Abstract：
The research examined the impact of an ethanolic extract from the leaves of Kratom (Mitragyna speciosa (Korth.) Havil.) on the growth, antioxidant capacity, immune-related gene expression, and resistance to disease caused by Edwardsiella tarda in Nile tilapia (Oreochromis niloticus). The findings revealed that the extract had the important phytochemical content in the extract included total phenolics content, total flavonoids content, vitamin C, and total antioxidant capacity and 5.42 % of the crude extract was mitragynine. The extract demonstrated antioxidant activity, as evidenced by its IC50 values against ABTS and DPPH radicals and its ferric reducing power in vitro. Moreover, the MIC-IC50 value of 0.625 mg/mL indicated that the growth of the bacteria was reduced by approximately 50 %, and the MBC was 2.50 mg/mL against E. tarda. Furthermore, the orally administered Kratom leaf extract to fingerling tilapia for 8 weeks exhibited a noticeable increase in oxidative stress, as demonstrated by the increase in MDA production in the 10 and 25 g/kg groups. It also exhibited an increase in acetylcholinesterase (AChE) activity in muscle tissue at the 50 g/kg group. However, when administered at a feeding rate of 5-10 g/kg feed, the extract showed an increase in the expression of immune-related genes (IL1, IL6, IL8, NF-kB, IFNγ, TNFα, Mx, CC-chemokine, CD4, TCRβ, MHC-IIβ, IgM, IgT, IgD) and enhanced resistance to E. tarda infection in fish. Conversely, administering the extract at 25-50 g/kg feed resulted in contrasting effects, suppressing and reducing the observed parameters. Nevertheless, feeding the extract at all concentrations for 8 weeks did not produce any changes in the histology or systemic functioning of the liver and intestines, as indicated by blood biochemistry. These findings suggest that the ethanolic leaf extract from Kratom has the potential to be used as a substitute for antibiotics in the management of bacterial infections in Nile tilapia culture, with a recommended dosage of 5-10 g/kg feed/day for a maximum of 8 weeks.
摘要：
研究检查了Kratom（Mitragynaspeciosa（Korth。）哈维尔。)关于增长，抗氧化能力，免疫相关基因表达，以及尼罗罗非鱼（Oreochromisniloticus）对塔塔爱德华氏菌引起的疾病的抵抗力。结果表明，提取物中重要的植物化学成分含量包括总酚含量，总黄酮含量，维生素C,总抗氧化能力和5.42%的粗提物是米拉参碱。提取物表现出抗氧化活性，其对ABTS和DPPH自由基的IC50值及其在体外的三价铁还原能力证明了这一点。此外，MIC-IC50值为0.625mg/mL，表明细菌的生长减少了约50％，和MBC为2.50mg/mL,相对于E.tarda。此外，口服Kratom叶提取物对鱼种罗非鱼8周表现出明显的氧化应激增加，如10和25g/kg组中MDA产生的增加所证明的。在50g/kg组的肌肉组织中，它还显示出乙酰胆碱酯酶（AChE）活性的增加。然而,当以5至10克/公斤饲料的饲喂率施用时，提取物显示免疫相关基因(IL1，IL6，IL8，NF-kB，IFNγ,TNFα,Mx,CC-趋化因子,CD4,TCRβ,MHC-IIβ,IgM,IgT,IgD）和增强鱼类对塔尔达大肠杆菌感染的抵抗力。相反，以25至50克/千克饲料施用提取物会产生相反的效果，抑制和减少观察到的参数。然而，喂食所有浓度的提取物8周没有产生组织学或肝脏和肠道的全身功能的任何变化，如血液生物化学所示。这些发现表明，Kratom的乙醇叶提取物有可能在尼罗罗非鱼培养中用作抗生素的替代品，推荐剂量为5至10g/kg饲料/天，最长8周。
