First screening report of immune and protective effect of non-toxic Jatropha vernicosa stem bark against Vibrio parahaemolyticus in Longfin yellowtail Seriola rivoliana leukocytes.

Abstract In Mexico, the infusion of Jatropha vernicosa stem bark has been used in folk medicine for many clinical situations, but no reports were available about this particular species of Jatropha in fish of mammals. In this first screening report, the phytochemical, antioxidant profile and antimicrobial properties of aqueous J. vernicosa stem bark extract were explored against Vibrio parahaemolyticus, an opportunist fish pathogen. To evaluate the cytotoxicity and immunological effect for the possible application of aqueous J. vernicosa stem bark in aquaculture, this study assessed it by using Longfin yellowtail Seriola rivoliana leukocytes. The results showed that phytochemical composition of the J. vernicosa extract was rich in phenol, flavonoid, saponin, and coumarin compounds. The antioxidant capacity of hydroxyl radical and superoxide anion scavenging activities, iron-chelation activity and β-carotene bleaching coupled to linoleic acid showed that J. vernicosa extracts had a moderate antioxidant effect compared with synthetic antioxidants (BHT, BHA and EDTA). No adverse effects were observed on spleen leukocytes (viability > 98%). Interestingly, J. vernicosa stem bark extract has immunostimulant and antioxidant effects, increasing phagocytosis, respiratory burns activity, and nitric oxide production, as well as superoxide dismutase and catalase activities. Additionally, J. vernicosa extract increased pro-inflammatory cytokine IL-1β and suppressed anti-inflammatory IL-10 gene expression upon stimuli and V. parahaemolyticus challenge. Finally, the data confirms that J. vernicosa stem bark extract is non-cytotoxic, rich in bioactive compounds with antioxidant effects, capable of enhancing the immune system in leukocytes and with great potential to fight against opportunistic diseases, such as vibriosis in fish.