BUSCADOR RECOLECTA

Carrageenan, a high molecular weight sulphated polysaccharide, has been used in the screening of anti-inflammatory molecules in mammals. In this sense, Chiliadenus glutinosus (L.) Fourr., an endemic species of plant has been reported in the Spanish popular medicine due to their anti-inflammatory properties in humans. However, their properties have poorly been studied in fish. In this assay, different concentrations (0, 0.001, 0.01, 0.125, 0.25, 0.5 and 1 mg mL-1) of aqueous, ethanolic and methanolic extracts of this plant were elaborated, and the antioxidant, bactericidal (against four marine fish pathogen) and cytotoxic activity, as well as several immunological parameters in head-kidney leucocytes (HKLs) of gilthead seabream (Sparus aurata) were evaluated in a first experiment to determinate the extract with the best properties. Our results showed a dose-dependent antioxidant activity of each plant extract increasing with the concentration, a species- and extract-specific bactericidal activity, as well as a cytotoxic activity against the PLHC1 tumour cell line by the ethanolic and methanolic extracts. However, taking into account the cytotoxic effects of these two extracts on HKLs and the strong immunosuppressive effects on the immunological parameters assayed (peroxidase, respiratory burst activity and phagocytic capacity), a second experiment was developed by using only adjusted doses of the aqueous extract (0, 0.25 and 0.5 mg mL-1), in which immune parameters, cell morphology and inflammatory-related genes were studied in HKLs stimulated with λ-carrageenan. The present results offer a detailed view of the biological effects of C. glutinosus extracts, which could be interesting to the aquaculture sector due to their possible anti-inflammatory effects.

Cantharidin is a natural compound with known therapeutic applications in humans. However, its properties have hardly been studied in fish. The aim of this study was to investigate the in vitro effects of cantharidin on gilthead seabream (Sparus aurata) head kidney leucocytes (HKL) stimulated with λ-carrageenan. Thus, HKLs were incubated for 24 h with cantharidin (0, 2.5 and 5 μg mL-1) and λ-carrageenan (0 and 1,000 μg mL-1) and cell viability and morphology, immunological parameters and several selected genes related to inflammation and apoptosis were evaluated. The results showed that cantharidin only decreased HKL viability when incubated with the highest dose (5 μg mL-1) and in combination with λ-carrageenan. As for the immunological parameters studied, cantharidin increased the peroxidase activity of HKLs only when incubated in combination with λ-carrageenan, but inhibited the respiratory burst and phagocytic activities even after being previously increased by λ-carrageenan. Furthermore, cantharidin induced morphological changes in HKLs with apoptotic and vacuolization signs that were enhanced when incubated in combination with λ-carrageenan. Considering the analysis of gene expression in HKLs, although λ-carrageenan up-regulated the expression of the proinflammatory gene il1b, cantharidin down-regulated its expression in HKLs exposed to both λ-carrageenan and cantharidin. In addition, cantharidin up-regulated casp3 and casp9 expression, which was down-regulated in HKLs incubated with both molecules. This combination also up-regulated casp1 expression. The present results provide detailed insight into the immune-depressive and anti-inflammatory properties of cantharidin on immune cells, which could be of interest to the aquaculture sector.