In this study,the secondary metabolites of an endophytic fungus were regulated by precursor mediated regulation.To study the secondary metabolites,various chromatographic techniques,including normal phase silica gel column chromatography and preparative HPLC were used.Their structures were determined by various spectroscopic data,such as NMR and MS.Finally,10 alkaloids were isolated from P.  brasiliense and their structures were identified as perlolyrine (1),1-(1′,2′-dideoxy-α-D-nucleopyranosyl)-β-carbamate porphyrin (2),flazin (3),tangutorid E (4),1-acetyl-β-carboline (5),4-(9H-β-carbolin-1-yl)-4-oxobutyric acid (6),1-(furan-2-yl)-9H-pyrido［3,4-b］indole (7),indole-3-ethanol (8),indole-3-acetic acid (9),and indole-3-carboxaldehyde (10).All the 10 alkaloids were isolated from this genus of Paraconiothyrium sp.for the first time.Among them,7 compounds were β-carboline alkaloids.In addition,the xanthine oxidase inhibitory activity was tested for compounds 1-10.The results showed that 7 compounds had significant inhibitory activity,and the IC₅₀ value ranged from 0.68 to 9.30 mM.It was worth noting that the inhibitory activities of compounds 2,3 and 6 were better than that of positive drug.