Ageloline A, new antioxidant and antichlamydial quinolone from the marine sponge-derived bacterium Streptomyces sp. SBT345

A new chlorinated quinolone, ageloline A, was isolated from the broth culture of Streptomyces sp. SBT345 that was cultivated from the Mediterranean sponge Agelas oroides. The structure of this compound was determined by spectroscopic analysis including 1D and 2D NMR as well as HR-ESI-MS experiments. Ageloline A exhibited antioxidant potential using cell-free and cell-based assays and was further able to reduce oxidative stress and genomic damage induced by the oxidative stress inducer 4-nitroquinoline-1-oxide (NQO). Moreover, ageloline A inhibited the formation and growth of Chlamydia trachomatis inclusion in a dose-dependent manner with an IC50 value of 9.54 ± 0.36 μM. Interestingly, experimental data showed that the antichlamydial activity of ageloline A might be related to its antioxidant potential. These results demonstrate that sponge-associated actinomycetes are rich sources for natural products with new pharmacological activities and relevance to drug discovery.