Asymmetric Primaquine and Halogenaniline Fumardiamides as Novel Biologically Active Michael Acceptors

Abstract

Novel primaquine (PQ) and halogenaniline asymmetric fumardiamides 4a–f, potential Michael acceptors, and their reduced analogues succindiamides 5a–f were prepared by simple three-step reactions: coupling reaction between PQ and mono-ethyl fumarate (1a) or mono-methyl succinate (1b), hydrolysis of PQ-dicarboxylic acid mono-ester conjugates 2a,b to corresponding acids 3a,b, and a coupling reaction with halogenanilines. 1-[bis(Dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate (HATU) was used as a coupling reagent along with Hünig′s base. Compounds 4 and 5 were evaluated against a panel of bacteria, several Mycobacterium strains, fungi, a set of viruses, and nine different human tumor cell lines. p-Chlorofumardiamide 4d showed significant activity against Staphylococcus aureus, Streptococcus pneumoniae and Acinetobacter baumannii, but also against Candida albicans (minimum inhibitory concentration (MIC) 6.1–12.5 µg/mL). Together with p-fluoro and p-CF3 fumardiamides 4b,f, compound 4d showed activity against Mycobacterium marinum and 4b,f against M. tuberculosis. In biofilm eradication assay, most of the bacteria, particularly S. aureus, showed susceptibility to fumardiamides. m-CF3 and m-chloroaniline fumardiamides 4e and 4c showed significant antiviral activity against reovirus-1, sindbis virus and Punta Toro virus (EC50 = 3.1–5.5 µM), while 4e was active against coxsackie virus B4 (EC50 = 3.1 µM). m-Fluoro derivative 4a exerted significant cytostatic activity (IC50 = 5.7–31.2 μM). Acute lymphoblastic leukemia cells were highly susceptible towards m-substituted derivatives 4a,c,e (IC50 = 6.7–8.9 μM). Biological evaluations revealed that fumardiamides 4 were more active than succindiamides 5 indicating importance of Michael conjugated system.

Primaquine derivatives: Modifications of the terminal amino group

“…The synthetic procedure shown in Scheme 6 was applied for the synthesis of PQ-halogenaniline asymmetric diamides of fumaric acid (138e143) and succinic acid (144e149) [106]. Fumardiamides were designed as Michael acceptor analogues of bis-ureas 87e93, and succindiamides as the saturated counterparts of fumardiamides missing a,b-unsaturated carbonyl group (Michael acceptor moiety).…”

“…To mention just the most important ones: 8hydroxyquinoline, nitroxoline and several generations of quinolone/fluoroquinolone derivatives (norfloxacin, ciprofloxacin, enoxacin, ofloxacin, moxifloxacin, etc.). Based on these facts, the in vitro antimicrobial activity of selected PQ derivatives (ureas 43e52, bisureas 85e94, ureidoamides 108e113, PQ-fumardiamides 138e143 and succindiamides 144e149) was carried out against a panel of Gram-positive bacteria, Gram-negative bacteria and fungi [83,94,106]. A list of microorganisms is given in Supplementary Material, SI Table 16.…”

“…Taking into account the fact that quinoline or quinolone pharmacophore is present in the antitubercular drugs bedaquiline and ciprofloxacin, antimycobacterial potential of more than seventy primaquine derivatives was evaluated against a number of Mycobacterium species (SI Table 16) [81,106,109]. After comparison of their activity and cytotoxicity several hits with MIC values from 2 to 16 mg/ml were identified: m-CF 3 -phenylurea 50, dimethoxybenzhydryl urea 76, urea 54 derived from (1-aminocyclobutyl) methanol, urea 58 and bis-urea 86 with phenol moieties [81].…”

“…After comparison of their activity and cytotoxicity several hits with MIC values from 2 to 16 mg/ml were identified: m-CF 3 -phenylurea 50, dimethoxybenzhydryl urea 76, urea 54 derived from (1-aminocyclobutyl) methanol, urea 58 and bis-urea 86 with phenol moieties [81]. Fumardiamides 139, 141 and 143 with p-fluorine, chlorine or CF 3 substituents and bis-CF 3 cinnamamide 11 also exerted significant antimycobacterial activity (MIC ¼ 16e64 mg/ml) [106,109].…”

“…PQ-urea derivatives 22e30 [79], bis-urea derivatives 95e99, 105, 106 [84], PQ-cinnamic acid derivatives 1e11 and 62e72 [64], PQ-fumardiamides 138e143 and PQ-succindiamides 144e149 [106] were evaluated against a broad variety of viruses (SI Table 17). The ureas with phenylethyl and pyridine moieties (28 and 29) showed specific activity against human cytomegalovirus (HCMV)…”