Synthesis of New Substituted 5-amino-8H-phthalazino[1,2-b]quinazolin-8-one Derivatives

The Synthesis and Biological Evaluation of 2-(1H-Indol-3-yl)quinazolin-4(3H)-One Derivatives

The treatment of many bacterial diseases remains a significant problem due to the increasing antibiotic resistance of their infectious agents. Among others, this is related to Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) and Mycobacterium tuberculosis. In the present article, we report on antibacterial compounds with activity against both S. aureus and MRSA. A straightforward approach to 2-(1H-indol-3-yl)quinazolin-4(3H)-one and their analogues was developed. Their structural and functional relationships were also considered. The antimicrobial activity of the synthesized compounds against Mycobacterium tuberculosis H₃₇Rv, S. aureus ATCC 25923, MRSA ATCC 43300, Candida albicans ATCC 10231, and their role in the inhibition of the biofilm formation of S. aureus were reported. 2-(5-Iodo-1H-indol-3-yl)quinazolin-4(3H)-one (3k) showed a low minimum inhibitory concentration (MIC) of 0.98 μg/mL against MRSA. The synthesized compounds were assessed via molecular docking for their ability to bind long RSH (RelA/SpoT homolog) proteins using mycobacterial and streptococcal (p)ppGpp synthetase structures as models. The cytotoxic activity of some synthesized compounds was studied. Compounds 3c, f, g, k, r, and 3z displayed significant antiproliferative activities against all the cancer cell lines tested. Indolylquinazolinones 3b, 3e, and 3g showed a preferential suppression of the growth of rapidly dividing A549 cells compared to slower growing fibroblasts of non-tumor etiology.

Discovery of glyantrypine-family alkaloids as novel antiviral and antiphytopathogenic-fungus agents

BACKGROUND

Plant diseases caused by viruses and fungi have caused great losses to crop quality and yield. The discovery of novel and efficient antiviral and antiphytopathogenic-fungus agents is urgently needed. It is the most important pesticide innovation strategy to find active compounds from natural products. Here, glyantrypine-family alkaloids were taken as the parent structures and a series of their derivatives were designed through molecular splicing, ring expansion, and ring contraction strategies, and synthesized. The anti-tobacco mosaic virus (TMV) activities and antifungal activities of these alkaloids were systematically investigated for the first time.

RESULT

The antiviral activities of compounds 7bb, 7bc, 11c, 18b, 18d, 28d, and 28e are equivalent to or better than that of ribavirin (inhibitory rates 39%, 37%, and 40% at 500 μg mL^-1 for inactivation, curative, and protection activity in vivo, respectively). Compounds 18d and 28d with good antiviral activities were selected for antiviral mode of action studies, which indicated that these alkaloids could achieve good antiviral effects by inhibiting TMV particle extension during assembly. These compounds also exhibited broad-spectrum fungicidal activities.

CONCLUSION

Glyantrypine-family alkaloids and their derivatives were synthesized and evaluated for anti-TMV and fungicidal activities for the first time. Compounds 18d and 28d with excellent antiviral activities and compound 7bc with remarkable fungicidal activity emerged as novel lead compounds. This study lays a foundation for the application of glyantrypine alkaloids in plant protection.

Synthesis, crystal structure and biological activity of 6-(3-chloropropoxy)-4-(2-fluorophenylamino)-7-methoxyquinazoline

The title compound, 6-(3-chloropropoxy)-4-(2-fluorophenylamino)-7-methoxyquinazoline, was synthesized by selective nucleophilic attack at C-1 of 1-bromo-3-chloropropane by the potassium salt of 4-(2-fluorophenylamino)-7-methoxyquinazolin-6-ol, which was prepared from 7-methoxy-4-oxo-3,4-dihydroquinazolin-6-yl acetate in three steps. The compound crystallized as an ethyl acetate complex (C20H21ClFN3O3, Mr = 405.85), and X-ray crystallography showed that the crystal belongs to the orthorhombic system, space group Pbca with a = 12.7407(4) Å, b = 14.0058(5) Å, c = 21.7726(7) Å, α = 90°, β = 90° and γ = 90°. The whole molecule is stacked into a three-dimensional structure via weak N–H…N hydrogen bonding between molecules. The compound acts as an effective inhibitor on the proliferation of a lung cancer cell line.