In an attempt to find new agents to fight against microbial infections, a series of coumarin-based 1,3,4-oxadiazol-2ylthio-N-phenyl/benzothiazolyl acetamides was synthesized starting from coumarin-3-carboxylic acid ethyl ester obtained through Knoevenagel and Pinner reaction In vitro antimicrobial activity against several bacteria (S aureus, B cereus, E coli, P aeruginosa, K pneumoniae, S typhi, P vulgaris, S flexneri), fungi (A niger, A fumigatus, A clavatus, C albicans) and antimycobacterial activity against Mycobacterium tuberculosis H37Rv strain was assessed This study shows to what extent the presence of various electron withdrawing/donating substituents on the phenyl or benzothiazole ring affects the activity profiles of the newer molecules The relationship between activity profiles (MICs, 312–25 μg/mL) and the lipophilic character (LogP) of the prepared products is also discussed and the MIC values of the active conjugates seem to correlate to some extent with the lipophilicity profiles Two (5e and 6c) of the final analogues displayed promising antimycobacterial activity at 125 μg/mL of MIC, half fold potent to the standard drug pyrazinamide (625 μg/mL) Compounds were characterized by IR, 1H NMR, 13C NMR spectroscopy and elemental analysis

Synthesis of coumarin-based 1,3,4-oxadiazol-2ylthio-N-phenyl/benzothiazolyl acetamides as antimicrobial and antituberculosis agents

The anti-proliferative activity of novel 4H-benzo[h]chromenes, 7H-benzo[h]-chromeno[2,3-d]pyrimidines and the structure–activity relationships of the 2-, 3-positions and fused rings at the 2, 3-positions

Three new series of chromene molecules have been synthesized in order to explore their antimicrobial activity. The series encompass 2-substituted 14-(4-halophenyl)-12-methoxy-14H-benzo[h]chromeno[3,2-e][1,2,4]-triazolo[1,5-c]pyrimidines 7a-o, 9-benzylideneamino-7-(4-halo-phenyl)-5-methoxy-8-imino-7H-benzo-[h]chromeno[2,3-d]pyrimidines 8a-b and 3-ethoxycarbonyl-14-(4-halophenyl)-12-methoxy-14H-benzo-[h]chromeno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine-2-one derivatives 12a-b. The structure of these novel compounds were confirmed using IR, ¹H- and 13C-NMR as well as MS spectroscopy. The new compounds were evaluated in vitro for their antimicrobial activity and it was demonstrated that 7H-benzochromenopyrimidine and derivatives of 14H-benzochromenotriazolopyrimidine exhibited the most promising antibacterial activities compared to the reference antimicrobial agents. The structure activity relationship (SAR) studies of the target compounds agreed with the in vitro essays and confirmed higher potent antimicrobial activity against some of the tested microorganisms.

Structural Characterization and Antimicrobial Activities of 7H-Benzo[h]chromeno[2,3-d]pyrimidine and 14H-Benzo[h]chromeno[3,2-e][1,2,4]triazolo[1,5-c] pyrimidine Derivatives

A series of 2-amino-4H-benzo[h]chromene and 2,7-diamino-4H-benzo[h]chromene derivatives were prepared as potential cytotoxic agents. The structures of the synthesised compounds were established on the basis of spectral data. The in-vitro cytotoxic activity of the synthesised compounds against the cell lines MCF-7, HCT-116 and HepG-2 was investigated in comparison with vinblastine and colchicine, using an MTT colorimetric assay. The structure-activity relationship of 4H-benzo[h]chromenes with modification at the 3-, 4- and 7-positions was explored. The results of the anti-tumour evaluation revealed that compounds VIIIc, VIId, VIIb, VIIe, VIIIg and VIIIc, VIId, VIIb, VIIe, VIIIg, VIIc, VIIIe, Vf, IIIa inhibited the growth of MCF-7 in comparison with vinblastine and colchicine, while VIIb, VIId, VIIe, IIIa, VIIa, VIIIc, VIIc, IIId, IIIg, IIIf, IIIb, IIIh, VIIIb, VIIIa, VIIIe, IIIc, Vg, IIIe, VIIIg, Vf, IIIf inhibited the growth of HCT-116 in comparison with colchicine. In addition, compounds VIIe, IIIg, IIIa, VIIc and VIIe, IIIg, IIIa, VIIc, VIIb, VIIa, VIIIf, VIIIe inhibited the growth of HepG-2 in comparison with vinblastine and colchicine, respectively.

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Xiao-Yan Nie

Papers

Novel Coumarin and 4H-Chromene Derivatives Containing 4,5- Dihydropyrazole Moiety: Synthesis and Antibacterial Activity