Effect of Excoecaria agallocha on non-specific immune responses and disease resistance of Oreochromis niloticus against Streptococcus agalactiae.

The current study was designed to evaluate the effects of Excoecaria agallocha leaf extracts on immune mechanisms and resistance of tilapia, Oreochromis niloticus, after challenge with Streptococcus agalactiae. Fish were divided into 6 groups; groups 1-5 fed with E. agallocha leaf extracts at 10, 20, 30, 40 and 50mgkg-1 level, respectively. Group 6 were fed without extract addition and acted as control. E. agallocha extracts were administered as feed supplement in fish diet for 28days and the hematological, immunological, and growth performance studies were conducted. Fish were infected with S. agalactiae at a dose of 15×105CFUmL-1 and the total white blood cell (WBC), phagocytosis and respiratory burst activities of leukocytes, serum bactericidal activity, lysozyme, total protein, albumin, and globulin levels were monitored and mortalities recorded for 15days post infection. Results revealed that feeding O. niloticus with 50mgkg-1 of E. agallocha enhanced WBC, phagocytic, respiratory burst, serum bactericidal and lysozyme activities on day 28 pre-challenge and on 3rd, 6th, 9th, 12th and 15th day post-challenge as compared to control. Total protein and albumin were not enhanced by E. agallocha diet. E. agallocha increased the survival of fish after challenge with S. agalactiae. The highest mortality rate (97%) was observed in control fish and the lowest mortality (27%) was observed with group fed with 50mgkg-1 extract. The results indicate that dietary intake of E. agallocha methanolic leaf extract in O. niloticus enhances the non-specific immunity and disease resistance against S. agalactiae pathogen.

Development of a peptide-containing chewing gum as a sustained release antiplaque antimicrobial delivery system.

The objective of this study was to characterize the stability of KSL-W, an antimicrobial decapeptide shown to inhibit the growth of oral bacterial strains associated with caries development and plaque formation, and its potential as an antiplaque agent in a chewing gum formulation. KSL-W formulations with or without the commercial antibacterial agent cetylpyridinium chloride (CPC) were prepared. The release of KSL-W from the gums was assessed in vitro using a chewing gum apparatus and in vivo by a chew-out method. A reverse-phase high-performance liquid chromatography method was developed for assaying KSL-W. Raw material stability and temperature and pH effects on the stability of KSL-W solutions and interactions of KSL-W with tooth-like material, hydroxyapatite discs, were investigated. KSL-W was most stable in acidic aqueous solutions and underwent rapid hydrolysis in base. It was stable to enzymatic degradation in human saliva for 1 hour but was degraded by pancreatic serine proteases. KSL-W readily adsorbed to hydroxyapatite, suggesting that it will also adsorb to the teeth when delivered to the oral cavity. The inclusion of CPC caused a large increase in the rate and extent of KSL-W released from the gums. The gum formulations displayed promising in vitro/in vivo release profiles, wherein as much as 90% of the KSL-W was released in a sustained manner within 30 minutes in vivo. These results suggest that KSL-W possesses the stability, adsorption, and release characteristics necessary for local delivery to the oral cavity in a chewing gum formulation, thereby serving as a novel antiplaque agent.