SMART-assisted discovery of butenolides from the marine-derived Aspergillus sp. NBU4698 with multidrug resistance reversing and anti-inflammatory activity

Using together HSQC NMR-guided fractionation and an in vivo screening zebrafish model for bioactivity-guided fractionation, four previously undescribed butenolides, perbutanolides A-D (1-4), were isolated from the marine-derived Aspergillus sp. NBU4698. HSQC NMR-based Small Molecule Accurate Recognition Technology (SMART 2.0) was used to simplify the process of discovering and characterizing these structurally related natural products. The structures and absolute configurations were determined by HRESIMS, NMR, polarimetry, and ECD calculations. All the compounds were evaluated for multidrug resistance (MDR) reversing activity in a zebrafish model, and compound 1 induced significant MDR reversal activity by inhibiting PXR-regulated efflux transporters. In addition, compounds 1-3 exhibited a moderate inhibitory effect on pro-inflammatory mediators in RAW264.7 macrophage cells. This is the first report of MDR reversal activity for marine-derived fungal butenolides. These results provide new insights for designing and developing probes and new drugs that can inhibit MDR.