# New Bioactive Polyketides from the Mangrove-Derived Fungus Daldinia eschscholzii HJX1P2

## TL;DR

This study discovers new bioactive compounds from a mangrove fungus that show anti-inflammatory and antioxidant properties.

## Contribution

The paper reports the isolation and characterization of new polyketides with potential therapeutic applications.

## Key findings

- Compound 1 inhibits nitric oxide production and interleukin-6 expression more effectively than dexamethasone.
- Compounds 7 and 8 show strong DPPH radical scavenging activity, comparable to ascorbic acid.
- Several compounds exhibit antibacterial activity against Staphylococcus aureus strains.

## Abstract

Three new naphthalene–chroman dimer derivatives, daldinaphchromes A–C (1–3), two new chroman derivatives, daldichromes A (5) and B (6), along with five known compounds (4, 7–10) were isolated from the mangrove-derived fungus Daldinia eschscholzii HJX1P2. Their structures and stereochemistries were elucidated through detailed NMR and MS analyses, calculated electronic circular dichroism, and comparison with previously reported data. Compound 1 demonstrated inhibitory effects on nitric oxide (NO) production in LPS-induced RAW 264.7 cells, with an IC50 value of 62.9 µM, and more effectively suppressed the expression of interleukin (IL)-6 than dexamethasone. A further mechanistic study suggested that 1 could prohibit the expression of iNOS in RAW 264.7 cells, and the molecular docking study suggested a possible interaction between 1 and the iNOS protein. Compounds 7 and 8 exhibited moderate to potent DPPH radical scavenging activity, with IC50 values of 117.4 and 46.2 µM, respectively, compared with the positive control ascorbic acid (IC50 = 45.6 µM). Compounds 4 and 10 showed ABTS+ radical scavenging activity, with IC50 values of 66.6 and 33.2 µM, respectively, which were equal to or lower than that of the positive control vitamin C (IC50 = 59.7 µM). Compounds 1–3, 7, and 9 showed antibacterial activity against three Staphylococcus aureus strains, with MIC values of 74.4–390.6 μM.