Low-Molecular-Weight Chitosan Produced by Gamma Irradiation and Hydrogen Peroxide Promotes Immune Readiness, Antioxidant Responses, and Survival in Photobacterium damselae-Challenged Asian Seabass (Lates calcarifer)

Rattanawongwiboon, Thitirat; Paankhao, Natthapong; Chumchuen, Ratchanon; Chinnabutra, Nattaset; Saisin, Wasin; Kumwan, Benchawan; Meachasompop, Pakapon; Adisornprasert, Yosapon; Chaemlek, Pimrawee; Srisapoome, Prapansak; Kingwascharapong, Passakorn; Tangthong, Theeranan; Buncharoen, Wararut; Uchuwittayakul, Anurak

doi:10.3390/ijms27177772

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Low-Molecular-Weight Chitosan Produced by Gamma Irradiation and Hydrogen Peroxide Promotes Immune Readiness, Antioxidant Responses, and Survival in Photobacterium damselae-Challenged Asian Seabass (Lates calcarifer)

by

Thitirat Rattanawongwiboon

^1,†

,

Natthapong Paankhao

^2,†,

Ratchanon Chumchuen

^3,4,5,

Nattaset Chinnabutra

^3,4,5,

Wasin Saisin

^3,4,5,

Benchawan Kumwan

^3,4,5

,

Pakapon Meachasompop

^3,4,5

,

Yosapon Adisornprasert

^3,4,5

,

Pimrawee Chaemlek

^3,4,5,

Prapansak Srisapoome

^3,4,5

,

Passakorn Kingwascharapong

⁶,

Theeranan Tangthong

¹,

Wararut Buncharoen

⁷ and

Anurak Uchuwittayakul

^3,4,5,*

¹

Thailand Institute of Nuclear Technology (Public Organization), Ongkharak, Nakhon Nayok 26120, Thailand

²

Kamphaeng Saen Fisheries Research Station, Faculty of Fisheries, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand

³

Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand

⁴

Laboratory of Aquatic Animal Health Management, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand

⁵

Center of Excellence in Aquatic Animal Health Management, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand

⁶

Department of Fishery Products, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand

⁷

Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand

^*

Author to whom correspondence should be addressed.

^†

These authors contributed equally to this work.

Int. J. Mol. Sci. 2026, 27(17), 7772; https://doi.org/10.3390/ijms27177772 (registering DOI)

Submission received: 12 July 2026 / Revised: 15 August 2026 / Accepted: 26 August 2026 / Published: 30 August 2026

(This article belongs to the Special Issue IJMS 25th Anniversary: Updates and Progress on Bioactives and Nutraceuticals)

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Abstract

Low-molecular-weight chitosan may exhibit improved dispersion and biological accessibility compared with high-molecular-weight chitosan, but direct comparisons in Asian seabass remain limited. This study evaluated dietary low-molecular-weight chitosan produced by combined gamma irradiation and hydrogen peroxide depolymerization. The untreated and degraded preparations had apparent GPC-derived molecular weights of approximately 85 and 10 kDa, respectively. Juvenile Asian seabass (Lates calcarifer) were fed a Control diet of 1.0% high-molecular-weight chitosan or low-molecular-weight chitosan at 0.25%, 0.5%, or 1.0% for four weeks. Growth, serum antioxidant and humoral immune parameters, tissue-specific gene expression, and resistance to Photobacterium damselae were evaluated. No treatment significantly affected growth or feed utilization. Both high- and low-molecular-weight chitosan reduced serum MDA relative to the Control, whereas selected antioxidant and immune responses differed among inclusion levels. The 0.5% low-molecular-weight treatment increased GSH and GPx activity, the 1.0% low-molecular-weight treatment produced the highest CAT activity, and the 0.25% low-molecular-weight treatment produced the highest total serum IgM. Low-molecular-weight chitosan generally produced broader tissue-specific transcriptional responses than 1.0% high-molecular-weight chitosan. Following bacterial challenge, all chitosan treatments improved survival relative to the Control, with the highest numerical RPS observed in the 0.5% low-molecular-weight group. These results indicate that molecular-weight reduction influenced the biological response to dietary chitosan. Among the tested levels, 0.5% produced the most consistent combined response, although the optimal level was endpoint-specific and requires longer-term validation.

Keywords: Asian seabass; Lates calcarifer; low-molecular-weight chitosan; gamma irradiation; hydrogen peroxide depolymerization; antioxidant defense; immune response; mucosal immunity; Photobacterium damselae; disease resistance

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MDPI and ACS Style

Rattanawongwiboon, T.; Paankhao, N.; Chumchuen, R.; Chinnabutra, N.; Saisin, W.; Kumwan, B.; Meachasompop, P.; Adisornprasert, Y.; Chaemlek, P.; Srisapoome, P.; et al. Low-Molecular-Weight Chitosan Produced by Gamma Irradiation and Hydrogen Peroxide Promotes Immune Readiness, Antioxidant Responses, and Survival in Photobacterium damselae-Challenged Asian Seabass (Lates calcarifer). Int. J. Mol. Sci. 2026, 27, 7772. https://doi.org/10.3390/ijms27177772

AMA Style

Rattanawongwiboon T, Paankhao N, Chumchuen R, Chinnabutra N, Saisin W, Kumwan B, Meachasompop P, Adisornprasert Y, Chaemlek P, Srisapoome P, et al. Low-Molecular-Weight Chitosan Produced by Gamma Irradiation and Hydrogen Peroxide Promotes Immune Readiness, Antioxidant Responses, and Survival in Photobacterium damselae-Challenged Asian Seabass (Lates calcarifer). International Journal of Molecular Sciences. 2026; 27(17):7772. https://doi.org/10.3390/ijms27177772

Chicago/Turabian Style

Rattanawongwiboon, Thitirat, Natthapong Paankhao, Ratchanon Chumchuen, Nattaset Chinnabutra, Wasin Saisin, Benchawan Kumwan, Pakapon Meachasompop, Yosapon Adisornprasert, Pimrawee Chaemlek, Prapansak Srisapoome, and et al. 2026. "Low-Molecular-Weight Chitosan Produced by Gamma Irradiation and Hydrogen Peroxide Promotes Immune Readiness, Antioxidant Responses, and Survival in Photobacterium damselae-Challenged Asian Seabass (Lates calcarifer)" International Journal of Molecular Sciences 27, no. 17: 7772. https://doi.org/10.3390/ijms27177772

APA Style

Rattanawongwiboon, T., Paankhao, N., Chumchuen, R., Chinnabutra, N., Saisin, W., Kumwan, B., Meachasompop, P., Adisornprasert, Y., Chaemlek, P., Srisapoome, P., Kingwascharapong, P., Tangthong, T., Buncharoen, W., & Uchuwittayakul, A. (2026). Low-Molecular-Weight Chitosan Produced by Gamma Irradiation and Hydrogen Peroxide Promotes Immune Readiness, Antioxidant Responses, and Survival in Photobacterium damselae-Challenged Asian Seabass (Lates calcarifer). International Journal of Molecular Sciences, 27(17), 7772. https://doi.org/10.3390/ijms27177772

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Low-Molecular-Weight Chitosan Produced by Gamma Irradiation and Hydrogen Peroxide Promotes Immune Readiness, Antioxidant Responses, and Survival in Photobacterium damselae-Challenged Asian Seabass (Lates calcarifer)

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