Microsphazaphilones H–Y: new azaphilone pigments with HIV latency reversal activity from the marine-derived fungus Microsphaeropsis arundinis P1B

Latency-reversing agents (LRAs) are molecular entities designed to reactivate latent HIV proviruses for subsequent elimination by the immune system or antiviral therapies. Interestingly, in our systematic exploration of fungal pigment diversity, the marine-derived strain Microsphaeropsis arundinis P1B was identified as a prolific azaphilone producer through phenotype-guided screening, suggesting that such fungal compounds may serve as novel LRAs with enhanced efficacy. Further investigation of its solid-fermented rice medium yielded 18 unprecedented sclerotiorin-type azaphilones (microsphazaphilones H–Y, 1–18). Extensive spectroscopic analysis, modified Mosher’s method, TDDFT-ECD calculation, and X-ray diffraction were used to determine their structures including absolute configurations. These compounds exhibit remarkable structural novelty, manifested by features such as unprecedented di- to tetra-carbon truncations in side chains, diverse oxidative modifications (e.g., epoxidation, hydroxylation), or unique stereochemical configurations in the pyranoquinone core. Biological screening identified microsphazaphilone W (16) as a potent HIV LRA. Mechanistic studies confirmed 16 reactivated latent HIV through NF-κB pathway activation, positioning it as a promising candidate for “shock and kill” strategies.