Synthesis of new arylaminoquinoxalines and their antimalarial activity in mice.

2-Arylaminoquinoxalines were prepared by the condensation of 2-chloroquinoxaline with the appropriate Mannich bases in the presence of HCl. To synthesize the Mannich bases, 4-acetamidophenol was reacted with formaldehyde and dialkylamine to yield 3-[(dialkylamino) methyl]-4-hydroxyacetanilide, followed by hydrolysis. Antimalarial activities of the new arylaminoquinoxalines were evaluated against the rodent malaria parasite Plasmodium yoelii at a dose of 75 mg kg(-1). Three compounds synthesized (2-[3-[(diethylamino) methyl]-4-hydroxyanilino]-quinoxaline dihydrochloride (2b), 2-[3-[(pyrrolidinyl) methyl]-4-hydroxyanilino]-quinoxaline dihydrochloride (2f), and 2-[3-[(piperidinyl) methyl]-4-hydroxyanilino]-quinoxaline dihydrochloride (2g)) showed moderate antimalarial activity.

Synthesis and preliminary pharmacological investigations of 1-(1,2-dihydro-2-acenaphthylenyl)piperazine derivatives as potential atypical antipsychotic agents in mice.

In research towards the development of new atypical antipsychotic agents, one strategy is that the dopaminergic system can be modulated through manipulation of the serotonergic system. The synthesis and preliminary pharmacological evaluation of a series of potential atypical antipsychotic agents based on the structure of 1-(1,2-dihydro-2-acenaphthylenyl)piperazine (7) is described. Compound 7e, 5-{2-[4-(1,2-dihydro-2-acenaphthylenyl)piperazinyl]ethyl}-2,3-dihy dro-1H- indol-2-one, from this series showed significant affinities at the 5-HT1A and 5-HT2A receptors and moderate affinity at the D2 receptor. 7e exhibits a high reversal of catalepsy induced by haloperidol indicating its atypical antipsychotic nature.

Simultaneous determination of tinidazole, furazolidone and diloxanide furoate in a combined tablet preparation by second-derivative spectrophotometry.

A second-derivative spectrophotometric procedure has been developed for the simultaneous determination of tinidazole (TD), furazolidone (FD) and diloxanide furoate (DF) in a commercial preparation. The method consists of the utilization of second-derivative absorption spectra of tablet extract in distilled water and then determination of the analyte concentration in the mixture was carried out using zero-crossing (ZC) and ratio-compensation (RC) techniques. Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of TD (5-20 microg ml(-1)), FD (2.5-10 microg ml(-1)) and DF (7.5-15 microg ml(-1)). The results were found to be accurate and free from interference. The details of the statistical treatment of analytical data are also presented.

"Resultant bond moment" as a newly developed electronic parameter in the design of antibacterial, antiprotozoal nitroimidazole derivatives.

Nineteen nitroimidazole derivatives have been reported to be effective antibacterial against one strain each of Bacteroides fragilis and Clostridium perfringens. The negative logarithms of minimum inhibitory concentrations (MICs) of these nitroimidazoles were fitted by a biostatistical relation involving a newly designed structural descriptor, the Resultant Bond Moment (RBM). RBM was developed on the basis of the chemical attribute of bond moments of heteroatoms. RBM reflects the electronic characteristic of the molecule. Apart from this, steric, electronic, and hydrophobic parameters were also utilised in the search of a best fit regression equation. On the basis of these equations new investigative nitroimidazole derivatives have been predicted concerning their antibacterial and antiprotozoal efficacy.

Spectrofluorometric estimation of aspirin and dipyridamole in pure admixtures and in dosage forms.

Aspirin and dipyridamole in pure admixtures and in dosage forms have been estimated by spectrofluorometry. Aspirin (2-12 mcg ml-1) was estimated in 1% v/v glacial acetic acid in chloroform using 246 and 345 nm for excitation and emission respectively. Dipyridamole (2-12 mcg ml-1) has been estimated in chloroform using 420 nm for excitation and 475 nm for emission. The non-interference of the excipients as well as the drugs in the estimation of each other, as evidenced by the results, indicate that this method may be used for the routine estimation of aspirin and dipyridamole in tablet preparations.

Differential derivative spectrophotometric determination of phenobarbitone and phenytoin sodium in combined tablet preparations.

A pH-induced differential derivative spectrophotometric procedure has been developed for the simultaneous determination of Phenobarbitone (PBT) and Phenytoin sodium (DPH Na) in tablet preparations. The method comprized of measurement of difference absorptivities derivatized in second order (DeltaD(2)) of a tablet extract in 0.01 N NaOH relative to that of an equimolar solution in 0.01 N HCl at wavelengths of 244.8 and 252.8 nm respectively. The presence of identical zero-crossing points for pure drug and tablet extract solutions established the non-interference of the excipients in the absorption at these wavelengths. The compliance of Beer's law was adhered over a concentration range of 7.5-25 mug ml(-1) for both PBT and DPH.

Simultaneous quantitative determination of metronidazole and nalidixic acid in tablets by difference spectroscopy.

A difference spectrophotometric procedure has been developed for simultaneous determination of metronidazole (MDZ) and nalidixic acid (NA) in tablets. The method comprised the measurement of the absorbance of a solution of the tablet extract in 0.1 M NaOH relative to that of an equimolar solution in 0.1 M HCl at 292 nm for NA and 325 nm for MDZ. The presence of identical isosbestic points for pure drug solutions and tablet extracts indicated the non-interference of excipients in the absorption at these wavelengths. Compliance with Beer's law was observed in the concentration ranges 5-25 micrograms ml(-1) for MDZ and 15-35 micrograms ml(-1) for NA these wavelengths.

Second-order derivative spectrophotometric assay for imipramine hydrochloride and diazepam in pure admixtures and in dosage forms.

The determination of imipramine HCl and diazepam in tablets by derivative spectrophotometry is described. The drugs in combined preparations have been quantified using the second-order derivative spectra of their solutions in 0.1 M HCl. The method has been applied to pure drug mixtures as well as commercial preparations and was found to be precise and reproducible. Compliance of Beer's Law was observed in the concentration range of 10-70 micrograms ml-1 for imipramine HCl and 2-8 micrograms ml-1 for diazepam. Lower limits of detection at the 95% confidence level were 1.96 micrograms ml-1 for imipramine HCl and 0.21 microgram ml-1 for diazepam.