Faikoh Elok Ning, Hong Yong-Han, Hu Shao-Yang
Department of Biological Science and Technology, National Pingtung University of Science and Technology, Pingtung 912, Taiwan; Department of Water Resources Management, Marine and Fisheries Faculty, University of Brawijaya, Indonesia.
Department of Nutrition, I-Shou University, Kaohsiung 824, Taiwan.
Fish Shellfish Immunol. 2014 May;38(1):15-24. doi: 10.1016/j.fsi.2014.02.024. Epub 2014 Mar 12.
Cinnamaldehyde, which is extracted from cinnamon, is a natural compound with activity against bacteria and a modulatory immune function. However, the antibacterial activity and immunostimulation of cinnamaldehyde in fish has not been well investigated due to the compound's poor water solubility. Thus, liposome-encapsulated cinnamaldehyde (LEC) was used to evaluate the effects of cinnamaldehyde on in vitro antibacterial activity against aquatic pathogens and in vivo immunity and protection parameters against Vibrio vulnificus and Streptococcus agalactiae. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) as well as bactericidal agar plate assay results demonstrated the effective bacteriostatic and bactericidal potency of LEC against Aeromonas hydrophila, V. vulnificus, and S. agalactiae, as well as the antibiotic-resistant Vibrio parahaemolyticus and Vibrio alginolyticus. Bacteria challenge test results demonstrated that LEC significantly enhances the survival rate and inhibits bacterial growth in zebrafish infected with A. hydrophila, V. vulnificus, and S. agalactiae. A gene expression study using a real-time PCR showed that LEC immersion-treated zebrafish had increased endogenous interleukin (IL)-1β, IL-6, IL-15, IL-21, tumor necrosis factor (TNF)-α, and interferon (INF)-γ expression in vivo. After the zebrafish were infected with V. vulnificus or S. agalactiae, the LEC immersion treatment suppressed the expression of the inflammatory cytokines IL-1β, IL-6, IL-15, NF-κb, and TNF-α and induced IL-10 and C3b expression. These findings demonstrate that cinnamaldehyde exhibits antimicrobial activity against aquatic pathogens, even antibiotic-resistant bacterial strains and immune-stimulating effects to protect the host's defenses against pathogen infection in bacteria-infected zebrafish. These results suggest that LEC could be used as an antimicrobial agent and immunostimulant to protect bacteria-infected fish in aquaculture.
肉桂醛是从肉桂中提取的一种天然化合物，具有抗菌活性和调节免疫功能。然而，由于肉桂醛水溶性差，其在鱼类中的抗菌活性和免疫刺激作用尚未得到充分研究。因此，采用脂质体包裹肉桂醛（LEC）来评估肉桂醛对水生病原菌的体外抗菌活性以及对创伤弧菌和无乳链球菌的体内免疫和保护参数。最低抑菌浓度（MIC）、最低杀菌浓度（MBC）以及杀菌琼脂平板试验结果表明，LEC对嗜水气单胞菌、创伤弧菌、无乳链球菌以及耐抗生素的副溶血性弧菌和溶藻弧菌具有有效的抑菌和杀菌效力。细菌攻毒试验结果表明，LEC能显著提高感染嗜水气单胞菌、创伤弧菌和无乳链球菌的斑马鱼的存活率，并抑制细菌生长。一项使用实时PCR的基因表达研究表明，经LEC浸泡处理的斑马鱼体内内源性白细胞介素（IL）-1β、IL-6、IL-15、IL-21、肿瘤坏死因子（TNF）-α和干扰素（INF）-γ的表达增加。斑马鱼感染创伤弧菌或无乳链球菌后，LEC浸泡处理抑制了炎性细胞因子IL-1β、IL-6、IL-15、NF-κb和TNF-α的表达，并诱导了IL-10和C3b的表达。这些发现表明，肉桂醛对水生病原菌具有抗菌活性，甚至对耐抗生素菌株也有效，并且具有免疫刺激作用，可保护宿主防御细菌感染的斑马鱼中的病原体感染。这些结果表明，LEC可作为一种抗菌剂和免疫刺激剂，用于保护水产养殖中受细菌感染的鱼类。
