Synthesis of new secretory phospholipase A2-inhibitory indole containing isoxazole derivatives as anti-inflammatory and anticancer agents

A review of synthetic strategy, SAR, docking, simulation studies, and mechanism of action of isoxazole derivatives as anticancer agents

Breast cancer (BC) is a global health concern and the leading cause of cancerous death among women across the world, BC has been characterized by fresh lump in the breast or underarm (armpit), thickened or swollen. Worldwide estimated 9.6 million deaths in 2018-2019. Numerous drugs have been approved by FDA for BC treatment but showed numerous adverse effects like bioavailability issues, selectivity issues, and toxicity issues. Therefore, there is an immediate need to develop new molecules that are non-toxic and more efficient for treating cancer. Isoxazole derivatives have gained popularity over the few years due to their effective antitumor potential. These derivatives work against cancer by inhibiting the thymidylate enzyme, inducing apoptosis, inhibiting tubulin polymerization, protein kinase inhibition, and aromatase inhibition. In this study, we have concentrated on the isoxazole derivative with structure-activity relationship study, various synthesis techniques, mechanism of action, docking, and simulation studies pertaining to BC receptors. Hence the development of isoxazole derivatives with improved therapeutic efficacy will inspire further progress in improving human health.Communicated by Ramaswamy H. Sarma.

One-Pot Three-Component Synthesis of Indolyl-4H-chromene-3-sulfonyl Fluoride: A Class of Important Pharmacophore

A one-pot, sequential three-component reaction between salicylaldehyde, indole, and 2-bromoprop-2-ene-1-sulfonyl fluoride (BPESF) has been demonstrated for the synthesis of sulfonyl fluoride substituted 4H-chromene derivatives in moderate to excellent yields (45%-94%). This one-pot sequential method features easily available starting materials, wide substrate scope, mild conditions, and great efficiency.

Effects of curcumin and ursolic acid in prostate cancer: A systematic review

The major barriers to phytonutrients in prostate cancer therapy are non-specific mechanisms and bioavailability issues. Studies have pointed to a synergistic combination of curcumin (CURC) and ursolic acid (UA). We investigate this combination using a systematic review process to assess the most likely mechanistic pathway and human testing in prostate cancer. We used the PRISMA statement to screen titles, abstracts, and the full texts of relevant articles and performed a descriptive analysis of the literature reviewed for study inclusion and consensus of the manuscript. The most common molecular and cellular pathway from articles reporting on the pathways and effects of CURC (n = 173) in prostate cancer was NF-κB (n = 25, 14.5%). The most common molecular and cellular pathway from articles reporting on the pathways and effects of UA (n = 24) in prostate cancer was caspase 3/caspase 9 (n = 10, 41.6%). The three most common molecular and cellular pathway from articles reporting on the pathways and effects of both CURC and UA (n = 193) in prostate cancer was NF-κB (n = 28, 14.2%), Akt (n = 22, 11.2%), and androgen (n = 19, 9.6%). Therefore, we have identified the potential synergistic target pathways of curcumin and ursolic acid to involve NF-κB, Akt, androgen receptors, and apoptosis pathways. Our review highlights the limited human studies and specific effects in prostate cancer.

Synthesis, crystal structure and molecular docking study of novel isoxazole derivatives as CYP450 inhibitors in search of anticancer agents

Synthesis of some novel isoxazole derivatives and their molecular docking with enzymes from CYP450 family carried out using erlotinib, gemcitabine and ketoconazole as reference drugs are reported in this work. Eight isoxazole derivatives of 3,4-substituted phenyl 3-chloroacrylaldehyde and one isoxazole derivative of cinnamaldehyde were synthesized. A molecular docking study of all nine compounds shows good docking score compared to standard drugs erlotinib, gemcitabine and ketoconazole. 4-OH and 4-F derivatives were found to have strong affinity for all six CYP450 proteins under study in the present work. 4-F and 3-NO2 derivatives could be a suitable lead compound inhibitor to CYP1A2 followed by 4-OH derivatives. 4-OH derivative with significant binding affinity showed encouraging inhibition of CYP1A2, CYP2C9, CYP2C8, CYP2C19 and CYP2D6. The current predictions over these nine isoxazole derivatives of 3,4-substituted phenyl 3-chloroacrylaldehyde will be needed to be further investigated in vivo and in vitro conditions to identify the optimum therapeutic efficacy. Synthesis of the isoxazole derivatives is the first known report of the Knoevenagal condensation of acrylaldehyde derivatives to form isoxazole derivatives as per the literature survey. A detailed crystal structure study of five analogues gives insight into the solid-state structural features of this new framework with isoxazole moieties.Communicated by Ramaswamy H. Sarma.

Helichrysum italicum: From Extraction, Distillation, and Encapsulation Techniques to Beneficial Health Effects

Helichrysum italicum (family Asteraceae), due to its various beneficial health effects, represents an important plant in the traditional medicine of Mediterranean countries. Currently, there is a renewed interest in this medicinal plant, especially in investigations involving the isolation and identification of its bioactive compounds from extracts and essential oils, as well as in experimental validation of their pharmacological activities. In this paper, we review the current knowledge on the beneficial health effects of Helichrysum italicum extracts, essential oils, and their major bioactive polyphenolic compounds, ranging from antioxidative, anti-inflammatory, and anticarcinogenic activities to their antiviral, antimicrobial, insecticidal, and antiparasitic effects. This review also provides an overview of the most promising extraction and distillation techniques for obtaining high-quality extracts and essential oils from Helichrysum italicum, as well as methods for determining their antioxidative, antimicrobial, anti-inflammatory, and anticarcinogenic activities. Finally, new ideas for in silico studies of molecular mechanisms of bioactive polyphenols from Helichrysum italicum, together with novel suggestions for their improved bioavailability through diverse encapsulation techniques, are introduced.

Pyridine and isoxazole substituted 3-formylindole-based chitosan Schiff base polymer: Antimicrobial, antioxidant and in vitro cytotoxicity studies on THP-1 cells

This paper presents the synthesis of two new chitosan Schiff base (CSB) polymers, namely, 2PCT and 4MCT based on pyridin-2-ylmethyl-1H-indole-3-carbaldehyde and 1-(4-methyl-3,5-dimethylisoxazole)-1H-indole-3-carbaldehyde with chitosan (CT). The structural features of CSB polymers were confirmed by Fourier-transform infrared (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopy and their antimicrobial activity was evaluated against Staphylococcus aureus, Escherichia coli and Candida albicans. The antioxidant studies found that both 2PCT and 4MCT presented significant free radical scavenging activity with IC₅₀ at 169.01 and 372.84 μg/mL, respectively. The cell viability results obtained from in vitro cytotoxicity studies performed using human monocyte leukemia (THP-1) cells were found to be 75.6 ± 0.25 % and 79.1 ± 1.5 % for 2PCT and 4MCT, respectively, at a concentration of 10 mg/mL. Flow cytometry analysis demonstrated the reducing ability of CSB polymers on intracellular reactive oxygen species (ROS) in THP-1 cells. The overall results of antioxidant activity, in vitro biocompatibility and ability to reduce the intracellular ROS production emphasized that the CSB polymers prepared could serve as a potential biomaterial in biomedical applications, such as wound treatment process.

Synthesis and Cytotoxic Activity of 1,2,4-Triazolo-Linked Bis-Indolyl Conjugates as Dual Inhibitors of Tankyrase and PI3K

A series of new 1,2,4-triazolo-linked bis-indolyl conjugates (15a–r) were prepared by multistep synthesis and evaluated for their cytotoxic activity against various human cancer cell lines. It was observed that they were more susceptible to colon and breast cancer cells. Conjugates 15o (IC₅₀ = 2.04 μM) and 15r (IC₅₀ = 0.85 μM) illustrated promising cytotoxicity compared to 5-fluorouracil (5-FU, IC₅₀ = 5.31 μM) against the HT-29 cell line. Interestingly, 15o and 15r induced cell cycle arrest at the G₀/G₁ phase and disrupted the mitochondrial membrane potential. Moreover, these conjugates led to apoptosis in HT-29 at 2 μM and 1 μM, respectively, and also enhanced the total ROS production as well as the mitochondrial-generated ROS. Immunofluorescence and Western blot assays revealed that these conjugates reduced the expression levels of the PI3K-P85, β-catenin, TAB-182, β-actin, AXIN-2, and NF-κB markers that are involved in the β-catenin pathway of colorectal cancer. The results of the in silico docking studies of 15r and 15o further support their dual inhibitory behaviour against PI3K and tankyrase. Interestingly, the conjugates have adequate ADME-toxicity parameters based on the calculated results of the molecular dynamic simulations, as we found that these inhibitors (15r) influenced the conformational flexibility of the 4OA7 and 3L54 proteins.

New Oxazolo[5,4-d]pyrimidines as Potential Anticancer Agents: Their Design, Synthesis, and In Vitro Biological Activity Research

Cancer is a large group of diseases in which the rapid proliferation of abnormal cells generally leads to metastasis to surrounding tissues or more distant ones through the lymphatic and blood vessels, making it the second leading cause of death worldwide. The main challenge in designing a modern anticancer therapy is to develop selective compounds that exploit specific molecular targets. In this work, novel oxazolo[5,4-d]pyrimidine derivatives were designed, synthesized, and evaluated in vitro for their cytotoxic activity against a panel of four human cancer cell lines (lung carcinoma: A549, breast adenocarcinoma: MCF7, metastatic colon adenocarcinoma: LoVo, primary colon adenocarcinoma: HT29), along with their P-glycoprotein-inhibitory ability and pro-apoptotic activity. These oxazolo[5,4-d]pyrimidine derivatives, which are structurally similar to nucleic purine bases in general, are characterized by the presence of a pharmacologically favorable isoxazole substituent at position 2 and aliphatic amino chains at position 7 of the condensed heterocyclic system. In silico analysis of the obtained compounds identified their potent inhibitory activity towards human vascular endothelial growth factor receptor-2 (VEGFR-2). Molecular docking was performed to assess the binding mode of new derivatives to the VEGFR-2 active site. Then, their physicochemical, pharmacokinetic, and pharmacological properties (i.e., ADME-administration, distribution, metabolism, and excretion) were also predicted to assess their druglikeness. In particular, compound 3g (with a 3-(N,N-dimethylamino)propyl substituent) was found to be the most potent against the HT29 cell line, with a 50% cytotoxic concentration (CC₅₀) of 58.4 µM, exceeding the activity of fluorouracil (CC₅₀ = 381.2 μM) and equaling the activity of cisplatin (CC₅₀ = 47.2 µM), while being less toxic to healthy human cells (such as normal human dermal fibroblasts (NHDFs)) than these reference drugs. The results suggest that compound 3g is a potentially promising candidate for the treatment of primary colorectal cancer.

Synthesis of novel isoxazole-carboxamide derivatives as promising agents for melanoma and targeted nano-emulgel conjugate for improved cellular permeability

BACKGROUND

Cancer is one of the most dangerous and widespread diseases in the world today and it has risen to the position of the leading cause of death around the globe in the last few decades. Due to the inherent resistance of many types of cancer to conventional radiotherapy and chemotherapy, it is vital to develop innovative anticancer medications. Recently, a strategy based on nanotechnology has been used to improve the effectiveness of both old and new cancer drugs.

OBJECTIVES

The present study aimed to design and synthesize a series of phenyl-isoxazole-Carboxamide derivatives, evaluate their anticancer properties, and improve the permeability of potent compounds into cancer cells by using a nano-emulgel strategy.

METHODS

The coupling reaction of aniline derivatives and isoxazole-Carboxylic acid was used to synthesize a series of isoxazole-Carboxamide derivatives. IR, HRMS, 1H-NMR, and 13C-NMR spectroscopy techniques, characterized all the synthesized compounds. The in-vitro cytotoxic evaluation was performed by using the MTS assay against seven cancer cell lines, including hepatocellular carcinoma (Hep3B and HepG2), cervical adenocarcinoma (HeLa), breast carcinoma (MCF-7), melanoma (B16F1), colorectal adenocarcinoma (Caco-2), and colon adenocarcinoma (Colo205), as well as human hepatic stellate (LX-2) in addition to the normal cell line (Hek293T). A nano-emulgel was developed for the most potent compound, using a self-emulsifying technique.

RESULTS

All synthesized compounds were found to have potent to moderate activities against B16F1, Colo205, and HepG2 cancer cell lines. The results revealed that the 2a compound has broad spectrum activity against B16F1, Colo205, HepG2, and HeLa cancer cell lines with an IC₅₀ range of 7.55-40.85 µM. Moreover, compound 2e was the most active compound against B16F1 with an IC₅₀ of 0.079 µM compared with Dox (IC₅₀ = 0.056 µM). Nanoemulgel was used to increase the potency of the 2e molecule against this cancer cell line, and the IC₅₀ was reduced to 0.039 µM. The antifibrotic activities were investigated against the LX-2 cell line, and it was found that our synthesized molecules showed better antifibrotic activities at 1 µM than 5-FU, and the cell viability values were 67 and 95%, respectively.

CONCLUSION

This study suggests that a 2e nano-formalized compound is a potential and promising anti-melanoma agent.

Design, Synthesis, Herbicidal Activity, and Molecular Docking Study of 2-Thioether-5-(Thienyl/Pyridyl)-1,3,4-Oxadiazoles as Potent Transketolase Inhibitors

Transketolase (TK) has been regarded as a new target for the development of novel herbicides. In this study, a series of 2-thioether-5-(thienyl/pyridyl)-1,3,4-oxadiazoles were designed and synthesized based on TK as the new target. The preliminary bioassay results indicated that compounds 4l and 4m displayed the best herbicidal activities against Amaranthus retroflexus (AR) and Digitaria sanguinalis (DS), with the inhibition exceeding 90% at 100-200 mg/L in vitro. Moreover, they also displayed higher postemergence herbicidal activities (90% control) against AR and DS than all of the positive controls at 45-90 g [active ingredient (ai)]/ha in a greenhouse. Notably, compounds 4l and 4m showed a broad spectrum of weed control at 90 g ai/ha. More significantly, compound 4l exhibited good crop selectivity against maize at 90 g ai/ha. Both fluorescent binding experiments and molecular docking analyses indicated that compounds 4l and 4m exhibited strong TK inhibitory activities with superior binding affinities than the others. Preliminary mechanism studies suggested that they might exert their TK inhibitory effects by occupying the active cavity of At TK and forming more strong interactions with amino acids in the active site. Taken together, these results suggested that compound 4l was a potential herbicide candidate for weed control in maize fields targeting TK.

The indole nucleus as a selective COX-2 inhibitor and anti-inflammatory agent (2011–2022)

Anti-inflammatory bioactivity of diversely substituted indole derivatives, mainly N-1 and C-3 substituted indoles.

Novel 3-chloro-6-nitro-1H-indazole derivatives as promising antileishmanial candidates: synthesis, biological activity, and molecular modelling studies

An efficient pathway was disclosed for the synthesis of 3-chloro-6-nitro-1H-indazole derivatives by 1,3-dipolar cycloaddition on dipolarophile compounds 2 and 3. Faced the problem of separation of two regioisomers, a click chemistry method has allowed us to obtain regioisomers of triazole-1,4 with good yields from 82 to 90% were employed. Also, the antileishmanial biological potency of the compounds was achieved using an MTT assay that reported compound 13 as a promising growth inhibitor of Leishmania major. Molecular docking demonstrated highly stable binding with the Leishmania trypanothione reductase enzyme and produced a network of hydrophobic and hydrophilic interactions. Molecular dynamics simulations were performed for TryR-13 complex to understand its structural and intermolecular affinity stability in a biological environment. The studied complex remained in good equilibrium with a structure deviation of ∼1-3 Å. MM/GBSA binding free energies illustrated the high stability of TryR-13 complex. The studied compounds are promising leads for structural optimisation to enhance the antileishmanial activity.

In vitro Evaluation of Isatin derivatives as Potent Anti-Breast Cancer Agents against MCF-7, MDA MB 231, MDA-MB 435 and MDA-MB 468 Breast Cancers cell lines: A Review

INTRODUCTION

Breast cancer (BC) is one of the most frequent malignancy and most common reasons of impermanence in women. The backbone of therapy for BC is principally chemotherapy, but due to its non-specific nature between normal cells and cancer cells and severe side effects are the main barriers in its therapy. So, there is an intense requirement for the enlargement of more efficacious, more specific and safer anti-BC agents.

OBJECTIVE

Isatin (IST) is an endogenous molecule which is a principal class of heterocyclic compounds and exhibits a wide range of therapeutic activities which can be used as a starting material for the synthesis of several drug molecules. Many literatures were reported previously on different pharmacological activities of IST derivatives and particularly on anticancer activity but this review mainly focus on anti-BC activities of IST derivatives through MCF-7, MDA MB 231, MDA-MB 435 and MDA-MB 468 cell lines. Here in we mentioned, a total 33 IST derivatives (compound 24- 56) which shown good anti-BC activity. IST derived compounds are also available in market and are used for various cancer types like sunitinib for renal cell carcinoma (RCC) and Nintedanib used for the cryptogenic fibrosing alveolitis treatment but when evaluated for BC did not get much success.

CONCLUSION

This review mainly highlights anti-BC activities of various IST analogues using MCF-7, MDA MB 231, MDA-MB 435 and MDA-MB 468 cell lines, display the potent compound of the series and structure-activity relationships of compounds with molecular docking also. So, this study mainly shows the importance of IST as major sources for drug design and development of newer anti-BC drugs.

Synthesis, Bioactivity, and QSAR Study of 3,4-Dichlorophenyl Isoxazole-Substituted Stilbene Derivatives against the Phytopathogenic Fungus Botrytis cinerea

Gray mold, caused by Botrytis cinerea, is one of the most destructive fungal diseases in crops, responsible for significant economic losses. In search of natural product-based fungicides, we designed and synthesized a series of novel 3,4-dichlorophenyl isoxazole-substituted stilbene derivatives, and their in vivo antifungal activities against B. cinerea were evaluated. The results indicated that some of the target molecules demonstrated remarkable efficiency for the control of tomato gray mold. In particular, compound 5r displayed the highest fungicidal potency with an inhibition rate of 56.11% comparable to that of positive control boscalid (66.96%). Moreover, a hologram quantitative structure-activity relationship (HQSAR) model with good predictive capability was developed to provide in-depth insight into the activity profiles of these compounds. Preliminary mechanism studies suggested that compound 5r might exert its antifungal effect by changing hyphal morphology and increasing the membrane permeability. The present study contributes to the development of natural stilbene derivatives as alternative bioactive agents against B. cinerea.

Design, synthesis, and biological evaluation of N-(4-substituted)-3-phenylisoxazolo[5,4-d]pyrimidin-4-amine derivatives as apoptosis-inducing cytotoxic agents

A library of new 3-phenylisoxazolo[5,4-d]pyrimidines (8-10) was designed based on a scaffold hybridization technique incorporating the important pharmacophoric features of 4-aminopyrimidine and phenyl isoxazole scaffold which is renowned for its BET inhibition activity. The designed molecules were synthesized and evaluated with the NCI-60 cell line panel. Examination by NCI-60 cell lines at single-dose and the five-dose study showed that compound 10h exhibited promising growth inhibitory effects with GI₅₀ values on various cancer cell lines such as HCT-15 (Colon Cancer)-0.0221 μM, MDA-MB-435 (Melanoma) - 0.0318 μM, SNB-75(CNS Cancer)-0.0263 μM, and MCF7 (Breast Cancer)-0.0372 μM. Further studies to know the mechanism of action of 10h based on the phase-contrast microscopic evaluation, DAPI, acridine orange/ethidium bromide (AO/EB) staining, and annexin V-FITC assays revealed that elevation in the intracellular ROS leads to alteration in mitochondrial membrane potential which in turn induced the apoptosis in BT-474 cancer cells, which could be the plausible mechanism of action for compound 10h.

Isoxazole derivatives as anticancer agent: A review on synthetic strategies, mechanism of action and SAR studies

Breast cancer is the second most leading cause of death among women. Multiple drugs have been approved by FDA for the treatment of BC. The major drawbacks of existing drugs are the development of resistance, toxicity, selectivity problem. The other therapies like hormonal therapy, surgery, radiotherapy, and immune therapy are in use but showed many side effects like bioavailability issues, non-selectivity, pharmacokinetic-pharmacodynamic problems. Therefore, there is an urgent need to develop new moieties that are nonviolent and more effective in the treatment of cancer. Isoxazole derivatives have gain popularity in recent years due to anticancer potential with the least side effects. These derivatives act as an anticancer agent with different mechanisms like inducing apoptosis, aromatase inhibition, disturbing tubulin congregation, topoisomerase inhibition, HDAC inhibition, and ERα inhibition. In this article, we have explored the synthetic strategies, anticancer mechanism of action along with SAR studies of isoxazole derivatives.

Synthesis and Biological Evaluation of Novel Isoxazole-Amide Analogues as Anticancer and Antioxidant Agents

Cancer now is one of the leading causes of mortality in the world. There has been a lot of effort to discover new anticarcinogenic agents that allow treatment with fewer side effects. A series of isoxazole-carboxamide derivatives (2a–2g) were synthesised and evaluated for their cytotoxic activity against breast (MCF-7), cervical (HeLa), and liver (Hep3B) cancer cell lines and their antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The results showed that 2d and 2e were the most active compounds against Hep3B cells, with a half-maximal inhibitory concentration (IC₅₀) of around 23 μg/ml; 2d showed the highest activity against HeLa cells, with an IC₅₀ 15.48 μg/ml. However, 2a had the lowest IC₅₀ (39.80 μg/ml) against MCF-7 cells. By contrast, compound 2g was inactive against all cancer cell lines, with IC₅₀ values >400 μg/ml. Both 2d and 2e reduced Hep3B secretion of alpha-fetoprotein (to 1829.33 ± 65.91 ng/ml and 1758.66 ± 54.04 ng/ml, respectively). Furthermore, in cell cycle analysis, 2d and 2e induced a delay in the G2/M phase of 18.07%, which is similar to the doxorubicin positive control. Moreover, 2d and 2e reduced the necrosis rate of Hep3B threefold and instead shifted the cells to apoptosis. Our results indicate that 2d and 2e have potent and promising anticancer activity. However, compound 2a was the most active as antioxidant agent (IC₅₀ = 7.8 ± 1.21 μg/ml) compared with Trolox as a positive control (IC₅₀ 2.75 μg/ml).

Molecular iodine mediated oxidative cleavage of the C–N bond of aryl and heteroaryl (dimethylamino)methyl groups into aldehydes

An efficient iodine mediated conversion of aryl or heteroaryl (dimethylamino)methyl compunds to aryl or heteroaryl aldehydes is achieved via cleavage of C-N bond.

Expression of Secretory Phospholipase A2 Group IIa in Breast Cancer and Correlation to Prognosis in a Cohort of Advanced Breast Cancer Patients

Secreted phospholipase A2 group IIa (sPLA2-IIa) has been shown to promote tumor genesis and cell proliferation. The properties of this group of enzymes are utilized in liposomal drug delivery of chemotherapy. sPLA2-IIa is also under investigation as a possible treatment target in itself, and as a prognostic marker. The expression of sPLA2-IIa in breast cancer has not been examined extensively, and never using immunohistochemistry. We sought to investigate the expression of sPLA2-IIa in a cohort of advanced breast cancer patients with correlation to known clinicopathologic risk factors and survival. Material from 525 breast cancer patients (426 primary tumors and 99 metastases or local recurrences) was examined for sPLA2-IIa expression using immunohistochemistry. Out of these, 262 showed expression of sPLA2-IIa. We found that there was no correlation to clinicopathologic characteristics, and no impact of sPLA2-IIa expression on prognosis. However, we found that a large proportion of patients in our study had high levels of sPLA2-IIa expression, and that sPLA2-IIa was equally expressed in primary tumors and metastases. These findings may be significant in the future development of liposomal drug delivery or targeted sPLA2-IIa treatment.

A brief review of the biological potential of indole derivatives

Background

Various bioactive aromatic compounds containing the indole nucleus showed clinical and biological applications. Indole scaffold has been found in many of the important synthetic drug molecules which gave a valuable idea for treatment and binds with high affinity to the multiple receptors helpful in developing new useful derivatives.

Main text

Indole derivatives possess various biological activities, i.e., antiviral, anti-inflammatory, anticancer, anti-HIV, antioxidant, antimicrobial, antitubercular, antidiabetic, antimalarial, anticholinesterase activities, etc. which created interest among researchers to synthesize a variety of indole derivatives.

Conclusion

From the literature, it is revealed that indole derivatives have diverse biological activities and also have an immeasurable potential to be explored for newer therapeutic possibilities.

2,4-Diketo esters: Crucial intermediates for drug discovery

Convenient structures such as 2,4-diketo esters have been widely used as an effective pattern in medicinal chemistry and pharmacology for drug discovery. 2,4-Diketonate is a common scaffold that can be found in many biologically active and naturally occurring compounds. Also, many 2,4-diketo ester derivatives have been prepared due to their suitable synthesis. These synthetic drugs and natural products have shown numerous interesting biological properties with clinical potential as a cure for the broad specter of diseases. This review aims to highlight the important evidence of 2,4-diketo esters as a privileged scaffold in medicinal chemistry and pharmacology. Herein, numerous aspects of 2,4-diketo esters will be summarized, including synthesis and isolation of their derivatives, development of novel synthetic methodologies, the evaluation of their biological properties as well as the mechanisms of action of the diketo ester derivates. This paperwork is expected to be a comprehensive, trustworthy, and critical review of the 2,4-diketo ester intermediate to the chemistry community.

Crystal structure of (R)-5-[(R)-3-(4-chloro-phen-yl)-5-methyl-4,5-di-hydro-isoxazol-5-yl]-2-methyl-cyclo-hex-2-enone

The title compound, C17H18ClNO2, was prepared and isolated as a pure diastereoisomer, using column chromatography followed by a succession of fractional crystallizations. Its exact structure was fully identified via 1H NMR and confirmed by X-ray diffraction. It is built up from a central five-membered di-hydro-isoxazole ring to which a p-chloro-phenyl group and a cyclo-hex-2-enone ring are attached in the 3 and 5 positions. The cyclo-hex-2-one and isoxazoline rings each exhibit an envelope conformation. The crystal packing features C-H⋯O, C-H⋯N and C-H⋯π inter-actions, which generate a three-dimensional network.

Synthesis, crystal structures, antiproliferative activities and reverse docking studies of eight novel Schiff bases derived from benzil

Eight novel Schiff bases derived from benzil dihydrazone (BDH) or benzil monohydrazone (BMH) and four fused-ring carbonyl compounds (3-formylindole, FI; 3-acetylindole, AI; 3-formyl-1-methylindole, MFI; 1-formylnaphthalene, FN) were synthesized and characterized by elemental analysis, ESI-QTOF-MS, ¹H and ¹³C NMR spectroscopy, as well as single-crystal X-ray diffraction. They are (1Z,2Z)-1,2-bis{(E)-[(1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethane (BDHFI), C₃₂H₂₄N₆, (1Z,2Z)-1,2-bis{(E)-[1-(1H-indol-3-yl)ethylidene]hydrazinylidene}-1,2-diphenylethane (BDHAI), C₃₄H₂₈N₆, (1Z,2Z)-1,2-bis{(E)-[(1-methyl-1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethane (BMHMFI) acetonitrile hemisolvate, C₃₄H₂₈N₆·0.5CH₃CN, (1Z,2Z)-1,2-bis{(E)-[(naphthalen-1-yl)methylidene]hydrazinylidene}-1,2-diphenylethane (BDHFN), C₃₆H₂₆N₄, (Z)-2-{(E)-[(1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethanone (BMHFI), C₂₃H₁₇N₃O, (Z)-2-{(E)-[1-(1H-indol-3-yl)ethylidene]hydrazinylidene}-1,2-diphenylethanone (BMHAI), C₂₄H₁₉N₃O, (Z)-2-{(E)-[(1-methyl-1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethanone (BMHMFI), C₂₄H₁₉N₃O, and (Z)-2-{(E)-[(naphthalen-1-yl)methylidene]hydrazinylidene}-1,2-diphenylethanone (BMHFN) C₂₅H₁₈N₂O. Moreover, the in vitro cytotoxicity of the eight title compounds was evaluated against two tumour cell lines (A549 human lung cancer and 4T₁ mouse breast cancer) and two normal cell lines (MRC-5 normal lung cells and NIH 3T3 fibroblasts) by MTT assay. The results indicate that four (BDHMFI, BDHFN, BMHMFI and BMHFN) are inactive and the other four (BDHFI, BDHAI, BMHFI and BMHAI) show severe toxicities against human A549 and mouse 4T₁ cells, similar to the standard cisplatin. All the compounds exhibited weaker cytotoxicity against normal cells than cancer cells. The Swiss Target Prediction web server was applied for the prediction of protein targets. After analyzing the differences in frequency hits between these active and inactive Schiff bases, 18 probable targets were selected for reverse docking with the Surflex-dock function in SYBYL-X 2.0 software. Three target proteins, i.e. human ether-á-go-go-related (hERG) potassium channel, the inhibitor of apoptosis protein 3 and serine/threonine-protein kinase PIM1, were chosen as the targets. Finally, the ligand-based structure-activity relationships were analyzed based on the putative protein target (hERG) docking results, which will be used to design and synthesize novel hERG ion channel inhibitors.

Design and synthesis of newer 1,3,4-oxadiazole and 1,2,4-triazole based Topsentin analogues as anti-proliferative agent targeting tubulin

A set of two series of 1,3,4-oxadiazole (11a-n) and 1,2,4-Triazole (12a, c, e, g, h, j-n) based topsentin analogues were prepared by replacing imizadole moiety of topsentin through a multistep synthesis starting from indole. All the compounds synthesized were submitted for single dose (10 µM) screening against a NCI panel of 60-human cancer cell lines. Among all cancer cell lines, colon (HCC-2998) and Breast (MCF-7, T-47D) cancer cell lines were found to be more susceptible for this class of compounds. Among the compounds tested, compounds 11a, 11d, 11f, 12e and 12h, were exhibited good anti-proliferative activity against various cancer cell lines. Compounds 11d, 12e and 12h demonstrated better activity with IC₅₀ 2.42 µM, 3.06 µM, and 3.30 µM respectively against MCF-7 human cancer cell line than that of the standard drug doxorubicin IC₅₀ 6.31 µM. Furthermore, 11d induced cell cycle arrest at G0/G1 phase and also disrupted mitochondrial membrane potential with reducing cell migration potential of MCF-7 cells in dose dependent manner. In vitro microtubule polymerization assays found that compound 11d disrupt tubulin dynamics by inhibiting tubulin polymerization with IC₅₀ 3.89 μM compared with standard nocodazole (IC₅₀ 2.49 μM). In silico docking studies represented that 11d was binding at colchicine binding site of β-tubulin. Compound 11d emerged as lead molecule from the library of compounds tested and this may serve as a template for further drug discovery.

Long non‑coding RNA SLNCR1 regulates non‑small cell lung cancer migration, invasion and stemness through interactions with secretory phospholipase A2

Long non-coding RNA (lncRNA) SRA-like non-coding RNA (SLNCR1; also known as linc00673) is a recently identified oncogenic lncRNA. The role of SLNCR1 in non-small cell lung cancer (NSCLC), a common malignancy, remains poorly understood. The present study aimed to investigate the involvement of long non-coding RNA SLNCR1 in the pathogenesis of NSCLC. Reverse transcription-quantitative PCR (RT-qPCR) and ELISA were performed to measure the levels of lncRNA SLNCR1 and secretory phospholipase A2 (sPLA2) in lung biopsies, respectively. Correlations between expression levels of lncRNA SLNCR1 and sPLA2 were analyzed by Pearson's correlation analysis. Diagnostic value of lncRNA SLNCR1 for NSCLC was evaluated by receiver operating characteristic curve analysis. lncRNA SLNCR1 small interfering (si)RNA and sPLA2 overexpression vector were transfected into NSCLC cells. Cell migration, invasion and stemness were examined by Transwell migration assay, Matrigel invasion assay and flow cytometric assay, respectively. Following transfection, expression of lncRNA SLNCR1 and sPLA2 was detected by RT-qPCR and western blotting, respectively. The results demonstrated that lncRNA SLNCR1 expression levels were upregulated in tumor tissues compared with adjacent healthy tissues of patients with NSCLC. Plasma lncRNA SLNCR1 and sPLA2 expression levels were upregulated in patients with NSCLC compared with healthy controls. Plasma lncRNA SLNCR1 and sPLA2 were positively correlated in patients with NSCLC, but not in healthy controls. lncRNA SLNCR1 siRNA silencing inhibited, whereas sPLA2 overexpression promoted cell migratory and invasive abilities and stemness. lncRNA SLNCR1 siRNA silencing led to downregulated sPLA2 expression, whereas sPLA2 overexpression did not significantly affect lncRNA SLNCR1 expression. sPLA2 overexpression attenuated the inhibitory effects of lncRNA SLNCR1 siRNA silencing on cell migration, invasion and stemness. In conclusion, lncRNA SLNCR1 may regulate cancer cell migration, invasion and stemness in NSCLC through interactions with sPLA2.

Small-molecule inhibitors as potential therapeutics and as tools to understand the role of phospholipases A2

Phospholipase A2 (PLA2) enzymes are involved in various inflammatory pathological conditions including arthritis, cardiovascular and autoimmune diseases. The regulation of their catalytic activity is of high importance and a great effort has been devoted in developing synthetic inhibitors. We summarize the most important small-molecule synthetic PLA2 inhibitors developed to target each one of the four major types of human PLA2 (cytosolic cPLA2, calcium-independent iPLA2, secreted sPLA2, and lipoprotein-associated LpPLA2). We discuss recent applications of inhibitors to understand the role of each PLA2 type and their therapeutic potential. Potent and selective PLA2 inhibitors have been developed. Although some of them have been evaluated in clinical trials, none reached the market yet. Apart from their importance as potential medicinal agents, PLA2 inhibitors are excellent tools to unveil the role that each PLA2 type plays in cells and in vivo. Modern medicinal chemistry approaches are expected to generate improved PLA2 inhibitors as new agents to treat inflammatory diseases.

Current insights into functions of phospholipase A2 receptor in normal and cancer cells: More questions than answers

Lipid signaling network was proposed as a potential target for cancer prevention and treatment. Several recent studies revealed that phospholipid metabolising enzyme, phospholipase A2 (PLA₂), is a critical regulator of cancer accelerating pathologies and apoptosis in several types of cancers. In addition to functioning as an enzyme, PLA₂ can activate a phospholipase A2 receptor (PLA2R1) in plasma membrane. While the list of PLA₂ targets extends to glucose homeostasis, intracellular energy balance, adipocyte development, and hepatic lipogenesis, the PLA2R1 downstream effectors are few and scarcely investigated. Among the most addressed PLA2R1 effects are regulation of pro-inflammatory signaling, autoimmunity, apoptosis, and senescence. Localized in glomeruli podocytes, the receptor can be identified by circulating anti-PLA2R1 autoantibodies leading to development of membranous nephropathy, a strong autoimmune inflammatory cascade. PLA2R1 was shown to induce activation of Janus-kinase 2 (JAK2) and estrogen-related receptor α (ERRα)-controlled mitochondrial proteins, as well as increasing the accumulation of reactive oxygen species, thus leading to apoptosis and senescence. These findings indicate the potential role of PLA2R1 as tumor suppressor. Epigenetic investigations addressed the role of DNA methylation, histone modifications, and specific microRNAs in the regulation of PLA2R1 expression. However, involvement of PLA2R1 in suppression of malignant growth and metastasis remains controversial. In this review, we summarize the recent findings that highlight the role of PLA2R1 in the regulation of carcinogenesis-related intracellular signaling.

Pyrrolizine-5-carboxamides: Exploring the impact of various substituents on anti-inflammatory and anticancer activities

Towards optimization of the pyrrolizine-5-carboxamide scaffold, a novel series of six derivatives (4a-c and 5a-c) was prepared and evaluated for their anti-inflammatory, analgesic and anticancer activities. The (EZ)-7-cyano-6-((4-hydroxybenzylidene)amino)-N-(p-tolyl)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (4b) and (EZ)-6-((4-chlorobenzylidene)-amino)-7-cyano-N-(p-tolyl)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (5b) bearing the electron donating methyl group showed the highest anti-inflammatory activity while (EZ)-6-((4-chlorobenzylidene)amino)-7-cyano-N-phenyl-2,3-dihydro-1H-pyrrolizine-5-carboxamide (5a) was the most active analgesic agent. Cytotoxicity of the new compounds was evaluated against the MCF-7, A2780 and HT29 cancer cell lines using the MTT assay. Compounds 4b and 5b displayed high anticancer activity with IC50 in the range of 0.30-0.92 μmol L-1 against the three cell lines, while compound (EZ)-N-(4-chlorophenyl)-7-cyano-6-((4-hydroxybenzylidene)-amino)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (4c) was the most active against MCF-7 cells (IC50 = 0.08 μmol L-1). Both the anti-inflammatory and anticancer activities of the new compounds were dependent on the type of substituent on the phenyl rings. Substituents with opposite electronic effects on the two phenyl rings are preferable for high cytotoxicity against the MCF-7 and A2780 cells. COX inhibition was suggested as the molecular mechanism of the anti-inflammatory activity of the new compounds while no clear relationship could be observed between COX inhibition and anticancer activity. Compound 5b, the most active against the three cell lines, induced dose-dependent early apoptosis with 0.1-0.2 % necrosis in MCF-7 cells. New compounds showed promising drug-likeness scores while the docking study revealed high binding affinity to COX-2. Taken together, this study highlighted the significant impact of the substituents on the anti-inflammatory and anticancer activity of pyrrolizine-5-carboxamides, which could help in further optimization to discover good leads for the treatment of cancer and inflammation.

Indolyl-isoxazolidines attenuate LPS-stimulated pro-inflammatory cytokines and increase survival in a mouse model of sepsis: Identification of potent lead

A library of indolyl-isoxazolidines (6-9) has been synthesized by regio- and stereoselective microwave irradiated 1,3-dipolar cycloadditions of C-(3-indolyl)-N-phenylnitrone (2') with variedly substituted dipolarophiles (3'-5') and screened for their anti-inflammatory activities through inhibition of pro-inflammatory cytokines such as TNF-α and IL-6. Amongst the evaluated compounds (6-9), bicyclic isoxazolidine (9a) was found to exhibit significant inhibitory potential against LPS induced human IL-6 and TNF-α in THP-1 cells. Compound 9a was further assessed for in vivo analgesic and anti-inflammatory activities via acetic acid induced writhing and carrageenan induced paw edema models in mice, respectively. The results showed that compound possesses potent anti-inflammatory-analgesic activity comparable to indomethacin and did not show toxicity up to a 2000 mg kg^-1 dose as evidenced by histopathological studies. Consequently, the most active compound 9a was also evaluated against LPS-induced septic death and exhibited a significant protection in in vivo mouse model. Taken all together, the results suggest that the compound 9a is able to attenuate pro-inflammatory cytokines such as IL-6 and TNF-α; accelerate resolution of inflammation, and also increased survival rate of septic mice. Therefore, these "lead" isoxazolidines can be used as promising candidate for further analgesic/anti-inflammatory drug design and development.

The synthetic and therapeutic expedition of isoxazole and its analogs

Isoxazole, constituting an important family of five-membered heterocycles with one oxygen atom and one nitrogen atom at adjacent positions is of immense importance because of its wide spectrum of biological activities and therapeutic potential. It is, therefore, of prime importance that the development of new synthetic strategies and designing of new isoxazole derivatives should be based on the most recent knowledge emerging from the latest research. This review is an endeavor to highlight the progress in the chemistry and biological activity of isoxazole derivatives which could provide a low-height flying bird's eye view of isoxazole derivatives to the medicinal chemists for the development of clinically viable drugs using this information.

Current research on anti-breast cancer synthetic compounds

Breast cancer (BC) is the most common cancer for females and its incidence tends to increase year by year.

Isoxazole ring as a useful scaffold in a search for new therapeutic agents

Due to its relatively easy synthesis, isoxazole ring has been as an object of interest for chemists and pharmacologists from research groups all over the world. Its chemical modifications include both connection of isoxazole with other aromatic, heteroaromatic or non aromatic rings and substitution with different alkyl groups. Thanks to their usually low cytotoxicity, isoxazole derivatives are still popular scaffolds for the development of new agents with variable biological activities, such as antimicrobial, antiviral, anticancer, anti-inflammatory, immunomodulatory, anticonvulsant or anti-diabetic properties. This review discusses the chemical structure of recently developed isoxazole derivatives with regards to their activity and potential therapeutic use.