Discovery of a novel class of negative allosteric modulator of the dopamine D2 receptor through fragmentation of a bitopic ligand

We recently demonstrated that SB269652 (1) engages one protomer of a dopamine D2 receptor (D2R) dimer in a bitopic mode to allosterically inhibit the binding of dopamine at the other protomer. Herein, we investigate structural deter- minants for allostery, focusing on modifications to three moieties within 1. We find that orthosteric “head” groups with small 7-substituents were important to maintain the limited negative cooperativity of analogues of 1, and replacement of the tetrahydroisoquinoline head group with other D2R “privileged structures” generated orthosteric antagonists. Additionally, replacement of the cyclohexylene linker with polymethylene chains conferred linker length dependency in allosteric pharmacology. We validated the importance of the indolic NH as a hydrogen bond donor moiety for maintaining allostery. Replacement of the indole ring with azaindole conferred a 30-fold increase in affinity while maintaining negative cooperativity. Combined, these results provide novel SAR insight for bitopic ligands that act as negative allosteric modulators of the D2R

Sinteza i biološko djelovanje novih 1-benzil i 1-benzoil 3-heterocikličkih derivata indola

Starting from 1-benzyl- (2a) and 1-benzoyl-3-bromoacetyl indoles (2b) new heterocyclic, 2-thioxoimidazolidine (4a,b), imidazolidine-2,4-dione (5a,b), pyrano(2,3-d)imidazole (8a,b and 9a,b), 2-substituted quinoxaline (11a,b–17a,b) and triazolo(4,3-a)quinoxaline derivatives (18a,b and 19a,b) were synthesized and evaluated for their antimicrobial and anticancer activities. Antimicrobial activity screening performed with concentrations of 0.88, 0.44 and 0.22 g mm2 showed that 3-(1-substituted indol-3-yl)quinoxalin-2(1H)ones (11a,b) and 2-(4-methyl piperazin-1-yl)-3-(1-substituted indol-3-yl) quinoxalines (15a,b) were the most active of all the tested compounds towards P. aeruginosa, B. cereus and S. aureus compared to the reference drugs cefotaxime and piperacillin, while 2-chloro-3-(1-substituted indol-3-yl)quinoxalines (12a,b) were the most active against C. albicans compared to the reference drug nystatin. On the other hand, 2-chloro-3-(1-benzyl indol-3-yl) quinoxaline (12a) display potent efficacy against ovarian cancer xenografts in nude mice with tumor growth suppression of 100 0.3 %.U radu je opisana sinteza, antimikrobno i antitumorsko djelovanje heterocikličkih derivata indola. Polazeći iz 1-benzil- i 1-benzoil-3-bromacetil indola (2a i 2b) sintetizirani su novi heterociklički spojevi 2-tioksoimidazolidini (4a,b), imidazolidin-2,4-dioni (5a,b), pirano(2,3-d)imidazoli (8a,b i 9a,b), 2-supstituirani kinoksalini (11a,b–17a,b) i triazolo(4,3-a)kinoksalini (18a,b i 19a,b). Sintetizirani spojevi testirani su na antimikrobno i antitumorsko djelovanje. Ispitivanje antimikrobnog djelovanja provedeno je s koncentracijama otopina 0,88, 0,44 i 0,22 g mm2 i uspoređeno s referentnim lijekovima cefotaksimom i piperacilinom. Rezultati pokazuju da su 3-(1-supstituirani indol-3-il)kinoksalin-2(1H)oni (11a,b) i 2-(4-metil piperazin-1-il)-3-(1-supstituirani indol-3-il) kinoksalini (15a,b) najaktivniji spojevi na sojeve P. aeruginosa, B. cereus i S. aureus, dok su 2-klor-3-(1-supstituirani indol-3-il)kinoksalini (12a,b) najaktivniji na C. albicans (usporedba s nistatinom). Osim toga, 2-klor-3-(1-benzil indol-3-il) kinoksalin (12a) pokazuje veliku učinkovitost na tumore ovarija miševa (supresija rasta tumora 100 0,3 %)

Sinteza, antimikrobno i antitumorsko djelovanje nekoliko novih N-etil, N-benzil i N-benzoil-3-indolil heterocikličkih spojeva

A series of 1-(N-substituted-1H-indol-3-yl)-3-arylprop-2-ene-1-ones (2a,b-4a,b) were prepared and allowed to react with urea, thiourea or guanidine to give pyrimidine derivatives 5a,b–13a,b. Reaction of 2a,b-4a,b with ethyl acetoacetate in the presence of a base gave cyclohexanone derivatives 14a,b-16a,b. Reaction of the latter compounds with hydrazine hydrate afforded indazole derivatives 17a,b-19a,b. On the other hand, reaction of 2a,b-4a,b with some hydrazine derivatives, namely hydrazine hydrate, acetyl hydrazine, phenyl- hydrazine and benzylhydrazine hydrochloride, led to the formation of pyrazole derivatives 20a,b-31a,b. Moreover, reaction of 2a,b-4a,b with hydroxylamine hydrochloride gave isoxazole derivatives 32a,b-34a,b. The newly synthesized compounds were tested for their antimicrobial activity and showed that 4-(N-ethyl-1H-indol-3-yl)-6-(p-chlorophenyl)-pyrimidine-2-amine (11b) was the most active of all the test compounds towards Candida albicans compared to the reference drug cycloheximide. Eighteen new compounds, namely pyrimidin-2(1H)-ones 5a,b-7a,b, pyrimidin-2(1H)-thiones 8a,b-10a,b and pyrimidin-2-amines 11a,b-13a,b derivatives, were tested for their in vitro antiproliferative activity against HEPG2, MCF7 and HCT-116 cancer cell lines. 4-(N-ethyl-1H-indol-3-yl)-6-(p-methoxyphenyl)-pyrimidin-2-amine (11a) was found to be highly active with IC50 of 0.7 µmol L1.Sintetizirana je serija 1-(N-supstituiranih-1H-indol-3-il)-3-arilprop-2-en-1-ona (2a,b-4a,b) i podvrgnuta reakciji s ureom, tioureom ili gvanidinom, pri čemu su nastali derivati pirimidina 5a,b–13a,b. Reakcijom 2a,b-4a,b s etil-acetoacetatom u prisutnosti baze nastali su derivati cikloheksanona 14a,b-16a,b. Njihovom reakcijom s hidrazin hidratom dobiveni su derivati indazola 17a,b-19a,b. S druge strane, reakcijom 2a,b-4a,b s određenim derivatima hidrazina, tj. s hidrazin hidratom, acetil hidrazinom, fenilhidrazinom i benzilhidrazin hidrokloridom, nastali su derivati pirazola 20a,b-31a,b. Nadalje, reakcijom 2a,b-4a,b s hidroksilamin hidrokloridom dobiveni su derivati izoksazola 32a,b-34a,b. Pripravljeni spojevi ispitani su na antimikrobno djelovanje. Pokazalo se da je 4-(N-etil-1H-indol-3-il)-6-(p-klorfenil)-pirimidin-2-amin (11b) najaktivniji spoj za Candida albicans (ATCC 10231) uz cikloheksimid kao poredbeni lijek. Testirano je antitumorsko djelovanje in vitro osamnaest novih spojeva, tj. pirimidin-2(1H)-ona 5a,b-7a,b, pirimidin-2(1H)-tiona 8a,b-10a,b i pirimidin-2-amina 11a,b-13a,b na tumorske stanice HEPG2, MCF7 i HCT-116. Najaktivniji spoj bio je 4-(N-etil-1H-indol-3-il)-6-(p-metoksifenil)-pirimidin-2-amin (11a) uz IC50 0,7 µmol L1