Evaluation of toxicity of capsaicin and zosteric acid and their potential application as antifoulants

Abstract

The toxicity of two natural product antifoulants, capsaicin and zosteric acid, was evaluated using the Microtox assay and a static toxicity test. The EC50 values obtained from the Microtox assay for capsaicin and zosteric acid were 11.75 +/- 1.02 and 442 +/- 100 mg/L, respectively. The static toxicity test, conducted with freshwater organisms, yielded capsaicin EC50 values of 5.5 +/- 0.5 and 23 +/- 2.0 mg/L for P. putida and Lake Erie bacteria, respectively. Zosteric acid EC50 values were 167 +/- 3.9 and 375 +/- 10 mg/L for P. putida and Lake Erie bacteria, respectively. Tests with marine organisms resulted in capsaicin EC50 values of 6.9 +/- 0.2 and 15.6 +/- 0.4 mg/L for V. natriegens and V. parahaemolyticus, respectively; whereas zosteric acid EC50 values were 7.4 +/- 0.1 and 18 +/- 0.6 mg/L for V. natriegens and V. parahaemolyticus, respectively. These results indicate that zosteric acid is much less toxic than capsaicin and that both are substantially less toxic than the currently used antifoulants, such as TBT (EC50< 0.01 ppb). Their effectiveness as natural antifoulants was demonstrated by preliminary attachments studies. As the aqueous antifoulant concentration increased, significant inhibition of bacteria attachment or prevention of biofilm formation was achieved. Hence, both capsaicin and zosteric acid could be attractive alternatives as new antifouling compounds.

Zosteric acid—An effective antifoulant for reducing fresh water bacterial attachment on coatings

“…Both cultures were maintained as described elsewhere. 24,28 A contact angle goniometer (Model 100-00 from RameHart, Inc.), optical microscopes (IX 70, Olympus and Infini Tube, Edmund Scientific), and an atomic force microscope (Metrology 2000, Molecular Imaging) were used for characterization of the coatings. They were all equipped with CCD video cameras for spontaneously capturing the images of interest.…”

“…5,12,19,20 Zosteric acid, a natural compound present in zostera marina, or eelgrass, has been found to prevent the attachment of some bacteria, algae, barnacles, and tubeworms at nontoxic concentrations. [21][22][23][24] The formula structure of zosteric acid or p-(sulfo-oxy) cinnamic acid is shown in Figure 1. The antifouling capability of zosteric acid was attributed to the sulfate ester group presented in the compound.…”

New Directions in Antifouling Technology

“…Other naturally occurring compounds have been explored as antifoulants. These include capsaicin and zosteric acid [47][48][49], tannins [18], tannin-aluminium complexes [50] and cupric tannate [51]. Synthetic analogues of naturally occurring antifoulants have also been found to deter fouling [52,53].…”

An exploration of the estrogen receptor transcription activity of capsaicin analogues via an integrated approach based on in silico prediction and in vitro assays

“…To realize the elimination of the corresponding contamination caused by DDT-based antifouling paint, the strong repelling capacity of capsaicin has been introduced to develop capsaicin analogues to replace DDT as the effective additive for antifouling paint since 1995 (Xu et al, 2005;Angarano et al, 2007;Wang et al, 2013). However, capsaicin itself may still exert biological effects on the cardiovascular, nervous and respiratory systems, even with the structure skeleton of natural alkaloids (Caterina et al, 1997;Kalliomäki et al, 2013).…”