Australian indigenous edible halophytes — nutritious and functional for a sustainable future: antioxidant capacity and antimicrobial properties

In recent years, edible halophytes have received more attention due to their ability to tolerate a wide range of salinities. Furthermore, halophytes have long been used for food, feed and medicinal purposes. However, available information on their nutritional profile (including antioxidant compounds) and bioactivity is still very limited. Therefore, the present study investigated the antioxidant capacity and antibacterial activity of three important Australian indigenous edible halophytes, Sesuvium sp. (Seapurslane), Suaeda sp. (Seablite) and Atriplex sp. (Saltbush), to assess their bioactive properties and potential to be used as functional food ingredients. The antioxidant capacity was determined by total phenolic content (TPC), total flavonoid content (TFC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and the antimicrobial activity was evaluated using the agar well diffusion method. The methanolic extract of Seapurslane showed the highest TPC (12.5 mg GAE/g DW), TFC (4.3 mg QE/g DW) and DPPH (102.6 µM TE/g DW), followed by Seablite and Saltbush. The ethanolic extract of Seapurslane had antimicrobial activity against Gram positive Staphylococcus aureus bacterium, a predominant food pathogen causing gastroenteritis and other health issues. These initial results are very promising and indicate that Australian-grown halophytes may have the potential to be utilised as novel sources of antioxidant and antimicrobial compounds for different food applications.