Paint & Coatings Industry - March 2008 - (Page 45)

Table 1 | Folpet antimicrobial activity – minimum inhibitory concentration (ppm). Microbial Species Fungal Species Aspergillus niger Aspergillus flavus Penicillium funiculosum Penicillium islandicum Penicillium glaucum Chaetomium globosum Trichoderma sp. Aureobasidium pullulans Alternaria alternata Coniophora puteana Lentinus tigrinus Polyporus versicolor Sclerophoma pityophila Candida albicans Candida krusei Rhodotorula mucilaginosa Saccharomyces cerevisiae Torula rubra Torula utilis 100 75 50 50 50 100 500 75 750 75 35 100 150 100 500 100 50 50 50 25 50 1000 75 100 25 100 Figure 3 | Agar plate first tier evaluation. Minimum Inhibitory Concentration (ppm) Surface growth (untreated sample). Protected sample (with biocide). Bacterial Species Bacillus subtilis Staphylococcus aureus Pseudomonas aeruginosa Aerobacter aerogenes Proteus vulgaris Brevibacterium sp. Streptomyces rubrireticuli Algae 20 Table 2 | IPBC antimicrobial activity – minimum inhibitory concentration (ppm). Microbial Species Fungi/Mold/Yeast Alternaria tenuis Aspergillus glaucus Aspergillus niger Aspergillus oryzae Aureobasidium pullulans Chaetomium globosum Penicillium brevicaule Penicillium funiculosum Trichoderma viride Candida albicans Saccharomyces cerevisiae Talaromyces flavus 5.0 4.0 5.0 4.0 6.0 5.0 1.0 6.0 10.0 8.0 5.0 6.0 50.0 100.0 50.0 1000.0 8.0 50.0 Minimum Inhibitory Concentration (ppm) Bacteria Bacillus subtilis Escherichia coli Klebsiella pneumoniae Pseudomonas aeruginosa Algae Chlorella pyrenoidosa Oscillatoria sp. pet) are biological alkylating agents that react with thiols producing compounds that indicate that the primary reaction is the transfer of the trichloromethylsulfenyl group to the sulfur atom of a thiol.4,5 This has been demonstrated in vitro as well as in vivo.6,7 It is generally thought that the principal mode of action involves the reaction of the trichloromethylsulfenyl moiety with cell components containing the thiol functionality. Microbial enzymes are denatured and normal cell division is inhibited.8 The possibility that thiophosgene is a transcient intermediate has been proposed.9 The toxicity of folpet might directly or indirectly result from oxidative stress. Induction of antioxidative enzymes has been reported in several studies that show increase in production of reactive oxidative species in cells.10 Folpet is also described as a potent inhibitor of spore germination by affecting cellular processes required for germination or interfering with respiration.11 To date, the mode of action of folpet has not been fully elucidated. Folpet is effective in organic solvent-based architectural coatings and stains and flexible PVC plastics for the prevention of fungal organism growth and staining by filamentous bacteria. It is active against mildew and wood-rot fungi. The minimum inhibitory concentrations (MICs) presented in Table 1 illustrate the spectrum of activity of folpet. Based on the proven fungicidal activity in plastics and coating formulations and its broad spectrum of antimicrobial activity, folpet was chosen as a candidate for evaluation in the wood plastic composite matrix. Figure 4 | Aspergillus niger. PA I N T & C O A T I N G S I N D U S T R Y 45

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Viewpoint Industry News Calendar of Events Company News Mergers and Acquisitions Names in the News Marketplace Quarterly Stock Watch Reaching Strict VOC Requirements With Outstanding Durability for Industrial Maintenance and Marine Coatings A Unique Fungicide for Wood-Filled Plastic deSigns of the Times: Slacking Off! From Rocks to Nanos Shear-Free Dispersion Process Fluorinated Oxetane Oligomers as Versatile Intermediates for Polymer Modification The Effects of TPO Composition on Adhesion and Proposed Chemical Mechanism Supplier Showcase Color Management Materials Watch Products Classifieds Advertiser Index

Paint & Coatings Industry - March 2008

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