Potential anti-neuroinflammatory triterpenoids isolated from Chinese acorns (Quercus serrata var. brevipetiolata)

Ilexchinene, a new seco-ursane triterpenoid from the leaves of Ilex chinensis with therapeutic effect on neuroinflammation by attenuating the MAPK/NF-κB signaling pathway

BACKGROUND

Neuroinflammation is a vital factor participating in the whole pathogenetic process of diverse neurodegenerative disorders, but accessible clinical drugs are still insufficient due to their inefficacy and side effects. Triterpenoids are reported to possess potential anti-neuroinflammatory activities, and the leaves of Ilex chinensis are a commonly used herbal medicine containing many ursane-type and oleanane-type triterpenoids. However, the novel triterpenoids from I. chinensis and their underlying mechanisms are still elusive.

PURPOSE

To isolate novel seco-ursane triterpenoids with anti-neuroinflammatory effects from the leaves of I. chinensis and reveal their underlying mechanisms.

STUDY DESIGN AND METHODS

The novel compound was purified by column chromatography and identified by comprehensive spectroscopic experiments. The LPS-induced BV-2 cell model and LPS-induced acute murine brain inflammation model were used to assess the anti-neuroinflammatory effect of the structure and further understand its underlying mechanisms by cell viability, ELISA, Western blot analysis, qRT‒PCR analysis, behavior analysis, H&E staining, and immunofluorescence staining experiments.

RESULTS

Ilexchinene is a novel ursane-type triterpenoid with a rare 18,19-seco-ring skeleton that was first isolated and identified from I. chinensis. Ilexchinene evidently reduced the overexpression of inflammatory substances in vitro. A mechanistic study suggested that ilexchinene could decrease NF-κB activation to prevent the formation of the NLRP3 inflammasome in the early neuroinflammatory response; in addition, it could prevent the phosphorylation of ERK and JNK. In vivo, ilexchinene remarkably improved LPS-induced mouse behavioral deficits and diminished the number of overactivated microglial cells. Furthermore, ilexchinene evidently diminished the overexpression of inflammatory substances in mouse brains. A mechanistic study confirmed that ilexchinene markedly suppressed the MAPK/NF-κB pathway to relieve the neuroinflammatory response.

CONCLUSION

We identified a novel 18,19-seco-ursane triterpenoid from the leaves of I. chinensis and revealed its underlying mechanism of neuroinflammation for the first time. These findings suggest that ilexchinene might possess promising therapeutic effects in neuroinflammation.

Pentacyclic Triterpenoid Saponins, Poterinasides A-J, from Silverweed Cinquefoil Roots Promising Hepatoprotective and Anti-inflammatory Agents

Silverweed cinquefoil roots, as dietary supplements, foods, and medicines, are widely used in western areas of China, specifically in Tibet Autonomous Region and Gansu and Qinghai Provinces. In this paper, 10 new natural pentacyclic triterpenoid saponins (1-10), named poterinasides A-J, along with 14 known compounds (11-24) were isolated and purified from silverweed cinquefoil roots. The chemical structures of 1-10 were established by extensive analysis of 1D and 2D NMR data and mass spectrometric data. Poterinasides A (1), B (2), and G (7) with the unique position of substituents on the E ring had never been discovered in natural products before. Saponins 1-8, 14, and 22 displayed potent hepatoprotective activities, and 1-8, 10, 11, 14, 16, 19, and 22-24 showed outstanding anti-inflammatory effects. On the basis of the present results, some structure-activity relationships were summarized, in which 3α-OH, 19β-CH₃, 20α-CH₃, 20β-CH₃, 21α-OH, and 30-OH groups in isolated pentacyclic triterpenoid saponins were found to strengthen the hepatoprotective and anti-inflammatory activities, respectively. Further, the following pharmacophore-based virtual screening and docking studies on special targets proteins, SIRT1 and COX-2, revealed roughly similar results with the structure-activity relationships, and this combination method was used for the first time for active natural compound screening.

Natural Terpenoids as Neuroinflammatory Inhibitors in LPS-stimulated BV-2 Microglia

Neuroinflammation is a typical feature of many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Microglia, the resident immune cells of the brain, readily become activated in response to an infection or an injury. Uncontrolled and overactivated microglia can release pro-inflammatory and cytotoxic factors and are the major culprits in neuroinflammation. Hence, research on novel neuroinflammatory inhibitors is of paramount importance for the treatment of neurodegenerative diseases. Bacterial lipopolysaccharide, widely used in the studies of brain inflammation, initiates several major cellular activities that critically contribute to the pathogenesis of neuroinflammation. This review will highlight the progress on terpenoids, an important and structurally diverse group of natural compounds, as neuroinflammatory inhibitors in lipopolysaccharidestimulated BV-2 microglial cells over the last 20 years.

Acorn flour properties depending on the production method and laboratory baking test results: A review

Acorns, the fruit of the oak, have long been an important source of food in different cultures around the world. Despite their long culinary tradition, they have become under-appreciated. Due to their high starch content, acorns are mainly used for flour production, and acorn flour is considered as a replacement for cereal flour in a wide range of applications in food production. This study reviewed the published literature concerning acorn flour production and composition as well as the possibility of using acorn flour in the most popular flour-based products such as bread, cake, and cookies. The study also presents the advantages resulting from acorn flour incorporation to the human diet and acorn flour influence on the quality of bread and pastry products. This review found that acorn flour is characterized by a lack of gluten proteins and a high content of fiber and minerals as well as the presence of polyphenols with antioxidant properties. However, negative impact of its larger amount on the dough rheological features and product physical properties has been emphasized in many studies. The researchers recommend the incorporation of acorn flour up to a level of 15% in formulating composite flour for bread production. However, the literature data indicates that acorn flour substitution for pastry production depends on the product type and ranges from 10 to even 60%. It is also highlighted that the application of acorn flour into gluten-free products is particularly favorable from a nutritional point of view.

Medicinal Uses, Phytochemistry, and Pharmacological Activities of Quercus Species

Quercus species, also known as oak, represent an important genus of the Fagaceae family. It is widely distributed in temperate forests of the northern hemisphere and tropical climatic areas. Many of its members have been used in traditional medicine to treat and prevent various human disorders such as asthma, hemorrhoid, diarrhea, gastric ulcers, and wound healing. The multiple biological activities including anti-inflammatory, antibacterial, hepatoprotective, antidiabetic, anticancer, gastroprotective, antioxidant, and cytotoxic activities have been ascribed to the presence of bioactive compounds such as triterpenoids, phenolic acids, and flavonoids. This paper aimed to provide available information on the medicinal uses, phytochemicals, and pharmacology of species from Quercus. However, further investigation is needed to fully clarify the mode of action of its bioactive compounds and to evaluate in vivo chronic toxicity, before exploring their potential use as a supplement in functional foods and natural pharmaceutics.

Anti-neuroinflammatory triterpenoids from the seeds of Quercus serrata Thunb

The seeds of Quercus serrata Thunb. (acorns) have been served as a healthy food in Asia. In this study, five previously undescribed triterpenoids, along with nineteen known triterpenoids were isolated from acorns. Their structures were identified on account of spectroscopic analysis and GC-MS analysis after acid hydrolysis. Meanwhile, the inhibitory effects on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in microglia cells (BV-2) of the identified triterpenoids were evaluated. All these compounds revealed overt anti-neuroinflammatory activity expect for 7. Compounds 1, 16 and 17 had potent inhibitory effects on protein and mRNA expression of iNOS and COX-2 in LPS-induced BV-2 cells. Bioactive triterpenoids 1, 2, 16 and 17 could block LPS-induced NF-κB nuclear translocation. This study suggested that acorns could be served as natural healthy product against neuroinflammatory-associated diseases, such as Alzheimer's disease.

Downregulating NF-κB signaling pathway with triterpenoids for attenuating inflammation: in vitro and in vivo studies

Two triterpenoids from Acanthopanax trifoliatus, an edible medicinal plant from Southeast Asia, attenuated lipopolysaccharides-induced inflammation in murine macrophage RAW246.7 cells and tetradecanoylphorbolacetate-induced mouse ear edema.