New sesquiterpene and thiophene derivatives from Artemisia rupestris

Thiophenes-Naturally Occurring Plant Metabolites: Biological Activities and In Silico Evaluation of Their Potential as Cathepsin D Inhibitors

Naturally, thiophenes represent a small family of natural metabolites featured by one to five thiophene rings. Numerous plant species belonging to the family Asteraceae commonly produce thiophenes. These metabolites possessed remarkable bioactivities, including antimicrobial, antiviral, anti-inflammatory, larvicidal, antioxidant, insecticidal, cytotoxic, and nematicidal properties. The current review provides an update over the past seven years for the reported natural thiophene derivatives, including their sources, biosynthesis, spectral data, and bioactivities since the last review published in 2015. Additionally, with the help of the SuperPred webserver, an AI (artificial intelligence) tool, the potential drug target for the compounds was predicted. In silico studies were conducted for Cathepsin D with thiophene derivatives, including ADMET (drug absorption/distribution/metabolism/excretion/and toxicity) properties prediction, molecular docking for the binding interaction, and molecular dynamics to evaluate the ligand-target interaction stability under simulated physiological conditions.

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.

Chemical constituents from Artemisia rupestris and their neuraminidase inhibitory activity

Two new thiophene derivatives (1 and 2), a new sesquiterpene (3), and 15 known compounds (4-18) were isolated from the whole plants of Artemisia rupestris. The new compounds (1-3) were elucidated by extensive spectroscopic techniques including 1 D (¹H and ¹³C) and 2 D NMR experiments (COSY, HSQC, HMBC and NOESY), and HR-ESI-MS. Most of the isolates (1-6, 8, 10-18) exhibited the neuraminidase inhibitory activity with IC₅₀ values ranging from 74.07-986.54 μM by a fluorescence-based assay. Two known flavonoids (chrysosplenetin B and luteolin) showed a comparable activity to oseltamivir acid on neuraminidase inhibition.

Isoastragaloside I inhibits NF-κB activation and inflammatory responses in BV-2 microglial cells stimulated with lipopolysaccharide

The excessive activation of microglia in many neurodegenerative diseases is detrimental to neuronal survival. Isoastragaloside I (ISO I) is a natural saponin molecule found within the roots of Astragalus membranaceus, a famous traditional Chinese medicine. In the present study, the anti‑inflammatory effects and the mechanisms of action of ISO I on activated BV-2 cells stimulated with lipopolysaccharide (LPS) were investigated. ISO I dose‑dependently inhibited the excessive release of nitric oxide (NO) and tumor necrosis factor (TNF)-α in the LPS-stimulated BV-2 cells. Moreover, it decreased the production of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), and mitigated the gene expression of interleukin (IL)-1β, TNF-α and iNOS induced by LPS. Further experiments revealed that ISO I decreased the phosphorylation levels of nuclear factor-κB (NF-κB), and suppressed its nuclear translocation and transactivation activity. In addition, it inhibited the activation of signaling pathway molecules, such as PI3K, Akt and mitogen-activated protein kinases (MAPKs). Taken together, our findings suggest that ISO I prevents LPS-induced microglial activation probably by inhibiting the activation of the NF-κB via PI3K/Akt and MAPK signaling pathways, indicating its therapeutic potential for neurological diseases relevant to neuroinflammation.