Types A and D Trichothecene Mycotoxins from the Fungus Myrothecium roridum.

Chromatographic separation of extracts from the fungal biomass of a plant pathogenic fungus, Myrothecium roridum, yielded 8 trichothecene toxins including 6 type D trichothecenes (1: -6: ) and 2 type A trichothecenes (7: -8: ). 6',12'-Epoxymyrotoxin A (1: ) and 7'-hydroxymytoxin B (2: ) were new macrocyclic trichothecenes, while the other trichothecenes were identified as myrotoxin B (3: ), myrotoxin D hydrate (4: ), 2',3'-epoxymyrothecine A (5: ), miotoxin A (6: ), and 2 trichothecenes lacking the macrocyclic lactone system, roridin L-2 (7: ) and trichoverritone (8: ). The structures of these mycotoxins were characterized using spectroscopic methods. The absolute configurations of 1: and 2: were determined by NOESY and a comparison of their experimental and calculated ECD spectra. Most of these mycotoxins (1: -4: and 6: ) exhibited highly potent antimalarial activity against Plasmodium falciparum. They also showed strong cytotoxicity towards KB and NCI-H187 cell lines (IC50 0.60 - 112.28 nM), as well as the Vero cell line (IC50 1.50 - 46.51 nM).

Bioactive homogentisic acid derivatives from fruits and flowers of Miliusa velutina.

Chromatographic separation of fruits and flowers of the Thai medicinal plant, Miliusa velutina, resulted in the isolation of five new rare homogentisic acid derivatives, miliusanal (1) and miliusanones A-D (2-5), together with fifteen known secondary metabolites (6-20). Their structures were determined through the use of extensive spectroscopic data. The absolute configurations of homogentisic acid derivatives 2-7 were identified using NOESY data and a comparison of experimental and calculated ECD spectral data. Compounds 2, 3, 6, and 7 showed antimalarial activity with IC50 values in the range of 3.3-5.2 µg/mL. Compound 6 also showed activity against Mycobacterium tuberculosis with an MIC value of 50 µg/mL. Compounds 1-3, 6 and 7 exhibited cytotoxicity againt KB, MCF-7, NCI-H187 and Vero cell lines with IC50 values in the range of 5.8-40.4 µg/mL. In addition, compounds 1, 2 and 6 showed moderate antibacterial activities against three Gram-positive bacteria (Bacillus cereus, Staphylococcus aureus, and Methicillin resistant S. aureus) with MICs in the range of 32-64 µg/mL.