Synthesis and docking studies of 2,4,6-trihydroxy-3-geranylacetophenone analogs as potential lipoxygenase inhibitor

Oral and topical administration of a geranyl acetophenone attenuates DNCB-induced atopic dermatitis-like skin lesions in BALB/c mice

Atopic dermatitis (AD) is a chronic, allergic inflammatory skin disorder that lacks a definite cure. Using a mouse DNCB-induced AD-like skin lesions model, this study evaluated the potential therapeutic utility of tHGA as an oral and topical treatment for AD. Male BALB/c mice were sensitised and challenged with 1% and 0.5% DNCB on their shaved dorsal skin. Mice in the treatment group were administered tHGA (20, 40, and 80 mg/kg) orally three times per week for 2 weeks, or tHGA (0.2%, 1%, and 5%) topically once daily for 12 days. On day 34, the mice were euthanized, and blood and dorsal skin samples were obtained for analysis. All doses of orally and topically administered tHGA significantly improved scratching, epidermal thickness, blood eosinophilia and mast cell infiltration. There was a minor discrepancy between the two routes of administration, with orally treated tHGA showing significant reductions in Scoring of Atopic Dermatitis (SCORAD), tissue eosinophil infiltration, serum IgE and skin IL-4 levels with treatment of 40 and 80 mg/kg tHGA, whereas topically applied tHGA showed significant reductions in all dosages. These findings suggest that tHGA exhibited therapeutic potential for AD as both oral and topical treatment ameliorates AD-like symptoms in the murine model.

Design, synthesis, and pharmacological evaluation of indazole carboxamides of N-substituted pyrrole derivatives as soybean lipoxygenase inhibitors

In this paper, we attempted to develop a novel class of compounds against lipoxygenase, a key enzyme in the biosynthesis of leukotrienes implicated in a series of inflammatory diseases. Given the absence of appropriate human 5-lipoxygenase crystallographic data, solved soybean lipoxygenase-1 and -3 structures were used as a template to generate an accurate pharmacophore model which was further used for virtual screening purposes. Eight compounds (1-8) have been derived from the in-house library consisting of N-substituted pyrroles conjugated with 5- or 6-indazole moieties through a carboxamide linker. This study led to the discovery of hit molecule 8 bearing a naphthyl group with the IC50 value of 22 μM according to soybean lipoxygenase in vitro assay. Isosteric replacement of naphthyl ring with quinoline moieties and reduction of carbonyl carboxamide group resulted in compounds 9-12 and 13, respectively. Compound 12 demonstrated the most promising enzyme inhibition. In addition, compounds 8 and 12 were found to reduce the carrageenan-induced paw edema in vivo by 52.6 and 49.8%, respectively. In view of the encouraging outcomes concerning their notable in vitro and in vivo anti-inflammatory activities, compounds 8 and 12 could be further optimized for the discovery of novel 5-lipoxygenase inhibitors in future. A structure-based 3D pharmacophore model was used in the virtual screening of in-house library to discover novel potential 5-lipoxygenase inhibitors.

Synthesis, Biological, Spectroscopic and Computational Investigations of Novel N-Acylhydrazone Derivatives of Pyrrolo[3,4-d]pyridazinone as Dual COX/LOX Inhibitors

Secure and efficient treatment of diverse pain and inflammatory disorders is continually challenging. Although NSAIDs and other painkillers are well-known and commonly available, they are sometimes insufficient and can cause dangerous adverse effects. As yet reported, derivatives of pyrrolo[3,4-d]pyridazinone are potent COX-2 inhibitors with a COX-2/COX-1 selectivity index better than meloxicam. Considering that N-acylhydrazone (NAH) moiety is a privileged structure occurring in many promising drug candidates, we decided to introduce this pharmacophore into new series of pyrrolo[3,4-d]pyridazinone derivatives. The current paper presents the synthesis and in vitro, spectroscopic, and in silico studies evaluating the biological and physicochemical properties of NAH derivatives of pyrrolo[3,4-d]pyridazinone. Novel compounds 5a-c-7a-c were received with high purity and good yields and did not show cytotoxicity in the MTT assay. Their COX-1, COX-2, and 15-LOX inhibitory activities were estimated using enzymatic tests and molecular docking studies. The title N-acylhydrazones appeared to be promising dual COX/LOX inhibitors. Moreover, spectroscopic and computational methods revealed that new compounds form stable complexes with the most abundant plasma proteins-AAG and HSA, but do not destabilize their secondary structure. Additionally, predicted pharmacokinetic and drug-likeness properties of investigated molecules suggest their potentially good membrane permeability and satisfactory bioavailability.

Investigation of the dual role of acyl phloroglucinols as a new hope for antibacterial and anti-SARS-CoV-2 agents employing integrated in vitro and multi-phase in silico approaches

With the rapid spread of multi-drug-resistant bacteria and more infectious or aggressive variants of SARS-CoV-2, it is critical to develop drugs that can quickly adapt to evolving bacterial and viral mutations. In this study, encouraged by nature, we synthesized a series of phloroglucinol (PG) derivatives, acyl phloroglucinols (ACPLs) 2a-4c by mimicking the structure of the natural antifungal 2,4-diacetylphloroglucinol 3a (2,4-DAPG). According to the quantum chemical calculation, these compounds were expected to be exceptionally favourable for intermolecular interaction with protein receptors. Intriguingly, the in vitro study of Staphylococcus aureus (S. aureus) ATCC 25923 and Escherichia coli (E. coli) ATCC 25922, showed that the four ACPLs 3a-4a had good antibacterial activity and selectivity against gram-positive bacteria, S. aureus. These results were then supported by in silico molecular docking and molecular dynamics simulations (MDs) between these potent compounds and the S. aureus FtsA protein (PDB ID: 3WQU). Furthermore, with the aid of the knowledge base Virus-CKB along with the molecular docking study, it was found that the three ACPLs 4a-4c showed potential inhibitors against SARS-CoV-2 PLpro (PDB ID: 7CMD). Additionally, 100 ns of MDs was carried out in order to assess the stability behaviour of ACPLs at the docked site. Moreover, in silico ADME/T and drug likeness of all studied ACPLs were also predicted. Finally, shape-based screening of FDA-approved drugs was performed using the most prominent synthesized ACPLs as a template, enabling us to include several medications that could be utilized as antibacterial and antiviral drug candidates.Communicated by Ramaswamy H. Sarma.

Interactions of N-Mannich Bases of Pyrrolo[3,4-c]pyrrole with Artificial Models of Cell Membranes and Plasma Proteins, Evaluation of Anti-Inflammatory and Antioxidant Activity

Despite the widespread and easy access to NSAIDs, effective and safe treatment of various inflammatory disorders is still a serious challenge because of the severe adverse effects distinctive to these drugs. The Mannich base derivatives of pyrrolo[3,4-c]pyrrole are potent, preferential COX-2 inhibitors with a COX-2/COX-1 inhibitory ratio better than meloxicam. Therefore, we chose the six most promising molecules and subjected them to further in-depth research. The current study presents the extensive biological, spectroscopic and in silico evaluation of the activity and physicochemical properties of pyrrolo[3,4-c]pyrrole derivatives. Aware of the advantages of dual COX-LOX inhibition, we investigated the 15-LOX inhibitory activity of these molecules. We also examined their antioxidant effect in several in vitro experiments in a protection and regeneration model. Furthermore, we defined how studied compounds interact with artificial models of cell membranes, which is extremely important for drugs administered orally with an intracellular target. The interactions and binding mode of the derivatives with the most abundant plasma proteins-human serum albumin and alpha-1-acid glycoprotein-are also described. Finally, we used computational techniques to evaluate their pharmacokinetic properties. According to the obtained results, we can state that pyrrolo[3,4-c]pyrrole derivatives are promising anti-inflammatory and antioxidant agents with potentially good membrane permeability.

Traveling across Life Sciences with Acetophenone-A Simple Ketone That Has Special Multipurpose Missions

Each metabolite, regardless of its molecular simplicity or complexity, has a mission or function in the organism biosynthesizing it. In this review, the biological, allelochemical, and chemical properties of acetophenone, as a metabolite involved in multiple interactions with various (mi-cro)organisms, are discussed. Further, the details of its biogenesis and chemical synthesis are provided, and the possibility of its application in different areas of life sciences, i.e., the status quo of acetophenone and its simple substituted analogs, is examined. In particular, natural and synthetic simple acetophenone derivatives are analyzed as promising agrochemicals and useful scaffolds for drug research and development.

Pharmacological Properties of 2,4,6-Trihydroxy-3-Geranyl Acetophenone and the Underlying Signaling Pathways: Progress and Prospects

2,4,6-Trihydroxy-3-geranyl acetophenone (tHGA) is a bioactive phloroglucinol compound found in Melicope pteleifolia (Champ. ex Benth.) T.G.Hartley, a medicinal plant vernacularly known as “tenggek burung”. A variety of phytochemicals have been isolated from different parts of the plant including leaves, stems, and roots by using several extraction methods. Specifically, tHGA, a drug-like compound containing phloroglucinol structural core with acyl and geranyl group, has been identified in the methanolic extract of the young leaves. Due to its high nutritional and medicinal values, tHGA has been extensively studied by using various experimental models. These studies have successfully discovered various interesting pharmacological activities of tHGA such as anti-inflammatory, endothelial and epithelial barrier protective, anti-asthmatic, anti-allergic, and anti-cancer. More in-depth investigations later found that these activities were attributable to the modulatory actions exerted by tHGA on specific molecular targets. Despite these findings, the association between the mechanisms and signaling pathways underlying each pharmacological activity remains largely unknown. Also, little is known about the medicinal potentials of tHGA as a drug lead in the current pharmaceutical industry. Therefore, this mini review aims to summarize and relate the pharmacological activities of tHGA in terms of their respective mechanisms of action and signaling pathways in order to present a perspective into the overall modulatory actions exerted by tHGA. Besides that, this mini review will also pinpoint the unexplored potentials of this compound and provide some valuable insights into the potential applications of tHGA which may serve as a guide for the development of modern medication in the future.

The phytochemistry, pharmacology and applications of Melicope pteleifolia: A review

ETHNOPHARMACOLOGY RELEVANCE

The leaves, stems and roots of Melicope pteleifolia (Champ. ex Benth.) T.Hartley (MP; Rutaceae, called sanyaku in Chinese; syn.: Euodia lepta), have been used traditionally for the treatment of sore throat, rheumatism, eczema, dermatitis, bruises, and insect, rat, snake bites based on traditional Chinese medicine concepts.

AIM OF THIS STUDY

This paper aims to provide a comprehensive and critical analysis of studies on MP and focusing on potential relationships between traditional uses and pharmacological effects, assessing the therapeutic potential as a medicine.

MATERIALS AND METHODS

Relevant data on MP were retrieved using the keywords "Melicope pteleifolia", "pharmacology", "toxicity" and "applications" in databases including "Pubmed", "SciFinder", "Springer", "Elsevier", "Wiley", "Web of Science", "Google Scholar", "China Knowledge Resource Integrated databases (CNKI)", "PhD" and "MSc dissertations", and a hand-search.

RESULTS AND DISCUSSION

The heat-clearing, dampness-removing and gallbladder-normalizing actions of MP have been linked to biomedical concepts like anti-inflammatory, antioxidant and hepatoprotective activities. The latter is potentially based on the presence of furaquinoline alkaloids, phenylpropanoids and flavonoids. Analgesic, antimicrobial and anti-tumor effects have also been reported. Currently limited evidence is available relating to potential toxicological risks especially of aqueous extracts with so far no reports signalling specific risks. Although some studies on the pharmacodynamics of MP have been reported, studies on action mechanisms of MP are still rare.

CONCLUSIONS

In the future and prior to initiating clinical trials, the safety, in vitro and in vivo pharmacology, and mechanism of action of MP needs to be assessed, including a focus on the link between traditional uses and modern applications. In addition, phytochemical and biological studies need to conduct on flowers and fruits of MP. Furthermore, strict quality control measures are needed in the studies investigating any aspect of the pharmacology, chemistry and biology of MP.

5-Lipoxygenase as a drug target: A review on trends in inhibitors structural design, SAR and mechanism based approach

The most common inflammatory disease of the airways is asthma among children affecting around 235 million people worldwide. 5-Lipoxygenase (5-LOX) is a crucial enzyme which helps in the conversion of arachidonic acid (AA) to leukotrienes (LTs), the lipid mediators. It is associated with several inflammation related disorders such as asthma, allergy, and atherosclerosis. Therefore, it is considered as a promising target against inflammation and asthma. Currently, the only drug against 5-LOX which is available is Zileuton, while a few inhibitors are in clinical trial stages such as Atreleuton and Setileuton. So, there is a dire requirement in the area of progress of novel 5-LOX inhibitors which necessitates an understanding of their structure activity relationship and mode of action. In this review, novel 5-LOX inhibitors reported so far, their structural design, SAR and developmental strategies along with clinical updates are discussed over the last two decades.

Applications of Friedel-Crafts reactions in total synthesis of natural products

Over the years, Friedel-Crafts (FC) reactions have been acknowledged as the most useful and powerful synthetic tools for the construction of a special kind of carbon-carbon bond involving an aromatic moiety. Its stoichiometric and, more recently, its catalytic procedures have extensively been studied. This reaction in recent years has frequently been used as a key step (steps) in the total synthesis of natural products and targeted complex bioactive molecules. In this review, we try to underscore the applications of intermolecular and intramolecular FC reactions in the total syntheses of natural products and complex molecules, exhibiting diverse biological properties.

Hits-to-Lead Optimization of the Natural Compound 2,4,6-Trihydroxy-3-geranyl-acetophenone (tHGA) as a Potent LOX Inhibitor: Synthesis, Structure-Activity Relationship (SAR) Study, and Computational Assignment

A new series of 2,4,6-trihydroxy-3-geranyl-acetophenone (tHGA) analogues were synthesized and evaluated for their lipoxygenase (LOX) inhibitory activity. Prenylated analogues 4a⁻g (half maximal inhibitory concentration (IC50) values ranging from 35 μ M to 95 μ M) did not exhibit better inhibitory activity than tHGA (3a) (IC50 value: 23.6 μ M) due to the reduction in hydrophobic interaction when the alkyl chain length was reduced. One geranylated analogue, 3d, with an IC50 value of 15.3 μ M, exhibited better LOX inhibitory activity when compared to tHGA (3a), which was in agreement with our previous findings. Kinetics study showed that the most active analogue (3e) and tHGA (3a) acted as competitive inhibitors. The combination of in silico approaches of molecular docking and molecular dynamic simulation revealed that the lipophilic nature of these analogues further enhanced the LOX inhibitory activity. Based on absorption, distribution, metabolism, excretion, and toxicity (ADMET) and toxicity prediction by komputer assisted technology (TOPKAT) analyses, all geranylated analogues (3a⁻g) showed no hepatotoxicity effect and were biodegradable, which indicated that they could be potentially safe drugs for treating inflammation.

Recent development of lipoxygenase inhibitors as anti-inflammatory agents

Inflammation is favorable in most cases, because it is a kind of body defensive response to external stimuli; sometimes, inflammation is also harmful, such as attacks on the body's own tissues. It could be that inflammation is a unified process of injury and resistance to injury. Inflammation brings extreme pain to patients, showing symptoms of rubor, swelling, fever, pain and dysfunction. As the specific mechanism is not clear yet, the current anti-inflammatory agents are given priority for relieving suffering of patients. Thus it is emergent to find new anti-inflammatory agents with rapid effect. Lipoxygenase (LOX) is a kind of rate-limiting enzyme in the process of arachidonic acid metabolism into leukotriene (LT) which mediates the occurrence of inflammation. The inhibition of LOX can reduce LT, thereby producing an anti-inflammatory effect. In this review, the LOX inhibitors reported in recent years are summarized, and, in particular, their activities, structure-activity relationships and molecular docking studies are emphasized, which will provide new ideas to design novel LOX inhibitors.

Molecular Docking Analysis of Phytic Acid and 4-hydroxyisoleucine as Cyclooxygenase-2, Microsomal Prostaglandin E Synthase-2, Tyrosinase, Human Neutrophil Elastase, Matrix Metalloproteinase-2 and -9, Xanthine Oxidase, Squalene Synthase, Nitric Oxide Synthase, Human Aldose Reductase, and Lipoxygenase Inhibitors

Background

The phytoconstituents phytic acid and 4-hydroxyisoleucine have been reported to posses various biological properties.

Objective

This prompted us to carry out the docking study on these two ligands (phytic acid & 4-hydroxyisoleucine) against eleven targeted enzymes.

Materials and Methods

Phytic acid & 4-hydroxyisoleucine were evaluated on the docking behaviour of cyclooxygenase-2 (COX-2), microsomal prostaglandin E synthase-2 (mPGES-2), tyrosinase, human neutrophil elastase (HNE), matrix metalloproteinase (MMP 2 and 9), xanthine oxidase (XO), squalene synthase (SQS), nitric oxide synthase (NOS), human aldose reductase (HAR) and lipoxygenase (LOX) using Discovery Studio Version 3.1 (except for LOX, where Autodock 4.2 tool was used).

Results

Docking and binding free energy analysis revealed that phytic acid exhibited the maximum binding energy for four target enzymes such as COX-2, mPGES-2, tyrosinase and HNE. Interestingly, we found that 4-hydroxyisoleucine has the potential to dock and bind with all of the eleven targeted enzymes.

Conclusion

This present study has paved a new insight in understanding 4-hydroxyisoleucine as potential inhibitor against COX-2, mPGES-2, tyrosinase, HNE, MMP 2, MMP 9, XO, SQS, NOS, HAR and LOX.

SUMMARY

4-hydroxyisoleucine has the potential to dock and bind with all 11targeted enzymes such as (cyclooxygenase-2 [COX-2], microsomal prostaglandin E synthase-2 [mPGES-2], tyrosinase, human neutrophil elastase [HNE], matrix metalloproteinase [MMP-2 and -9], xanthine oxidase, squalene synthase, nitric oxide synthase, human aldose reductase, and lipoxygenase)Moreover, docking studies and binding free energy calculations revealed that phytic acid exhibited the maximum binding energy for four target enzymes such as COX-2, mPGES-2, tyrosinase, and HNE; however, for other six target enzymes, it fails to dock. Abbreviations used: COX-2: Cyclooxygenase-2, mPGES-2: Microsomal prostaglandin E synthase-2, HNE: Human neutrophil elastase, MMP-2 and -9: Matrix metalloproteinase-2 and -9, XO: Xanthine oxidase, SQS: Squalene synthase, NOS: Nitric oxide synthase, HAR: Human aldose reductase, LOX: Lipoxygenase, ADME: Absorption, distribution, metabolism, and excretion, TOPKAT: Toxicity Prediction by Computer-assisted Technology.

Evaluation of Dual 5-Lipoxygenase/Microsomal Prostaglandin E2 Synthase-1 Inhibitory Effect of Natural and Synthetic Acronychia-Type Isoprenylated Acetophenones

Among the pathways responsible for the development of inflammatory responses, the cyclooxygenase and lipoxygenase pathways are among the most important ones. Two key enzymes, namely, 5-LO and mPGES-1, are involved in the biosynthesis of leukotrienes and prostaglandins, respectively, which are considered attractive therapeutic targets, so their dual inhibition might be an effective strategy to control inflammatory deregulation. Several natural products have been identified as 5-LO inhibitors, with some also being dual 5-LO/mPGES-1 inhibitors. Here, some prenylated acetophenone dimers from Acronychia pedunculata have been identified for their dual inhibitory potency toward 5-LO and mPGES-1. To gain insight into the SAR of this family of natural products, the synthesis and biological evaluation of analogues are presented. The results show the ability of the natural and synthetic molecules to potently inhibit 5-LO and mPEGS-1 in vitro. The potency of the most active compound (10) has been evaluated in vivo in an acute inflammatory mouse model and displayed potent anti-inflammatory activity comparable in potency to the drug zileuton used as a positive control.

Synthesis of Natural Acylphloroglucinol-Based Antifungal Compounds against Cryptococcus Species

Thirty-three natural-product-based acylphloroglucinol derivatives were synthesized to identify antifungal compounds against Cryptococcus spp. that cause the life-threatening disseminated cryptococcosis. In vitro antifungal testing showed that 17 compounds were active against C. neoformans ATCC 90113, C. neoformans H99, and C. gattii ATCC 32609, with minimum inhibitory concentrations (MICs) in the range 1.0-16.7 μg/mL. Analysis of the structure and antifungal activity of these compounds indicated that the 2,4-diacyl- and 2-acyl-4-alkylphloroglucinols were more active than O-alkyl-acylphloroglucinols. The most promising compound found was 2-methyl-1-(2,4,6-trihydroxy-3-(4-isopropylbenzyl)phenyl)propan-1-one (11j), which exhibited potent antifungal activity (MICs, 1.5-2.1 μg/mL) and low cytotoxicity against the mammalian Vero and LLC-PK1 cell lines (IC50 values >50 μg/mL). This compound may serve as a template for further synthesis of new analogues with improved antifungal activity. The findings of the present work may contribute to future antifungal discovery toward pharmaceutical development of new treatments for cryptococcosis.

Penchinones A–D, two pairs of cis-trans isomers with rearranged neolignane carbon skeletons from Penthorum chinense

Two pairs of cis-trans isomers with new rearranged neolignane carbon skeletons from Penthorum chinense.