungal colonies and concentration of compounds in the substrate.