Theophylline derivatization

Fig. 1 Comparison of the detection sensitivity after derivatization of three purine derivatives with chloramine T - sulfuric acid (A) and chloramine T - hydrochloric acid (B). Measurement X. (. = 365 nm, A.(, = 440 nm (monochromatic filter M 440) 1 = theophylline, 2 = theobromine, 3 = caffeine.

N-Mannich derivatization has also been documented to improve skin delivery [91][92], In the case of theophylline (11.56) and 5-fluorouracil (11.58), a much improved solubility in water of the various N-Mannich bases examined was observed. To avoid breakdown, however, the prodrugs had to be dissolved in a polar nonaqueous solvent (isopropyl myristate) for pharmaceutical use. The delivery of theophylline and 5-fluorouracil through hairless mouse skin was, thus, accelerated approximately sixfold through use of the prodrugs 11.57 and 11.59, respectively. 

Theophylline has been derivatized to prodnce amino-phylline, choline theophyllinate, and other componnds. 

Floberg et al. applied glass capillary gas chromatography for the analysis of theophylline and caffeine in plasma. The alkaloids were analyzed as such, or after derivatization. 

Because of the extensive use of theophylline for the treatment of bronchial asthma and other cardiorespiratory disorders, many investigations have been carried out by means of gas chromatography to determine theophylline in serum, plasma and saliva. In many cases theophylline has been gas chromatographed as such, in some other cases after derivatization. Methyl derivatives15,16 17,18, n-butyl derivatives19,20,21,22,23,24,25,26, propyl derivatives27, pentyl derivatives and pentafluorobenzyl derivatives 3 have been made in order to obtain better gas chromatographic properties of theophylline and thus better detection possibilities. A number of stationary phases have been applied, from non-polar ones (SE-30) to very polar ones (HI-EFF 8B). OV-17 is the stationary phase that has mostly been used. 

Gas chromatographic methods have been developed to solve this problem. Theophylline has been gas chromatographed and determined as such, but in most cases derivatization has been carried out to obtain better gas chromatographic properties and better detection possibilities. For quantitative work several substances have been used as internal standard, mainly barbiturates (alphenal, amobarbital, aprobarbital, heptabarbital, hexabarbital, thiobarbital), but also other substances have been used (fluoranthene, codeine, theobromine, medazepam, pramoxine hydrochloride, cyheptamine, probenecid propylester). Recently 3-isobutyl-1-methyl... 

Because most gas chromatographic methods for the determination of theophylline in biological fluids involve tedious extraction procedures and/or derivatization prior to the gas... 

The extraction procedure and the derivatization give the method high selectivity. Quantitative determinations down to 2 ug theophylline and 4 ug probenecid can be done. The addition of 5 ug theophylline to a sample gave an absolute recovery of 91 5 . 

To be able to determine theophylline in the ng range, Arbin and Edlund improved their method by derivatizing theophylline and the internal standard theobromine using penta-fluorobenzyl bromide, in connection with an electron capture detector. To 100 ul samples of plasma containing 50-1000 ng theophylline, 100 yl of a solution of the internal standard were added. The extraction was performed by column extraction (cellulose) using dichloro-methane as solvent. After back extraction into an alkaline aqueous phase (NaOH), theophylline and theobromine were alkylated with pentafluorobenzyl bromide by an extractive alkylation technique. The derivatives were extracted with cyclohexane and, after concentration to 3 ml, 2 yl were injected for the gas chromatographic assay. Standard deviation of the method was 2.5 % at a concentration level of 200 ng per sample, and 8 % at 20 ng per sample. The sample amounts were 100 yl plasma and 250 mg rat brain tissue, and the sensitivity limit... 

Schwertner et al. introduced a salting-out procedure, in combination with single extraction using chloroform-isopropanol (95 5). 100 pi plasma samples could be effectively extracted with 2 ml chloroform-isopropanol. Theophylline was derivatized with pentafluoroben-zyl chloride, and 3-isobutyl-l-methylxanthine was used as an internal standard. This standard is similar to theophylline in extractability, derivatization rates, stability and chromatographic properties. Accurate measurements of plasma concentrations ( + 0.22 ug/ml) could be obtained with little or no interference from theophylline metabolites and other coextract-able material. A packed column with 3 OV-17 on Gas Chrom Q and temperature programming from 150°C to 250°C was used in combination with an electron capture detector. 

CNTs) with theophylline as the template molecule [78] and from porous silica beads with thiabendazole as the print molecule [79], and these have been applied as molecular recognition agents. Qin et al. [80] made use of the stability of the dithiocarbamyl radicals generated upon photoactivation of iniferters to synthesize lysozyme-imprinted hydrophilic MlPs. These were created by Sl-lMP of acrylamide and N,N -methylenebisacrylamide from iniferter-derivatized mesoporous polystyrene beads (in the presence of the template protein lysozyme) and used in chromatographic separations that employed an aqueous mobile phase. They found that the control and stability imparted by Sl-lMP are crucial elements that enhance the separation of lysozyme from other competing proteins. 

Cytidine has been converted into l-(5-amino-5-deoxy-j8-D-arabinofuranosyl) cytosine by a sequence of reactions involving A-benzoylation, sulphonation, acetylation, displacement with azide ion, e/c., and l-(3-amino-3-deoxy-jS-D-arabinofuranosyl)-6-azauracil was derived from 2, 3 -di-0-methanesulphonyl-5 -O-trityl-6-azauridine via 2,2 - and 2, 3 -anhydro-nucleosides. Other syntheses have been accomplished by the condensation of an appropriately derivatized amino-sugar with either a pyrimidine or purine derivative for example, the Hilbert route was used to prepare l-(2-amino-2-deoxy-a-D-arabino- and -jS-o-xylo-furanosyl)cytosine. > The reactivity of l,3,4,6-tetra-0-acetyl-2-acyl-amido-2-deoxy-j3-D-glucopyranoses in condensation reactions with 2,6-dichloro-purine, theophylline, and 6-benzylaminopurine was shown to be in the order benzamido > acetamido > phthalimido. 9-(3-Acetamido-2,5-di-0-acetyl-3-deoxy-j8-D-ribofuranosyl)-2,6-dichloropurine has been synthesized and converted into the corresponding 2,6-diamino- and 6-amino-2-chloro(fluoro)-nucleosides. ... 

---