Synthesis of novel benzocoumarin derivatives as lipid lowering agents

Design and Synthesis of Coumarin Derivatives as Cytotoxic Agents through PI3K/AKT Signaling Pathway Inhibition in HL60 and HepG2 Cancer Cells

In this study, a series of coumarin derivatives, either alone or as hybrids with cinnamic acid, were synthesized and evaluated for their cytotoxicity against a panel of cancer cells using the MTT assay. Then, the most active compounds were inspected for their mechanism of cytotoxicity by cell-cycle analysis, RT-PCR, DNA fragmentation, and Western blotting techniques. Cytotoxic results showed that compound (4) had a significant cytotoxic effect against HL60 cells (IC₅₀ = 8.09 µM), while compound (8b) had a noticeable activity against HepG2 cells (IC₅₀ = 13.14 µM). Compounds (4) and (8b) mediated their cytotoxicity via PI3K/AKT pathway inhibition. These results were assured by molecular docking studies. These results support further exploratory research focusing on the therapeutic activity of coumarin derivatives as cytotoxic agents.

Synthesis, cytotoxicity and in silico study of some novel benzocoumarin-chalcone-bearing aryl ester derivatives and benzocoumarin-derived arylamide analogs

The development of new prostate cancer protein receptor cytochrome P450 17A1 inhibitors offers the possibility of generating structures of increased potency. To this end, the chalcone analogs 7 and 8 were prepared from treatment of methyl 3-oxo-3H-benzocoumarin-2-carboxylate (4) with aryl aldehydes. Treatment of 7 and 8 with three anti-inflammatory drugs, flurbiprofen, ketoprofen and ibuprofen, in the presence of POCl3/DMAP gave the ester analogs 9–12. Analogously, treatment of ethyl 3-oxo-3H-benzocoumarin-2-carboxylate (15), prepared previously from 2-hydroxy-1-naphthaldehyde (13) and dimethylmalonate (14), with various arylamines: 4-bromoaniline, 2-amino-6-methylpyridine, amino-antipyrine and 2-amino-5-nitrothiazole, in the presence of potassium tert-butoxide gave the benzocoumarine-3-arylamide analogs. The in vitro cytotoxic activities of 9–12 and 16–19 were evaluated against human prostate cancer cell lines (PC-3) and normal human liver epithelia (WRL-68) by MTT assay. Compounds 10 and 17 were the most active cytotoxic agents among the series against PC-3 cells with IC50 values of 71.35 and 78.25 μg mL–1 with SI values of 3.0 and 4.2, respectively (calculated from the cytotoxicity effects of 10 and 17 on the normal human liver epithelia [WRL-68]). Furthermore, compounds 11 and 12 were tested against breast cancer (HER2 cell lines), prostate cancer (DU-135 cell lines) and MCF-7 but were inactive. Molecular docking studies between the protein receptor CYPP450 17A1 and compounds 10 and 17 revealed that these compounds primarily form hydrophobic interactions with the receptor.

Coumarin hybrid derivatives as promising leads to treat tuberculosis: Recent developments and critical aspects of structural design to exhibit anti-tubercular activity

Tuberculosis (TB) is a highly contagious airborne disease with nearly 25% of the world's population infected with it. Challenges such as multi drug resistant TB (MDR-TB), extensive drug resistant TB (XDR-TB) and in rare cases totally drug resistant TB (TDR-TB) emphasizes the critical and urgent need in developing novel TB drugs. Moreover, the prolonged and multi drug treatment regime suffers a major drawback due to high toxicity and vulnerability in TB patients. This calls for intensified research efforts in identifying novel molecular scaffolds which can combat these issues with minimal side effects. In this pursuit, researchers have screened many bio-active molecules among which coumarin have been identified as promising candidates for TB drug discovery and development. Coumarins are naturally occurring compounds known for their low toxicity and varied biological activity. The biological spectrum of coumarin has intrigued medicinal researchers to investigate coumarin scaffolds for their relevance as anti-TB drugs. In this review we focus on the recent developments of coumarin and its critical aspects of structural design required to exhibit anti-tubercular (anti-TB) activity. The information provided will help medicinal chemists to design and identify newer molecular analogs for TB treatment and also broadens the scope of exploring future generation potent yet safer coumarin based anti-TB agents.

Coumarin-based Scaffold as α-glucosidase Inhibitory Activity: Implication for the Development of Potent Antidiabetic Agents

BACKGROUND

Delaying the absorption of glucose through α-glucosidase enzyme inhibition is one of the therapeutic approaches in the management of Type 2 diabetes, which can reduce the incidence of postprandial hyperglycemia. The existence of chronic postprandial hyperglycemia impaired the endogenous antioxidant defense by inducing oxidative stress-induced pancreatic β-cell destruction through uncontrolled generation of free radicals such as ROS, which in turn, leads to various macrovascular and microvascular complications. The currently available α -glucosidase inhibitors, for instance, acarbose, have some side effects such as hypoglycemia at higher doses, liver problems, meteorism, diarrhea, and lactic acidosis. Therefore, there is an urgent need to discover and develop potential α-glucosidase inhibitors.

OBJECTIVE

Based on suchmotifs, researchers are intrigued to search for the best scaffold that displays various biological activities. Among them, coumarin scaffold has attracted great attention. The compound and its derivatives can be isolated from various natural products and/or synthesized for the development of novel α-glucosidase inhibitors.

RESULTS

This study focused on coumarin and its derivatives as well as on their application as potent antidiabetic agents and has also concentrated on the structure-activity relationship.

CONCLUSION

This review describes the applications of coumarin-containing derivatives as α - glucosidase inhibitors based on published reports which will be useful for innovative approaches in the search for novel coumarin-based antidiabetic drugs with less toxicity and more potency.

Rationally synthesized coumarin based pyrazolines ameliorate carrageenan induced inflammation through COX-2/pro-inflammatory cytokine inhibition

In the present work, coumarin based pyrazolines (7a-g) have been synthesized and investigated for their in vitro and in vivo anti-inflammatory potential. Amongst the synthesized compounds, compounds 7a, 7d and 7f exhibited significant in vitro anti-inflammatory activity as compared to the standard etoricoxib. Keeping this in mind, in vivo investigations were carried out via carrageenan induced inflammation and acetic acid induced writhing models in male Wistar rats and compound 7a was found to possess appreciable anti-inflammatory and analgesic potential. The mode of action of compound 7a was also investigated by using substance P as the biomarker, which shows promising results. Further, the selectivity of the most active compound 7a against the cyclooxygenase enzyme was supported by molecular docking studies which reveal that compound 7a has greater binding affinity towards COX-2 over COX-1 and 5-LOX enzymes. In silico ADME analysis of compound 7a confirms the drug-like characteristics and the in vivo acute toxicity study showed the safety of the compound even up to a 2000 mg kg-1 dose. Thus, compound 7a was identified as an effective anti-inflammatory agent, and can be explored for further analgesic/anti-inflammatory drug design and development.

New Hybrid Scaffolds based on Hydrazinyl Thiazole Substituted Coumarin; As Novel Leads of Dual Potential; In Vitro α-Amylase Inhibitory and Antioxidant (DPPH and ABTS Radical Scavenging) Activities

Background:

Despite many side effects associated, there are many drugs which are being clinically used for the treatment of type-II diabetes mellitus (DM). In this scenario, there is still need to develop new therapeutic agents with more efficacy and less side effects. By keeping in mind the diverse spectrum of biological potential associated with coumarin and thiazole, a hybrid class based on these two heterocycles was synthesized.

Method:

Hydrazinyl thiazole substituted coumarins 4-20 were synthesized via two step reaction. First step was the acid catalyzed reaction of 3-formyl/acetyl coumarin derivatives with thiosemicarbazide to form thiosemicarbazone intermediates 1-3, followed by the reaction with different phenacyl bromides to afford products 4-20. All the synthetic analogs 4-20 were characterized by different spectroscopic techniques such as EI-MS, HREI-MS, 1H-NMR and 13C-NMR. Stereochemical assignment of the iminic double bond was carried out by the NOESY experiments. Elemental analysis was found in agreement with the calculated values.

Results:

Compounds 4-20 were screened for α-amylase inhibitory activity and showed good activity in the range of IC50 = 1.829 ± 0.102-3.37 ± 0.17 µM as compared to standard acarbose (IC50 = 1.819 ± 0.19 µM). Compounds were also investigated for their DPPH and ABTS radical scavenging activities and displayed good radical scavenging potential. In addition to that molecular modelling study was conducted on all compounds to investigate the interaction details of compounds 4-20 (ligands) with active site (receptor) of enzyme.

Conclusion:

The newly identified hybrid class may serve as potential lead candidates for the management of diabetes mellitus.

Syntheses of new 3-thiazolyl coumarin derivatives, in vitro α-glucosidase inhibitory activity, and molecular modeling studies

3-Thiazolylcoumarin derivatives 1-14 were synthesized via one-pot two step reactions, and screened for in vitro α-glucosidase inhibitory activity. All compounds showed inhibitory activity in the range of IC50 = 0.12 ± 0.01-16.20 ± 0.23 μM as compared to standard acarbose (IC50 = 38.25 ± 0.12 μM), and also found to be nontoxic. Molecular docking study was carried out in order to establish the structure-activity relationship (SAR) which demonstrated that electron rich centers at one and electron withdrawing centers at the other end of the molecules showed strong inhibitory activity. All the synthesized compounds were characterized by spectroscopic techniques such as EI-MS, HREI-MS, (1)H NMR and (13)C NMR. CHN analysis was also performed.

Esculin and its oligomer fractions inhibit adhesion and migration of U87 glioblastoma cells and in vitro angiogenesis

Cancer metastasis is the major cause of cancer-related death. Chemoprevention is defined as the use of natural or synthetic substances to prevent cancer formation or cancer progress. In the present study, we investigate the antitumor activity of esculin and its oligomer fractions in U87 glioblastoma cells. We showed that esculin and its oligomers reduced U87 cell growth in a dose dependent manner. They also inhibited cell adhesion to collagen IV and vitronectin by interfering with the function of their respective receptors α2β1 and αvβ5 integrins. Furthermore, the tested samples were able to reduce migration of U87 cells towards another extracellular matrix fibronectin. Moreover, esculin and its oligomer fractions inhibited in vitro angiogenesis of endothelial cells (HMEC-1). In summary, our data provide the first evidence that esculin and its oligomer fractions are able to reduce adhesion, migration of glioblastoma cells and in vitro angiogenesis. Esculin and its oligomers may thus exert multi-target functions against cancer cells.

Pentafluorophenylammonium triflate (PFPAT) catalyzed facile construction of substituted chromeno[2,3-d]pyrimidinone derivatives and their antimicrobial activity

A new, simple thermally efficient and solvent-free condensation of 2-amino-3-cyano-6-methyl-4-phenyl-4H-pyran-5-ethylcarboxylate derivatives with coumarin-3-carboxylic acid employing pentafluorophenylammonium triflate (PFPAT) as an inexpensive organocatalyst for the synthesis of a series of ethyl 4,5-dihydro 7-methyl-2-(2-oxo-2H-chromen-3-yl)-4-oxo-5-aryl-3H-chromeno[2,3-d]pyrimidine-6-carboxylate derivatives is described. This method has the advantages of high yields, a cleaner reaction, simple methodology, short reaction times, easy workup, and greener conditions. All the compounds were evaluated for their in vitro antimicrobial activity against different bacterial and fungal strains.

Synthesis and evaluation of new 3-phenylcoumarin derivatives as potential antidepressant agents

A series of amine substituted 3-phenyl coumarin derivatives were designed and synthesized as potential antidepressant agents. In preliminary screening, all compounds were evaluated in forced swimming test (FST), a model to screen antidepressant activity in rodents. Among the series, compounds 5c and 6a potentially decreased the immobility time by 73.4% and 79.7% at a low dose of 0.5 mg/kg as compared to standard drug fluoxetine (FXT) which reduced the immobility time by 74% at a dose of 20 mg/kg, ip. Additionally, these active compounds also exhibited significant efficacy in tail suspension test (TST) (another model to screen antidepressant compounds). Interestingly, rotarod and locomotor activity tests confirmed that these two compounds do not have any motor impairment effect and neurotoxicity in mice. Our studies demonstrate that the new 3-phenylcoumarin derivatives may serve as a promising antidepressant lead and hence pave the way for further investigation around this chemical space.

Pentafluorophenylammonium triflate (PFPAT) catalyzed facile construction of substituted chromeno[2,3-d]pyrimidinone derivatives and their antimicrobial activity

A new, simple thermally efficient and solvent-free condensation of 2-amino-3-cyano-6-methyl-4-phenyl-4H-pyran-5-ethylcarboxylate derivatives with coumarin-3-carboxylic acid employing pentafluorophenylammonium triflate (PFPAT) as an inexpensive organocatalyst for the synthesis of a series of ethyl 4,5-dihydro 7-methyl-2-(2-oxo-2H-chromen-3-yl)-4-oxo-5-aryl-3H-chromeno[2,3-d]pyrimidine-6-carboxylate derivatives is described. This method has the advantages of high yields, a cleaner reaction, simple methodology, short reaction times, easy workup, and greener conditions. All the compounds were evaluated for their in vitro antimicrobial activity against different bacterial and fungal strains.

Discovery of coumarin-dihydropyridine hybrids as bone anabolic agents

The concept of molecular hybridization led us to discover a novel series of coumarin-dihydropyridine hybrids that have potent osteoblastic bone formation in vitro and that prevent ovariectomy-induced bone loss in vivo. In this context, among all the compounds screened for alkaline phosphatase activity, four compounds 10, 14, 18, and 22 showed significant activity at picomolar concentrations. A series of other in vitro data strongly suggested compound 18 as the most promising bone anabolic agent, which was further evaluated for in vivo studies. From these studies compound 18 proved to be useful, which at low oral dose of 1 (mg/kg)/day body weight increased bone mass density and volume, expression of osteogenic genes (RUNX2, BMP-2, and ColI), bone formation rate (BFR), and mineral apposition rate (MAR), improved the trabecular microarchitecture, and decreased bone turn over markers in an ovariectomized rodent model for postmenopausal osteoporosis.

Synthesis, spectroscopic characterization and biological evaluation studies of Schiff's base derived from naphthofuran-2-carbohydrazide with 8-formyl-7-hydroxy-4-methyl coumarin and its metal complexes

Metal complexes of the type ML(2), where M=Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and L=Schiff's base derived from the condensation of naphthofuran-2-carbohydrazide with 8-formyl-7-hydroxy-4-methyl coumarin have been synthesized. The chelation of the complexes have been elucidated in the light of analytical, IR, UV-vis, (1)H NMR, mass, ESR spectral data, thermal and magnetic studies. The measured molar conductance values indicate that, the complexes are non-electrolytic in nature. The redox behavior of one of the synthesized metal complexes was investigated by cyclic voltammetry. The Schiff's base and its metal complexes have been screened for their in vitro antibacterial and antifungal activities by MIC method. The DNA cleavage activities of all the complexes were studied by agarose gel electrophoresis method. In addition, the free ligand along with its complexes has been studied for their antioxidant activity.

Bergapten induces ER depletion in breast cancer cells through SMAD4-mediated ubiquitination

ERα function is crucial for the development of normal mammary gland as well as in the process of progression of breast cancer cells. Signals that target receptor levels contribute to regulate estrogens effects in the cells. An intricate cross-regulation has been documented between ERα and TGF-β down-stream molecules: SMAD2, SMAD3, and SMAD4, that can bind ERα and regulate their signaling. Thus, identification of natural anticancer drugs able to influence the latter molecule might provide alternative choices for breast cancer treatment. Taking into account our previous published data we wanted to study the effect of 5-Methoxypsoralen (bergapten) on ERα and on TGF-β pathway. We reported that bergapten, a coumarin containing compound, effectively depletes ERα in MCF-7 breast cancer sensitive cells and in tamoxifen-resistant clone. The decrease of ERα protein after bergapten treatment results from the ubiquitine-proteasome pathway as demonstrated by the use of MG-132. IP experiments with ER antibody, demonstrated that the protein has physical interaction with SMAD4 and poly-ubiquitine and the amount of ubiquitinated receptor, linked to SMAD4, is greater under bergapten. The crucial role played by SMAD4, in this process, emerges from the observation that in breast cancer cells, silencing of SMAD4, resulted in increased expression of endogenous ERα in both control and bergapten-treated cells, compared to wild- type cells. The same results were confirmed in siRNA TGF-β RII cells. The results suggest a novel negative regulation of ERα by TGF-β/SMAD4 in breast cancer cells and indicate that the SMAD4 protein is involved in the degradation of ERα induced by bergapten. We propose that bergapten may efficiently act as a natural antitumoral agent, able to deplete ERα from breast cancer tamoxifen-sensitive and resistant cells, thereby retraining the effect of membrane signals targeting ERα and in such way its mitogenic potentiality.

Coumarin-trioxane hybrids: synthesis and evaluation as a new class of antimalarial scaffolds

First synthesis of novel coumarin-trioxane hybrids is reported. The synthesis was achieved via condensation of β-hydroxyhydroperoxides with coumarinic-aldehydes in presence of p-toluenesulfonic acid in good yields and the novel hybrids were evaluated for their antimalarial activity both in vitro and in vivo.

In vitro and in vivo antifilarial activity evaluation of 3,6-epoxy [1,5]dioxocines: a new class of antifilarial agents

A series of 3,6-epoxy [1,5]dioxocines were synthesized and evaluated for their antifilarial activity against adult parasites of human lymphatic filarial parasite Brugia malayi (sub-periodic strain) in vitro. Out of these, six compounds (4a-f) possessed improved in vitro anti-filarial activity and examples 4d and 4f were also found to be active in the in vivo experiments. These results demonstrate that 3,6-epoxy [1,5]dioxocines exhibits potent antifilarial activity and might be developed into a new class of antifilarial drug.

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.