An improved HPLC assay for S-2-(3-aminopropylamino)ethyl phosphorothioate (WR-2721) in plasma.

An HPLC assay is presented for the detection and quantitation of the radioprotective drug S-2-(3-aminopropylamino)ethyl phosphorothioate (WR-2721, ethiofos) present in plasma. Improved selectivity and a 40-fold increase in sensitivity have been demonstrated over the method previously reported by this laboratory. Using precolumn derivatization with fluorescamine and S-3-(4-aminobutylamino)propyl phosphorothioate (WR-80855, a homolog of WR-2721) as the internal standard, drug levels of 0.05 to 1000 micrograms/mL were determined with excellent precision (CV less than or equal to 5% over the concentration range). An isocratic mobile phase of acetonitrile/ethanol/water (16:7:77) modified with 0.01 M tetrabutylammonium phosphate eluted the drug and the internal standard from the C-18 reverse-phase column in 23 minutes and 26 minutes, respectively. Detector response was linear over the entire range. The assay uses 150 microL of plasma and requires a total chromatography time of about 50 minutes. The method was found suitable for pharmacokinetic studies in a preliminary experiment with a beagle dog in which no interferences due to plasma constituents or drug metabolites were observed.

HPLC assay for 2-(3-aminopropylamino)ethanethiol (WR-1065) in plasma.

A high pressure liquid chromatography (HPLC) plasma assay for WR-1065 is described which is both precise (coefficient of variation less than 5%) and accurate (% average deviation less than or equal to 6.1) throughout the concentration range from 1 to 500 micrograms/mL of plasma. The analyte is separated by HPLC and detected with a thiol specific electrochemical transducer cell. The detector response is linear over the ranges 1 to 10 micrograms/mL (R2 = 0.995), 10 to 100 micrograms/mL (R2 = 0.995), and 100 to 500 micrograms/mL (R2 = 0.974). The absolute retention times for WR-1065 and WR-1729 are 9 and 12 minutes, respectively. The assay uses 100 microL of plasma and requires a total chromatography cycle time of 40 minutes. The method has been found suitable for the determination of WR-1065 in plasma from a beagle dog after i.v. administration of S-2-(3-aminopropylamino)ethyl phosphorothioate (WR-2721).

Biosynthesis of flaviolin and 5,8-dihydroxy-2,7-dimethoxy-1,4-naphthoquinone.

Tracer experiments indicate a polyketide origin for the production of flaviolin (2,5,7-trihydroxy-1,4-naphthoquinone) by Aspergillus niger and 2,7-dimethoxynaphthazarin (5,8-dihydroxy-2,7-dimethoxy-1,4-naphthoquinone) by Streptomyces no. 12396. With the Streptomycete, a "solid state fermentation" technology was used for the incorporation studies. Radioactivity from shikimic acid was effectively incorporated into flaviolin; this conversion, however, proceeded by way of acetic acid. The latter stages of biosynthesis of 2,7-dimethoxynaphthazarin by the Streptomycete were shown to be as follows: flaviolin leads to mompain leads to 2,7-dimethoxynaphthazarin.

Generation of monodisperse fibrous glass aerosols.

Investigations of the aerodynamic behavior of fibers, lung deposition studies which involve fibers and investigations which are concerned with the biological effects of fibers create the need for fibrous aerosols monodisperse with respect to both fiber length and diameter. The method of preparation presented in this paper is primarily based on embedding the bulk quantity of fibers in a plastic histological preparation medium and subsequently cutting the fibers to the desired lengths. The slices which are obtained by the microtoming process are purified of the plastic medium by burning and ashing and the fibrous dust obtained in this manner is then cleared of any debris by liquid elutriation. The results show that gram quantities of nearly monodisperse glass fiber dust with lengths of up to 50 micrometers can be obtained.

Measurement of WR-1065 in plasma: preliminary pharmacokinetics in the beagle.

Described is a high-performance liquid chromatographic (HPLC) method for the quantification of WR-1065 [2-(3-aminopropylamino)-ethanethiol] in plasma. After a brief sample preparation, the drug and internal standard were separated in less than 15 minutes using a reversed-phase column and ion-pairing reagent. An electrochemical detector provided a minimum quantifiable limit of 0.05 microgram/mL. The analytical method was applied in three experiments to measure drug concentrations in the plasma of beagle dogs following IV administration of WR-1065 (60 mg/kg). The concentration-time data, best described by a three-compartment open kinetic model, were used to estimate pharmacokinetic parameters. Mean values were: steady state volume of distribution--2.27 L X kg-1; clearance--0.064 L X min-1 X kg-1; and terminal elimination half-life--81.4 min. The high clearance is consistent with the formation of mixed disulfides in the circulation.