Exploring Marine Macroalgae as Natural Sources of Vitamin K1 Using Supercritical CO₂ Extraction

Authors: Dina C. Simes1,2, Bárbara Vieira1, Carla Viegas1,2, Aschwin Engelen1, Ana B. Paninho3,4, Ana V. M. Nunes3,4

Affiliations: 1) Centre of Marine Sciences (CCMAR), University of Algarve, Faro, Portugal; 2) GenoGla Diagnostics, CCMAR, University of Algarve, Faro, Portugal, 3) i3N/CENIMAT, Department of Materials Science, NOVA School of Science and Technology and CEMOP/UNINOVA, Campus de Caparica, Caparica 2829-516, Portugal 4) LAQV-REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, Campus de Caparica, Caparica 2829-516, Portugal.

Abstract: Marine macroalgae represent a promising yet underexplored source of high-value bioactive compounds, offering opportunities for sustainable biomass valorization within the blue bioeconomy. Vitamin K1 (phylloquinone) is an essential micronutrient with important biological functions, but its occurrence and sustainable recovery from marine macroalgae remain poorly explored. In this study, supercritical carbon dioxide (ScCO₂) extraction was investigated as a sustainable approach for the recovery of vitamin K1 from different marine macroalgae. A reverse-phase HPLC method with fluorescence detection was established for vitamin K1 quantification, and the identity of naturally occurring vitamin K1 isolated from selected macroalgal extracts was further confirmed by mass spectrometry. Macroalgae belonging to different taxonomic groups, including brown, green and red species, were screened under controlled ScCO₂ extraction conditions. Vitamin K1 was successfully detected and quantified in the ScCO₂ extracts, revealing marked differences in its recovery among the macroalgal species investigated. The results demonstrate that taxonomically diverse marine macroalgae can provide natural sources of vitamin K1 and highlight the potential of ScCO₂ as a solvent-free extraction strategy for its recovery from marine biomass. Overall, this work supports the exploration of marine macroalgal resources, including invasive species, as sources of high-value bioactives and contributes to the development of sustainable approaches for marine biomass valorization.