Constituents from the Polar Extract of Pisolithus arhizus and Their Anti-inflammatory Activity

The phytochemical study of the Pisolithus arhizus fruiting body methanol extract led to the isolation of six new triterpenoids (1–6) and one new naphthalenoid pulvinic acid derivative (7), together with five known compounds, including norbadione A (8). Their structure was established from 1D and 2D NMR spectroscopy and HRESIMS analyses. The absolute configuration of the triterpenoids was determined by circular dichroism. The two pulvinic acid derivatives 7 and 8, showing the highest activity in modulating IL-6 secretion, were tested for their effect on COX-2, STAT3, and p-STAT3 proteins; both compounds were able to downregulate p-STAT3.