Natural product-driven dual COX-LOX inhibitors: Overview of recent studies on the development of novel anti-inflammatory agents

Forsythia velutina Nakai extract: A promising therapeutic option for atopic dermatitis through multiple cell type modulation

BACKGROUND

Atopic dermatitis (AD) is a complex condition characterized by impaired epithelial barriers and dysregulated immune cells. In this study, we demonstrated Forsythia velutina Nakai extract (FVE) simultaneously inhibits basophils, macrophages, keratinocytes, and T cells that are closely interrelated in AD development.

METHODS

We analyzed the effect of FVE on nitric oxide and reactive oxygen species (ROS) production in macrophages, basophil degranulation, T cell activation, and tight junctions in damaged keratinocytes. Expression of cell-type-specific inflammatory mediators was analyzed, and the underlying signaling pathways for anti-inflammatory effects of FVE were investigated. The anti-inflammatory effects of FVE were validated using a DNCB-induced mouse model of AD. Anti-inflammatory activity of compounds isolated from FVE was validated in each immune cell type.

RESULTS

FVE downregulated the expression of inflammatory mediators and ROS production in macrophages through TLR4 and NRF2 pathways modulation. It significantly reduced basophil degranulation and expression of type 2 (T2) and pro-inflammatory cytokines by perturbing FcεRI signaling. Forsythia velutina Nakai extract also robustly inhibited the expression of T2 cytokines in activated T cells. Furthermore, FVE upregulated the expression of tight junction molecules in damaged keratinocytes and downregulated leukocyte attractants, as well as IL-33, an inducer of T2 inflammation. In the AD mouse model, FVE showed superior improvement in inflammatory cell infiltration and skin structure integrity compared to dexamethasone. Dimatairesinol, a lignan dimer, was identified as the most potent anti-inflammatory FVE compound.

CONCLUSION

Forsythia velutina Nakai extract and its constituent compounds demonstrate promising efficacy as a therapeutic option for prolonged AD treatment by independently inhibiting various cell types associated with AD and disrupting the deleterious link between them.

Critical review on anti-inflammation effects of saponins and their molecular mechanisms

This review highlights the increasing interest in one of the natural compounds called saponins, for their potential therapeutic applications in addressing inflammation which is a key factor in various chronic diseases. It delves into the molecular mechanisms responsible for the anti-inflammatory effects of these amphiphilic compounds, prevalent in plant-based foods and marine organisms. Their structures vary with soap-like properties influencing historical uses in traditional medicine and sparking renewed scientific interest. Recent research focuses on their potential in chronic inflammatory diseases, unveiling molecular actions such as NF-κB and MAPK pathway regulation and COX/LOX enzyme inhibition. Saponin-containing sources like Panax ginseng and soybeans suggest novel anti-inflammatory therapies. The review explores their emerging role in shaping the gut microbiome, influencing composition and activity, and contributing to anti-inflammatory effects. Specific examples, such as Panax notoginseng and Gynostemma pentaphyllum, illustrate the intricate relationship between saponins, the gut microbiome, and their collective impact on immune regulation and metabolic health. Despite promising findings, the review emphasizes the need for further research to comprehend the mechanisms behind anti-inflammatory effects and their interactions with the gut microbiome, underscoring the crucial role of a balanced gut microbiome for optimal health and positioning saponins as potential dietary interventions for managing chronic inflammatory conditions.

Edible insects as a source of biopeptides and their role in immunonutrition

Many edible insect species are attracting the attention of the food industry and consumers in Western societies due to their high content and quality of protein, and consequently, the potential to be used as a more environmentally friendly dietary source could be beneficial for humans. On the other hand, prevention of inflammatory diseases using nutritional interventions is currently being proposed as a sustainable and cost-effective strategy to improve people's health. In this regard, finding bioactive compounds such as peptides with anti-inflammatory properties from sustainable sources (e.g., edible insects) is one area of particular interest, which might have a relevant role in immunonutrition. This review aims to summarize the recent literature on the discovery of immunomodulatory peptides through in vitro studies from edible insects, as well as to describe cell-based assays aiming to prove their bioactivity. On top of that, in vivo studies (i.e., animal and human), although scarce, have been mentioned in relation to the topic. In addition, the challenges and future perspectives related to edible-insect peptides and their role in immunonutrition are discussed. The amount of literature aiming to demonstrate the potential immunomodulatory activity of edible-insect peptides is scarce but promising. Different approaches have been employed, especially cell assays and animal studies employing insect meal as supplementation in the diet. Insects such as Tenebrio molitor or Gryllodes sigillatus are some of the most studied and have demonstrated to contain bioactive peptides. Further investigations, mostly with humans, are needed in order to clearly state that peptides from edible insects may contribute to the modulation of the immune system.

Computational screening of potential anti-inflammatory leads from Jeevaneeya Rasayana plants targeting COX-2 and 5- LOX by molecular docking and dynamic simulation approaches

Inflammation plays a pivotal role in various pathological processes, ranging from routine injuries and infections to cancer. Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) are two major enzymes involved in the formation of lipid mediators of inflammation, such as prostaglandins and leukotrienes, through the arachidonic acid pathway. Despite the frequent use of nonsteroidal anti-inflammatory drugs for managing inflammatory disorders by inhibiting these enzymes, there is a wide spectrum of adverse effects linked to their usage. Jeevaneeya Rasayana (JR), a polyherbal formulation traditionally used in India, is renowned for its anti-inflammatory properties. The present study aimed to identify the potential phytocompounds in JR plants against COX-2 and 5-LOX, utilizing molecular docking and dynamic simulations. Among the 429 identified phytocompounds retrieved from publicly available data sources, Terrestribisamide and 1-(9Z-octadecenoyl)-sn-glycero-3-phosphoethanolamine have shown potential binding affinity and favorable interactions with COX-2 and 5-LOX arachidonic acid binding sites. The physicochemical properties and ADMET profiles of these compounds determined their drug-likeness and pharmacokinetics features. Additional validation using molecular dynamics simulations, SASA, Rg, and MM-PBSA binding energy calculations affirmed the stability of the complex formed between those compounds with target proteins. Together, the study identified the effectual binding potential of those bioactive compounds against COX-2 and 5-LOX, providing a viable approach for the development of effective anti-inflammatory medications.

Use of Callistemon citrinus as a gastroprotective and anti-inflammatory agent on indomethacin-induced gastric ulcers in obese rats

Background

Obesity leads to an elevated risk of developing gastrointestinal disease such as gastric ulcers. Callistemon citrinus leaf extract has shown antioxidant, antimicrobial, hepatoprotective, and chemoprotective effects against colon cancer. The aim of this study is to evaluate the gastroprotective effect of C. citrinus leaf extract on indomethacin-induced gastric ulcers in obese rats.

Methods

Gastric ulcers were induced in female obese Wistar rats using a single oral dose of indomethacin (IND). In the first stage, the rats were fed with a high fat sugar diet (HFSD) for 15 weeks to induce obesity and, at the same time, the diet of the other group of animals included daily administration of ethanolic C. citrinus leaf extract (250 mg/kg) in addition to HFSD. In the second stage, gastric ulcers were induced with IND (30 mg/kg). The gastroprotective activity of C. citrinus, the inflammatory enzyme activities, and cytokines in the stomach were determined.

Results

C. citrinus produced a reduction of gastric lesions caused by IND. Myeloperoxidase (MPO), cyclooxygenase-2 (COX-2), and 5-lipoxygenase (5-LOX) activities also decreased. Although inflammatory biomarkers such as TNFα, IL-6, AOPP, and leptin were significantly decreased by C. citrinus, adiponectin levels increased. Moreover, C. citrinus decreased weight gain and morphological and biochemical parameters.

Conclusion

The use of indomethacin in rats fed with a high fat-sugar diet increased gastric ulcers. Gastroprotective effect of C. citrinus in obese rats is attributed to the reduction of pro-inflammatory cytokines and the inflammatory enzymes.

Therapeutic potential of propolis in alleviating inflammatory response and promoting wound healing in skin burn

Burns can cause inflammation and delayed healing, necessitating alternative therapies due to the limitations of conventional treatments. Propolis, a natural bee-produced substance, has shown promise in facilitating burn healing. This literature review provides a comprehensive overview of propolis' mechanisms of action, wound-healing properties, and its application in treating skin burns. Propolis contains bioactive compounds with antimicrobial, antioxidant, and anti-inflammatory properties, making it a promising candidate for managing skin burn injuries. It helps prevent infections, neutralize harmful free radicals, and promote a well-balanced inflammatory response. Moreover, propolis aids in wound closure, tissue regeneration, collagen synthesis, cellular proliferation, and angiogenesis, contributing to tissue regeneration and remodeling. The article discusses various propolis extracts, extraction methods, chemical composition, and optimized formulations like ointments and creams for burn wound treatment. Considerations regarding dosage and safety are addressed. Further research is needed to fully understand propolis' mechanisms, determine optimal formulations, and establish suitable clinical dosages. Nevertheless, propolis' natural origin and demonstrated benefits make it a compelling avenue for burn care exploration, potentially complementing existing therapies and improving burn management outcomes.

Dual COX-2/5-LOX inhibitors from Zanthoxylum simulans inhibit gastric cancer cells by cross-mediating thyroid, estrogen, and oxytocin signaling pathways

Cyclooxygenase 2 (COX-2) and 5-lipoxygenase (5-LOX) are overexpressed in gastric cancer cells, the dual inhibitors of which exhibit potential against metastasis and invasion with fewer side effects. To discover inhibitors targeting COX-2 and 5-LOX, we conducted ultrafiltration and enrichment calculation to screen candidates in quaternary alkaloids (QAs) from Zanthoxylum simulans through LC and LC-Q-TOF. For intensive peaks, peaks 19 (berberine) and 21 (chelerythrine) were observed as the most potent dual candidates and showed selective affinity to 5-LOX over COX-2. Peak 19 showed an enrichment at 4.36 for COX-2 and 22.81 for 5-LOX, while peak 21 showed an enrichment at 7.81 for COX-2 and 24.49 for 5-LOX. Molecular docking results revealed chelerythrine as a better dual inhibitor, showing time- and dose-dependent anti-proliferation against AGS cells. Bio-informatics strategies, such as Gene Expression Omnibus (GEO), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG), suggested that hormone pathways in gastric cancer cells might be mediated by chelerythrine. Further reviews and summaries helped outline the mechanisms by which COX-2/5-LOX inhibitors might promote apoptosis in gastric cancer cells via estrogen, thyroid, and oxytocin signaling pathways. Chelerythrine was also added to gastric cancer cells to verify the regulation of these three signaling pathways. As a result, significant calling back of thyroid-stimulating hormone receptor (TSHR), thyroid hormone α3 (TRα3), and thyroid hormone receptor β1 (TRβ1) and suppressing estrogen receptor α36 (ER-α36)-Src could benefit the anti-proliferation of chelerythrine. However, it was disappointing that regulation of estrogen receptor α66 (ER-α66), estrogen receptor β (ER-β), and oxytocin receptor (OTR) contributed inversely negative effects on anti-gastric cancer cells. At present, the integrative study not only revealed chelerythrine as the most potent dual COX-2/5-LOX inhibitor from QAs but also generally highlighted that comprehensive regulation of the estrogen, thyroid, and oxytocin pathway should be noted once gastric cancer cells were treated with inflammatory inhibitors.

Development of nanostructured formulation from naringenin and silk fibroin and application for inhibition of lipoxygenase (LOX)

A simple low-energy method was used to obtain polymeric nanoparticles containing silk fibroin (SF), fatty butyl esters (oily phase) and the flavonoid naringenin. Experimental planning (Box-Behnken) was applied to investigate the optimal conditions for three factors (variation of the concentrations of SF, naringenin and fatty butyl ester) at three levels, with evaluation of particle size, polydispersity index (PDI) and zeta potential (ZP) as responses. The results showed that the polymeric particle was formed with sizes of 179.6 to 633.9 nm, PDI of 0.33 to 0.77 and ZP of -60.4 to -38.8 mV. The best responses under the optimized conditions (Nari-SF 9 and 15) were characterized through transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR), visible ultraviolet (UV-vis) and fluorescence, which confirmed that coated nanoparticles had been obtained. It was shown that the nanoformulation had excellent stability, the bioavailability of naringenin had been improved through use of the biopolymer and high inhibition of the enzyme lipoxygenase had been achieved in vitro.