Physicochemical profile and bioactivity of oligo-ulvan from Ulva ohnoi seaweed depolymerized by different physical methods: Profil fisikokimia dan bioaktivitas oligo-ulvan dari rumput laut Ulva ohnoi yang didepolimerisasi dengan berbagai metode

Caddoumy Zahrel  Ben; Safrina Dyah  Hardinigtyas; Wahyu  Ramadhan

doi:10.17844/deq82q94

Authors

Caddoumy Zahrel Ben Department of Aquatic Products Technology, Faculty of Fisheries and Marine Sciences, IPB University https://orcid.org/0009-0006-2863-017X
Safrina Dyah Hardinigtyas Department of Aquatic Products Technology, Faculty of Fisheries and Marine Sciences, IPB University https://orcid.org/0000-0002-6514-1248
Wahyu Ramadhan Department of Aquatic Products Technology, Faculty of Fisheries and Marine Sciences, IPB University https://orcid.org/0000-0003-1289-215X

DOI:

https://doi.org/10.17844/deq82q94

Keywords:

antidiabetic, cell antiproliferative, microwave, ultrasonication, ultraviolet

Abstract

Ulva ohnoi is a fast-growing green seaweed with high biomass productivity but remains underutilized beyond food and agricultural uses. Their main bioactive compound, ulvan, a sulfated polysaccharide, exhibits enhanced antioxidant and therapeutic activities when depolymerized into lower-molecular-weight forms. This study aimed to determine the effects of three physical depolymerization methods–ultrasound, ultraviolet (UV) radiation, and microwaves–on the physicochemical properties and bioactivity of ulvan extracted from Ulva ohnoi. Ulvan was extracted using hot maceration at 90°C for 2 h. The extracted ulvan was subjected to three treatments: ultrasonication for 60, 120, and 180 min; UV exposure for 60, 120, and 180 min; and microwave irradiation for 5, 10, and 15 min. Each treatment was performed in triplicates using a completely randomized design. The resulting oligo-ulvan was analyzed for molecular weight, viscosity, and bioactivities, including antioxidant activity (DPPH assay), α-glucosidase inhibition, and antiproliferative effects on fibroblast cells. Among the treatments, ultrasonication for 180 min produced oligo-ulvan with the lowest viscosity (1.41±0.06 cP) and molecular weight (78.2±2.5 kDa), along with significantly improved antioxidant activity (IC₅₀: 303.33 ppm), α-glucosidase inhibition (IC₅₀: 111.63±1.47 ppm), and antiproliferative effects (45.73±7.83% at 125 μg/mL). These findings highlight ultrasound-assisted depolymerization as a promising and environmentally friendly method for enhancing the therapeutic potential of ulvan for biomedical applications.

References

Aaron-Amper, J., Largo, D. B., Handugan, E. R. B., Nini, J. L., Alingsasa, K. M. A., & Gulayan, S. J. (2020). Culture of the tropical brown seaweed Sargassum aquifolium: from hatchery to field out-planting. Aquaculture Reports, 16(1), 1–8. https://doi.org/10.1016/j.aqrep.2019.100265.

Abeln, F., Fan, J., Budarin, V. L., Briers, H., Parsons, S., Allen, M. J., Henk, D. A., Clark, J., & Chuck, C. J. (2019). Lipid production through the single-step microwave hydrolysis of macroalgae using the oleaginous yeast Metschnikowia pulcherrima. Algal Research, 38, 101411. https://doi.org/10.1016/j.algal.2019.101411.

Adrien, A., Bonnet, A., Dufour, D., Baudouin, S., Maugard, T., & Bridiau, N. (2017). Pilot production of ulvans from Ulva sp. and their effects on hyaluronan and collagen production in cultured dermal fibroblasts. Carbohydrate Polymers, 157, 1306–1314. https://doi.org/10.1016/j.carbpol.2016.11.014

Al-Arthitaya, K., Taehwan, K. A., & Moo, K. S. (2019). Inhibitory activities of microalgal fucoxanthin against α-amylase, α-glucosidase, and glucose oxidase in 3T3-L1 cells linked to type 2 diabetes. Journal of Oceanology and Limnology, 37(3), 928–937. https://doi.org/10.1007/s00343-019-8098-9.

Al-Badaani, A. A., Adam, M. S., Hifney, A. F., & Gomaa, M. (2025). Development of Ulva lactuca-derived cellulose/nanocellulose edible films with enhanced light, oxygen, and water vapor barrier properties and natural antioxidant properties. Journal of Aquatic Food Product Technology, 34(2), 105–121. https://doi.org/10.1080/10498850.2025.2484353.

Alves, A., Sousa, R. A., & Reis, R. L. (2013). A practical perspective on ulvan extracted from green algae. Journal of Applied Phycology, 25, 407–424. https://doi.org/10.1007/s10811-012-9875-4.

Amor, C. B., Jmel, M. A., Chevallier, P., Mantovani, D., & Smaali, I. (2021). Efficient extraction of a high molecular weight ulvan from stranded Ulva sp. biomass: application on the active biomembrane synthesis. Biomass Conversion and Biorefinery, 13, 3975–3985. https://doi.org/10.1007/s13399-021-01426-9.

André, J., Flórez-Fernández, N., Domínguez, H., & Torres, M. D. (2023). Microwave-assisted extraction of Ulva spp. including a stage of selective coagulation of ulvan stimulated by a bio-ionic liquid. International Journal of Biological Macromolecules, 225, 952–963. https://doi.org/10.1016/j.ijbiomac.2022.11.158.

[AOAC] Association of Official Analytical Chemists. (1995). Official Method of Analysis of The Association of Official Analytical of Chemist. Virginia (US): The Association of Official Analytical Chemist, Inc.

[AOAC]. Association of Official Analytical Chemists. (2005). Official Methods of Analysis of The Association of Official Analitical of Chemist. Virginia (US): The Association of Official Analytical Chemist, Inc.

Araujo, R. G., Alcantar-Rivera, B., Meléndez-Sánchez, E. R., Martínez-Prado, M. A., Sosa-Hernández, J. E., Iqbal, H. M. N., Parra-Saldivar, R., & Martínez-Ruiz, M. (2022). Effects of UV and UV-vis irradiation on the production of microalgae and macroalgae: New alternatives to produce photobioprotectors and biomedical compounds. Molecules, 27(16), 1–16 https://doi.org/10.3390/molecules27165334.

Ashour, N. A., Saleh, M. M., Mostafa, N. Y., & El-Shoubaky, G. A. (2025). Isolation, characterization, and antimicrobial potential of ulvan from abundant green marine macroalgae, Egypt. GSC Biological and Pharmaceutical Sciences, 31(1), 212–224. https://doi.org/10.30574/gscbps.2025.31.1.0133.

Baltrusch, K. L., Torres, M. D., & Domínguez, H. (2024). Characterization, ultrafiltration, depolymerization and gel formulation of ulvans extracted via a novel ultrasound–enzyme assisted method. Ultrasonics Sonochemistry, 111, 107072. https://doi.org/10.1016/j.ultsonch.2024.107072.

Barakat, K. M., Ismail, M. M., Abou El Hassayeb, H. E., et al. (2022). Chemical characterization and biological activities of ulvan extracted from Ulva fasciata (Chlorophyta). Rendiconti Lincei. Scienze Fisiche e Naturali, 33, 829–841. https://doi.org/10.1007/s12210-022-01103-7.

Bast, F., Bhushan, S., & Ahmad, J. A. (2015). Brown barcoded as red but reality is green! How epiphytic green algae confuse phycologists? Webbia, 70(1), 59–63. https://doi.org/10.1080/00837792.2015.1014217.

Beaumont, M., Tran, R., Vera, G., Niedrist, D., Rousset, A., Pierre, R., Shastri, V. P., & Forget, A. (2021). Hydrogel-forming algae polysaccharides: from seaweed to biomedical applications. Biomacromolecules, 22(3), 1027–1052. https://doi.org/10.1021/acs.biomac.0c01406.

Bounanti, T., Colson, E., Moins, S., Cabrera, J. C., Eeckhaut, I., Raquez, J. M., & Gerbaux, P. (2020). Microwave-assisted depolymerization of carrageenans from Kappaphycus alvarezii and Eucheuma spinosum: controlled and green production of oligosaccharides from the algae biomass. Algal Research, 51, 1–10. https://doi.org/10.1016/j.algal.2020.102054.

Bradford, M. M. (1976). A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Analytical Biochemistry, 72(1–2), 248–254. https://doi.org/10.1016/0003-2697(76)90527-3.

Bringloe, T. T., Dunton, K. H., & Saunders, G. W. (2017). Updates to the marine algal flora of the Boulder Patch in the Beaufort Sea off northern Alaska as revealed by DNA barcoding. Arctic, 70(4), 343–348. https://doi.org/10.14430/arctic4679.

Bruhn, A., Dahl, J., Nielsen, H. B., Nikolaisen, L., Rasmussen, M. B., Markager, S., Olesen, B., Arias, C., & Jensen, P. D. (2011). Bioenergy potential of Ulva lactuca: biomass yield, methane production and combustion. Bioresource Technology, 102(3), 2595–2604. https://doi.org/10.1016/j.biortech.2010.10.010.

Cavari, S., Ruggiero, M., & Vannucchi, S. (1993). Antiproliferative effect of heparin on normal and transformed NIH/3T3 fibroblasts. Cell Biology International, 17(8), 781–786. https://doi.org/10.1006/cbir.1993.1140.

Chaouch, M. A., Hafsa, J., Rihouey, C., Le, C. D., & Majdoub, H. (2015). Depolymerization of polysaccharides from Opuntia ficus-indica: antioxidant and antiglycated activities. International Journal of Biological Macromolecules, 79(1), 779–786. https://doi.org/10.1016/j.ijbiomac.2015.06.003

Chen, X., Wang, J., Wang, Z., Xu, H., Liu, C., Huo, B., Meng, F., Wang, Y., & Sun, C. (2023). Low-frequency mechanical energy in the environment for energy production and piezocatalytic degradation of organic pollutants in water: a review. Journal of Water Process Engineering, 56, 104312. https://doi.org/10.1016/j.jwpe.2023.104312.

Cirik, S., Cetin, Z., A. I., Cirik, S., & Goksan, T. (2010). Greenhouse cultivation of Gracilaria verrucosa (Hudson) papenfuss and determination of chemical composition. Turkish Journal of Fisheries and Aquatic Sciences, 10(4), 559–564. https://doi.org/10.4194/trjfas.2010.0417.

Crescencio, K., Amaral, V., Souza, A. B. D., Barros, C. D., Souza, J., Baldo, D., Oliveira J. J., Horta, P., Oliveira, B. D., E., Behling, R., Batain, F., Severino, P., Alves, T., Souto, E. B., & Chaud, M. (2024). Ulvan from Ulva ohnoi macroalgae: green extraction method and physicochemical characterization of the ulvan. Research Square, 1(1), 1–7. https://doi.org/10.21203/rs.3.rs-4751748/v1

Dobrynin, A. V., Sayko, R., & Colby, R. H. (2023). Viscosity of polymer solutions and molecular weight characterization. ACS Macro Letters, 12(6), 773–779. https://doi.org/10.1021/acsmacrolett.3c00219.

Fort, A., McHale, M., Cascella, K., Potin, P., Perrineau, M.-M., Kerrison, P. D., Costa, D. E., Calado, R., Domingues, M. D. R., Costa A. I., Sousa-Pinto, I., Gachon, C., Werf, A. V. D., Visser, W. D., Beniers, J. E., Jansen, H., Guiry, M. D., & Sulpice, R. (2022). Exhaustive reanalysis of barcode sequences from public repositories highlights ongoing misidentifications and impacts taxa diversity and distribution. Molecular Ecology Resources, 22(1), 86–101. https://doi.org/10.1111/1755-0998.13453.

Gajanayaka, N. D., Jo, E., Bandara, M. S., Marasinghe, S. D., Bawkar, C., Lee, Y. J., Park, G. H., Oh, C., & Lee, Y. (2024). Characterisation of high alkaline-tolerant novel ulvan lyase from Pseudoalteromonas agarivorans: potential applications of enzyme-derived oligo-ulvan as anti-diabetic agent. Marine Drugs, 22(12), 577–590. https://doi.org/10.3390/md22120577.

Gajanayaka, N. D., Jo, E., Bandara, M. S., Marasinghe, S. D., Hettiarachchi, S. A., Wijewickrama, S., Park, G.-H., Oh, C., & Lee, Y. (2025). Pseudoalteromonas agarivorans-derived novel ulvan lyase of polysaccharide lyase family 40: potential application of ulvan and partially hydrolyzed products in cosmetic industry. Journal of Industrial Microbiology and Biotechnology, 52(1), 1–14. https://doi.org/10.1093/jimb/kuaf004.

Garg, H. G., Thompson, T., & Hales, C. A. (2002). Structural determinants of antiproliferative activity of heparin on pulmonary artery smooth muscle cells. American Journal of Physiology-Lung Cellular and Molecular Physiology, 279(5), L779–L789. https://doi.org/10.1152/ajplung.2000.279.5.L779.

Glasson, C. R. K., Sims, I. M., Carnachan, S. M., Nys, R. D., & Magnusson, M. (2017). A cascading biorefinery process targeting sulfated polysaccharides (ulvan) from Ulva ohnoi. Algal Research, 27, 383–391. https://doi.org/10.1016/j.algal.2017.07.001.

Guo, Q., Sun, D.-W., Cheng, J.-H., & Han, Z. (2018). Microwave processing techniques and their recent applications in the food industry. Trends in Food Science & Technology, 67(1), 236–247. https://doi.org/10.1016/j.tifs.2017.07.007

Hamouda, M. M., Saad-Allah, K. M., & Gad, D. (2022). Potential of seaweed extract on growth, physiological, cytological and biochemical parameters of wheat (Triticum aestivum L.) seedlings. Journal of Soil Science and Plant Nutrition, 22, 1818–1831. https://doi.org/10.1007/s42729-022-00774-3.

Hernández-Garibay, E., Zertuche-González, J. A., & Pacheco-Ruíz, I. (2011). Isolation and chemical characterization of algal polysaccharides from the green seaweed Ulva clathrata (Roth) C. Agardh. Journal of Applied Phycology, 23(3), 537–542. https://doi.org/10.1007/s10811-010-9629-0.

Ho, K., Yazan, L. S., Ismail, N., & Ismail, M. (2009). Apoptosis and cell cycle arrest of human colorectal cancer cell line HT-29 induced by vanillin. Cancer Epidemiology, 33(2), 155–160. https://doi.org/10.1016/j.canep.2009.06.003.

Houwink, R. (1940). Relationship between viscosimetric and osmotically determined degrees of polymerization in high polymers. Journal für Praktische Chemie, 157, 15-18. https://doi.org/10.1002/prac.19401570102.

Hsu, W. K., Hsu, T. H., Lin, F. Y., Cheng, Y. K., & Yang, J. P. (2013). Separation, purification, and α-glucosidase inhibition of polysaccharides from Coriolus versicolor LH1 mycelia. Carbohydrate Polymers, 92(1), 297–306. https://doi.org/10.1016/j.carbpol.2012.10.001.

Huggins, M. L. (1942). The viscosity of dilute solutions of long chain molecules. IV. Dependence on concentration. Journal of the American Chemical Society, 64(11), 2716–2718. https://doi.org/10.1021/ja01263a056.

Jacoeb, A. M., Abdullah, A., & Hakimah, S. N. (2024). Potensi ulvan dari Ulva lactuca sebagai sumber antioksidan. Jurnal Pengolahan Hasil Perikanan Indonesia, 27(3), 242–251. https://doi.org/10.17844/jphpi.v27i3.46950.

Jatmiko, T., Prasetyo, D. J., Dewi, C., Hernawan, H., & Khasanah, Y. (2019). Nutritional evaluation of Ulva sp. from Sepanjang Coast, Gunungkidul, Indonesia. IOP Conference Series: Earth and Environmental Science, 251(1), 1–5. https://doi.org/10.1088/1755-1315/251/1/012011.

Khmelev, V. N., Golykh, R. N., Bobrova, G. A., Shakura, V. A., & Ilchenko, E. V. (2018). The modeling of ultrasonic cavitation depolymerization causing reducing of polymer viscosity. In Proceedings of the International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM). https://doi.org/10.1109/EDM.2018.8435073.

Kidgell, J. T., Magnusson, M., Nys, R. D., & Glasson, C. R. K. (2019). Ulvan: a systematic review of extraction, composition and function. Algal Research, 39(1), 1–20. https://doi.org/10.1016/j.algal.2019.101422.

Kraithong, S., Ke, X., Lee, S., Bunyameen, N., Kuang, W., Huang, Q., Zhang, X., & Huang, R. (2025). Characterization of ulvan polysaccharide extracted from Ulva pertusa and its effect on thermal, rheological, and gelling properties of rice flour. Food Chemistry, 465(1), 1–12. https://doi.org/10.1016/j.foodchem.2024.141974.

Krangkratok, W., Chantorn, S., Choosuwan, P., Phomkaivon, N., La-ongkham, O., Kosawatpat, P., Tamtin, M., & Praiboon, J. (2023). Production of prebiotic ulvan-oligosaccharide from the green seaweed Ulva rigida by enzymatic hydrolysis. Biocatalysis and Agricultural Biotechnology, 54, 102922. https://doi.org/10.1016/j.bcab.2023.102922.

Kurniasih, S. D., Pramesti, R., & Ridlo, A. (2014). Penentuan aktivitas antioksidan ekstrak rumput laut Ulva sp. dari Pantai Krakal–Yogyakarta. Journal of Marine Research, 3(4), 617–626. https://doi.org/10.14710/jmr.v3i4.11423

Lahaye, M., & Robic, A. (2007). Structure and functional properties of ulvan, a polysaccharide from green seaweeds. Biomacromolecules, 8(6), 1765–1774. https://doi.org/10.1021/bm0607699.

Lei, N., Wang, M., Zhang, L., Xiao, S., Fei, C., Wang, X., Zhang, K., Zheng, W., Wang, C., Yang, R., & Xue, F. (2015). Effects of low molecular weight yeast β-glucan on antioxidant and immunological activities in mice. International Journal of Molecular Sciences, 16(9), 21575–21590. https://doi.org/10.3390/ijms160921575.

Li, C., Tang, T., Du, Y., Jiang, L., Yao, Z., Ning, L., & Zhu, B. (2023). Ulvan and Ulva oligosaccharides: a systematic review of structure, preparation, biological activities and applications. Bioresources, and Bioprocessing, 10(66), 1–17. https://doi.org/10.1186/s40643-023-00690-z.

Lin, J., Jiao, G., & Kermanshahi-pour, A. (2022). Algal polysaccharides-based hydrogels: extraction, synthesis, characterization, and applications. Marine Drugs, 20(5), 306–364. https://doi.org/10.3390/md20050306.

Ling, J., Hua, L., Qin, Y., Gu, T., Jiang, S., & Zhao, J. (2023). Perfluorooctane sulfonate promotes hepatic lipid accumulation and steatosis in high-fat diet mice through AMP-activated protein kinase/acetyl-CoA carboxylase (AMPK/ACC) pathway. Journal of Applied Toxicology, 43(2), 312–322. https://doi.org/10.1002/jat.4383

Long, X., Hu, X., Zhou, S., Xiang, H., Chen, S., Li, L., Liu, S., & Yang, X. (2022). Optimized degradation and inhibition of α-glucosidase activity by Gracilaria lemaneiformis polysaccharide and its production in vitro. Marine Drugs, 20(1), 13–34. https://doi.org/10.3390/md20010013.

Mission, E. G., Agutaya, J. K. C. N., Quitain, A. T., Sasaki, M., & Kida, T. (2019). Carbocatalysed hydrolytic cleaving of the glycosidic bond in fucoidan under microwave irradiation. RSC Advances, 9(52), 30325–30334. https://doi.org/10.1039/C9RA03594J.

Montes, L., Gisbert, M., Hinojosa, I., Sineiro, J., & Moreira, R. (2021). Impact of drying on the sodium alginate obtained after polyphenols ultrasound-assisted extraction from Ascophyllum nodosum seaweeds. Carbohydrate Polymers, 272, 118455. https://doi.org/10.1016/j.carbpol.2021.118455

Murphy, V., Hughes, H., & McLoughlin, P. (2008). Comparative study of chromium biosorption by red, green, and brown seaweed biomass. Chemosphere, 70(6), 1128–1134. https://doi.org/10.1016/j.chemosphere.2007.08.015.

Mutizabal-Aros, J., Ramírez, M. E., Haye, P. A., Meynard, A., Pinilla-Rojas, B., Núñez, A., Latorre-Padilla, N., Search, F. V., Tapia, F. J., Saldías, G. S., Navarrete, S. A., & Contreras-Porcia, L. (2024). Morphological and molecular identification of Ulva spp. (Ulvophyceae; Chlorophyta) from Algarrobo Bay, Chile: understanding the composition of green tides. Plants, 13(9), 1258–1276. https://doi.org/10.3390/plants13091258.

Muzzarelli, R. A. A., Stanic, V., & Ramos, V. (1999). Enzymatic depolymerization of chitins and chitosans. In C. Bucke (Ed.), Carbohydrate biotechnology protocols (1st ed., pp. 197–211). Humana Press. https://doi.org/10.1007/978-1-59259-261-6_16.

Najafabadi, S. A. A., Honarkar, H., Moghadam, M., et al. (2018). UV irradiation–H₂O₂ system as an effective combined depolymerization technique to produce oligosaccharides from chitosan. Bio-Design and Manufacturing, 1, 62–68. https://doi.org/10.1007/s42242-018-0005-2

Ng, Y. F., & Huang, D. (2024). Species diversity and phylogeny of the green macroalga Ulva (Ulvophyceae, Chlorophyta) in Singapore. Phytotaxa, 662(1), 67–79. https://doi.org/10.11646/phytotaxa.662.1.5

Ngo, D. H., Ngo, D. N., Kim, S.-K., & Vo, T. S. (2019). Antiproliferative effect of aminoethyl-chitooligosaccharide on human lung A549 cancer cells. Biomolecules, 9(5), 195. https://doi.org/10.3390/biom9050195.

Noguchi, S., & Kobayashi, T. (2022). Ultrasound viscoelastic properties of biomass polysaccharide hydrogels as evaluated by rheometer equipped with sono-device. Gels, 8(3), 172–183. https://doi.org/10.3390/gels8030172.

Omar, N. N., Ibrahim, N. H., Mohamad, N. J., Achudan, S. N., & Mat A. A. (2024). Optimization of ultrasound-assisted enzymatic extraction conditions on yield, DPPH antioxidant activity, and gel strength of agar from Gracilaria fisheri. Journal of Aquatic Food Product Technology, 33(9), 765–777. https://doi.org/10.1080/10498850.2024.2414432.

Pang, X., Wang, H., Guan, C., Chen, Q., Cui, X., & Zhang, X. (2024). Impact of molecular weight variations in Dendrobium officinale polysaccharides on antioxidant activity and anti-obesity in Caenorhabditis elegans. Foods, 13(7), 1040–1055. https://doi.org/10.3390/foods13071040.

Pari, R. F., Mayangsari, D., & Hardiningtyas, S. D. (2022). Depolimerisasi kitosan dari cangkang udang dengan enzim papain dan iradiasi sinar ultraviolet. Jurnal Pengolahan Hasil Perikanan Indonesia, 25(1), 118–131. https://doi.org/10.17844/jphpi.v25i1.40311.

Pari, R. F., Uju, U., Hardiningtyas, S. D., Ramadhan, W., Wakabayashi, R., Goto, M., & Kamiya, N. (2025). Ulva seaweed-derived ulvan: a promising marine polysaccharide as a sustainable resource for biomaterial design. Marine Drugs, 23(2), 56. https://doi.org/10.3390/md23020056.

Pari, R. F., Uju, Wijayanti, A. T., Ramadhan, W., Hardiningtyas, S. D., Kurnia, K. A., Firmansyah, M. L., Hana, A., Abrar, M. N., Wakabayashi, R., Kamiya, N., & Goto, M. (2024). Prospecting Ulva lactuca seaweed in Java Island, Indonesia, as a candidate resource for industrial applications. Fisheries Science, 90(1), 1–14 https://doi.org/10.1007/s12562-024-01799-6.

Patil, S., Alegaon, S. G., Gharge, S., Ranade, S. D., & Khatif, N. A. (2024). Molecular hybridization, synthesis, in vitro α-glucosidase inhibition, in vivo antidiabetic activity and computational studies of isatin based compounds. Bioorganic Chemistry, 153(11), 1–18. https://doi.org/10.1016/j.bioorg.2024.107783.

Peng, W., Xiaoman, Y., Bingna, C., Hua, C., Huili, S., Deke, C., & Jianyu, P. (2015). Ultrasonic extraction of polysaccharides from Laminaria japonica and their antioxidative and glycosidase inhibitory activities. Journal of Oceanic and Coastal Sea Research, 14(4), 651–662. https://doi.org/10.1007/s11802-015-2648-3.

Perumal, K. P., Huang, C.-Y., Chen, C.-W., Anisha, G. S., Singhania, R. R., Dong, C.-D., & Patel, A. K. (2023). Advances in oligosaccharides production from brown seaweeds: extraction, characterization, antimetabolic syndrome, and other potential applications. Bioengineered, 14(1), 1–27. https://doi.org/10.1080/21655979.2023.2252659.

Pradhan, B., Bhuyan, P. P., & Ki, J. S. (2023). Immunomodulatory, antioxidant, anticancer, and pharmacokinetic activity of ulvan, a seaweed-derived sulfated polysaccharide: an updated comprehensive review. Marine Drugs, 21, 300–316. https://doi.org/10.3390/md21050300.

Prajapat, A. L., & Gogate, P. R. (2019). Depolymerization of carboxymethyl cellulose using hydrodynamic cavitation combined with ultraviolet irradiation and potassium persulfate. Ultrasonics Sonochemistry, 51, 258–263. https://doi.org/10.1016/j.ultsonch.2018.10.009.

Prasetyaningrum, A., Purwati, D., Dharmawan, Y., Ratnawati, R., & Jos, B. (2020). Effect of H₂O₂ concentration on molecular weight and functional properties of sulfated polysaccharides from red seaweed (Kappaphycus alvarezii). AIP Conference Proceedings, 2197(1), 070002. https://doi.org/10.1063/1.5140935

Qi, H., & Sun, Y. (2015). Antioxidant activity of high sulfate content derivative of ulvan in hyperlipidemic rats. International Journal of Biological Macromolecules, 76, 326–329. https://doi.org/10.1016/j.ijbiomac.2015.03.006

Qi, H., Zhao, T., Zhang, Q., Li, Z., Zhao, Z., & Xing, R. (2005). Antioxidant activity of different molecular weight sulfated polysaccharides from Ulva pertusa Kjellm (Chlorophyta). Journal of Applied Phycology, 17, 527–534. https://doi.org/10.1007/s10811-005-9003-9.

Qiu, W. Y., Cai, W. D., Wang, M., & Yan, J. K. (2019). Effect of ultrasonic intensity on the conformational changes in citrus pectin under ultrasonic processing. Food Chemistry, 297, 125021. https://doi.org/10.1016/j.foodchem.2019.125021

Que, Y., Zhang, Y., Liang, F., Wang, L., Yang, Y., Zhang, J., Wang, W., Sun, Y., Zhong, C., Zhang, H., He, C., Guan, L., & Ma, H. (2024). Structural characterization, antioxidant activity, and fermentation characteristics of Flammulina velutipes residue polysaccharide degraded by ultrasonic-assisted H₂O₂–Vc technique. Ultrasonics Sonochemistry, 111, 107085. https://doi.org/10.1016/j.ultsonch.2024.107085.

Ramadhan, W., Alamsyah, A., Uju, Hardiningtyas, S. D., Pari, R. F., Wakabayashi, R., Kamiya, N., & Goto, M. (2024a). Facilitating ulvan extraction from Ulva lactuca via deep eutectic solvent and peracetic acid treatment. ASEAN Journal of Chemical Engineering, 24(1), 90–101. https://doi.org/10.22146/ajche.12272.

Ramadhan, W., Kagawa, G., Hamada, Y., Moriyama, K., Wakabayashi, R., Minamihata, K., Goto, M., & Kamiya, N. (2019). Enzymatically prepared dual functionalized hydrogels with gelatin and heparin to facilitate cellular attachment and proliferation. ACS Applied Bio Materials, 2(6), 2600–2609. https://doi.org/10.1021/acsabm.9b00275.

Ramadhan, W., Ohama, Y., Minamihata, K., Moriyama, K., Wakabayashi, R., Goto, M., & Kamiya, N. (2020). Redox-responsive functionalized hydrogel marble for the generation of cellular spheroids. Journal of Bioscience and Bioengineering, 130(4), 416–423. https://doi.org/10.1016/j.jbiosc.2020.05.010.

Ramadhan, W., Ramadhani, F. A., Sevica, D., Hardiningtyas, S. D., & Desniar. (2024b). Synthesis and characterization of ulvan-alginate hydrogel beads as a scaffold for probiotic immobilization. BIO Web of Conferences, 92, 1-13 https://doi.org/10.1051/bioconf/20249202020.

Sanchez, J. A. V. (2013). Effect of ultrasound on hydrogen bond breaking appeared in aqueous polymers. [Disertasi]. Nagaoka University of Technology.

Sandria, N., Uju, & Suptijah, P. (2017). Depolimerisasi kappa karaginan dengan menggunakan peracetic acid. Jurnal Pengolahan Hasil Perikanan Indonesia, 20(3), 524–535. https://doi.org/10.17844/jphpi.v20i3.19809.

Santunione, G., Masino, F., Montevecchi, G., & Sgarbi, E. (2024). UV-B light (radiation) affects the metabolism of pigments and fatty acids in green algae Edaphochlorella mirabilis and Klebsormidium flaccidum in vitro. Algal Research, 83(1), 1–9. https://doi.org/10.1016/j.algal.2024.103736.

Sari-Chmayssem, N., Taha, S., Mawlawi, H., Guegan, P., Jeftic, J., & Benvegnu, T. (2019). Extracted ulvans from green algae Ulva linza of Lebanese origin and amphiphilic derivatives: evaluation of their physico-chemical and rheological properties. Journal of Applied Phycology, 31, 1931–1946. https://doi.org/10.1007/s10811-018-1668-y.

Shao, P., Shao, J., Han, L. L. R., & Sun, P. (2015). Separation, preliminary characterization, and moisture-preserving activity of polysaccharides from Ulva fasciata. International Journal of Biological Macromolecules, 72, 924–930. https://doi.org/10.1016/j.ijbiomac.2014.09.048.

Song, J., Wu, Y., Jiang, G., Feng, L., Wang, Z., Yuan, G., & Tong, H. (2019). Sulfated polysaccharides from Rhodiola sachalinensis reduce d-gal-induced oxidative stress in NIH 3T3 cells. International Journal of Biological Macromolecules, 140(1), 288–293. https://doi.org/10.1016/j.ijbiomac.2019.08.052.

Sulastri, E., Lesmana, R., Zubair, M. S., Elamin, K. M., & Wathonni, N. (2021). A comprehensive review on ulvan based hydrogel and its biomedical applications. Chemical and Pharmaceutical Bulletin, 69(5), 432–443. https://doi.org/10.1248/cpb.c20-00763.

Sun, H., Wang, D., Song, X., Zhang, Y., Ding, W., Peng, X., Zhang, X., Li, Y., Ma, Y., Wang, R., & Yu, P. (2017). Natural prenylchalconaringenins and prenylnaringenins as antidiabetic agents: α-glucosidase and α-amylase inhibition and in vivo antihyperglycemic and antihyperlipidemic effects. Journal of Agricultureal and Food Chemistry, 65(8), 1574–1581. https://doi.org/10.1021/acs.jafc.6b05445.

Suresh, V., Senthilkumar, N., Thangam, R., Rajkumar, M., Anbazhagan, C., Rengasamy, R., Gunasekaran, P., Kannan, S., & Palani, P. (2013). Separation, purification and preliminary characterization of sulfated polysaccharides from Sargassum plagiophyllum and its in vitro anticancer and antioxidant activity. Process Biochemistry, 48(2), 364–373. https://doi.org/10.1016/j.procbio.2012.12.014

Tako, M., Tamanaha, M., Tamashiro, Y., & Uechi, S. (2015). Structure of ulvan isolated from the edible green seaweed, Ulva pertusa. Advances in bioscience and biotechnology, 6, 645–655. https://doi.org/10.4236/abb.2015.610068

Tarman, K., Zuhair, M. W., Uju, U., & Pari, R. F. (2023). Ultrasound-assisted depolymerization of carrageenan from Kappaphycus alvarezii hydrolyzed by a marine fungus. IOP Conference Series: Earth and Environmental Science, 1137, 012048. https://doi.org/10.1088/1755-1315/1137/1/012048

Tecson, M. G., Abad, L. V., Ebajo Jr, J. V. D., Camacho, D. H. (2021). Ultrasound-assisted depolymerization of kappa-carrageenan and characterization of degradation product. Ultrasonic Sonochemistry, 73(1), 1–9. https://doi.org/10.1016/j.ultsonch.2021.105540.

Tran, V. H. N., Mikkelsen, M. D., Truong, H. B., Vo, H. N. M., Pham, T. D., Cao, H. T. T., Nguyen, T. T., Meyer, A. S., Thanh, T. T. T., & Van, T. T. T. (2023). Structural characterization and cytotoxic activity evaluation of ulvan polysaccharides extracted from the green algae Ulva papenfussii. Marine Drugs, 21(11), 556. https://doi.org/10.3390/md21110556

Trivedi, N., Gupta, V., Reddy, C. R. K., Jha, B. (2013). Enzymatic hydrolysis and production of bioethanol from common macrophytic green alga Ulva fasciata Delile. Bioresource Technology, 150(1), 106–112. https://doi.org/10.1016/j.biortech.2013.09.103.

Tziveleka, L.-A., Ioannou, E., & Roussis, V. (2019). Ulvan, a bioactive marine sulphated polysaccharide as a key constituent of hybrid biomaterials: a review. Carbohydrate Polymers, 218(1), 355–370. https://doi.org/10.1016/j.carbpol.2019.04.074.

Widowaty, W., Setiawan, Y., & Perdana, W. (2020). Aktivitas antioksidan ekstrak metanol Gracilaria sp. dan Ulva sp. dari Pantai Sayang Heulang. AgroScience, 10(2), 203–209. https://doi.org/10.35194/agsci.v10i2.1163.

Widyartini, D. S., Hidayah, H. A., & Insan, A. I. (2023). Diversity and distribution pattern of bioactive compound potential seaweed in Menganti Beach, Central Java, Indonesia. Biodiversitas, 24(2), 1125–1135. https://doi.org/10.13057/biodiv/d240252

Yaich, H., Amira, A. B., Abbes, F., Bouzazis, M., Besbes, S., Richel, A., Bleeker, C., Attia, H., & Garna, H. (2017). Effect of extraction procedures on structural, thermal and antioxidant properties of ulvan from Ulva lactuca collected in Monastir Coast. International Journal of Biological Macromolecules, 105(2), 1430-1439. https://doi.org/10.1016/j.ijbiomac.2017.07.141.

Yan, F., Jiang, H., Ma, Y., Cui, C., Qin, H., Liu, L., Zhang, S., Xing, X., Xu, Z., & Wu, H. (2022). Combined influences of light and nitrogen enrichment on the physiological performance of a golden tide alga (Sargassum horneri). Journal of Marine Science and Engineering, 10(9), 1–13. https://doi.org/10.3390/jmse10091195.

Zeng, W., Chen, L., Xiao, Z., Li, Y., Ma, J., Ding, J., Yang, J. (2023). Comparative study on the structural properties and bioactivities of three different molecular weights of Lycium barbarum polysaccharides. Molecules, 28(1), 1–20. https://doi.org/10.3390/molecules28020701

Zhang, M., Chen, Y., Chen, R., Wen, Y., Huang, Q., Liu, Y., Zhao, C. (2022). Research status of the effects of natural oligosaccharides on glucose metabolism. eFood, 3(6), 1–20. https://doi.org/10.1002/efd2.54.

Zhou, C., He, S., Gao, S., Huang, Z., Wang, W., Hong, P., & Jia, R. B. (2024). Effects of ultrasound-assisted treatment on physicochemical properties and biological activities of polysaccharides from Sargassum. Foods, 13(23), 1–15. https://doi.org/10.3390/foods13233941.

Zhu, B., Li, L., Hileuskaya, K., Xu, B. (2024). Evaluation of free radical‐induced structural changes and their effect on antioxidant and anti‐inflammatory activities of UV/H2O2‐degraded dextrans. eFood, 5(3), 1–8. https://doi.org/10.1002/efd2.147.