틸라피아(Oreochromis niloticus)의 비가식부를 이용한 생리활성물질의 탐색 및 정제

Abstract

Nile tilapia (Oreochromis niloticus) is a species of tilapia native to Africa and is of interest in aquaculture because these fish are fast growing and known to produce good fillets. The visceral and skin tissues of this fish are discarded as industrial waste during fillet production process. Investigating possible use of the visceral tissues of Nile tilapia by screening the biological activities could make Nile tilapia aquaculture more economic. In this study, we evaluated three biological activities of Nile tilapia visceral and skin extracts: the antimicrobial, the antioxidant, and the myoactive activities. The visceral and skin tissues of Nile tilapia was extracted with water containing 5 % acetic acid and then with ethanol. The antimicrobial activity assay of the visceral and skin extracts against 10 bacterial strains and 1 fungal strain revealed that the extracts has broad spectrum antimicrobial activity. The most susceptible strains were Salmonella enterica ATCC13311 and Vibrio anguillarum KCTC 2711. The antioxidant activity of extracts determined through DPPH scavenging assay showed approximately low antioxidant activity compared to that of L-ascorbic acid used as standard reagent. The visceral and skin extracts induced contraction of intestinal smooth muscle from Eptatretus burgeri and relaxation of apical muscle from starfish Patiria pectinifera.

Nile Tilapia (Oreochromis niloticus) is a fish species that live in fresh water of Africa. Industrially, merely Tilapia meat is consumed in forms of pillets while its viscera and skin are discarded as waste, creating massive amount of industrial waste. Fish viscera is known to contain diverse immune factors such as lysozymes, lectins, antimicrobial proteins and peptides. Thus, fish viscera is a suitable source for the purification of antimicrobial materials. Fish skin acts as a barrier of fish. Therefore, it has a lot of immune factors like fish viscera. In this study, viscera extract of O. niloticus was used to isolate the materials with antimicrobial activity against Bacillus subtilis KCTC1021 and Vibrio anguillarum KCTC2711. O. niloticus viscera (313 g) was extracted with 5% AcOH and separated into three fractions containing eluents of 10%, 60% and 100% MeOH (containing 0.1% TFA) using Sep-pak C18 solid phase extraction cartridge. The eluents of 60% MeOH exerted the most powerful antimicrobial activity, which was then used for the purification of antimicrobial material. Through a series of high performance liquid chromatography, single peak was isolated from tilapia viscera extract. However, molecular weight of the single peak by mass spectrometry was about 2000~4000 meaning there is a complex substances. Investigation of this single peak is in progress to purify single material.