Toxicological and hematological effect of Terminalia arjuna bark extract on a freshwater catfish, Heteropneustes fossilis

Terminalia arjuna Bark Powder as a Potential Immunomodulator in Labeo rohita: Enhanced Hematological, Adaptive, and Humoral Responses against Bacterial Pathogens and Concordant Liver Histomorphology

This study investigated the dietary immunomodulatory effects of Terminalia arjuna bark powder (TABP) in Labeo rohita, a freshwater fish model. Four iso-nitrogenous and iso-caloric diets containing graded levels of TABP (0, 1, 10, and 15 g/kg were fed to fish for 90 days, followed by a 10 day challenge with pathogenic bacteria Aeromonas hydrophila and Edwardsiella tarda. An integrated biomarker response (IBR) approach assessed the impact of TABP on hematological, adaptive, and humoral immune parameters, along with liver histomorphology. Dietary TABP at 10 g/kg significantly enhanced (p < 0.05) hematological indices (hemoglobin, red blood cell count, hematocrit), specific immune parameters (lysosomal enzyme activity, phagocytosis, respiratory burst), and non-specific immune parameters (serum lysozyme, alternative complement activity), and exhibited improvements in liver architecture consistent with the enhanced immune response. Broken line regression analysis showed 11.5 g/kg to be an optimum dose. However, at 15 g/kg, a compromised trend was observed in some parameters. These findings suggest an optimal dosage range for TABP's immunomodulatory effects. The study highlights the potential of TABP as a natural immunomodulator in fish aquaculture. The improved immune response and concomitant liver health observed in Labeo rohita opens avenues for further research on TABP's applicability in animal health, using fish as a model organism. Additionally, the IBR approach proved effective in evaluating TABP's immunomodulatory properties, paving the way for similar studies on other natural products in aquaculture.

Phenolic content of Terminalia catappa L. leaf and toxicity evaluation on red hybrid tilapia (Oreochromis sp.)

Despite the use of Terminalia catappa (TC) leaf by traditional fish farmers around the world to improve the health status of cultured fish, there is a paucity of information on comprehensive metabolite profile and the maximum safe dose of the plant. This study aims at profiling the methanol leaf extract of T. catappa, quantifying total phenolic content (TPC) as well as the total flavonoid content (TFC) and evaluating its acute toxicity on blood, plasma biochemical parameters and histopathology of some vital organs in red hybrid tilapia (Oreochromis sp.). The experimental fish were acclimatised for 2 weeks and divided into six groups. Group (1) served as a control group and was administered 0.2 ml,g^-1 of phosphate buffer saline (PBS). Groups 2-6 were orally administered T. catappa leaf extracts (0.2 ml.50 g^-1 ) in the following sequence; 31.25, 62.5, 125, 250 and 500 mg.kg^-1 body weight. The metabolites identified in T. catappa using liquid chromatography-tandem mass electrospray ionisation spectrometry (LC-ESI-MS/MS) revealed the presence of organic acids, hydrolysable tannins, phenolic acids and flavonoids. Phenolic quantification revealed reasonable quantity of phenolic compounds (217.48 μg GAEmg^-1 for TPC and 91.90 μg. QCEmg^-1 for TFC). Furthermore, there was no significant difference in all the tested doses in terms of blood parameters and plasma biochemical analysis except for the packed cell volume (PCV) at 500 mg.kg^-1 when compared to the control. Significant histopathological changes were observed in groups administered with the extract at 125, 250 and 500 mg.kg^-1 doses. To a very large extent it is therefore safe to administer the extract at 31.25 and 62.5 mg.kg^-1 in tilapia.