Targeted delivery of seaweed bioactives: liposomal encapsulation of Ulva lactuca and Codium fragile for antibacterial enhancement.

Abstract

Seaweeds are promising natural sources of antimicrobials and antioxidants; however, their direct use is often limited by the lack of effective targeted delivery systems. The main objective of this study was to investigate the effects of liposomal encapsulation on enhancing the antimicrobial action of seaweed bioactives. A liposomal formulation was developed to encapsulate extracts from the green seaweeds Ulva lactuca and Codium fragile subsp. fragile, sourced from the Aegean Sea and the Marmara Sea. Physicochemical characterizations of liposomal formulations (size, charge, polydispersity index) were evaluated by dynamic light scattering technique. The encapsulation efficiency (EE%) of liposomal U. lactuca Marmara (Lipo-ULM), liposomal U. lactuca Aegean (Lipo-ULA), liposomal C. fragile subsp. fragile Marmara (Lipo-CM), liposomal C. fragile subsp. fragile Aegean (Lipo-CA) were calculated as 61.63, 70.73, 67.56, and 76.92, respectively. FTIR analysis has confirmed the encapsulation. Antibacterial activities of the free extracts and the liposomal formulations were evaluated against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 using minimum inhibitory concentration (MIC) assays. Lipo-ULM and Lipo-ULA displayed MIC values of 1.25 µg/µL against both bacterial strains, compared to 2.5 µg/µL for their free extracts. Lipo-CM and Lipo-CA showed even more activity, with MIC values of 0.0025 µg/µL, while the free extracts of CM and CA presented 0.0050 µg/µL. Furthermore, free and liposomal encapsulated extracts revealed similar DPPH radical scavenging capacity. This study presents a novel liposomal encapsulation system that holds promise for enhancing the effectiveness of edible seaweed extracts as antibacterial agents for application in the pharmaceutical and food industries.