Epigenetic Manipulation to Trigger Production of Guaiane-Type Sesquiterpenes from a Marine-Derived Spiromastix sp. Fungus with Antineuroinflammatory Effects

Epigenetic manipulation of a deep-sea sediment-derived Spiromastix sp. fungus using suberoylanilide hydroxamic acid (SAHA) induction resulted in the activation of a terpene-related biosynthetic gene cluster, and nine new guaiane-type Sesquiterpenes, spiromaterpenes A-I (1-9), were isolated. Their structures were determined using various spectroscopic techniques, in association with the modified Mosher's method, computed electronic circular dichroism (ECD) spectra, and chemical conversion for configurational assignments. Compounds 4-6 exhibited significant effects against the NO production on lipopolysaccharide (LPS)-induced microglia cells BV2, and the preliminary SAR analyses demonstrated that a 2(R),11-diol unit is favorable. The most active 5 abolished LPS-induced NF-κB translocation from the cytosol to the nucleus in BV-2 microglial cells, accompanied by the marked reduction of the transcription levels of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α dose-dependently in both LPS-induced BV-2 and BV-2 cells, as well as the protein and mRNA levels of iNOS and COX-2. This study complements the gap in knowledge regarding the anti-neuroinflammatory activity of guaiane-type sesquiterpenoids at the cellular level and suggests that 5 is promising for further optimization as a multifunctional agent for antineuroinflammation.