Butyrolactones and Diketopiperazines from Marine Microbes: Inhibition Effects on Dengue Virus Type 2 Replication.

Two new compounds, 4,10-dihydroxy-11-methyl-dodec-2-en-1,4-olide () (butyrolactone-type) and cyclo-(4--6-dihydroxy-proline-D-leucine) () (diketopiperazine-type), as well as one known 4,10-dihydroxy-10-methyl-dodec-2-en-1,4-olide () and three known diketopiperazines, cyclo-(L-proline-L-leucine) (), cyclo-(4--hydroxy-L-proline-L-leucine) (), and cyclo-(4--hydroxy-L-proline-L-phenylalanine) (), were isolated from the ethyl acetate extracts of GT and C-03. Compounds , and exhibited a significant reduction effect on dengue virus type 2 replication with EC values of 21.2, 16.5, 12.3, and 11.2 µM, respectively.