Analysis of amino acid enantiomers derived from antitumor antibiotics using chiral capillary electrophoresis

The chiral separation of enantiomeric forms of derivatized amino acids have been achieved based on a metalchelate chiral capillary electrophoretic method and a cyclodextrin mediated host-guest interaction approach in micellar electrokinetic chromatography (MEKC) mode with laser-induced fluorescence detection. This approach has been applied to the determination of enantiomeric forms of amino acids derived from novel depsipeptide antitumor antibiotics, BMY-45012 and its analogs. Amino acids were analyzed by complete hydrolysis and the hydrolysate was derivatized with either dansyl chloride for UV absorbance detection or fluorescein isothiocyanate for laser based fluorescence detection. The presence of several amino acids, serine and beta-hydroxyl-N-methy-valine in the proposed structure have been confirmed as D-serine and L-beta-hydroxyl-N-methy-valine enantiomeric forms by both chiral capillary electrophoresis (chiral CE) and MEKC approaches. A non-chiral amino acid, sarcosine, was also confirmed. These methodologies provide a quick and sensitive approach for the determination of amino acids racemization of pharmaceutical natural products and have proven to be useful for structural elucidation refinement.

CP-225,917 and CP-263,114, novel Ras farnesylation inhibitors from an unidentified fungus. I. Taxonomy, fermentation, isolation, and biochemical properties

During the course of our screening for squalene synthase inhibitors and Ras farnesylation inhibitors, a novel fungal culture was discovered to produce two structurally unique compounds, CP-225,917 and CP-263,114, as well as zaragozic acid A (squalestatin I). The two compounds are characterized by a bicyclo[4.3.1]dec-1,6-diene core plus two extended alkyl chains. CP-225,917 and CP-263,114 inhibit Ras farnesyl transferase from rat brain with IC50 values of 6 microM and 20 microM, respectively. CP-225,917 inhibits squalene synthase with an IC50 value of 43 microM and CP-263,114 with an IC50 of 160 microM. The producing organism, though not fully classified, exhibits the characteristics of a sterile Phoma species.

Korkormicins, novel depsipeptide antitumor antibiotics from Micromonospora sp C39500: fermentation, precursor directed biosynthesis and biological activities

Micromonospora sp C39500, isolated in our laboratory from a soil sample, produced a complex of seven novel depsipeptide antitumor antibiotics, designated korkormicins. The major component of the complex, korkormicin A, has a MW of 1452 and a molecular formula of C66H84N16O22. Korkormicin A exhibits potent in vivo antitumor activity against P388 leukemia and M109 lung carcinoma implanted intraperitoneally (ip) in mice, with effective doses of 0.05-0.20 mg kg-1 injection-1, for five or three ip injections, respectively. It is also active against Gram-positive bacteria but inactive against Gram-negative bacteria. The production of korkormicin A was enhanced by 3-fold when 0.1% L-valine was added to the production culture at 48 h. A titer of 401.0 micrograms ml-1 was achieved in the fermenter culture supplemented with 0.1% L-valine.

Improved processes for the production and isolation of dynemicin A and large-scale fermentation in a 10000-liter fermentor

Supplementing the culture of Micromonospora chersina sp. nov. No. M956-1 with NaI (0.5 mg/l) enhanced the production of dynemicin A by 35-fold in shake flask culture. Homogeneous dynemicin A was obtained from the whole broth extract by Dicalite chromatography, Sephadex LH-20 chromatography and vacuum liquid chromatography. Gram quantities of dynemicin A were obtained from the fermentation of M. chersina sp. nov. No. M956-1 in a 10,000-liter fermentor.

Rollinone, a new cytotoxic acetogenin from Rollinia papilionella

Rollinone, a new member of a series of cytotoxic, linear acetogenins bearing a bistetrahydrofuran moiety and a gamma-lactone, has been isolated from Rollinia papilionella. The structure elucidation of rollinone was achieved by interpretation of the pmr and cmr data and mass spectral fragmentation patterns.