Bioactive Compounds from Polygala tenuifolia and Their Inhibitory Effects on Lipopolysaccharide-Stimulated Pro-inflammatory Cytokine Production in Bone Marrow-Derived Dendritic Cells

Phytochemical determination and mechanistic investigation of Polygala tenuifolia root (Yuanzhi) extract for bronchitis: UPLC-MS/MS analysis, network pharmacology and in vitro/in vivo evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

Bronchitis is a respiratory disease characterized by a productive cough. Polygala tenuifolia Willd., commonly known as Yuan zhi, is a traditional Chinese herbal medicine used for relieving cough and removing phlegm. Despite its historical use, studies are lacking on the effectiveness of P. tenuifolia in treating bronchitis. Furthermore, the molecular mechanisms underlying the action of its bioactive compounds remain unknown.

AIM OF THE STUDY

This study aims to identify the main bioactive compounds responsible for the effects of P. tenuifolia liquid extract (PLE) in treating bronchitis and to elucidate the associated molecular mechanisms.

MATERIALS AND METHODS

The main chemical compounds in PLE were identified and determined using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The antitussive, expectorant and anti-inflammatory activities of PLE were evaluated in an ammonia-induced mouse cough model, a tracheal phenol red excretion mouse model, and a xylene-induced ear swelling mouse model, respectively. A network pharmacology analysis was conducted to investigate the associated gene targets, gene ontology, and KEGG pathways related to the main bioactives in PLE targeting bronchitis. PLE and its five bioactive compounds were assessed for their potential anti-inflammatory activities in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Western blot analysis was conducted to elucidate the associated molecular mechanisms.

RESULTS

Thirty-seven compounds in PLE were identified, and twelve main compounds were further quantified in PLE using UPLC-MS/MS. PLE oral gavage administrations (0.6 and 0.12 mg/kg) for 7 days markedly reduced cough frequency, prolonged latency period of cough, reduced phlegm and inflammation in mice. The network pharmacology analysis identified 57 gene targets of PLE against bronchitis. The PI3K/AKT and MAPK signalling pathways were the top two modulated pathways. In RAW264.7 cells, PLE (12.5-50 μg/mL) significantly reduced cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α. PLE downregulated LPS-elevated protein targets in both PI3K/AKT and MAPK signaling pathways. In PLE, tenuifolin, polygalaxanthone ⅠⅠⅠ, polygalasaponin ⅩⅩⅤⅢ, tenuifoliside B, and 3,6'-Disinapoyl sucrose, were identified as the top five core components responsible for treating bronchitis. These compounds were also found to modulate the protein targets in the PI3K/AKT and MAPK signalling pathways.

CONCLUSIONS

This study demonstrated the potential therapeutic effects of PLE on bronchitis by reducing cough, phlegm and inflammation. The anti-inflammatory action and molecular mechanisms of the 5 main bioactive compounds in PLE were partly validated through the in vitro assays. The findings provide valuable insights into the mechanisms underlying the traditional use of PLE for bronchitis.

Two New Steroidal Saponins with Potential Anti-Inflammatory Effects from the Aerial Parts of Gnetum formosum Markgr

Gnetum formosum Markgr., a member of the Gnetaceae family, is distributed in Vietnam. This plant remains a botanical enigma with an unexplored diversity of chemical constituents and pharmacological effects. In this study, two new steroidal saponins, namely gnetumosides A (1) and B (2), were isolated from the aerial parts of G. formosum. Their chemical structures were elucidated using spectroscopic techniques, including high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) and NMR, along with chemical hydrolysis and comparison with the reported literature. The potential anti-inflammatory effects of the isolated compounds were evaluated by measuring lipopolysaccharide-stimulated nitric oxide (NO) production in murine macrophage cells. Notably, compound 1 exhibited the most potent inhibitory activity (IC50 = 14.10 ± 0.75 µM), comparable to dexamethasone. Additionally, the mechanisms underlying the observed anti-inflammatory effects were investigated through molecular docking and molecular dynamics simulations on inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins. This study is the first to investigate the chemical constituents and pharmacological effects of G. formosum.

Saponin components in Polygala tenuifolia as potential candidate drugs for treating dementia

Objective

This study aims to elucidate the intervention effects of saponin components from Polygala tenuifolia Willd (Polygalaceae) on dementia, providing experimental evidence and new insights for the research and application of saponins in the field of dementia.

Materials and Methods

This review is based on a search of the PubMed, NCBI, and Google Scholar databases from their inception to 13 May 2024, using terms such as "P. tenuifolia," "P. tenuifolia and saponins," "toxicity," "dementia," "Alzheimer's disease," "Parkinson's disease dementia," and "vascular dementia." The article summarizes the saponin components of P. tenuifolia, including tenuigenin, tenuifolin, polygalasaponins XXXII, and onjisaponin B, as well as the pathophysiological mechanisms of dementia. Importantly, it highlights the potential mechanisms by which the active components of P. tenuifolia prevent and treat diseases and relevant clinical studies.

Results

The saponin components of P. tenuifolia can reduce β-amyloid accumulation, exhibit antioxidant effects, regulate neurotransmitters, improve synaptic function, possess anti-inflammatory properties, inhibit neuronal apoptosis, and modulate autophagy. Therefore, P. tenuifolia may play a role in the prevention and treatment of dementia.

Conclusion

The saponin components of P. tenuifolia have shown certain therapeutic effects on dementia. They can prevent and treat dementia through various mechanisms.

Acetylcholinesterase inhibition studies of alkaloid components from Crinum asiaticum var. sinicum: in vitro assessments by molecular docking and molecular dynamics simulations

Alkaloids are among the most important and best-known secondary metabolites as sources of new drugs from medicinal plants and marine organisms. A phytochemical investigation of the whole plant of Crinum asiaticum var. sinicum resulted in the isolation of seven alkaloids (1-7), including one new dimeric compound, bis-(-)-8-demethylmaritidine (1). Their structures were elucidated using NMR and HR-ESI-MS. The absolute configuration of new compound 1 was established by circular dichroism spectroscopy. All isolated compounds were evaluated for their inhibitory effects on acetylcholinesterase (AChE) activity in vitro. Among them, compound 1 exhibited the most potent AChE inhibition. Moreover, molecular docking and molecular dynamics simulations were carried out for the most active compound to investigate their binding interactions and dynamics behavior of the AChE protein-ligand complex. Therefore, compound 1 may be a potential candidate for effectively treating Alzheimer's disease.

Comparative phytochemical studies on the roots of Polygala azizsancarii and P. peshmenii and neuroprotective activities of the two xanthones

Six known sucrose mono-, di- and triesters and five xanthone derivatives were isolated from the roots of Polygala peshmenii Eren, Parolly, Raus & Kürschner which is a narrow species endemic to Türkiye. Among the xanthones, 1,7-dihydroxy-2,3-methylenedioxy-5,6-dimethoxy-xanthone is an undescribed compound isolated for the first time from a natural source. The studies on the roots of P. azizsancarii Dönmez have resulted in the isolation of four known compounds including sucrose mono-, di- and triesters. The structures of the sucrose esters and xanthones isolated from P. azizsancarii and P. peshmenii were established by spectroscopic methods, including 1D-NMR (¹H NMR, ¹³C NMR, DEPT-135), 2D-NMR (COSY, NOESY, HSQC, HMBC). Neuroprotective activities of two xanthones, 1,3,6-trihydroxy-2,5,7-trimethoxyxanthone and 3-O-β-D-glucopyranosyloxy-1,6-dihydroxy-2,5,7-trimethoxyxanthone isolated from the roots of P. azizsancarii were evaluated in vitro using in a cellular model of Alzheimer's disease. SKNAS human neuroblastoma cells were used in the study and treated with different consecrations of Aβ₂₅₋₃₅ oligomer for up to 48 h. Cell viability was evaluated using MTT assay. The distribution of β-amyloid, α-synuclein, tau, JAK2, STAT3, caspase 3 and BMP-2 were investigated using indirect immunoperoxidase staining. Our results suggested that both xanthones control tau aggregation with no effect on β-amyloid plaque formation. In addition, for neuronal pathophysiology in AD cell model, decreased distributions of JAK/STAT3 and BMP2 signaling pathways were demonstrated, therefore they play a role in the protective effect on neurons in neurodegenerative disease. A significant decrease in caspase 3 immunoreactivity was detected after the administration of both compounds in AD cells. Therefore, both compounds control neuronal pathophysiology and rescue cell death in AD disease.

Xanthones and Xanthone O-β-D-glucosides from the Roots of Polygala azizsancarii Dönmez

Nine xanthone derivatives (1-9) were isolated from the roots of Polygala azizsancarii, which is a narrow endemic species for the flora of Türkiye. Based on all of the evidence, the structures of 1-9 were established as two previously undescribed xanthone O-glucosides, 3-O-β-D-glucopyranosyloxy-1,6-dihydroxy-2,5,7-trimethoxyxanthone (1), 3-O-β-D-glucopyranosyloxy-1,6-dihydroxy-2,7-dimethoxyxanthone (2), and seven previously described xanthones, 1,3,6-trihydroxy-2,5,7-trimethoxyxanthone (3), 1,3,6-trihydroxy-2,7-dimethoxyxanthone (4), 1,2,3,4,7-pentamethoxyxanthone (5), 1,3-dihydroxy-2,5,6,7-tetramethoxyxanthone (6), 1,3-dihydroxy-4,7-dimethoxyxanthone (7), 1,7-dihydroxy-3-methoxyxanthone (8), 1,7-dihydroxy-2,3-methylenedioxy-xanthone (9). The structures of the compounds were determined by spectroscopic methods, including 1D-NMR (1H NMR, 13C NMR, DEPT-135), 2D-NMR (COSY, NOESY, HSQC, HMBC, INADEQUATE), and HRMS. The solid-state structures of 1-4, including the absolute configurations of the stereogenic carbons of the sugar moiety in 1 and 2, were established by X-ray crystal-structure analyses. For the newly described compounds, the trivial names sancarosides A (1) and B (2) are proposed.

Isolation, Characterization and In Silico Studies of Secondary Metabolites from the Whole Plant of Polygala inexpectata Peşmen & Erik

Polygala species are frequently used worldwide in the treatment of various diseases, such as inflammatory and autoimmune disorders as well as metabolic and neurodegenerative diseases, due to the large number of secondary metabolites they contain. The present study was performed on Polygala inexpectata, which is a narrow endemic species for the flora of Turkey, and resulted in the isolation of nine known compounds, 6,3'-disinapoyl-sucrose (1), 6-O-sinapoyl,3'-O-trimethoxy-cinnamoyl-sucrose (tenuifoliside C) (2), 3'-O-(O-methyl-feruloyl)-sucrose (3), 3'-O-(sinapoyl)-sucrose (4), 3'-O-trimethoxy-cinnamoyl-sucrose (glomeratose) (5), 3'-O-feruloyl-sucrose (sibiricose A5) (6), sinapyl alcohol 4-O-glucoside (syringin or eleutheroside B) (7), liriodendrin (8), and 7,4'-di-O-methylquercetin-3-O-β-rutinoside (ombuin 3-O-rutinoside or ombuoside) (9). The structures of the compounds were determined by the spectroscopic methods including 1D-NMR (¹H NMR, ¹³C NMR, DEPT-135), 2D-NMR (COSY, NOESY, HSQC, HMBC), and HRMS. The isolated compounds were shown in an in silico setting to be accommodated well within the inhibitor-binding pockets of myeloperoxidase and inducible nitric oxide synthase and anchored mainly through hydrogen-bonding interactions and π-effects. It is therefore plausible to suggest that the previously established anti-inflammatory properties of some Polygala-derived phytochemicals may be due, in part, to the modulation of pro-inflammatory enzyme activities.

Inhibitory Activity of 4-O-Benzoyl-3'-O-(OMethylsinapoyl) Sucrose from Polygala tenuifolia on Escherichia coliβ-Glucuronidase

Bacterial β-glucuronidase in the intestine is involved in the conversion of 7-ethyl-10- hydroxycamptochecin glucuronide (derived from irinotecan) to 7-ethyl-10-hydroxycamptothecin, which causes intestinal bleeding and diarrhea (side effects of anti-cancer drugs). Twelve compounds (1-12) from Polygala tenuifolia were evaluated in terms of β-glucuronidase inhibition in vitro. 4-O-Benzoyl-3'-O-(O-methylsinapoyl) sucrose (C3) was highly inhibitory at low concentrations. C3 (an uncompetitive inhibitor) exhibited a k_i value of 13.4 μM; inhibitory activity increased as the substrate concentration rose. Molecular simulation revealed that C3 bound principally to the Gln158-Tyr160 enzyme loop. Thus, C3 will serve as a lead compound for development of new β- glucuronidase inhibitors.

Inhibitory Effects of Cucurbitane-Type Triterpenoids from Momordica charantia Fruit on Lipopolysaccharide-Stimulated Pro-Inflammatory Cytokine Production in Bone Marrow-Derived Dendritic Cells

The bitter melon, Momordica charantia L., was once an important food and medicinal herb. Various studies have focused on the potential treatment of stomach disease with M. charantia and on its anti-diabetic properties. However, very little is known about the specific compounds responsible for its anti-inflammatory activities. In addition, the in vitro inhibitory effect of M. charantia on pro-inflammatory cytokine production by lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells (BMDCs) has not been reported. Phytochemical investigation of M. charantia fruit led to the isolation of 15 compounds (1-15). Their chemical structures were elucidated spectroscopically (one- and two-dimensional nuclear magnetic resonance) and with electrospray ionization mass spectrometry. The anti-inflammatory effects of the isolated compounds were evaluated by measuring the production of the pro-inflammatory cytokines interleukin IL-6, IL-12 p40, and tumor necrosis factor α (TNF-α) in LPS-stimulated BMDCs. The cucurbitanes were potent inhibitors of the cytokines TNF-α, IL-6, and IL-12 p40, indicating promising anti-inflammatory effects. Based on these studies and in silico simulations, we determined that the ligand likely docked in the receptors. These results suggest that cucurbitanes from M. charantia are potential candidates for treating inflammatory diseases.