Paecilodepsipeptide A (1), a new cyclohexadepsipeptide possessing three d-amino acid residues, together with its linear analogues paecilodepsipeptides B (2) and C (3), was isolated from the insect pathogenic fungus Paecilomyces cinnamomeus BCC 9616. Structures of these compounds were elucidated primarily by NMR and mass spectroscopic analyses. The absolute configurations of the amino acid and hydroxy acid residues of 1 were addressed by HPLC analysis of its acid hydrolyzate using a chiral column and Marfey's method. Paecilodepsipeptide A (1) showed activity against the malarial parasite Plasmodium falciparum K1 with an IC50 value of 4.9 microM. This compound also showed cytotoxicity to two cancer cell lines, KB (IC50 5.9 microM) and BC (IC50 6.6 microM); however, it was inactive against noncancerous Vero cells up to 67 microM (50 microg/mL).

Our results demonstrate that there is positive feedback regulation of COX-2 expression by PG metabolites, but not COX-1, indicating that PG levels per se do not play an important role in the compensatory regulation between the two COX isoenzymes, but may play an important role in mediating increased COX-2 expression and activity.

A novel 24-membered polyene lactam macrolide, micromonosporin A (=(3E,5E,7Z,15E,17E,19E,21E)-9,11,13-trihydroxy-14,19,24-trimethyl-1-azacyclotetracosa-3,5,7,15,17,19,21-heptaen-2-one; 1) was isolated from the actinomycete, Micromonospora sp. strain TT1-11, which was isolated from a very acidic peat swamp forest.

Two new cyclohexadepsipeptides, hirsutatins A (1) and B (2), were isolated from a culture filtrate of the insect pathogenic fungus Hirsutella nivea BCC 2594. Structures of these compounds were elucidated primarily by NMR and mass spectroscopic analyses. The alpha-carbon stereochemistry of 1 was established by HPLC analysis of its acid hydrolysate using a chiral column. Hirsutatin B (2) exhibited activity against the malarial parasite Plasmodium falciparum K1 with an IC50 value of 5.8 microg/mL, while hirsutatin A (1) was inactive at a concentration of 20 microg/mL.