Protective effect of Ocimum gratissimum leaf aqueous extract on antioxidant capacity, immunocompetence, and disease resistance of Nile tilapia (Oreochromis niloticus) fingerlings against Vibrio parahaemolyticus infection

Innate immunity Cytokine Nile tilapia Pathogenic organism

Authors

  • Rasaq Ibrahim
    ibrahim.rasaq@ksusta.edu.ng
    Department of Biology, Ahmadu Bello University, Zaria, Nigeria.
  • Jehu Auta Department of Biology, Ahmadu Bello University, Zaria, Nigeria.
  • John Ameh Adakole Department of Biology, Ahmadu Bello University, Zaria, Nigeria.
  • Abdullateef Yusuf Department of Biology, Ahmadu Bello University, Zaria, Nigeria.
  • Esther Yogbabaliat Yashim Department of Zoology, Ahmadu Bello University, Zaria, Nigeria.
  • Abdullahi Bala Alhassan Department of Biology, Ahmadu Bello University, Zaria, Nigeria.
  • Rilwanu Umar National Agricultural Extension and Research Liaison Services, Ahmadu Bello University, Zaria, Nigeria.
  • Harrison Charo-Karisa WorldFish, Abbassa, Abou-Hammad, Sharkia, Egypt.
  • Femi John Fawole Department of Aquaculture and Fisheries, University of Ilorin, Ilorin, Nigeria.
  • Hien Van Doan Department of Animal and Aquatic Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand.
Vol. 14: Accepted Articles
Articles
July 13, 2026

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Infectious diseases are major constraints on the aquaculture industry, and they frequently arise from stress factors associated with intensive aquaculture practices. This study was carried out to assess the protective effect of Ocimum gratissimum leaf aqueous extract on immunological responses, antioxidant capacity, and disease resistance of Oreochromis niloticus fingerlings against Vibrio parahaemolyticus infection. Five iso-nitrogenous (30.02%) diets containing 0 (control), 2, 4g, 8, and 16 g Ocimum-leaf extract (g/kg) were fed to triplicate groups of fish (initial weight 3.31±0.05g) for 90 days. After a 90-day feeding trial, test fish were injected with pathogenic V. parahaemolyticus, and survival was recorded over the next 14 days. The white blood cell (12.29±0.35×103/µl), red blood cells (3.60±0.21×103/µl), packed cell volume (27.76±0.08 g/dl), and haemoglobin (7.21±0.47 g/dl) were all highest in fish fed 8 g/kg of Ocimum leaf extract. The biochemical parameters, such as alkaline phosphatase (ALP), total protein, albumin, and globulin contents, increased significantly in Ocimum leaf extracts fed groups compared with the control; these groups also registered the lowest values of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and malondialdehyde (MDA). Following a challenge with V. parahaemolyticus, the study indicated that Ocimum leaf extract reduced metabolic stress in infected fish compared with the control. There is a significant increase in glucose (101.00±2.89 mg/dl) levels and liver enzymes ALT (74.14±2.31 UI/ L) and AST (49.00±1.73 UI/L) in the control group (0 g/kg), whereas the opposite was true for diets supplemented with Ocimum leaf extract. The Ocimum leaf extract group significantly enhanced immune parameters, including lysozyme, immunoglobulin (IgM), and Interleukin-1? (IL-1?), in the spleen, skin, and kidney. After infection, the supplemented diets containing Ocimum leaf extract showed significantly higher lysozyme and IgM activities in the spleen, skin, and kidney. The result of the challenge test with V. parahaemolyticus revealed that the highest survival (80%) was recorded in the group fed Ocimum-supplemented diets at 8 and 16 g/kg, and the lowest skin lesion morbidity (15%) was observed in fish fed 8 g/kg. This study revealed that the inclusion of O. gratissimum leaf extract in the diet of O. niloticus enhanced biochemical parameters and immune response, and improved resistance to V. parahaemolyticus.