Rationally designed hybrid molecules with appreciable COX-2 inhibitory and anti-nociceptive activities

Research status of indole-modified natural products

Indole is a heterocyclic compound formed by the fusion of a benzene ring and pyrrole ring, which has rich biological activity. Many indole-containing compounds have been sold on the market due to their excellent pharmacological activity. For example, vincristine and reserpine have been widely used in clinical practice. The diverse structures and biological activities of natural products provide abundant resources for the development of new drugs. Therefore, this review classifies natural products by structure, and summarizes the research progress of indole-containing natural product derivatives, their biological activities, structure-activity relationship and research mechanism which has been studied in the past 13 years, so as to provide a basis for the development of new drug development.

Development of novel pyrazole, imidazo[1,2-b]pyrazole, and pyrazolo[1,5-a]pyrimidine derivatives as a new class of COX-2 inhibitors with immunomodulatory potential

Searching for new compounds with anti-inflammatory properties is a significant target since inflammation is a major cause of pain. A series of pyrazole, imidazopyrazolone, and pyrazolopyrimidine derivatives were designed and synthesized by reaction of 3,5-diamino-1H-pyrazole derivative with cyclic and acyclic carbonyl reagents. The structure of the newly synthesized derivatives were fully characterized using different spectroscopic data and elemental analysis, and therefore, evaluated as COX-2 inhibitors. The in vitro COX-2 activity of the tested derivatives 2-13 displayed moderate to good potency with two derivatives 8 and 13 that exhibiting high potency to COX-2 with IC₅₀ values of 5.68 ± 0.08 and 3.37 ± 0.07 μM compared with celecoxib (IC₅₀ = 3.60 ± 0.07 μM) and meloxicam (IC₅₀ = 7.58 ± 0.13 μM). Furthermore, the most active pyrazolo[1,5-a]pyrimidine derivatives 8 and 13 were evaluated to measure the levels of pro-inflammatory proteins such as TNF-α and IL-6 using qRT-PCR in RAW264.7 cells, and the results showed down-regulation of two immunomodulatory proteins. Surprisingly, these derivatives 8 and 13 revealed a decrease in IL-6 level with inhibition percentages of 65.8 and 70.3%, respectively, compared with celecoxib (% = 76.8). Further, compounds 8 and 13 can regulate and suppress the TNF-α with percentage inhibition of 63.1 and 59.2% to controls, while celecoxib displayed an inhibition percentage of 72.7. The Quantum chemical calculation was conducted, and data explained the structural features crucial to the activity. The molecular docking simulation and ADMET predictions revealed that the most active derivatives have good binding affinity, possess appropriate drug-likeness properties and low toxicity profiles. Finally, compounds 8 and 13 demonstrated COX-2 inhibitors with α-TNF and IL-6 suppression capabilities as a dual-action strategy to get more effective treatment.

Human health-related properties of chromones: an overview

Natural compounds occurring throughout the world are scientifically and practically valuable because of their unique and beneficial properties to control a wide range of disorders in the human body. Chromones are attracting increasing attention as novel therapeutic agents due to their effective bioactivities for human health. Accordingly, the present overview article was designed to scan the biological and pharmacological performance of chromones, including their anti-inflammatory, anticancer, anti-oxidant, and anti-microbial activities.

Examining barbiturate scaffold for the synthesis of new agents with biological interest

Aim: Barbiturates have a long history of being used as drugs presenting wide varieties of biological activities (antimicrobial, anti-urease and antioxidant). Reactive oxygen species are associated with inflammation implicated in cancer, atherosclerosis and autoimmune diseases. Multitarget agents represent a powerful approach to the therapy of complicated inflammatory diseases. Results: A novel series of barbiturates has been synthesized and evaluated in several in vitro assays. Compound 16b (lipoxygenases inhibitor, 55.0 μM) was found to be a cyclooxygenase-2 inhibitor (27.5 μM). Compound 8b was profiled as a drug-like candidate. Conclusion: The barbiturate core represents a new scaffold for lipoxygenases inhibition, and the undertaken derivatives show promise as multiple-target agents to combat inflammatory diseases.

Classification of Cyclooxygenase-2 Inhibitors Using Support Vector Machine and Random Forest Methods

This work reports the classification study conducted on the biggest COX-2 inhibitor data set so far. Using 2925 diverse COX-2 inhibitors collected from 168 pieces of literature, we applied machine learning methods, support vector machine (SVM) and random forest (RF), to develop 12 classification models. The best SVM and RF models resulted in MCC values of 0.73 and 0.72, respectively. The 2925 COX-2 inhibitors were reduced to a data set of 1630 molecules by removing intermediately active inhibitors, and 12 new classification models were constructed, yielding MCC values above 0.72. The best MCC value of the external test set was predicted to be 0.68 by the RF model using ECFP_4 fingerprints. Moreover, the 2925 COX-2 inhibitors were clustered into eight subsets, and the structural features of each subset were investigated. We identified substructures important for activity including halogen, carboxyl, sulfonamide, and methanesulfonyl groups, as well as the aromatic nitrogen atoms. The models developed in this study could serve as useful tools for compound screening prior to lab tests.

Design, Synthesis and Pharmacological Evaluation of Gastro- Protective Anti-inflammatory Analgesic Agents based on Dual Oxidative Stress / Cyclooxygenase Inhibition

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) derived local generation of reactive oxygen species (ROS) plays a crucial role in the formation of gastric ulceration.

OBJECTIVE

Therefore, anti-inflammatory analgesics with potent antioxidant activity could be a potential therapeutic strategy for the treatment of pain and inflammatory disorders without gastrointestinal (GI) side effects.

METHODS

In an effort to develop gastroprotective analgesic and anti-inflammatory agents, a series of 2-methylamino-substituted-1H-benzo[d] imidazol-1-yl) (phenyl) methanone derivatives were synthesized and evaluated in vitro for cyclooxygenase (COX) inhibition as well as anti-oxidant potential by the FRAP assay. The compounds with significant in vitro COX-1/COX-2 inhibitory activity and antioxidant activity were further screened in vivo for their anti-inflammatory and analgesic activities. Moreover, the ulcerogenic potential of test compounds was also studied. To gain insight into the plausible mode of interaction of compounds within the active sites of COX-1 and COX-2, molecular docking simulations were performed.

RESULTS

Among the various synthesized molecules, most of the compounds showed good cyclooxygenase inhibitory activity and efficient antioxidant activity in FRAP assay. After preliminary and indicative in vitro assays, three compounds exhibited most significant antiinflammatory and analgesic activity with better gastric tolerability during their in vivo evaluation. Ligand interaction studies indicated highest dock score -43.05 of 1,2- disubstituted benzimidazole derivatives in comparison to the reference ligand -30.70. Overall studies provided us (2-((4-methoxyphenylamino) methyl) -1h-benzo [d] imidazol- 1-yl) (phenyl) methanone as a lead with potent gastro-protective anti-inflammatory and analgesic activities that can be used for future research.

CONCLUSION

From the above results, it can be concluded that designing of multifunctional molecules with COX-1/COX-2 inhibitory and anti-oxidant activities could hold a great promise for further development of GI-safer NSAIDs.

Synergy of Physico-chemical and Biological Experiments for Developing a Cyclooxygenase-2 Inhibitor

The physiological consequences of COX-2 overexpression in the development of cancer, diabetes and neurodegenerative diseases have made this enzyme a promising therapeutic target. Herein, COX-2 active site was analyzed and new molecules were designed. We identified a highly potent molecule (S)-3a with IC50 value and the selectivity for COX-2 0.6 nM and 1666, respectively. The MTD of (S)-3a was 2000 mg kg-1 and its pharmacokinetic studies in rat showed t1/2 7.5 h. This compound reversed acetic acid induced analgesia and carragennan induced inflammation by 50% and 25% in rat when used at a dose 10 mg kg-1. Mechanistically, it was found that compound (S)-3a inhibits COX-2. Overall, the combination of physico-chemical and biological experiments facilitated the development of a new lead molecule to anti-inflammatory drug.

Design and Synthesis of Aza-/Oxa Heterocycle-Based Conjugates as Novel Anti-Inflammatory Agents Targeting Cyclooxygenase-2

A library of hybrid molecules was procured by the combination of triazine-indole adduct with morpholine/piperidine/pyrrolidine and pyrazole/pyrimidine/oxindole moieties. Enzyme immunoassays on cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) identified compound 6 having an IC₅₀ value of 20 nM for COX-2 and 3000 nM for COX-1. The significant reduction in the formation of prostaglandin E₂ in the lipopolysaccharide-treated (COX-2-activated) human whole blood, almost no change in the production of thromboxane B₂ in the calcium ionophore-treated (COX-1-activated) sample of human whole blood, and the mechanistic studies on Swiss albino mice ensured that compound 6 is selective for COX-2. The association constant (K_a) of compound 6 with COX-2 was found to be of the order of 0.48 × 10⁶ M^-1. The diffusion spectroscopy experiments and relaxation time (T₁) calculations of compound 6 in the presence of COX-2 assisted in identifying the site-specific interactions of 6 with the enzyme, and these results fall into nice correlation with the theoretical data obtained from molecular docking and quantitative structure-activity relationship studies. With maximum tolerable dose >2000 mg kg^-1, compound 6 made 68 and 32% reduction in formalin-induced analgesia and carrageenan-induced inflammation in Swiss albino mice.

Chromones: A Promising Ring System for New Anti-inflammatory Drugs

The quest for safer anti-inflammatory drugs is still the focus of several medicinal chemistry programs. Chromones (4H-chromen-4-ones) are a group of naturally occurring compounds ubiquitous in plants, and the chromone core has proven to be a privileged scaffold in medicinal chemistry. Herein we provide an overview of the relevance of chromones as anti-inflammatory agents, specifically as inhibitors of cyclooxygenase (COX), 5-lipoxygenase (5-LOX), interleukin-5 (IL-5), and nitric oxide (^. NO) production. Numerous structure-activity relationships and mechanisms of action are discussed. This review is therefore intended to provide a foundation for the design and synthesis of novel chromone-based compound libraries for further development into safer and more efficient anti-inflammatory agents.

Hybrid molecules: The privileged scaffolds for various pharmaceuticals

The practice of polypharmacology is not a new concept but the approaches which are being adopted for administering the two or more drugs together are varied from time to time. Taking two or more drugs simultaneously, co-formulation of two or more active agents in a single tablet and development of hybrid molecular entities capable to modulate multiple targets are the three popular approaches for multidrug therapy. The simultaneous use of more than one drug for the chemotherapy of a single disease demands a lot of patient compliance. Hence the present form of polypharmacology is gaining popularity in the form of hybrid molecules (multiple ligand approach). From the last 1-2 decades, the synthesis of hybrid molecules by the combination of different biologically relevant moieties has been under constant escalation along with their evaluation as diverse range of pharmacological agents and as potent drugs. This review is focused on the biological potential of hybrid molecules with particular mention of those exhibiting anti-fungal, anti-tuberculosis, anti-malarial, anti-inflammatory and anti-cancer activities. A comparison of the drug potency of the hybrid molecules with their individual counterparts is discussed for quantifying the significance of the concept of molecular hybridisation.

An overview of molecular hybrids in drug discovery

INTRODUCTION

The hybridization of biologically active molecules is a powerful tool for drug discovery used to target a variety of diseases. It offers the prospect of better drugs for the treatment of a number of illnesses including cancer, malaria, tuberculosis and AIDS. Hybrid drugs can provide combination therapies in a single multi-functional agent and, by doing so, be more specific and powerful than conventional classic treatments. This research field is in great expansion and attracts many researchers worldwide.

AREA COVERED

This review covers the main research published between early 2013 to mid-2015 and takes into account several previous reviews on the subject. Its intention is to showcase the most recent advances reported towards the development of molecular hybrids in drug discovery. Particular attention is given to anticancer hybrids throughout the review.

EXPERT OPINION

Current advances show that molecular hybrids of biologically active molecules can lead to powerful therapeutics. Natural products play a key role in this field. It is also believed that toxin hybrids present a great opportunity for future progress and should be further explored. Furthermore, the synthesis of hybrid organometallics should be systematically studied as it can lead to potent drugs. The crucial requirement for growth still remains the efficacy of synthesis. Hence, the development of efficient synthetic methods allowing rapid access to diverse series of hybrids must be further investigated by researchers.