Isolation of long-chain esters from the rhizome of Polygonatum verticillatum by potent tyrosinase inhibition

A New Ceramide from Cissus Aralioides Baker (Vitaceae) and its Antimicrobial Activity

Purification through repeated column chromatography over silica gel and Sephadex LH-20 of the ethanol extract of the stems of Cissus aralioides (Baker) Planch. resulted in the isolation of a new ceramide, aralioidamide A (1), along with five known compounds (2-6). Their structures were determined by the extensive analyses of their spectroscopic (1D and 2D NMR) and spectrometric data, and comparison with those reported in the literature. Aralioidamide A (1) displayed weak antibacterial activity (MIC=256 μg/mL) against Bacillus subtilis, Staphylococcus aureus and Shigella flexneri and was inactive (MIC>256 μg/mL) against the tested fungi.

Mechanistic insights and perspectives involved in neuroprotective action of quercetin

Neurodegenerative diseases (NDDs) are the primary cause of disabilities in the elderly people. Growing evidence indicates that oxidative stress, mitochondrial dysfunction, neuroinflammation and apoptosis are associated with aging and the basis of most neurodegenerative disorders. Quercetin is a flavonoid with significant pharmacological effects and promising therapeutic potential. It is widely distributed among plants and typically found in daily diets mainly in fruits and vegetables. It shows a number of biological properties connected to its antioxidant activity. Neuroprotection by quercetin has been reported in many in vitro as well as in in vivo studies. However, the exact mechanism of action is still mystery and similarly there are a number of hypothesis exploring the mechanism of neuroprotection. Quercetin enhances neuronal longevity and neurogenesis by modulating and inhibiting wide number of pathways. This review assesses the food sources of quercetin, its pharmacokinetic profile, structure activity relationship and its pathophysiological role in various NDDs and it also provides a synopsis of the literature exploring the relationship between quercetin and various downstream signalling pathways modulated by quercetin for neuroprotection for eg. nuclear factor erythroid 2-related factor 2 (Nrf2), Paraoxonase-2 (PON2), c-Jun N-terminal kinase (JNK), Tumour Necrosis Factor alpha (TNF-α), Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha (PGC-1α), Sirtuins, Mitogen-activated protein kinases (MAPKs) signalling cascades, CREB (Cyclic AMP response element binding protein) and Phosphoinositide 3- kinase(PI3K/Akt). Therefore, the aim of the present review was to elaborate on the cellular and molecular mechanisms of the quercetin involved in the protection against NDDs.

Neuroprotective Effects of Quercetin in Alzheimer's Disease

Quercetin is a flavonoid with notable pharmacological effects and promising therapeutic potential. It is widely distributed among plants and found commonly in daily diets predominantly in fruits and vegetables. Neuroprotection by quercetin has been reported in several in vitro studies. It has been shown to protect neurons from oxidative damage while reducing lipid peroxidation. In addition to its antioxidant properties, it inhibits the fibril formation of amyloid-β proteins, counteracting cell lyses and inflammatory cascade pathways. In this review, we provide a synopsis of the recent literature exploring the relationship between quercetin and cognitive performance in Alzheimer's disease and its potential as a lead compound in clinical applications.

Phytochemical analysis, antibacterial, and antifungal assessment of aerial parts of Polygonatumverticillatum

The current study was designed to assess the phytochemical profile, antibacterial, and antifungal activities of the crude methanol extract of the aerial parts of Polygonatum verticillatum (PA) and its various subsequent solvent fractions using agar well diffusion, agar tube dilution, and microdilution methods. Phytochemical analysis showed positive for different chemical groups and also contained marked quantity of saponin and flavonoid contents. Significant antibacterial activity was observed against various tested pathogenic bacteria. The only susceptible Gram-positive bacterium was Bacillus subtilis and their minimum inhibitory concentrations (MICs) measured ranged from 11–50 µg/ml. The sensitive Gram-negative bacteria were Salmonella typhi and Shigella flexeneri. The estimated MICs were in the range of 2–7 µg/ml and 8–50 µg/ml for S. typhi and S. flexeneri, respectively. However, the antifungal activity of the plant was limited to Microsporum canis and their MICs ranged from 60 to 250 µg/ml. Our study confirmed significant antibacterial potential of the plant and substantiated its folk use in dysentery and pyrexia of multiple origins.

Antispasmodic and antidiarrheal activities of rhizomes of Polygonatum verticillatum maneuvered predominately through activation of K⁺ channels: Components identification through TLC

Polygonatum verticillatum has traditionally been used for various purposes. The present study was aimed to validate the antispasmodic and antidiarrheal properties of crude methanolic extract of rhizomes of P. verticillatum (PR). Isolated rabbit jejunum preparations were suspended in tissue baths to measure the isotonic responses using Power Lab data acquisition system for the antispasmodic activity of PR, while the antidiarrheal activity was conducted in vivo in mice. PR caused complete relaxation of the spontaneous contractions of isolated rabbit jejunum preparations in a dose-dependent mode. A complete inhibition was observed against low potassium (K(+); 25 mM)-induced contractions, while the plant extract partially inhibited the high K(+)(80 mM)-induced contractions. From a mechanistic point of view, the spasmolytic effect of PR against low K(+)was antagonized by glibenclamide similar to the effect of cromakalim, thus showing the presence of constituents in PR mediating spasmolytic activity predominantly through the activation of adenosine triphosphate-sensitive K(+)channels. When tested against castor oil-induced diarrhea in mice, oral administration of the plant extract manifested marked antidiarrheal activity at the doses of 500 and 1000 mg/kg similar to loperamide. This study provided a pharmacological basis for the medicinal use of PR in abdominal colic and diarrhea.

Antioxidant profile of constituents isolated from Polygonatum verticillatum rhizomes

The purpose of the current study was to estimate the antioxidant profile of two compounds, diosgenin and santonin, isolated from Polygonatum verticillatum rhizomes. Stable free radical, 2, 2-diphenyl-1-picrylhydrazyl and reducing power assays were employed for this purpose. The results showed profound free radical scavenging effect of both diosgenin and santonin in a concentration-dependent manner. The calculated half maximal inhibitory concentration (IC50) values for both diosgenin and santonin was 65.80 and 50.03 μg/ml, respectively. Similarly, in reducing power assay, diosgenin and santonin exhibited marked quenching effect. The corresponding IC50 values for both the compounds were 62.10 and 46.40 μg/ml, respectively. In conclusion, both the isolated compounds have strong antioxidant potential, which is consistent with the results of the extracts of the plant.

Studies on tracheorelaxant and anti-inflammatory activities of rhizomes of Polygonatum verticillatum

Background

The present study describes the tracheorelaxant and anti-inflammatory effects of Polygonatum verticillatum which may support its medicinal use in hyperactive airway complaints and inflammatory disorders.

Methods

The tracheorelaxant activity of crude extract of the rhizomes of P. verticillatum (PR) was assessed in isolated guinea-pig tracheal tissues immersed in tissue organ bath filled with Tyrode’s solution and a continuous supply of carbogen gas (95% O₂ and 5% CO₂). The contractile and relaxant responses of the tissue were measured using isometric transducers coupled with Power-Lab data acquisition system. The anti-inflammatory effect was evaluated in carrageenan-induced rat paw edema model, while the lipoxygenase inhibitory activity was performed in the in-vitro assay. Various chromatographic and spectroscopic techniques were used for the isolation and characterization of pure molecules.

Results

In isolated guinea-pig tracheal preparations, PR caused complete inhibition of the high K⁺ (80 mM) and carbachol-induced contractions however, it was more potent against K⁺ than CCh, similar to verapamil. Pretreatment of the tissue with PR, displaced the Ca²⁺ concentration-response curves to the right, similar to that induced by verapamil, indicating the presence of Ca²⁺ channel blocking like activity. When tested on carrageenan-induced rat paw edema, PR demonstrated a marked reduction in edema with 65.22% protection at 200 mg/kg, similar to aspirin. In the in-vitro assay, PR showed lipoxygenase inhibitory activity (IC₅₀: 102 ± 0.19 μg/mL), similar to baicalein. Bioactivity-guided fractionation led to the isolation of 2-hydroxybenzoic acid and β-sitosterol.

Conclusions

These results indicate that the plant possesses tracheorelaxant, mediated possibly through a Ca²⁺ channel blockade mechanism, and anti-inflammatory activities, which may explain the medicinal use of this plant in airway disorders and inflammation.

Bronchodilator activity of aerial parts of Polygonatum verticillatum augmented by anti-inflammatory activity: attenuation of Ca²⁺ channels and lipoxygenase

Polygonatum verticillatum is commonly used for the treatment of asthma and inflammation. The current study was aimed to scrutinize the pharmacological profile of methanolic extract of the aerial parts (PA). Isolated tracheal preparations were used for the evaluation of bronchodilatory activity, whilst the in vivo carrageenan-induced paw oedema test and an in vitro lipoxygenase (LOX) inhibitory assay were used for the assessment of the anti-inflammatory profile of PA. When tested against carbachol and K⁺ (80 mM)-induced contractions, PA caused complete inhibition of isolated rabbit tracheal preparations in a dose-dependent mode, similar to verapamil. While elucidating possible mechanism, PA shifted the Ca²⁺ concentration-response curves to the right, analogous to that produced by verapamil, confirming a Ca²⁺ channel blocker-like activity. PA provoked profound reduction in paw oedema with a maximum protection of 60.87% at 200 mg/kg i.p. in a dose-dependent manner which was augmented by its prominent LOX inhibitory activity (IC₅₀ : 125 µg/mL). These findings authenticated its therapeutic potential in the treatment of asthmatic and inflammatory conditions.