Alichondrichlorin, a Novel Chlorohydrin‐Containing Natural Product With Tumoral Cytotoxic Activity Isolated From the <i>Planctomycetota</i> Bacterium <i>Alienimonas chondri</i> <scp> LzC2 ^T </scp>

To address the on-going need for chemical novelty and the limited information on Planctomycetota secondary metabolism, we focused on exploring the recently isolated marine planctomycetal strain Alienimonas chondri LzC2^T to uncover its potential production of novel compounds. This work contemplates the description of a large-scale cultivation study of strain LzC2^T, followed by metabolite extraction and compound isolation using chromatographic approaches, which resulted in the isolation of a novel molecule designated as alichondrichlorin. Structural elucidation of this new molecule was accomplished by a combination of high-resolution mass spectrometry and nuclear magnetic resonance. The molecule was additionally screened for anti-proliferative bioactivity against human tumoral and non-tumoral cell lines. These cytotoxicity assays revealed a targeted effect of alichondrichlorin in the growth of tumoral cell lines, especially human breast adenocarcinoma MCF-7 cell line (EC₅₀ = 4.06 μM) without effect on the human non-tumoral THLE-2 cell line (EC₅₀ > 50 μM).