David Heyne1,, Peter Brooks1, Martina Jelocnik1, Nick Paul1
1UniSC Seaweed Research Group, University of the Sunshine Coast, Queensland, Australia
Asparagopsis taxiformis is renowned for its production of antimethanogenic bromoform, or tribromomethane. However, the genus produces hundreds of other halogenated compounds including halo- alcohols, ketones, acids and other alkanes, most of which were identified in the 1970s and early 80s. Many of these compounds are volatiles and/or present at low concentrations, meaning that their bioactivities remain largely uncharacterised. Recently, while evaluating different drying protocols for Asparagopsis as a feed additive, we inadvertently recovered a range of volatile halogenated compounds that we had not detected in any format of dried biomass. Here, we report the method for recovering and concentrating the volatile natural products of Asparagopsis in the condensed water from low-moderate heat drying. Bioassay guided fractionation was done with four levels of comparison, starting with three environmental samples. Overall, the three condensates were tested against four pathogenic bacteria, exhibiting a bactericidal effect similar to the antibiotic gentamicin. Fractionation and further partitioning of the compounds allowed us to evaluate different concentrations and combinations of compounds against Salmonella enterica subsp. typhimurium and Acinetobacter baumannii which are responsible for the majority of food-borne pathogen-related deaths and increasing incidences of nosocomial infections, respectively. These results identified that most of the activity was due to ~10 different compounds, none of which were bromoform. This paper highlights a process whereby multiple bioactive compounds can in turn be targeted for multiple applications by applying a biorefinery approach to utilising the ‘waste’ of the seaweed drying processes.