Quinazoline antifolates inhibiting thymidylate synthase: synthesis of four oligo(L-.gamma.-glutamyl) conjugates of N10-propargyl-5,8-dideazafolic acid and their enzyme inhibition

Abstract

The synthesis is described of four oligo(gamma-glutamyl) conjugates of N10-propargyl-5,8-dideazafolic acid containing a total of two, three, four, and five L-glutamic acid residues. The tert-butyl group was chosen as the carboxyl protecting group in order to obviate the use of alkali and thus the possibility of gamma----alpha transpeptidation. The starting material, di-tert-butyl glutamate, was coupled to N-(benzyloxycarbonyl)-L-glutamic acid alpha-tert-butyl ester via a mixed anhydride with isobutyl chloroformate. Hydrogenolysis of the benzyloxycarbonyl group in the product gave a carboxyl-protected diglutamate, which either was acylated with 4-[(benzyloxycarbonyl)amino] benzoyl chloride to give a protected aminobenzamide or was cycled further by using the above mixed anhydride/hydrogenolysis sequence into tri-, tetra-, and pentaglutamates. Each of the last named was also acylated, as above, to give a benzamide. The benzyloxycarbonyl group in the benzamides was removed by hydrogenolysis and the amino groups thus exposed were N-alkylated with propargyl bromide. The resulting proparglyamines were further alkylated with 2-amino-6-(bromomethyl)-4-hydroxyquinazoline hydrobromide to give the antifolate poly(t-Bu) esters. Deprotection with trifluoroacetic acid in the final step delivered the desired antifolates as their trifluoroacetate salts. The di- to pentaglutamates were, respectively, 31-, 97-, 171-, and 167-fold more inhibitory to WI-L2 human thymidylate synthase than the parent compound.

Thermodynamic studies on the interaction of folic acid with bovine serum albumin

“…Rapidly proliferating cells, such as cancer cells need large supplies of thymine for DNA synthesis [16]. For this reason, this pathway is useful for developing the target molecules which are analogous to folic acid that function by inhibiting these enzymes and halting DNA synthesis [17][18][19]. In this work, we have investigated the interaction of folic acid with BSA by a combination of isothermal titration calorimetry (ITC), fluorescence and circular dichroism spectroscopy.…”

Identification of highly potent and selective MMP2 inhibitors addressing the S1′ subsite with d-proline-based compounds

“…In a dry round bottom flask, compound 12 (150 mg, 0.55 mmol) and DMAP (13 mg, 0.11 mmol) were added under a nitrogen atmosphere, followed by DCM (5.5 mL) and triethylamine (111 mg, 1.10 mmol). The solution was cooled in an ice bath, benzyl 4-(chlorocarbonyl)benzylcarbamate (200 mg, 0.66 mmol), prepared as reported, 37 was added portionwise, then the reaction was left at room temperature for 16 h. Successively, the mixture was diluted with dichloromethane and washed with 1M HCl (3 x 20 mL), a saturated solution of NaHCO3 (3 x 20 mL) and brine (20 mL). The organic solution was dried over Na2SO4 and concentrated under reduced pressure to obtain a crude mixture that was purified by Flash Chromatography (AcOEt / EtPet = 1 : 1) giving compound 16 as a yellow oil in 95% yield.…”

TomudexTM (ZD1694): from concept to care, a programme in rational drug discovery

“…Pharmacokinetic measurements indicated that desamino-CB3717 was more rapidly cleared from plasma than CB3717 [44], an observation which party explained its equal rather than greater potency against the L1210:ICR tumour [43]. CB3717 had by now been shown to form polyglutamates in tissues, metabolites that were a) more potent TS inhibitors than the parent drug (,-~ 100-fold) and b) not readily effluxed from cells [45,46]. More extensive polyglutamation of desamino-CB3717 was thought to account for its increased cytotoxicity.…”