February 15-18, 2009 Washington State Convention Center Seattle ...

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AQUAFRIN: A NOVEL PHOTO-ACTIVATED ANTIMICROBIAL AGENT FOR
AQUACULTURE
Glenn D. Prestwich, Jerry Bommer and Jason Henderson
Frontier Scientific, Inc.
P.O. Box 31
Logan, UT 84323 USA
An unmet need in aquaculture is a broad-spectrum, easy to use antifungal/antibacterial agent that is (i) safe, (ii) has low vertebrate
toxicity, (iii) does not select for resistance, (iv) is free of hazardous peroxides, radicals, and odors, and (v) does not harm
plants, algae, cyanobacteria, or aquatic invertebrates. Such an agent should be environmentally benign and have a degradation
profile consistent with use in both indoor and outdoor fishery facilities. We now describe results for AquaFrin (Lauryl Methyl
Pyrifrin), a water-soluble and amphiphilic porphyrin that meets these criteria. AquaFrin is a photosensitizer that disrupts
bacterial, protozoal and fungal cell walls and membranes by local production of singlet oxygen, a potent oxidant that diffuses
less than 0.1 mm before. Structure activity studies demonstrate that the monolauryl compound shown has optimal antibacterial
and antifungal properities relative to other cationic porphyrins with longer or shorter alkyl chains. AquaFrin is activated by
white light, with optimal activation occurring in blue wavelengths most readily transmitted in water.
AquaFrin shows low dark toxicity yet potent light toxicity to bacterial, fungal, and protozoal pathogens, including spores.
The selective toxicity is due to association with the anionic, lipophilic membranes of the microbial pathogens. For example,
Candida albicans has a light-activated MIC of 5 µg/ml. Concentrations as low as 0.2 µM, or only 0.3 g/1000 L tank, controls
Saprolegnia parasitica with 1-h treatments on two or three consecutive days. These concentrations are 100 to 1000-fold lower
than concentrations of chloramine-T, formalin, hydrogen peroxide, hydrogen peroxide-peracetic acid, copper sulfate, or potassium
permanganate solutions used as approved antimicrobials in aquaculture. Finally, AquaFrin is not a primary skin irritant
(Draize test, murine model) even at a dose of 300 µΜ, over 1000-fold higher than the concentrations used for decontamination
of tanks or races containing juvenile or adult fish.
This presentation will describe the latest results on optimization of wavelength and light flux to achieve selectivity and potency
for selected aquaculture pathogens. We will also present the newest evidence in support of environmental and food safety, as
well as target animal species safety and efficacy of this investigational new animal drug (INAD), which is being assembled with
the support of the Aquatic Animal Drug Approval Program and its affiliated laboratories.