Design, synthesis and anticancer activities of stilbene-coumarin hybrid compounds: Identification of novel proapoptotic agents

Targeting adenosine receptors with coumarins: synthesis and binding activities of amide and carbamate derivatives

OBJECTIVES

With the aim of finding the structural features governing binding activity and selectivity against adenosine receptors (ARs), several 3-subtituted coumarins with amide (compounds 3-6) and carbamate (7-9) functions were synthesized. To study its possible influence on the binding activity and selectivity, a hydroxyl substituent was also introduced at position 4 of the coumarin moiety.

METHODS

A new series of coumarins (3-9) were synthesized and evaluated by radioligand binding studies towards ARs.

KEY FINDINGS

None of the 4-hydroxy derivatives (4, 8 and 9) showed binding affinity for any of the ARs. None of the compounds interacted with the hA(2B) AR (K(i) > 100,000 nM). Compounds 3, 5, 6 and 7 had different activity profiles with dissimilar binding affinity and selectivity towards human A₁, A(2A) and A₃ ARs.

CONCLUSIONS

 The most remarkable derivative is compound 7, which presents the best affinity and selectivity for the A₃ adenosine receptor (K(i) = 5500 nM).

Synthesis and structure-activity relationships of novel amino/nitro substituted 3-arylcoumarins as antibacterial agents

A new series of amino/nitro-substituted 3-arylcoumarins were synthesized and their antibacterial activity against clinical isolates of Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) was evaluated. Some of these molecules exhibited antibacterial activity against S. aureus comparable to the standards used (oxolinic acid and ampicillin). The preliminary structure-activity relationship (SAR) study showed that the antibacterial activity against S. aureus depends on the position of the 3-arylcoumarin substitution pattern. With the aim of finding the structural features for the antibacterial activity and selectivity, in the present manuscript different positions of nitro, methyl, methoxy, amino and bromo substituents on the 3-arylcoumarin scaffold were reported.

Design, synthesis and biological evaluation of novel 7-mercaptocoumarin derivatives as α(1)-adrenoceptor antagonists

Study on the pharmacophore model of α(1)-adrenoceptor (α(1)-AR) antagonists led to design a series of novel 7-mercaptocoumarin derivatives as α(1)-AR antagonists. All designed compounds have been synthesized and biologically evaluated. The results showed that most of them exhibited strong antagonistic activity. Especially compound 6 showed excellent activity, which was better than that of the reference compound prazosin. Structure-activity relationship studies revealed that small hydrophobic group at the terminal heterocyclic ring and ortho substituents on the phenyl ring of phenylpiperazine moiety were the essential structural factors for α(1)-AR antagonistic activity. The pharmacophore modeling studies further clarified their structural contributions to antagonistic activity and also demonstrated that 7-mercaptocoumarin moiety could be a useful scaffold for design of α(1)-AR antagonists.

Synthesis and Microbial Activity of Novel 3-Methyl-2-pyrazolin-5-one Derivatives

2-Oxo-2H-chromene-3-carbohydrazide derivatives2a,breact with 2-{[4-(substituted thiazol-2-yl)iminoethyl)-phenyl]hydrazono}-3-oxo-butyric acid ethyl esters4a–cto give 3-methyl-1-[(2-oxo-2H-chromen-3-yl) carbonyl]-4-{[4-(substituted thiazol-2-yl)iminoethyl)-phenyl]hydrazono}]-2-pyrazolin-5-one derivatives5a–f. A considerable increase in the reaction rate had been observed with better yield using microwave irradiation for the synthesis of compounds2a,b,3a–c, and5a–f. The synthesized products were tested againstB. subtilis,S. aureus, andE. colias well asC. albicanscompared with tetracycline and nystatin as reference drugs.

Pharmacological Evaluation and Docking Studies of 3-Thiadiazolyl- and Thioxo-1,2,4-triazolylcoumarin Derivatives as Cholinesterase Inhibitors

Inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) is considered a promising strategy for the treatment of Alzheimer's disease (AD). This research project aims to provide a comprehensive knowledge of newly synthesized coumarin analogues with anti-AD potential. In the present work a series of 3-thiadiazolyl- and thioxo-1,2,4-triazolylcoumarins derivatives were designed, synthesized, and tested as potent inhibitors of cholinesterases. These compounds were assayed against AChE from electrophorus electricus and rabbit; and BChE from horse serum and rabbit by Ellman's method using neostigmine methylsulphate and donepezil as reference drugs. Some of the assayed compounds proved to be potent inhibitors of AChE and BChE with K_i values in the micromolar range. 4b was found to be the most active compound with K_i value 0.028 ± 0.002 μM and higher selectivity for AChE/BChE. The ability of 4b to interact with AChE was further confirmed through computational studies, in which a primary binding was proved to occur at the active gorge site, and a secondary binding was revealed at the peripheral anionic site. Structure activity relationships of prepared compounds were also discussed.

3-Phenylcoumarins as inhibitors of HIV-1 replication

We have synthesized fourteen 3-phenylcoumarin derivatives and evaluated their anti-HIV activity. Antiviral activity was assessed on MT-2 cells infected with viral clones carrying the luciferase gene as reporter. Inhibition of HIV transcription and Tat function were tested on cells stably transfected with the HIV-LTR and Tat protein. Six compounds displayed NF-κB inhibition, four resulted Tat antagonists and three of them showed both activities. Three compounds inhibited HIV replication with IC₅₀ values < 25 µM. The antiviral effect of the 4-hydroxycoumarin derivative 19 correlates with its specific inhibition of Tat functions, while compound 8, 3-(2-chlorophenyl)coumarin, seems to act through a mechanism unrelated to the molecular targets considered in this research.

Biological evaluation of coumarin derivatives as mushroom tyrosinase inhibitors

A series of coumarin derivatives were synthesised and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were evaluated. The results showed that some of the synthesised compounds exhibited significant inhibitory activities. Especially, 2-(1-(coumarin-3-yl)ethylidene)hydrazinecarbothioamide bearing thiose-micarbazide group exhibited the most potent tyrosinase inhibitory activity with IC(50) value of 3.44μM. The inhibition mechanism analysis of 2-(1-(coumarin-3-yl)-ethylidene)hydrazinecarbothioamide and 2-(1-(6-chlorocoumarin-3-yl)ethylidene)-hydrazinecarbothioamide demonstrated that the inhibitory effects of the compounds on the tyrosinase were irreversible. Preliminary structure activity relationships' (SARs) analysis suggested that further development of such compounds might be of interest.

3,6,8-Tribromo-7-ethyl-amino-4-methyl-2H-chromen-2-one

In the title mol-ecule, C(12)H(10)Br(3)NO(2), the 2H-chromen ring is essentially planar (r.m.s. deviation = 0.022 Å) with the ethyl-amino group oriented at 13.9 (5)° with respect to the ring. The mol-ecular structure is stabilized by intra-molecular N-H⋯Br and C-H⋯Br interactions.

3,6-Dibromo-7-ethyl-amino-4-methyl-2H-chromen-2-one

In title compound, C(12)H(11)Br(2)NO(2), the coumarin ring system is almost planar, the two rings being inclined to one another by 1.40 (15)°. There are two short intra-molecular inter-actions (N-H⋯Br and C-H⋯Br) involving the Br atoms. In the crystal, mol-ecules stack along the a-axis direction via π-π inter-actions; the centroid-centroid distances vary from 3.6484 (19) to 3.7942 (19) Å.

Design, synthesis and cytotoxic activities of novel hybrid compounds between 2-phenylbenzofuran and imidazole

A series of novel hybrid compounds between 2-phenylbenzofuran and imidazole have been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that substitution of the imidazolyl-3-position with a naphthylacyl or bromophenacyl group, were vital for modulating cytotoxic activity. In particular, hybrid compound 15 was found to be the most potent compound against 4 strains human tumor cell lines and more active than cisplatin (DDP), and exhibited cytotoxic activity selectively against liver carcinoma (SMMC-7721).

Novel microtubule-targeted agent 6-chloro-4-(methoxyphenyl) coumarin induces G2-M arrest and apoptosis in HeLa cells

AIM

To identify a novel coumarin analogue with the highest anticancer activity and to further investigate its anticancer mechanisms.

METHODS

The viability of cancer cells was investigated using the MTT assay. The cell cycle progression was evaluated using both flow cytometric and Western blotting analysis. Microtubule depolymerization was observed with immunocytochemistry in vivo and a tubulin depolymerization assay in vitro. Apoptosis was demonstrated using Annexin V/Propidium Iodide (PI) double-staining and sub-G(1) analysis.

RESULTS

Among 36 analogues of coumarin, 6-chloro-4-(methoxyphenyl) coumarin showed the best anticancer activity (IC(50) value about 200 nmol/L) in HCT116 cells. The compound had a broad spectrum of anticancer activity against 9 cancer cell lines derived from colon cancer, breast cancer, liver cancer, cervical cancer, leukemia, epidermoid cancer with IC(50) value of 75 nmol/L-1.57 μmol/L but with low cytotocitity against WI-38 human lung fibroblasts (IC(50) value of 12.128 μmol/L). The compound (0.04-10 μmol/L) induced G(2)-M phase arrest in HeLa cells in a dose-dependent manner, which was reversible after the compound was removed. The compound (10-300 μmol/L) induced the depolymerization of purified porcine tubulin in vitro. Finally, the compound (0.04-2.5 μmol/L) induced apoptosis of HeLa cells in dose- and time-dependent manners.

CONCLUSION

6-Chloro-4-(methoxyphenyl) coumarin is a novel microtubule-targeting agent that induces G(2)-M arrest and apoptosis in HeLa cells.

Tyrosine-like condensed derivatives as tyrosinase inhibitors

Objectives

We report the pharmacological evaluation of a new series of 3-aminocoumarins differently substituted with hydroxyl groups, which have been synthesized because they include in their structures the tyrosine fragment (tyrosine-like compounds), with the aim of discovering structural features necessary for tyrosinase inhibitory activity.

Methods

The synthesized compounds 4 and 7–9 were evaluated in vitro as mushroom tyrosinase inhibitors.

Key findings

Two of the described compounds showed lower IC50 (concentration giving 50% inhibition of tyrosinase activity) than umbelliferone, used as a reference compound.

Conclusions

Compound 7 (IC50 = 53 µm) was the best tyrosinase inhibitor of this small series, having an IC50 value 10-fold lower than umbelliferone. Compound 7 (3-amino-7-hydroxycoumarin) had amino and hydroxyl groups precisely mimicking the same positions that both groups occupy on the tyrosine molecule.

Synthesis and study of a series of 3-arylcoumarins as potent and selective monoamine oxidase B inhibitors

New series of 6-substituted-3-arylcoumarins displaying several alkyl, hydroxyl, halogen, and alkoxy groups in the two benzene rings have been designed, synthesized, and evaluated in vitro as human monoamine oxidase A and B (hMAO-A and hMAO-B) inhibitors. Most of the studied compounds showed a high affinity and selectivity to the hMAO-B isoenzyme, with IC(50) values on nanomolar and picomolar range. Ten of the 22 described compounds displayed higher MAO-B inhibitory activity and selectivity than selegiline. Coumarin 7 is the most active compound of this series, being 64 times more active than selegiline and also showing the highest hMAO-B specificity. In addition, docking experiments were carried out on hMAO-A and h-MAO-B structures. This study provided new information about the enzyme-inhibitor interaction and the potential therapeutic application of this 3-arylcoumarin scaffold.

Synthesis and in vitro evaluation of novel coumarin-chalcone hybrids as potential anticancer agents

A series of coumarin-chalcone hybrids have been synthesized and evaluated for their in vitro cytotoxicity against a panel of four human cancer cell lines and normal fibroblasts (NIH3T3). Among 21 compounds screened, three compounds (23, 25 and 26) showed IC(50) range from 3.59 to 8.12 μM. The most promising compound 26 showed around 30-fold more selectivity towards C33A (cervical carcinoma) cells over normal fibroblast NIH3T3 cells with an IC(50) value of 3.59 μM.