# Polyketides with a 6/6/6/6 Oxaphenalene Pyranone Skeleton from Marine-Derived Streptomyces sp. HDN150000

## TL;DR

New polyketide compounds with a unique structure were isolated from a marine bacteria and showed cancer cell toxicity.

## Contribution

Discovery of three new polyketide structures with a 6/6/6/6 oxaphenalene pyranone skeleton from a marine Streptomyces species.

## Key findings

- Naphpyrone K exhibited cytotoxic effects against multiple cancer cell lines with low IC50 values.
- Structures were confirmed using NMR, X-ray diffraction, and theoretical calculations.
- The compounds suggest potential for drug development from marine actinobacteria.

## Abstract

Three new structures named naphpyrone I–K (1–3) that contain a 6/6/6/6 oxaphenalene pyranone skeleton were isolated and purified from a marine-derived Streptomyces sp. HDN155000. Their chemical structures, including configurations, were elucidated by extensive NMR, MS, single-crystal X-ray diffraction, theoretical NMR calculations, DP4+ probability analysis, and ECD analyses. Naphpyrone K (3) showed cytotoxic activities against L-02, K562, NCI-H446/EP, MDA-MB-231, and NCI-H446 cancer cells with IC50 values of 5.13, 3.34, 2.50, 2.61, and 2.20 μM, respectively. These findings highlight the potential for screening and developing therapeutic drugs from aromatic polyketides derived from marine actinobacteria.