Seaweeds and their derived products represent huge resources that are still underexploited as functional ingredients in fish feeds. This study evaluated the growth performance, nutrient utilisation, antioxidation status, and immunity of Clarias gariepinus fed diets containing Dictyota ciliolata extract (DCE). Ethanolic extract of the brown seaweed D. ciliolata was obtained using the Maceration extraction method. Afterwards, four diets were prepared with DCE at inclusion levels of 0 g/kg (control), 0.25 g/kg (DCE-0.25), 0.5 g/kg (DCE-0.5) and 1.0 g/kg (DCE-1.0). One hundred and twenty fish (14.47 g/fish) were allotted to four triplicate groups (10 fish per group) and fed thrice daily with diets containing DCE at various graded levels. At the end of the feeding trial, there were no statistical differences (p > 0.05) in final weight, weight gain and specific growth rate among the dietary group. Fish fed DCE-based diet had lower feed conversion ratio and higher protein efficiency ratio that differs significantly (p < 0.05) from the control. Erythrocytes and leukocytes were significantly higher (p < 0.05) in C. gariepinus fed DCE-0.25 and DCE-0.5 diets in comparison to the control. The liver function enzyme alkaline phosphatase was higher (p < 0.05) in fish fed DCE-0.5 and DCE-1.0 diets than the control and DCE-0.25 groups. Dietary DCE improved antioxidant activities and decreased peroxidation of lipid in the hepatic tissue of C. gariepinus. The cytokines (Tumour Necrosis Factor – alpha, Interleukin-6, Interleukin-1 Beta) were significantly elevated (p < 0.05) in the liver tissue of C. gariepinus fed DCE-based diets. Therefore, these results indicate that fish fed DCE diet had better nutrient utilisation, enhanced antioxidants activities and immune responses, suggesting the high suitability of D. ciliolata extract as a functional ingredient to improve the welfare of C. gariepinus.

The brown seaweed (Dictyota ciliolataa Sonder ex Kutzing) has been identified as a valuable source of anionic polysaccharides with remarkable biological properties that may render them suitable for application in aquaculture. In this study, the chemical composition of D. ciliolata polysaccharides (DCP) was analysed using spectrophotometry and HighPerformance Anion-Exchange Chromatography/ Pulsed Amperometric Detection (HPAEC-PAD). The result showed that DCP had a total carbohydrate content of 56.56 ± 1.17 %, sulphate content of 4.58 ± 0.26 %, uronic acid content of 6.54 ± 0.26 %, and protein content of 7.31 ± 0.24 %. HPAEC-PAD revealed that DCP composed of fucose (27.16 ± 4.27 mg/l), galactose (11.47 ± 1.38 mg/l), arabinose (11.88 ± 1.24 mg/l) and glucose (1.64 ± 0.07 mg/l). DCP was non-toxic to carp leukocytes at dosages ≤ 50 µg/ml but was found to induce cell proliferative activity. Cellular antioxidant assays showed that DCP did not disrupt glutathione and superoxide dismutase activities in carp leukocytes cells when compared to the control. However, a decrease in malondialdehyde levels in carp leukocytes cells indicated that DCP did not induce oxidative stress. Therefore, DCP is a promising antioxidant source that could be effectively utilised in enhancing the health status of cultured fish species.

The development of aquafeeds that enhance immunity in fish represents an effective strategy for disease management in aquaculture. This approach involves incorporating functional ingredients with immunostimulatory properties to improve fish welfare. The use of dietary immunostimulants is considered a suitable, safe, and eco‐friendly alternative to mitigate the adverse effects of antibiotics and chemotherapeutics. Hence, there is growing interest among aquaculture stakeholders in immunostimulant sources such as algae, plant derivatives, trace minerals, prebiotics, and probiotics. However, earlier studies have relied on biochemical markers to evaluate the interactions of dietary immunostimulants with the fish immune system, which provide limited mechanistic insights and reduce reproducibility for large‐scale applications. Recent advances in molecular approaches, including genomics, transcriptomics, proteomics, metabolomics, and small RNA profiling, have been increasingly applied to elucidate the underlying mechanisms of dietary immunostimulants and to guide the development of species‐specific formulations. By integrating these molecular tools, researchers can design sustainable, species‐tailored immunostimulant diets that reduce the reliance on antibiotics. This review synthesizes molecular evidence on nutrient‐, plant‐, microbial‐, and algae‐based immunostimulants, highlighting how omics tools elucidate their mechanisms and support the design of species‐specific functional feeds.

Symptoms of respiratory tract infections (RTI) caused by viral or bacterial triggers include sore throat and cough. Plantago lanceolata (ribwort plantain) is used in herbal medicine to treat symptoms of RTI. This study evaluated the pharmacological actions of P. lanceolata extract (PL) and StrepCough Plantain-Dry cough syrup (PLS) in in vitro models of sore throat and cough. Human tonsil epithelial cells (HTEpiC) cells were stimulated with a combination of lipoteichoic acid and peptidoglycan in the presence or absence of PL or PLS. Levels of TNF-α, IL-6, PGE₂, and COX-2 were measured using ELISA, while phospho-p65 protein levels were measured using Lumit^® immunoassay. The effects of PL and PLS on bradykinin-induced inflammation and increased intracellular Ca²⁺ were investigated in bronchial epithelial cells (BEAS-2B), cells over-expressing TRPV1. Results showed that the pre-treatment of HTEpiC cells with PL and PLS resulted in a significant (p < 0.05) reduction in the LTA + PGN-induced increased production of TNFα, IL-6, PGE₂, as well as COX-2 and phospho-p65 protein levels. Bradykinin-induced increased levels of TNFα, IL-6, and PGE₂ in BEAS-2B cells over-expressing TRPV1 were also reduced by PL and PLS, while reducing levels of intracellular Ca²⁺. This study has demonstrated that extract of P. lanceolata and StrepCough Plantain-Dry cough syrup reduce inflammation in human tonsil epithelial cells. The extract and syrup also reduced TRPV1-mediated inflammation and increased intracellular Ca²⁺ in BEAS-2B bronchial epithelial cells. This study has provided pharmacological evidence for the use of P. lanceolata in healthcare interventions to treat symptoms of respiratory tract infection.

Acute respiratory infections (ARIs) are among the most common infectious diseases worldwide and represent a substantial clinical and socioeconomic burden. Despite their predominantly viral aetiology, inappropriate antibiotic prescribing remains common, highlighting the need for effective non-antibiotic treatment strategies. In this narrative review, we summarize the pharmacological properties and potential clinical relevance of Plantago lanceolata and Sisymbrium officinale in the symptomatic management of uncomplicated upper airway infections. A narrative literature search of PubMed/MEDLINE, Google Scholar, and the herbal monographs and assessment reports of the European Medicines Agency was conducted, focusing on experimental, clinical, and real-world evidence related to symptom relief, anti-inflammatory effects, and cough modulation. Emphasis was placed on recent in vitro studies investigating epithelial inflammatory responses and cough-related signalling pathways. In cell-based experimental models, both extracts reduced key inflammatory mediators, including prostaglandin E₂, tumour necrosis factor-α, and interleukin-6, in human tonsil epithelial cells stimulated with bacterial cell wall components. In addition, both plant extracts attenuated bradykinin-induced intracellular calcium signalling in bronchial epithelial cells, which is consistent with, but does not demonstrate, modulation of cough-related pathways. These in vitro findings provide a biological rationale for their traditional use in relieving sore throat, irritation, and cough, but they are not direct evidence of clinical efficacy, and clinical trials of these two extracts are lacking. Given the central role of symptom burden in driving healthcare utilization and antibiotic-seeking behaviour, effective symptomatic therapies are important. Whether herbal medicinal products with anti-inflammatory and cough-modulating properties improve symptom control and thereby support antimicrobial stewardship remains to be demonstrated. Future research should include randomized controlled trials with validated symptom outcomes and real-world studies evaluating the impact of these extracts on antibiotic prescribing in clinical practice.