**Metabolomic Characterization of a cf.** *Neolyngbya* **Cyanobacterium from the South China Sea Reveals Wenchangamide A, a Lipopeptide with In Vitro Apoptotic Potential in Colon Cancer Cells**

**Lijian Ding 1,2,†, Rinat Bar-Shalom 3,†, Dikla Aharonovich 2, Naoaki Kurisawa 4, Gaurav Patial 1, Shuang Li 1, Shan He 1, Xiaojun Yan 1, Arihiro Iwasaki 4,5, Kiyotake Suenaga 4,5, Chengcong Zhu 5, Haixi Luo 5, Fuli Tian 5, Fuad Fares 3, C. Benjamin Naman 1,5,\* and Tal Luzzatto-Knaan 2,\***


**Abstract:** Metabolomics can be used to study complex mixtures of natural products, or secondary metabolites, for many different purposes. One productive application of metabolomics that has emerged in recent years is the guiding direction for isolating molecules with structural novelty through analysis of untargeted LC-MS/MS data. The metabolomics-driven investigation and bioassay-guided fractionation of a biomass assemblage from the South China Sea dominated by a marine filamentous cyanobacteria, cf. *Neolyngbya* sp., has led to the discovery of a natural product in this study, wenchangamide A (**1**). Wenchangamide A was found to concentration-dependently cause fast-onset apoptosis in HCT116 human colon cancer cells in vitro (24 h IC50 = 38 μM). Untargeted metabolomics, by way of MS/MS molecular networking, was used further to generate a structural proposal for a new natural product analogue of **1**, here coined wenchangamide B, which was present in the organic extract and bioactive sub-fractions of the biomass examined. The wenchangamides are of interest for anticancer drug discovery, and the characterization of these molecules will facilitate the future discovery of related natural products and development of synthetic analogues.

**Keywords:** metabolomics; secondary metabolites; natural products; cyanobacteria; *Neolyngbya*; anticancer; drug discovery; South China Sea; wenchangamide
