Background: Leptospirosis is a zoonotic disease that transmitted to humans by rodents and domestic animals that infected by Leptospira bacteria and considered as a endemic disease in South India and North-East India. Andrographis paniculata is an ancient herb with various therapeutic properties and has Andrographolide bioactive compound. Purpose: The aim of the present study is to isolate and molecular identification by ITS sequencing of the Leptospira interrogans from the soil sample of paddy field and to analyse the anti-leptospirosis activity of Andrographis paniculata extract in in vitro. Methods: Andrographis paniculata extract was extracted using methanol and screening of phytocompound was done by GC-MS analysis. Leptospira species was isolated from the soil sample and molecular identification was performed by 16s rRNA gene sequencing. BLAST and phylogenetic tree analysis confirmed the presence of Leptospira interrogans. Molecular Docking analysis was performed to study the interaction between the Andrographolide and Leptospira LRR protein. Anti-leptospirosis activities of Andrographis paniculata extracted using different solvents were determined by Minimum Inhibitory Concentration (MIC) methods. Results: The 16s rRNA sequencing and BLAST results confirmed the presence of Leptospirosis interrogans. The phylogenetic tree analysis showed the distance between the Leptospirosis species. Furthermore, the GCMS analysis of Andrographis paniculata methanolic extract showed the presence of phytocompound Andrographolide. Molecular docking analysis of Andrographolide with the LRR protein showed stable binding. The in vitro anti-leptospiral activity of different Andrographis paniculata extract showed the maximum inhibition at 500 μg/mL and the maximum MIC was observed at methanolic extract of A. paniculata at 31.2 μg/mL with 64.65 ± 7.33% of inhibition. Conclusion: From our study we concluded that Andrographis paniculata extracted using methanol has good anti-leptospirosis activity and Andrographolide will act as a good therapeutic agent against leptospirosis.

背景：钩端螺旋体病是一种人畜共患疾病，由感染钩端螺旋体细菌的啮齿动物和家畜传播给人类，被认为是印度南部和东北部的地方病。穿心莲是一种古老的草药，具有多种治疗功效，并含有穿心莲内酯生物活性化合物。目的：通过ITS测序对稻田土壤样品中问号钩端螺旋体进行分离和分子鉴定，并分析穿心莲提取物的体外抗钩端螺旋体活性。方法：用甲醇提取 穿心莲提取物，并通过GC-MS分析筛选植物化合物。从土壤样品中分离出钩端螺旋体物种，并通过 16s rRNA 基因测序进行分子鉴定。BLAST 和系统发育树分析证实了问号钩端螺旋体的存在。进行分子对接分析以研究穿心莲内酯和钩端螺旋体LRR蛋白之间的相互作用。采用最低抑菌浓度（MIC）法测定不同溶剂提取的穿心莲的抗钩端螺旋体活性。结果： 16s rRNA测序和BLAST结果证实了问号钩端螺旋体的存在。系统发育树分析显示了钩端螺旋体病物种之间的距离。此外，穿心莲甲醇提取物的 GCMS 分析表明存在植物化合物穿心莲内酯。穿心莲内酯与LRR蛋白的分子对接分析显示出稳定的结合。不同穿心莲提取物的体外抗钩端螺旋体活性在 500 μg/mL 时表现出最大抑制，而穿心莲甲醇提取物在31.2 μg/mL 时观察到最大 MIC，抑制率为 64.65 ± 7.33%。结论：通过我们的研究，我们得出结论，用甲醇提取的穿心莲具有良好的抗钩端螺旋体病活性，穿心莲内酯可作为治疗钩端螺旋体病的良好药物。