Evaluation of the antiparasitic activities of imidazol-2-ylidene–gold(I) complexes

A series of cationic gold(I)–carbene complexes with various 4,5-diarylimidazolylidene ligands were either newly prepared or repurposed for testing against protozoal Leishmania major, Toxoplasma gondii, and Trypanosoma brucei parasites. The syntheses of the new complexes 1b and 1c were described. Ferrocene compound 1a showed the highest activities against L. major amastigotes and T. gondii and distinct selectivity for T. gondii cells when compared with the activity against nonmalignant Vero cells. The ferrocene derivatives 1a–c are generally more active against the L. major amastigotes and the T. gondii tachyzoites than the other tested anisyl gold complexes and the approved drugs atovaquone and amphotericin B. Compounds 1a and 1e showed the highest selectivities for L. major amastigotes. Compounds 1d and 1f showed the highest selectivities for L. major promastigotes; 1f was the most active compound against L. major promastigotes of this series of compounds. The 3,4,5-trimethoxyphenyl analog 1b also exhibited a much greater selectivity for T. b. brucei cells when compared with its activity against human HeLa cells.     

Discriminative stimulus effects of BAY 38-7271, a novel cannabinoid receptor agonist

BAY 38-7271 [(-)-(R)-3-(2-hydroxymethylindanyl-4-oxy)phenyl-4,4,4-trifluoro-1-sulfonate] is a novel, highly potent and selective cannabinoid CB(1)/CB(2) receptor agonist with neuroprotective properties. It was the aim of the present study to further confirm its cannabinoid CB(1) receptor agonist properties in a highly sensitive in vivo assay. Male Wistar rats (n=24) were trained to discriminate BAY 38-7271 (0.05 mg/kg, i.p., t-30 min) from vehicle in a fixed-ratio:10, food-reinforced two-lever standard procedure. The animals acquired the discrimination after a median number of 52 training sessions. BAY 38-7271 generalized dose-dependently when tested after different routes of administration (ED(50): 0.018 mg/kg, i.p.; 0.001 microg/kg, i.v.; 0.18 mg/kg, p.o.). A time-dependency study indicated that the cue (0.05 mg/kg, i.p.) was detectable between 15 min and 4 h, with a maximum of generalization obtained at 30 min after administration. Pretreatment with the selective cannabinoid CB(1) receptor antagonist SR 141716A [N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride] completely antagonized the effects of BAY 38-7271 (ID(50): 1.1 mg/kg, i.p.). Dose-dependent and complete generalization was also obtained after i.p. administration of the reference cannabinoid CB(1) receptor agonists HU-210 [(-)-11-OH-Delta(8)-tetrahydrocannabinol-dimethylheptyl, ED(50): 0.003 mg/kg], CP 55,940 [(-)-cis-3-[2-hydroxy-4(1,1-dimethyl-heptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol, 0.007 mg/kg], WIN 55,212-2 [(R)-4,5-dihydro-2-methyl-4(4-morpholinylmethyl)-1-(1-naphtalenylcarbonyl)-6H-pyrrolo [3,2,1-ij] quinolin-6-one, 0.28 mg/kg] and (-)-Delta(9)-tetrahydrocannabinol (0.34 mg/kg). The present study confirms that BAY 38-7271 is a highly potent cannabinoid CB(1) receptor agonist in vivo.