Nuciferine Relaxes Tracheal Rings via the Blockade of VDLCC and NSCC Channels

Study on the vasodilatory activity of lotus leaf extract and its representative substance nuciferine on thoracic aorta in rats

Lotus (Nelumbo nucifera) leaves are widely used for both edible and medicinal applications. For its further utilization, we studied the vasodilatory activity of lotus leaf extract for the first time. In this study, we obtained the extracts using different ratios of water and ethanol, which was followed by polarity-dependent extraction. We found that the CH₂Cl₂ layer exhibited better vasodilatory activity (EC₅₀ = 1.21 ± 0.10 μg/ml). HPLC and ESI-HRMS analysis of the CH₂Cl₂ layer using the standard product as a control revealed that nuciferine (E_max = 97.95 ± 0.76%, EC₅₀ = 0.36 ± 0.02 μM) was the main component in this layer. Further research revealed that nuciferine exerts a multi-target synergistic effect to promote vasodilation, via the NO signaling pathway, K⁺ channel, Ca²⁺ channel, intracellular Ca²⁺ release, α and β receptors, etc. Nuciferine exhibits good vasodilatory activity, and it exhibits the potential to be utilized as a lead compound.

Nuciferine, an active ingredient derived from lotus leaf, lights up the way for the potential treatment of obesity and obesity-related diseases

Obesity, is an increasingly global public health problem associated complications. However, the proven anti-obesity agents are inefficient with adverse side effects; hence attention is being paid to novel drugs from natural resources to manage obesity and obesity-related diseases. Nuciferine (NF) is a high-quality aporphine alkaloid present in lotus leaf. Unlike the chemical drugs, NF elicits anti-obesity, anti-dyslipidemia, anti-hyperglycemic, anti-hypouricemic, anti-inflammatory, and anti-tumor effects, and affinity to neural receptors, and protection against obesity-related diseases. The underlying mechanism of NF includes the regulation of targeted molecules and pathways related to metabolism, inflammation, and cancer and modulation of Ca²⁺ flux, gut microbiota, and ferroptosis. Besides, the clinical application, availability, pharmacokinetics, pharmaceutics, and security of NF have been established, highlighting the potential of developing NF as an anti-obesity agent. Therefore, this review provides a comprehensive summarization, which sheds light on future research in NF.

Natural Aporphine Alkaloids with Potential to Impact Metabolic Syndrome

The incidence and prevalence of metabolic syndrome has steadily increased worldwide. As a major risk factor for various diseases, metabolic syndrome has come into focus in recent years. Some natural aporphine alkaloids are very promising agents in the prevention and treatment of metabolic syndrome and its components because of their wide variety of biological activities. These natural aporphine alkaloids have protective effects on the different risk factors characterizing metabolic syndrome. In this review, we highlight the activities of bioactive aporphine alkaloids: thaliporphine, boldine, nuciferine, pronuciferine, roemerine, dicentrine, magnoflorine, anonaine, apomorphine, glaucine, predicentrine, isolaureline, xylopine, methylbulbocapnine, and crebanine. We particularly focused on their impact on metabolic syndrome and its components, including insulin resistance and type 2 diabetes mellitus, endothelial dysfunction, hypertension and cardiovascular disease, hyperlipidemia and obesity, non-alcoholic fatty liver disease, hyperuricemia and kidney damage, erectile dysfunction, central nervous system-related disorder, and intestinal microbiota dysbiosis. We also discussed the potential mechanisms of actions by aporphine alkaloids in metabolic syndrome.

In vitro and in vivo relaxation and anti-inflammation of natural flavonoids from Elaeagnus pungens leaf via L-type calcium channel and targeting MAPK signal pathway

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine (TCM), the leaf of Elaeagnus pungens Thunb. (Family Elaeagnaceae) is a herb documented as an antiasthmatic remedy to treat the severe asthma, bronchitis and other respiratory diseases in the early material medica "Bencao Gangmu" (Ming dynasty, about 442 years ago).

AIM OF THE STUDY

This work is purposed to investigate the pharmacological effects and mechanism of total flavonoids from Elaeagnus pungens leaves (FLA) on asthma in vivo and vitro.

MATERIALS AND METHODS

Female BALB/c mice were sensitized by intraperitoneal injection of OVA with aluminum hydroxide and intranasal challenged with OVA. After treatment with FLA (10, 20 mg/kg p.o.), the behaviors of mice were observed by score evaluation. Enumeration of total cells and OVA-specific IgE assay in the blood were measured as well as enumeration of total cells and cytokines assay in the BALF. Furthermore, histopathological analysis was performed by HE staining. The in vitro relaxing action on muscle force of FLA (0.0316-10.0 mg/ml) was evaluated using isometric tension in tracheal rings, and VDLCC currents were recorded to explore the relaxation mechanism in the isolated tracheal rings and mouse ASM cells, respectively. In vitro anti-inflammatory actions were assessed with LPS-stimulated RAW 264.7 macrophages. The production of inflammatory mediators and MAPK signaling pathway was estimated using ELISA and Western blotting analysis, respectively.

RESULTS

The high dose of flavones from E. pungens leaf (20 mg/kg) can significantly improve the symptom of asthma breakout and relieve the lung swelling. FLA treatment decreased eosinophils and leukocytes numbers in blood and BLAF with a dosedependent manner. Furthermore, the inhibiting effect of FLA on the level of Ig E and inflammatory-related cytokines including TNF-α, IL-5 showed dose-independent. FLA relaxed high K + -induced contraction in a dose-dependent manner. The maximal relaxation produced by FLA was 99.7% (IC 50 = 0.46 mg/ml). The whole-cell VDLCC currents were abolished by FLA (3.16 mg/ml) and FLA significantly decreased the maximal amplitude of VDLCCs. No cytotoxic effect of FLA was observed in RAW264.7 cells under the tested concentrations (1-300 μg/mL). The increased IL-6 and NO by the stimulation of LPS in RAW264.7 cells were significantly inhibited by FLA in the dosedependent manner. Treatment with LPS in the presence of FLA, LPS-induced phosphorylation of ERK1/2 and JNK was inhibited in the macrophages.

CONCLUSION

FLA from Elaeagnus pungens leaf can alleviate the inflammation symptom via reducing the eosinophils and leukocytes numbers as well as the production of pro-inflammatory cytokines. This anti-inflammatory effect is related to the modulation of the MAPK signaling pathway. FLA can relax the precontracted TRs by blocking the VDLCCs, which interrupts extracellular Ca 2+ influx and inhibit the rise of [Ca 2+ ]i. It strongly suggests that these flavonoids components are the substances basis of Elaeagnus pungens leaves for allergic action, bronchospasm and inflammation in asthma.

Relaxant Action of Diclofenac Sodium on Mouse Airway Smooth Muscle

Diclofenac sodium (DCF) is a nonsteroidal anti-inflammatory drug (NSAID) and is widely used as an analgesic and anti-inflammatory agent. Herein, we found that DCF could relax high K⁺ (80 mM K⁺)-/ACh-precontracted tracheal rings (TRs) in mice. This study aimed to elucidate the underlying mechanisms of DCF-induced relaxations. The effects of DCF on airway smooth muscle (ASM) cells were explored using multiple biophysiological techniques, such as isometric tension measurement and patch-clamping experiments. Both high K⁺- and ACh-evoked contraction of TRs in mice were relaxed by DCF in a dose-dependent manner. The results of isometric tension and patch-clamping experiments demonstrated that DCF-induced relaxation in ASM cells was mediated by cytosolic free Ca²⁺, which was decreased via inhibition of voltage-dependent L-type Ca²⁺ channels (VDLCCs), nonselective cation channels (NSCCs), and Na^+/Ca²⁺ exchange. Meanwhile, DCF also enhanced large conductance Ca²⁺ activated K⁺ (BK) channels, which led to the relaxation of ASMs. Our data demonstrated that DCF relaxed ASMs by decreasing the intracellular Ca²⁺ concentration via inhibition of Ca²⁺ influx and Na⁺/Ca²⁺ exchange. Meanwhile, the enhanced BK channels also played a role in DCF-induced relaxation in ASMs. These results suggest that DCF is a potential candidate for antibronchospasmic drugs used in treating respiratory diseases such as asthma and chronic obstructive pulmonary disease.