Design and synthesis of new 2,4,5-triarylimidazole derivatives as selective cyclooxygenase (COX-2) inhibitors

Natural-Derived COX-2 Inhibitors as Anticancer Drugs: A Review of their Structural Diversity and Mechanism of Action

Cyclooxygenase-2 (COX-2) is a key-type enzyme playing a crucial role in cancer development, making it a target of high interest for drug designers. In the last two decades, numerous selective COX-2 inhibitors have been approved for various clinical conditions. However, data from clinical trials propose that the prolonged use of COX-2 inhibitors is associated with life-threatening cardiovascular side effects. The data indicate that a slight structural modification can help develop COX-2 selective inhibitors with comparative efficacy and limited side effects. In this regard, secondary metabolites from natural sources offer great hope for developing novel COX-2 inhibitors with potential anticancer activity. In recent years, various nature-derived organic scaffolds are being explored as leads for developing new COX-2 inhibitors. The current review attempts to highlight the COX-2 inhibition activity of some naturally occurring secondary metabolites, concerning their capacity to inhibit COX-1 and COX-2 enzymes and inhibit cancer development, aiming to establish a structure-activity relationship.

Learning from Nature: From a Marine Natural Product to Synthetic Cyclooxygenase-1 Inhibitors by Automated De Novo Design

The repertoire of natural products offers tremendous opportunities for chemical biology and drug discovery. Natural product-inspired synthetic molecules represent an ecologically and economically sustainable alternative to the direct utilization of natural products. De novo design with machine intelligence bridges the gap between the worlds of bioactive natural products and synthetic molecules. On employing the compound Marinopyrrole A from marine Streptomyces as a design template, the algorithm constructs innovative small molecules that can be synthesized in three steps, following the computationally suggested synthesis route. Computational activity prediction reveals cyclooxygenase (COX) as a putative target of both Marinopyrrole A and the de novo designs. The molecular designs are experimentally confirmed as selective COX-1 inhibitors with nanomolar potency. X-ray structure analysis reveals the binding of the most selective compound to COX-1. This molecular design approach provides a blueprint for natural product-inspired hit and lead identification for drug discovery with machine intelligence.

Prophylactic effect of Biochanin A in lipopolysaccharide-stimulated BV2 microglial cells

Aim/Purpose of the study:Inhibition of microglial activation using phytochemicals may be a potential candidate for the prevention of neurodegenerative diseases caused by neuroinflammation and oxidative stress. The goal of this study was to investigate the protective role of Biochanin A on lipopolysaccharide (LPS)-stimulated BV2 microglial cells. BV2 microglial cells were treated with LPS in the presence and absence of Biochanin A. Materials and methods: For this aim, nitric oxide production, nuclear factor kappa B (NF-κB), tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, Prostaglandin E2 (PGE2), and reactive oxygen species (ROS) levels, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), myeloid differentiation factor-88 (MyD88), and toll like receptor-4 (TLR-4) protein expressions, Akt and ERK1/2 phosphorylation levels were measured. Results:Biochanin A pretreatment resulted in significant and concentration-dependently reduced the LPS-induced production of nitric oxide, NF-κB p65, TNF-α, IL-1β, IL-6, PGE2, and ROS compared to the untreated group. Biochanin A prophylaxis exerted an anti-inflammatory effect by suppressing iNOS, COX-2, MyD88, and TLR-4 protein expressions and Akt and ERK1/2 pathway activation. Conclusion:Taken together, these results show that Biochanin A exerts antioxidant and anti-inflammatory activities, thus may be beneficial for preventing neurodegenerative diseases mediated by microglial cells.

Design, synthesis, and biological evaluation of new 1,4-diarylazetidin-2-one derivatives (β-lactams) as selective cyclooxygenase-2 inhibitors

A new series of 1,4-diarylazetidin-2-one derivatives (β-lactams) were designed and synthesized to evaluate their biological activities as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1 and COX-2 inhibition studies showed that all compounds were selective inhibitors of the COX-2 isozyme with IC₅₀ values in the 0.05-0.11 µM range, and COX-2 selectivity indexes in the range of 170-703.7. Among the synthesized β-lactams, 3-methoxy-4-(4-(methylsulfonyl)phenyl)-1-(3,4,5-trimethoxyphenyl)azetidin-2-one (4j) possessing trimethoxy groups at the N-1 phenyl ring exhibited the highest COX-2 inhibitory selectivity and potency, even more potent than the reference drug celecoxib. The analgesic activity of the synthesized compounds was also determined using the formalin test. Compound 4f displayed the best analgesic activity among the synthesized molecules. Molecular modeling studies indicated that the methylsulfonyl pharmacophore group can be inserted into the secondary pocket of the COX-2 active site for interactions with Arg⁵¹³ . The structure-activity data acquired indicate that the β-lactam ring moiety constitutes a suitable scaffold to design new 1,4-diarylazetidin-2-ones with selective COX-2 inhibitory activity.

Molecular Modeling Studies of Halogenated Imidazoles against 14α- Demethylase from Candida Albicans for Treating Fungal Infections

BACKGROUND

Imidazole is one of the most explored and marketed azole utilized for the treatment of fungal infections. Lanosterol 14α-demethylase (Cytochrome P450DM) is the active target site for azole antifungals.

AIM AND OBJECTIVE

This study emphasized on evaluation of a series of halogenated imidazole analogues using molecular docking studies for anti-Candidal activity. Furthermore, the model was refined by molecular dynamic simulation.

METHODS

Halogenated imidazole analogues (PS1-PS30) were obtained from literature for the study. The imidazole analogues were prepared using Chem sketch and molecular docking was performed using Molergo Virtual Docker program and ADMET study was carried out by using Accelry's Accord for Excel programme.

RESULTS

The docking study indicated that all the imidazole analogues (PS1-PS30) and standard drugs i.e., Ketoconazole, Miconazole and Clotrimazole possessed interaction with protein residue, heme cofactor and water molecule positioned above Heme cofactor of 14α-demethylase. Further, the ADMET study indicated that most of the halogenated imidazoles possessed good absorption, human intestinal absorption, aqueous solubility and blood brain penetration.

CONCLUSION

Halogenated imidazole analogues may be used as potential lead molecules as 14α- demethylase inhibitors.

Inhibition of proinflammatory mediators by coumaroyl lupendioic acid, a new lupane-type triterpene from Careya arborea, on inflammation-induced animal model

ETHNOPHARMACOLOGICAL RELEVANCE

Careya arborea Roxb. (Lecythidaceae) is a large tree found throughout India in deciduous forests and grasslands. C. arborea is traditionally used in tumors, inflammation, anthelmintic, bronchitis, epileptic fits, astringents, antidote to snake-venom, skin disease, diarrhea, dysentery with bloody stools, dyspepsia, ulcer, tooth ache, and ear pain.

AIM OF THE STUDY

In our previous work, the methanolic extract of Careya arborea stem bark showed significant anti-inflammatory activity. As a continuity of that work, this study aimed at the isolation and evaluation of the anti-inflammatory effect of coumaroyl lupendioic acid, a new lupane-type triterpene from Careya arborea stem bark. Further, to give an insight into the underlying mechanism of action of the compound on the modulation of proinflammatory mediators.

MATERIALS AND METHODS

Methanolic extract of Careya arborea stem bark was suspended in water, and sequentially fractionated with n-hexane and ethyl acetate. Further ethyl acetate fraction was subjected to medium pressure liquid chromatography (MPLC) to isolate the active molecules. The isolated compounds were characterized by the various spectral techniques namely UV, IR, ¹H NMR, ¹³C NMR, DEPT, ¹H-¹H COSY, HMBC and Mass spectral techniques. In vitro COX-1 and COX-2 enzyme inhibition assays using human whole blood was performed to investigate the inhibitory effect of the isolated compounds. The resulted potent COX-2 inhibitor of the isolated constituents compound 5, designated as coumaroyl lupendioic acid (CLA), was investigated in carrageenan induced inflammation and its effect was also compared with betulinic acid (BA) at the doses of 10 and 20mgkg^-1, p.o. using indomethacin and celecoxib (10 and 20mgkg^-1, p.o., respectively) as reference drugs. The effect of CLA on the production of NO, MPO, PGE2, TNF-α, IL-1β and IL-6 were assessed. In addition, the histopathology and immunohistochemistry (NF-ҡB, COX-2 and TNF-α protein expression) in paw tissues were also carried out.

RESULTS

The chromatographic fractionation of the methanolic extract resulted in isolation of six new derivatives of lupane type triterpenes for the first time from the stem bark of C. arborea; 3β-hydroxy-lup-5,20 (29),21-trien-28-oic acid (Compound 1), 1, 3, 13, 16-tetrahydroxy-lup-9(11), 20(29)-diene-28-oic acid (Compound 2), 1, 7-di hydroxy betulinic acid (Compound 3), 3β-O-dihydrocinnamyl betulinic acid (Compound 4), 3β-O-trans-coumaryl-lup-6, 9(11), 20(29)-triene-27, 28-dioic acid (Compound 5), 16β-hydroxy-2, 3-seco-lup-5, 20(29)-dien-2, 3, 28-trioic acid (Compound 6). Among the all isolated compounds 3β-O-trans-coumaryl-lup-6, 9(11), 20(29)-triene-27, 28-olioic acid designated as coumaroyl lupendioic acid (CLA) showed higher COX-2 selectivity which is comparable to reference drug (celecoxib). CLA significantly reduced carrageenan induced inflammation whereas CLA revealed greater effect as compared to BA at the similar corresponding doses. Moreover, CLA significantly inhibited pro-inflammatory mediators elevated by carrageenan. CLA also preserved the tissue architecture as evidenced by the histopathology. Furthermore, immunohistochemical studies revealed that CLA significantly down regulated NF-ҡB, COX-2 and TNF-α protein expression.

CONCLUSION

The study gives an insight into the molecular mechanisms of coumaroyl lupendioic acid and suggests that the down-regulations of proinflammatory mediators provide credence to the ethno botanical use of the plant in the management of inflammation.

Apoptotic effects of two COX-2 inhibitors on breast adenocarcinoma cells through COX-2 independent pathway

Recently, much effort has been directed toward the search for compounds that influence apoptosis and to understand their mechanisms of action. Cyclooxygenase (COX)-2 inhibitors may induce apoptosis through the COX-2-independent mechanism via a mitochondrial pathway. In view of the reported antiproliferative activities of two COX-2 inhibitor derivatives (1, 2) in breast cancer cells (MCF-7), the present study was undertaken to evaluate the potential of these compounds to induce apoptosis and unravel the associated mechanisms. The apoptotic activities of the two compounds were assessed using flow cytometry, fluorescence microscope, and Western blot analysis. Compounds 1 and 2-treated MCF-7 cells revealed the apoptotic cell death, as confirmed by the changes in nuclear morphology and the increased annexin-V/PI staining. Elevation of Bax to Bcl-2 ratio and activation of caspase-3 were found to be associated with the initiation of apoptosis induced by compound 1. Further investigation showed that compounds 1 and 2 inhibited NF-κB, FHC, and ERK activation, while no dramatic change was revealed in c-Myc and EGR-1 levels. Our data suggest that induction of apoptosis by compounds 1 and 2 is not associated with COX-2 expression and occurs through the NF-κB pathway, which sequentially inhibits P-ERK and FHC expression.

The discovery and development of cyclooxygenase-2 inhibitors as potential anticancer therapies

INTRODUCTION

In the past, clinical studies had demonstrated that aspirin and NSAIDs reduce the risk of colorectal cancer. After the discovery of selective prostaglandin-endoperoxide synthase 2 (PTGS2) inhibitors, the further beneficial effects of celecoxib and some other related structures (coxibs) have been demonstrated in both in vivo and in vitro studies.

AREAS COVERED

The authors illustrate the role of prostaglandins following the overexpression of PTGS2 (COX-2) in signaling pathways. The authors elucidate the role of coxibs in cell proliferation, apoptosis, angiogenesis and multi-drug resistance and discuss the molecular mechanisms involved. The authors also present the strong evidence related to the usefulness of coxibs in several cancer cell lines.

EXPERT OPINION

There have been a number of PTGS2 (COX-2) selective inhibitors suggested as potential anticancer therapies. In recent years, the development of nanotechnology has also had an impact on chemotherapy. Indeed, nanoparticles of cytotoxic drug carriers have demonstrated potential through their accumulation in cancer cells, and targeting these nanoparticles has been under evaluation. This area could be opened up for coxib development as they are potentially important targets in cancer cells. Further research using celecoxib as a co-drug with PTGS2-overexpressed and PTGS2-independent cancer is still needed.