Inhibition of dihydrofolate reductases by derivatives of 2,4-diaminopyrroloquinazoline

Exploration and Biological Evaluation of 1,3-Diamino-7H-pyrrol[3,2-f]quinazoline Derivatives as Dihydrofolate Reductase Inhibitors

Dihydrofolate reductase (DHFR), a core enzyme of folate metabolism, plays a crucial role in the biosynthesis of purines and thymidylate for cell proliferation and growth in both prokaryotic and eukaryotic cells. However, the development of new DHFR inhibitors is challenging due to the limited number of scaffolds available for drug development. Hence, we designed and synthesized a new class of DHFR inhibitors with a 1,3-diamino-7H-pyrrol[3,2-f]quinazoline derivative (PQD) structure bearing condensed rings. Compound 6r exhibited therapeutic effects on mouse models of systemic infection and thigh infection caused by methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300. Moreover, methyl-modified PQD compound 8a showed a strong efficacy in a murine model of breast cancer, which was better than the effects of taxol. The findings showcased in this study highlight the promising capabilities of novel DHFR inhibitors in addressing bacterial infections as well as breast cancer.

Design, synthesis, docking and in vitro antifungal study of 1,2,4-triazole hybrids of 2-(aryloxy)quinolines

Substituted quinolines containing a 1,2,4-triazole moiety were synthesized using reported methods. The molecular docking studies support the experimental results that these compounds are active against

The chemistry and pharmacology of privileged pyrroloquinazolines

The advent of next-generation sequencing (NGS) technology has plummeted the cost of whole genome sequencing, which has provided a long list of putative drug targets for a variety of diseases ranging from infectious diseases to cancers. The majority of these drug targets are still awaiting high-quality small molecule ligands to validate their therapeutic potential and track their druggability. Screening compound libraries based on privileged scaffolds is an efficient strategy to identify potential ligands to distinct biological targets. 7H-Pyrrolo[3,2-f]quinazoline (PQZ) is a potential privileged heterocyclic scaffold with diverse pharmacological properties. A number of biological targets have been identified for different derivatives of PQZ. This review summarized the synthetic strategies to access the chemical space associated with PQZ and discussed their unique biological profiles.

Discovery of a Potent Anti-tumor Agent through Regioselective Mono-N-acylation of 7H-Pyrrolo[3,2-f]quinazoline-1,3-diamine

7H-Pyrrolo[3,2-f]quinazoline-1,3-diamine (1) is a privileged chemical scaffold with significant biological activities. However, the currently accessible chemical space derived from 1 is rather limited. Here we expanded the chemical space related to 1 by developing efficient methods for regioselective monoacylation at N¹ , N³ and N⁷ , respectively. With this novel methodology, a focused library of mono-N-acylated pyrroloquinazoline-1,3-diamines were prepared and screened for anti-breast cancer activity. The structure-activity relationship (SAR) results showed that N³ -acylated compounds were in general more potent than N¹ -acylated compounds while N⁷ -acylation significantly reduced their solubility. Among the compounds evaluated, 7f possessed 8-fold more potent activity than 1 in MDA-MB-468 cells. More importantly, 7f was not toxic to normal human cells. These results suggest that 7f is a novel compound as a potential anti-breast cancer agent without harming normal cells.

Antimalarial activities of new pyrrolo[3,2-f]quinazoline-1,3-diamine derivatives

WR227825 is an antimalarial pyrroloquinazolinediamine derivative with a high potency but a low therapeutic index. A series of carbamate, carboxamide, succinimide, and alkylamine derivatives of WR227825 were prepared to search for compounds with an improved therapeutic index. The new acetamides and imide showed potent cell growth inhibition against four clones of Plasmodium falciparum (D-6, RCS, W-2, and TM91C235), with a 50% inhibitory concentration of approximately 0.01 ng/ml, and were highly active against Plasmodium berghei, with 100% cure at doses from <0.1 mg/kg of body weight to 220 mg/kg. The carbamates and alkyl derivatives, however, showed weak activity against Plasmodium falciparum cell growth but were highly efficacious in tests against P. berghei by the Thompson test. The best compounds, bis-ethylcarbamate (compound 2a) and tetra-acetamide (3a) derivatives, further demonstrated high potency against the sporozoite Plasmodium yoelii in mice and P. falciparum and Plasmodium vivax in aotus monkeys. Against the AMRU-1 strain of P. vivax, which has four dihydrofolate reductase mutations and is highly resistant to antifolates, tetra-acetamide 3a cured the monkeys at doses of 1 and 3 mg/kg. Compound 2a cured only one out of two monkeys at 3 mg/kg. The results indicated that the new derivatives 2a and 3a not only have retained/improved the antimalarial efficacy of the parent compound WR227825 but also were less toxic to the animals used in the tests.

High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size

A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.