Roxanne Huimin Chen

Learn More
Two novel triterpene sulfates have been isolated from Fusarium compactum by bioactivity-directed fractionation using an assay which measures the inhibition of proteolytic activity of rhinovirus 3C protease on a fluorogenic peptide substrate. The compounds were purified by countercurrent and reverse phase chromatographies. NMR, MS, UV and IR studies revealed(More)
The novel antifungal agents, calbistrins A, B, C and D have been isolated from a strain of Penicillium restrictum (AB 1875C-28). The four congeners were separated by bioactivity directed fractionation using countercurrent chromatography and preparative-HPLC. NMR studies revealed that the calbistrins each contain a carboxylic acid conjugated tetraene(More)
A novel class of antibiotics was isolated from cultures of Streptomyces coeruleorubidus strain AB 1183F-64. The antimicrobial activity of the pacidamycins is selective against Pseudomonas aeruginosa. The various congeners are nucleoside peptides which differ in the terminal amino acid residues. The structures were determined using MS-MS and 2D NMR(More)
The pacidamycins are a new complex of nucleosidyl-peptide antibiotics with highly specific activity against Pseudomonas aeruginosa. They are produced by Streptomyces coeruleorubidus AB 1183F-64 which was isolated from a soil sample collected at Offenburg in the FRG. The mature spore masses of the producing organism are greenish gray to blue, and the spore(More)
Pacidamycins are nucleosidyl-peptide antibiotics which have activity only against Pseudomonas aeruginosa. Their MICs for other organisms such as Enterobacteriaceae, Staphylococcus aureus, most Streptococci and other Pseudomonas species are greater than 100 micrograms/ml. These compounds had no activity against erythromycin-susceptible Streptococci. The MICs(More)
The novel calcineurin inhibitor, dibefurin, has been isolated from the fungal culture AB 1650I-759. The isolation was bioactivity-directed fractionation using an assay which measures the phosphatase activity of calcineurin. The compound was purified by countercurrent, reverse phase and gel filtration chromatographies. Several studies, including(More)
Two novel, isomeric compounds, coumamidines gamma 1 and gamma 2, were isolated from fermentations of an actinomycete. The structures were elucidated spectroscopically using 2D NMR correlation experiments and mass spectral data. The coumamidines were found to be close structural relatives of the cinodines (LL-BM123 gamma 1 and gamma 2).