Design, Synthesis, and Anti-Bacterial Evaluation of Triazolyl-Pterostilbene Derivatives

Progress of Antimicrobial Mechanisms of Stilbenoids

Antimicrobial drugs have made outstanding contributions to the treatment of pathogenic infections. However, the emergence of drug resistance continues to be a major threat to human health in recent years, and therefore, the search for novel antimicrobial drugs is particularly urgent. With a deeper understanding of microbial habits and drug resistance mechanisms, various creative strategies for the development of novel antibiotics have been proposed. Stilbenoids, characterized by a C6-C2-C6 carbon skeleton, have recently been widely recognized for their flexible antimicrobial roles. Here, we comprehensively summarize the mode of action of stilbenoids from the viewpoint of their direct antimicrobial properties, antibiofilm and antivirulence activities and their role in reversing drug resistance. This review will provide an important reference for the future development and research into the mechanisms of stilbenoids as antimicrobial agents.

Evaluation of novel compounds as anti-bacterial or anti-virulence agents

Antimicrobial resistance is a global threat, leading to an alarming increase in the prevalence of bacterial infections that can no longer be treated with available antibiotics. The World Health Organization estimates that by 2050 up to 10 million deaths per year could be associated with antimicrobial resistance, which would equal the annual number of cancer deaths worldwide. To overcome this emerging crisis, novel anti-bacterial compounds are urgently needed. There are two possible approaches in the fight against bacterial infections: a) targeting structures within bacterial cells, similar to existing antibiotics; and/or b) targeting virulence factors rather than bacterial growth. Here, for the first time, we provide a comprehensive overview of the key steps in the evaluation of potential new anti-bacterial and/or anti-virulence compounds. The methods described in this review include: a) in silico methods for the evaluation of novel compounds; b) anti-bacterial assays (MIC, MBC, Time-kill); b) anti-virulence assays (anti-biofilm, anti-quorum sensing, anti-adhesion); and c) evaluation of safety aspects (cytotoxicity assay and Ames test). Overall, we provide a detailed description of the methods that are an essential tool for chemists, computational chemists, microbiologists, and toxicologists in the evaluation of potential novel antimicrobial compounds. These methods are cost-effective and have high predictive value. They are widely used in preclinical studies to identify new molecular candidates, for further investigation in animal and human trials.

Novel imidazo[1,2,4] triazole derivatives: Synthesis, fluorescence, bioactivity for SHP1

The Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP1) is a convergent node for oncogenic cell-signaling cascades. Consequently, SHP1 represents a potential target for drug development in cancer treatment. The development of efficient methods for rapidly tracing and modulating the SHP1 activity in complex biological systems is of considerable significance for advancing the integration of diagnosis and treatment of the related disease. Thus, we designed and synthesized a series of imidazo[1,2,4] triazole derivatives containing salicylic acid to explore novel scaffolds with inhibitory activities and good fluorescence properties for SHP1. The photophysical properties and inhibitory activities of these imidazo[1,2,4] triazole derivatives (5a-5y) against SHP1PTP were thoroughly studied from the theoretical simulation and experimental application aspects. The representative compound 5p exhibited remarkable fluorescence response (P: 0.002) with fluorescence quantum yield (QY) of 0.37 and inhibitory rate of 85.21 ± 5.17% against SHP1PTP at the concentration of 100 μM. Furthermore, compound 5p showed obvious aggregation caused quenching (ACQ) effect and had high selectivity for Fe3+ ions, good anti-interference and relatively low detection limit (5.55 μM). Finally, the cellular imaging test of compound 5p also exhibited good biocompatibility and certain potential biological imaging application. This study provides a potential way to develop molecules with fluorescent properties and bioactivities for SHP1.

Recent advances in 1,2,3- and 1,2,4-triazole hybrids as antimicrobials and their SAR: A critical review

With the widespread use and sometimes even abuse of antibiotics, the problem of bacterial resistance to antibiotics has become very serious, and it is posing a great threat to global health. Therefore, development of new antibiotics is imperative. Triazoles are five-membered, nitrogen-containing aromatic heterocyclic scaffolds, with two isomeric forms, i.e. 1,2,3-triazole and 1,2,4-triazole. Triazole-containing compounds have a wide range of biological activities such as antibacterial, antifungal, anticancer, antioxidant, antitubercular, antimalarial, anti-HIV, anticonvulsant, anti-inflammatory, antiulcer, analgesic, and etc. The bioactivities and the diversity of triazole-containing drugs have attracted wide interest in these heterocycles. Various antibiotic triazole hybrids have been developed, and most of which have shown potent antimicrobial activities. In this review, we summarized the recent advances in triazole hybrids as potential antibacterial agents and their structure-activity relationships (SARs). The information gained through SAR studies will provide further insights into the development of new triazole antimicrobials.

Chemistry and Therapeutic Aspect of Triazole: Insight into the Structure-activity Relationship

The triazole ring is a highly significant heterocycle that occurs naturally in many commodities and is a common feature in pharmaceuticals. Recently, heterocyclic compounds and their derivatives have been getting a lot of attention in medicinal chemistry because they have a lot of pharmacological and biological potential. For example, a lot of drugs have nitrogen-containing heterocyclic moieties. The triazole ring is often used as a bio-isostere of the oxadiazole nucleus. The oxygen atom in the oxadiazole nucleus is replaced by nitrogen in the triazole analogue. This article explores the pharmacological properties of the triazole moiety, including but not limited to antibacterial, analgesic, anticonvulsant, anthelmintic, anti-inflammatory, antitubercular, antimalarial, antioxidant, antiviral, and other properties. Additionally, we discuss the diverse multi- target pharmacological activities exhibited by triazole-based compounds. Based on a literature review, it is evident that triazole-based chemicals hold significant potential for various applications.

Pterostilbene pre-treatment reduces LPS-induced acute lung injury through activating NR4A1

CONTEXT

Pterostilbene (PTE), a common polyphenol compound, exerts an anti-inflammatory effect in many diseases, including acute lung injury (ALI).

OBJECTIVE

This study explores the potential mechanism of PTE pre-treatment against lipopolysaccharide (LPS)-induced ALI.

MATERIALS AND METHODS

Sixty Sprague-Dawley rats were divided into control, ALI, 10 mg/kg PTE + LPS, 20 mg/kg PTE + LPS, and 40 mg/kg PTE + LPS groups. At 24 h before LPS instillation, PTE was administered orally. At 2 h before LPS instillation, PTE was again administered orally. After 24 h of LPS treatment, the rats were euthanized. The levels of inflammatory cells and inflammatory factors in the bronchoalveolar lavage fluid (BALF), the expression of nuclear receptor subfamily 4 group A member 1 (NR4A1), and the nuclear factor (NF)-κB pathway-related protein levels were detected. NR4A1 agonist was used to further investigate the mechanism of PTE pre-treatment.

RESULTS

After PTE pre-treatment, the LPS induced inflammation was controlled and the survival rate was increased to 100% from 70% after LPS treatment 24 h. For lung injury score, it decreased to 1.5 from 3.5 after treating 40 mg/kg PTE. Compared with the control group, the expression of NR4A1 in the ALI group was decreased by 20-40%. However, the 40 mg/kg PTE pre-treatment increased the NR4A1 expression by 20-40% in the lung tissue. The results obtained with pre-treatment NR4A1 agonist were similar to those obtained by pre-treatment 40 mg/kg PTE.

CONCLUSIONS

PTE pre-treatment might represent an appropriate therapeutic target and strategy for preventing ALI induced by LPS.

Application of triazoles in the structural modification of natural products

Nature products have been extensively used in the discovery and development of new drugs, as the most important source of drugs. The triazole ring is one of main pharmacophore of the nitrogen-containing heterocycles. Thus, a new class of triazole-containing natural product conjugates has been synthesised. These compounds reportedly exert anticancer, anti-inflammatory, antimicrobial, antiparasitic, antiviral, antioxidant, anti-Alzheimer, and enzyme inhibitory effects. This review summarises the research progress of triazole-containing natural product derivatives involved in medicinal chemistry in the past six years. This review provides insights and perspectives that will help scientists in the fields of organic synthesis, medicinal chemistry, phytochemistry, and pharmacology.

Click Chemistry in Natural Product Modification

Click chemistry is perhaps the most powerful synthetic toolbox that can efficiently access the molecular diversity and unique functions of complex natural products up to now. It enables the ready synthesis of diverse sets of natural product derivatives either for the optimization of their drawbacks or for the construction of natural product-like drug screening libraries. This paper showcases the state-of-the-art development of click chemistry in natural product modification and summarizes the pharmacological activities of the active derivatives as well as the mechanism of action. The aim of this paper is to gain a deep understanding of the fruitful achievements and to provide perspectives, trends, and directions regarding further research in natural product medicinal chemistry.

Assessment of the Antibacterial Mechanism of Pterostilbene against Bacillus cereus through Apoptosis-like Cell Death and Evaluation of Its Beneficial Effects on the Gut Microbiota

Foods contaminated by harmful substances such as bacteria and viruses have caused more than 200 kinds of diseases, ranging from diarrhea to cancer. Among them, Bacillus cereus (B. cereus) is a foodborne pathogen that commonly contaminates raw meat, fresh vegetables, rice, and uncooked food. The current chemical preservatives may have adverse effects on food and even human health. Therefore, natural antibacterial agents are sought after as alternative preservatives. Stilbene compounds, including pterostilbene (PT), pinostilbene (PS), and piceatannol (PIC), which have many health benefits and exhibit antibacterial activity, were tested against B. cereus. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of PT, PS, and PIC against B. cereus ranged from 25 to 100 μg/mL. From the time-kill curve assay, PT reduced B. cereus cell survival, increased intracellular reactive oxygen species (ROS), and induced apoptosis-like cell death (ALD) in a dose-dependent manner. The quantitative real-time polymerase chain reaction (qPCR) results confirmed that treatment with PT induced genetic changes related to ALD, such as an increase in RecA gene expression and a decrease in LexA gene expression. In addition, PT showed a beneficial effect on the gut microbiota that increased the abundance of Bacteroidetes and lowered the abundance of Firmicutes. Taken together, our results showed that PT has antibacterial effects against B. cereus via ALD and is beneficial for promoting healthy gut microbiota that is worthy for the development of antibacterial agents for the food industry.

Enhancement of Anticancer Potential of Pterostilbene Derivative by Chalcone Hybridization

Pterostilbene, a natural metabolite of resveratrol, has been indicated as a potent anticancer molecule. Recently, several pterostilbene derivatives have been reported to exhibit better anticancer activities than that of the parent pterostilbene molecule. In the present study, a series of pterostilbene derivatives were designed and synthesized by the hybridization of pterostilbene, chalcone, and cinnamic acid. The cytotoxic effect of these hybrid molecules was determined using two oral cancer cell lines, HSC-3 and OECM-1. (E)-3-(2-((E)-4-Hydroxystyryl)-4,6-dimethoxyphenyl)-1-(2-methoxyphenyl)prop-2-en-1-one (4d), with IC₅₀ of 16.38 and 18.06 μM against OECM-1 and HSC-3, respectively, was selected for further anticancer mechanism studies. Results indicated that compound 4d effectively inhibited cell proliferation and induced G2/M cell cycle arrest via modulating p21, cyclin B1, and cyclin A2. Compound 4d ultimately induced cell apoptosis by reducing the expression of Bcl-2 and surviving. In addition, cleavage of PARP and caspase-3 were enhanced following the treatment of compound 4d with increased dose. To conclude, a number of pterostilbene derivatives were discovered to possess potent anticancer potentials. Among them, compound 4d was the most active, more active than the parent pterostilbene.

Triazole analogues as potential pharmacological agents: a brief review

Background

A large number of studies have recently reported that, because of their significant biological and pharmacological properties, heterocyclic compounds and their derivatives have attracted a strong interest in medicinal chemistry. The triazole nucleus is one of the most important heterocycles which has a feature of natural products as well as medicinal agents. Heterocyclic nitrogen is abundantly present in most medicinal compounds. The derivatization of triazole ring is based on the phenomenon of bio-isosteres in which substituted the oxygen atom of oxadiazole nucleus with nitrogen triazole analogue.

Main text

This review focuses on recent synthetic procedure of triazole moiety, which comprises of various pharmacological activities such as antimicrobial, anticonvulsant, anti-inflammatory, analgesic, antitubercular, anthelmintic, antioxidant, antimalarial, antiviral, etc..

Conclusion

This review highlights the current status of triazole compounds as different multi-target pharmacological activities. From the literature survey, triazole is the most widely used compound in different potential activities.

Discovery of triazolyl thalidomide derivatives as anti-fibrosis agents

Triazolyl thalidomide derivative 10e inhibits fibrogenesis by SOCE and TGF-β1/SMAD2/3 signaling pathways.

1,2,3-Triazole-containing hybrids with potential antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA), as a classic reason for genuine skin and flimsy tissues diseases, is a worldwide general wellbeing risk and has already tormented humanity for a long history, creating a critical need for the development of new classes of antibacterials. 1,2,3-Triazole moiety, readily interact with diverse enzymes and receptors in organisms through weak bond interaction, is among the most common frameworks present in the bioactive molecules. 1,2,3-Triazole derivatives, especially 1,2,3-triazole-containing hybrids, possess broad-spectrum activity against a panel of clinically important bacteria including drug-resistant pathogens, so rational design of 1,2,3-triazole derivatives may open a door for the opportunities on the development of novel anti-MRSA agents. This review is an endeavour to highlight the current scenario of 1,2,3-triazole-containing hybrids with potential anti-MRSA activity, covering articles published between 2010 and 2020.

Stilbenoids: A Natural Arsenal against Bacterial Pathogens

The escalating emergence of resistant bacterial strains is one of the most important threats to human health. With the increasing incidence of multi-drugs infections, there is an urgent need to restock our antibiotic arsenal. Natural products are an invaluable source of inspiration in drug design and development. One of the most widely distributed groups of natural products in the plant kingdom is represented by stilbenoids. Stilbenoids are synthesised by plants as means of protection against pathogens, whereby the potential antimicrobial activity of this class of natural compounds has attracted great interest in the last years. The purpose of this review is to provide an overview of recent achievements in the study of stilbenoids as antimicrobial agents, with particular emphasis on the sources, chemical structures, and the mechanism of action of the most promising natural compounds. Attention has been paid to the main structure modifications on the stilbenoid core that have expanded the antimicrobial activity with respect to the parent natural compounds, opening the possibility of their further development. The collected results highlight the therapeutic versatility of natural and synthetic resveratrol derivatives and provide a prospective insight into their potential development as antimicrobial agents.

Tellimagrandin II, A Type of Plant Polyphenol Extracted from Trapa bispinosa Inhibits Antibiotic Resistance of Drug-Resistant Staphylococcus aureus

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has become a critical global concern. Identifying new candidates of anti-S. aureus agents is urgently required because the therapeutic strategies for infected patients are limited currently. Therefore, the present study investigated whether Tellimagrandin II (TGII), a pure compound extracted from the shells of Trapa bispinosa, exhibits antibacterial effects against MRSA. We first showed that TGII exerted potent inhibitory activity against MRSA with a minimum inhibitory concentration of 128 μg/mL. The obtained fractional inhibitory concentration suggested that TGII could alone exert antistaphylococcal activity, and TGII combined with low doses of antibiotics displayed synergistic effects against MRSA. Moreover, we found that TGII exerted bactericidal activity by reducing the expression of mecA followed by the negative regulation of the penicillin-binding protein 2a (PBP2a) of MRSA. Transmission electron microscopy (TEM) images further confirmed that TGII destroyed the integrity of the cell wall of MRSA and caused the loss of cytoplasm content. In conclusion, we evidenced the antibacterial effects of TGII against MRSA, which enables the effective dose of current antibiotics to be reduced and the predicament of drug-resistant S. aureus isolates to be overcome.