Abstract Five new α -pyrones, diaporpyrones G-K ( 1 – 5 ) and three new γ -butenolide derivatives, porbutenolides A-C ( 6 – 8 ), along with seven known compounds ( 9 – 15 ), were isolated from the culture extract of the endophytic fungus Diaporthe sp. CCY4. Their structures were elucidated by comprehensive spectroscopic analysis, including 1D/2D NMR and HRESIMS data. The absolute configurations of 7 and 8 were assigned using electronic circular dichroism (ECD) calculations. All compounds were evaluated for inhibitory activity against ubiquitin-specific peptidase 4 (USP4). Compounds 2 , 5 , 9 , and 13 exhibited significant anti-ubiquitination effects at 40 μM, with 13 showing the most potent inhibition (IC 50 = 20.85 μM). Graphical Abstract
Zeng et al. (Tue,) studied this question.