Bioactive constituents from the edible Seaweed halymenia hawaiiana (Rhodophyta)

Authors: RAKSAT, ANCHARA - University Of Hawaii; ATANU, SAMIUL - University Of Hawaii; MCDERMID, KARLA - University Of Hawaii; Wall, Marisa; CHANG, BOON LOONG - Department Of Traditional Chinese Medicine, School Of Pharmacy, Management And Science University; WONGWIWATTHANANUKIT, SUPAKIT - University Of Hawaii; CHANG, LENG CHEE - University Of Hawaii

Submitted to: Pharmaceutical Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2025
Publication Date: 6/26/2025
Citation: Raksat, A., Atanu, M.S.H., McDermid, K.J., Wall, M.M., Chang, B.L., Wongwiwatthananukit, S., Chang, L.C. 2025. Bioactive constituents from the edible Seaweed halymenia hawaiiana (Rhodophyta). Pharmaceutical Biology. 63:1, 447-459. https://doi.org/10.1080/13880209.2025.2521285.
DOI: https://doi.org/10.1080/13880209.2025.2521285

Interpretive Summary: The red marine macroalgae, Halymenia hawaiiana, is an edible seaweed with potential medicinal properties. This species is native to the Hawaiian Islands and is used as food as a valuable source of protein, vitamins, minerals, and dietary fiber. In this study, eleven compounds were isolated and characterized, and their structures were elucidated using spectroscopic methods. Two nucleosides, a cytosine analog, five saturated long-chain fatty acids, and three cholesterol derivatives were isolated. A variety of secondary metabolites were revealed, and several isolated compounds showed antimicrobial, anti-inflammatory and anti-tumor activity in vitro. The cholesterol derivative compounds feature peroxide side chains and demonstrate promise as lead compounds for development as anti-inflammatory and antimicrobial agents.

Technical Abstract: The marine macroalgae, Halymenia hawaiiana, has commercial potential because of culinary uses among ethnic groups in Hawaii and its success in aquaculture. Our objectives were to study the chemical components and potential medicinal properties of H. hawaiiana. Dried, ground H. hawaiiana was extracted with solvents: ethyl acetate, methanol, and n-butanol, respectively.Chromatographic procedures were applied leading to the isolation of several compounds. Structure determination was performed using spectroscopic methods. Compounds were assessed with several in vitro assays. Two nucleosides (1 and 2), a cytosine analog (3), five saturated long-chain fatty acids (4-8), and three cholesterol derivatives (9-11) were isolated. Compounds 10 and 11 displayed promising antimicrobial activity against Staphylococcus aureus, both with MIC values of 8 µg/mL, and methicillin-susceptible S. aureus, with MIC values of 32 and 64 µg/mL, respectively. Additionally, using a cell culture model, the cholesterol derivatives 9, 10, and 11 exhibited anti-inflammatory effects as indicated by the inhibition of lipopolysaccharide (LPS)-induced nitric oxide (NO) production, with IC50 values of 50.2, 53.6, and 60.8 µM, respectively. These three derivatives also inhibited the generation of reactive oxygen species (ROS)/reactive nitrogen species (RNS) in RAW 264.7 cells with IC50 values of 55, 65, and 73.7 µM, respectively. Compounds 9-11 also exhibited mild cytotoxicity with non-small cell lung cancer cell line A549, with compound 10 mediating the strongest response (IC50 86.1 µM). This study uncovered a variety of secondary metabolites from H. hawaiiana. Compounds 10 and 11 feature peroxide side chains and demonstrate promise as lead compounds for development as anti-inflammatory and antimicrobial agents.