The ethyl acetate extract of cultures of Janibacter limosus showed a high biological activity against bacteria, and fungi and delivered two new natural products, a tetrahydroquinoline derivative designated as helquinoline (1), and the N-acetylkynuramine (3a), along with other known secondary metabolites. The structure of 1 has been elucidated as 4-methoxy-2-methyl-1,2,3,4-tetrahydroquinoline-8-carboxylic acid on the basis of 1D and 2D NMR and mass spectra. The relative stereochemistry of the compound 1 was assigned as 2R*,4R* with the aid of coupling constants, NOESY correlation and by comparison with a related compound.

中文翻译：

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Helquinoline，一种来自Janibacter limosus Hel 1+的新型四氢喹啉抗生素。

詹姆杆菌属细菌培养物中的乙酸乙酯提取物对细菌和真菌具有很高的生物活性，并提供了两种新的天然产物，一种称为Helquinoline的四氢喹啉衍生物（1）和N-乙酰基尿嘧啶（3a），以及其他已知的次级代谢产物。基于1D和2D NMR和质谱，已将1的结构阐明为4-甲氧基-2-甲基-1,2,3,4-四氢喹啉-8-羧酸。借助于偶合常数，NOESY相关性以及与相关化合物的比较，将化合物1的相对立体化学指定为2R *，4R *。