Monoterpenoid indole alkaloid dimers from Kopsia arborea inhibit cyclin-dependent kinase 5 and tau phosphorylation

Phytomolecules as Alzheimer's therapeutics: A comprehensive review

Alzheimer's disease (AD) is a leading neurodegenerative disorder recognized by progressive cognitive decline and behavioral changes. The pathology of AD is characterized by the accumulation of amyloid-β (Aβ) plaques and the hyperphosphorylation of tau protein, which leads to synaptic loss and subsequent neurodegeneration. Additional contributors to disease progression include metabolic, vascular, and inflammatory factors. Glycogen synthase kinase-3β (GSK-3β) is also implicated, as it plays a crucial role in tau phosphorylation and the progression of neurodegeneration. This review provides a comprehensive analysis of various phytomolecules and their potential to target multiple aspects of AD pathology. We examined natural products from diverse classes, including stilbenes, flavonoids, phenolic acids, alkaloids, coumarins, terpenoids, chromenes, cannabinoids, chalcones, phloroglucinols, and polycyclic polyprenylated acylphloroglucinols (PPAPs). The key mechanisms of action of these phytomolecules include modulating tau protein dynamics to reduce aggregation, inhibiting acetylcholinesterase (AChE) to maintain neurotransmitter levels and enhance cognitive function, and inhibiting β-secretase (BACE1) to decrease Aβ production. Additionally, some phytomolecules were found to influence GSK-3β activity, thereby impacting tau phosphorylation and neurodegeneration. By addressing multiple targets, Aβ production, tau hyperphosphorylation, AChE activity, and GSK-3β, these natural products offer a promising multi-targeted approach to AD therapy. This review highlights their potential to develop effective treatments that not only mitigate core pathological features but also manage the complex, multifactorial aspects of AD progression.

Bioassay and NMR-HSQC-Guided Isolation and Identification of Phthalide Dimers with Anti-Inflammatory Activity from the Rhizomes of Angelica sinensis

Under the guidance of a bioactivity-guided approach and HSQC characteristic signals, nine pairs of phthalic dimers, angesilides A-I (1-9), with complex polycyclic skeletons featuring bridged, fused, and spiro ring systems were discovered from the rhizomes of Angelica sinensis. Their structures and absolute configurations were established by comprehensive spectroscopic methods, X-ray diffraction analysis, and chiral separation. Plausible biosynthetic pathway for 1-9 was proposed. Moreover, the anti-inflammatory activities of all isolates were evaluated in lipopolysaccharide (LPS) stimulated mouse leukemia cells of monocyte macrophages (RAW = 264.7). Among them, compound 9 showed a remarkable inhibitory activity with IC50 values of 425 nM and could significantly decrease IL-1β and IL-6 transcription levels. Interestingly, (+)-9 has superior NO inhibitory activity compared to that of (-)-9, which was verified by further molecular docking analysis. The findings provide new insights into A. sinensis as a functional food or for the development of new anti-inflammatory drug candidates.

Structural diversity and chemical logic underlying the assembly of monoterpene indole alkaloids oligomers

Covering: up to 2024This review aims to draw a parallel between all known oligomers of monoterpene indole alkaloids (MIAs) by illustrating the chemical logic underlying their assembly. For this purpose, oligomeric MIAs were first comprehensively listed and organized according to the names of the backbones of their constitutive monomers and the binding sites. From this extensive list, an oligomer network was generated and unprecedented MIA statistics were mined and shared herein. Subsequently, oligomeric MIAs were categorized according to the number of connections instigated between their monomeric components (single, double, triple, and mixed tethering), then subdivided according to the uniqueness or combination of oligomerization assembly reactions. This effort outlined oligomerization trends in a scaffold-specific manner, and established binding reactivity patterns facilitating the comprehension of the associated biosynthetic processes. At last, this review illustrates a unique initiative in crafting a comprehensive repository of machine-readable metadata for MIA oligomers that could be leveraged for chemoinformatic purposes.

Hypecotumines A-D, new isoquinoline alkaloids with potential PCSK9 inhibition activity from Hypecoum erectum L

Four new isoquinoline alkaloids, hypecotumines A-D (1-4), were isolated and identified from the whole herbs of Hypecoum erectum L. Their structures were determined by a combination of HRESIMS, NMR, and X-ray diffraction analysis methods. Compounds 1-4 were characterized by a terminal double bond at C-9 and their plausible biosynthetic pathway was hypothesized. Since PCSK9 plays a key role in the development of cardiovascular disease (CVD), exploration of PCSK inhibitors from natural products are beneficial for drug discovery of CVD treatment. SPR and Western blot assays showed compound 4 had PCSK9 inhibition activity with KD value of 59.9 µM and thus elevated the LDLR level. Further molecular docking studies demonstrated that 4 and PCSK9 could form stable interactions via key hydrogen bonds.

Lycocasine A, a Lycopodium Alkaloid from Lycopodiastrum casuarinoides and Its Acid-Sensing Ion Channel 1a Inhibitory Activity

A novel Lycopodium alkaloid, lycocasine A (1), and seven known Lycopodium alkaloids (2-8), were isolated from Lycopodiastrum casuarinoides. Their structures were determined through NMR, HRESIMS, and X-ray diffraction analysis. Compound 1 features an unprecedented 5/6/6 tricyclic skeleton, highlighted by a 5-aza-tricyclic[6,3,1,02,6]dodecane motif. In bioactivity assays, compound 1 demonstrated weak inhibitory activity against acid-sensing ion channel 1a.

New Monoterpenoid Indole Alkaloids from Tabernaemontana crassa Inhibit β-Amyloid42 Production and Phospho-Tau (Thr217)

Eleven monoterpenoid indole alkaloids, including three new ones, tabercrassines A-C (1-3), were isolated from the seeds of Tabernaemontana crassa. Tabercrassine A (1) is an ibogan-ibogan-type bisindole alkaloid which is formed by the polymerization of two classic ibogan-type monomers through a C3 unit aliphatic chain. Their structures were established by extensive analysis of HRESIMS, NMR, and ECD spectra. Cellular assays showed that alkaloids 1-3 all reduce Aβ42 production and inhibit phospho-tau (Thr217), a new biomarker of Alzheimer's disease [AD] associated with BACE1-, NCSTN-, GSK3β-, and CDK5-mediated pathways, suggesting these alkaloids' potential against AD.