Loperamide-based compounds as additives for biofouling management

The commercial pharmaceutical Imodium™, which contains the active ingredient loperamide hydrochloride, has been shown to have biofouling control properties. However, due to concerns associated with safety and persistence of this active pharmaceutical ingredient (API) in the environment, the development of loperamide as an anti-fouling additive is not desirable. In this paper, we report our efforts directed towards the design and synthesis of small molecule anti-foulants using the loperamide parent compound as the lead compound. These loperamide-based compounds can be synthesized readily and inexpensively. Several of the compounds identified are potentially useful as additives in marine antifouling coatings as they control attachment of barnacles in laboratory tests and an estimation program (BIOWIN) developed by the US Environmental Protection Agency predicts that they will degrade completely in weeks to months. [Display omitted] •Structure–activity relationships of loperamide and analogues were observed.•The biodegradability of compounds was predicted using BIOWIN modelling programme.•Selection of anti-foulants should consider therapeutic ratios and biodegradability.