Défense de thèse de doctorat en sciences biologiques

Immunomodulatory potential of different herbal plant extracts on striped catfish (Pangasianodon hypophthalmus): in vitro and in vivo approaches

Jury

• Frederik DE LAENDER (UNamur), President
• Patrick KESTEMONT (UNamur), Secretary
• Hang BUI THI BICH (Can Tho University, Vienam)
• Robert MANDIKI (UNamur)
• Joëlle LECLERCQ (UCLouvain)
• Marie-Louise SCIPPO (ULiège)
• Silvia torrecillas (ULPGC, Spain)
  

Abstract

Striped catfish (Pangasianodon hypophthalmus) is one of the economically important fish species, which is widely developed in several Asian countries. Many medicinal plants have been documented to possess positive effects on the immune responses of aquatic cultivated animals. However, the use of natural products has not been yet popularly applied in striped catfish farms. Based on bibliography review data and on a survey in fish farms of Mekong Delta, 20 plants possessing potential immunostimulatory activities were selected for in vitro study using the striped catfish peripheral blood mononuclear cells -PBMCs and head kidney leukocytes- HKLs models. Five plant extracts were then validated for their effects on the blood indices, humoral immune responses and disease resistance in striped catfish via oral administration. Moreover, the effects of single supply diets versus mixture diets with Phyllanthus amarus and Psidium guajava extracts on striped catfish health were continuously submitted. In addition, the protein expression profile was also investigated to provide a better understanding of the metabolic pathways related to immune response, antioxidation and lipid metabolism in the fish liver after oral administrated plant extracts. The different polarities of the extract solvents may cause a wide variation in the level of bioactive compounds in the extract and result in different immune responses in hosts. The immunomodulatory effects of crude ethanol extract of P. amarus and P. guajava, as well as their fractions including n-hexane, dichloromethane, ethyl acetate, aqueous and non-tannin were therefore compared via in vitro experiment. The effects of different pure compounds isolated from P. amarus and P. guajava were also investigated in this study. Furthermore, biological activities plant products related to inflammation are largely unknown in fish. The molecular mechanism behind the effects of P. guajava extracts on fish immune responses were also highlighted and discussed.

 

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