3.1.2. Chromones

The chromone and its derivatives have been identified as the central backbone in several functional organic compounds, with strategic importance in many research and industrial domains. Until now, 85 new chromone derivatives have been identified from the mangrove-associated fungal species.

In 2019, two new polycyclic chromones, penixanthones C (**35**) and D (**36**) (Figure 11), possessing an unprecedented 6/6/6/5 polycyclic skeleton with a signature C2 bridge, were isolated from the mangrove sediment-derived fungus *Penicillium* sp. SCSIO041218 [46]. However, **35** and **36** only showed weak cytotoxicity. Furthermore, the configurations of **35** and **36** remain elusive.

**Figure 11.** Structures of compounds **35** and **36**.
