Secondary Metabolites and PI3K Inhibitory Activity of Colletotrichum gloeosporioides, a Fungal Endophyte of Uncaria rhynchophylla

In the present study, nine compounds ( 1–9 ) were isolated from Colletotrichum gloeosporioides (an endophytic fungus from Uncaria rhynchophylla ) which was cultured in wheat bran medium. Their structures were elucidated as 4-Epi-14-hydroxy-10, 23-dihydro-24, 25-dehydroaflavinine ( 1 ), 10, 23-Dihydro-24,25 -dehydro-21–oxoaflavinine ( 2 ), Ergosterol ( 3 ), Ergosterol peroxide ( 4 ), Mellein ( 5 ), 4, 5-dihydroblumenol A ( 6 ), Colletotrichine A ( 7 ), Cyclo( L -leucyl- L -leucyl) ( 8 ), and Brevianamide F (9) based on NMR spectral data, as well as comparing with previous literature data. This is the first report about the isolation of compounds 1–2 , 6 , and 8–9 from Colletotrichum genus. All compounds were tested for their phosphoinositide 3-kinase (PI3Kα) inhibitory activity. Compounds 8 and 9 showed potent PI3K α inhibitory activity with IC 50 values of 38.1 and 4.8 µM, respectively, while the other compounds showed very weak activity at a concentration of 20 µg/mL.