Isolation and purification of alkaloids from lotus leaves by ionic-liquid-modified high-speed countercurrent chromatography

Natural Products Targeting Tau Protein Phosphorylation: A Promising Therapeutic Avenue for Alzheimer's Disease

Alzheimer's disease is a progressive neurodegenerative disorder characterized by tau protein hyperphosphorylation and neurofibrillary tangle formation, which are central to its pathogenesis. This review focuses on the therapeutic potential of natural products in targeting tau phosphorylation, a key factor in Alzheimer's disease progression. It comprehensively summarizes current research on various natural compounds, including flavonoids, alkaloids, saponins, polysaccharides, phenols, phenylpropanoids, and terpenoids, highlighting their multitarget mechanisms, such as modulating kinases and phosphatases. The ability of these compounds to mitigate oxidative stress, inflammation, and tau pathology while enhancing cognitive function underscores their value as potential anti-Alzheimer's disease therapeutics. By integrating recent advances in extraction methods, pharmacological studies, and artificial intelligence-driven screening technologies, this review provides a valuable reference for future research and development of natural product-based interventions for Alzheimer's disease.

Optimisation of isolation of polyphenols from Malus pumila Mill. Leaves by high-speed countercurrent chromatography using response surface methodology

Considering comprehensive utilization of natural products, isolation and activity determination processes of bioactive compounds are essential. In this study, a combined high-speed countercurrent chromatography (HSCCC) with preparative HPLC method was developed to isolate the five antioxidant polyphenols from 75% ethanol extract of Malus pumila Mill. leaves. The HSCCC conditions were optimized by response surface methodology (RSM) considering two response indexes including retention of stationary phase and analysis time. The optimal HSCCC conditions were flow rate of 2.11 mL/min, revolution speed of 717 rpm, and temperature of 25℃, with a solvent system of ethyl acetate/methanol/water (10:1:10, v/v/v). The unseparated fractions obtained from HSCCC were subjected to preparative HPLC for further isolation. As a result, phloridzin (15.3 mg), isoquercitrin (2.1 mg), quercetin 3-O-xyloside (1.9 mg), quercetin-3-O-arabinoside (4.0 mg), and quercitrin (2.0 mg) were isolated from 200.0 mg extracts. The purities of these compounds were all above 92%. Their chemical structures were identified by mass spectrometer and nuclear magnetic resonance. The five isolated compounds were further investigated for their rat hippocampal neuroprotective effects against hydrogen peroxide-induced oxidative stress. No cytotoxicity was observed in all tested concentrations. While all five compounds except phloridzin showed significantly neurogenic activities and neuroprotective effects, especially at the concentration of 0.5 mg/L. These results demonstrate that RSM is a suitable technique for optimisation of HSCCC and the isolated polyphenols can be used as antioxidants in pharmaceutical and food products.

Structure-activity relationship, bioactivities, molecular mechanisms, and clinical application of nuciferine on inflammation-related diseases

Nuciferine aporphine alkaloid mainly exists in Nelumbo nucifera Gaertn and is a beneficial to human health, such as anti-obesity, lowering blood lipid, prevention of diabetes and cancer, closely associated with inflammation. Importantly, nuciferine may contribute to its bioactivities by exerting intense anti-inflammatory activities in multiple models. However, no review has summarized the anti-inflammatory effect of nuciferine. This review critically summarized the information regarding the structure-activity relationships of dietary nuciferine. Moreover, biological activities and clinical application on inflammation-related diseases, such as obesity, diabetes, liver, cardiovascular diseases, and cancer, as well as their potential mechanisms, involving oxidative stress, metabolic signaling, and gut microbiota has been reviewed. The current work provides a better understanding of the anti-inflammation properties of nuciferine against multiple diseases, thereby improving the utilization and application of nuciferine-containing plants across functional food and medicine.

Advances of Imidazolium Ionic Liquids for the Extraction of Phytochemicals from Plants

In this review, we present the research from 2013 to 2022 about the character of ionic liquids, the categories of phytochemicals, and the reasons for selecting imidazolium ionic liquids for phytochemical extraction. Then we introduce the structural formulae of the imidazolium ionic liquids commonly used in the extraction of phytochemicals, the methods used to prepare imidazolium ionic liquids, and a comprehensive introduction of how imidazolium ionic liquids are applied to extract phytochemicals from plants. Importantly, we discuss the strategies for studying the extraction mechanisms of imidazolium ionic liquids to extract phytochemicals, and the recovery methods regarding imidazolium ionic liquids and their recyclability are analyzed. Then the toxicity in imidazolium ionic liquids is pointed out. Finally, the challenges and prospects of extracting phytochemicals by imidazolium ionic liquids are summarized, and they are expected to provide some references for researchers.

An eco-friendly extraction and purification method of nuciferine from Folium nelumbinis with p-sulfonatocalix[6]arenes

INTRODUCTION

Folium nelumbinis is used as vegetable, functional food and herbal medicine in Asia. p-Sulfonatocalix[6]arene (SC6A) is a water-soluble supramolecular macrocycle and has never been applied to the extraction of herbal products.

OBJECTIVE

In this study, SC6A-assisted extraction of nuciferine from Folium nelumbinis has been carried out to develop an eco-friendly extraction process with high extraction efficacy and easy operation.

METHODS

Single-factor experiments were adopted to obtain the optimal conditions for the SC6A-assisted extraction of nuciferine from Folium nelumbinis, and then nuciferine and SC6A were separated easily by one-step alkalization. The host-guest complexes between nuciferine and SC6A were analyzed by competitive fluorescence titration, DSC, FT-IR and ¹ H-NMR.

RESULTS

The optimal SC6A/Folium nelumbinis/solution ratio for extraction was 0.4:1:20 (g/g/mL), with a granulometric fraction below 180 μm and an extraction time of 1 h with soaking. The purity and recovery of nuciferine extracted with SC6A were increased 29.24 and 35.73 times compared with extraction with aqueous solution, respectively. Moreover, a good reusability of SC6A in the extraction of nuciferine was demonstrated. Competitive fluorescence titration, DSC, FT-IR and ¹ H-NMR characterization indicated that SC6A could form host-guest complexes with nuciferine at a ratio of 1:1.

CONCLUSION

The study provided an eco-friendly, safe and effective nuciferine extraction method, which can be used for the development of nutrition supplements containing nuciferine.

Alkaloids from lotus (Nelumbo nucifera): recent advances in biosynthesis, pharmacokinetics, bioactivity, safety, and industrial applications

Different parts of lotus (Nelumbo nucifera Gaertn.) including the seeds, rhizomes, leaves, and flowers, are used for medicinal purposes with health promoting and illness preventing benefits. The presence of active chemicals such as alkaloids, phenolic acids, flavonoids, and terpenoids (particularly alkaloids) may account for this plant's pharmacological effects. In this review, we provide a comprehensive overview and summarize up-to-date research on the biosynthesis, pharmacokinetics, and bioactivity of lotus alkaloids as well as their safety. Moreover, the potential uses of lotus alkaloids in the food, pharmaceutical, and cosmetic sectors are explored. Current evidence shows that alkaloids, mainly consisting of aporphines, 1-benzylisoquinolines, and bisbenzylisoquinolines, are present in different parts of lotus. The bioavailability of these alkaloids is relatively low in vivo but can be enhanced by technological modification using nanoliposomes, liposomes, microcapsules, and emulsions. Available data highlights their therapeutic and preventive effects on obesity, diabetes, neurodegeneration, cancer, cardiovascular disease, etc. Additionally, industrial applications of lotus alkaloids include their use as food, medical, and cosmetic ingredients in tea, other beverages, and healthcare products; as lipid-lowering, anticancer, and antipsychotic drugs; and in facial masks, toothpastes, and shower gels. However, their clinical efficacy and safety remains unclear; hence, larger and longer human trials are needed to achieve their safe and effective use with minimal side effects.

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.

Preparative Separation of Alkaloids from Stem of Euchresta tubulosa Dunn. by High-Speed Counter-Current Chromatography Using Stepwise Elution

Euchresta tubulosa Dunn. is a Chinese herbal medicine with biological activity, but there are few studies on its components at present. Alkaloids in the stem of Euchresta tubulosa Dunn. were isolated and purified by high-speed counter-current chromatography (HSCCC) using stepwise elution. First of all, liquid-liquid extraction (methylene chloride-methanol-water, 5:1:4, v/v) was used for the preliminary enrichment. According to the partition coefficient (K) of a target compound in a series of different two-phase solvents, the final result was that carbon tetrachloride-methylene chloride-methanol-water (2:3:3:2, v/v) (1) and methylene chloride-methanol-water (5:3:2, v/v) (2) were suitable for the HSCCC using stepwise elution. As a result, the purity was all higher than 93% and matrine (1), oxymatrine (2), N-formyl cytisine (3), and N-acetyl cytisine (4) can be eluted at one time by this mode. Cytisine-type alkaloids were isolated for the first time in this plant. Finally, the applicability of the mode was verified.

Counter-current chromatography melamine-modified column and its separation mechanism

In this work, to further verify and develop the novel counter-current chromatography modified column separate mode, a melamine modified counter-current chromatography column was prepared. Meanwhile, the modified counter-current chromatography column was used to separate stevioside and rebaudioside A with the same partition coefficient in chosen solvent system to evaluate its separation efficiency. The results show that because of the presence of intermolecular forces between melamine and model compounds, better separation could be achieved on the modified column while it's almost impossible to be separated on the unmodified column. So the results of this research further show that column modified method is a possible approach to further increase the separation ability of counter-current chromatography. Take advantage of large sample handing capacity of counter-current chromatography, the mothed may have great potential to be an efficient method of separation and preparation enantiomer compounds.

A simple gradient equilibrium method for better separation in countercurrent chromatography

The stationary phase retention is one of the most important parameters in countercurrent chromatography. In this work, a simple gradient equilibrium method was developed to further improve the stationary phase retention based on the optimized condition in the traditional equilibrium model. Meanwhile, this novel gradient equilibrium method was used to separate three flavone model compounds and compared with the conventional isocratic equilibrium method to evaluate the separation efficiency. The results show that better resolution or shorter separation time could be achieved with gradient equilibrium compared to isocratic equilibrium. So this novel equilibrium method has enormous potential for obtaining a better separation or saving the separating time in the preparative separation of target compounds.

Ionic Liquid Solutions as a Green Tool for the Extraction and Isolation of Natural Products

In the past few years, the application of ionic liquids (ILs) had attracted more attention of the researchers. Many studies focused on extracting active components from traditional herbals using ILs as alternative solvents so as to address the issue caused by the traditional methods for extraction of natural products (NPs) with organic chemical reagents. Through the summary of reported research work, an overview was presented for the application of ILs or IL-based materials in the extraction of NPs, including flavonoids, alkaloids, terpenoids, phenylpropanoids and so on. Here, we mainly describe the application of ILs to rich the extraction of critical bioactive constituents that were reported possessing multiple therapeutic effects or pharmacological activities, from medicinal plants. This review could shed some light on the wide use of ILs in the field of natural products chemistry to further reduce the environmental damage caused by large quantity of organic chemical reagents.

Green techniques in comparison to conventional ones in the extraction of Amaryllidaceae alkaloids: Best solvents selection and parameters optimization

An undisputed trend in sample preparation at present is to meet the requirements of green chemistry especially in the field of natural products. Green technology continuously pursues new solvents to replace common organic solvents that possess inherent toxicity. Over the past two decades, non-ionic surfactants have gained enormous attention from the scientific community. The micelle-mediated extraction and cloud-point preconcentration (CPE) methods offer a convenient alternative to the conventional extraction systems. Recently, natural deep eutectic solvents (NDESs) have emerged as green and sustainable solvents for efficient extraction of bioactive compounds or drugs. They are generally composed of neutral, acidic or basic compounds that form liquids of high viscosity when mixed in certain molar ratio. The presented work aimed to comprehensively compare and evaluate the potential and effectiveness of NDES as well as non-ionic surfactants (Genapol X-080, Triton X-100 and Triton X-114) for extraction of Amaryllidaceae alkaloids from Crinum powellii bulbs as representative example of plant material, in comparison to the conventional solvents (methanol, ethanol and water).A new validated high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous quantitation of three alkaloids markers, lycorine, crinine and crinamine, in the bulbs of C. powellii. Extraction efficiency of the targeted alkaloids from the bulb matrix with organic and ecofriendly (green) solvents were studied. Results revealed that NDES and surfactants were significantly more efficient in alkaloid extraction than previous methods requiring the consumption of organic solvents and water. Genapol X-80 demonstrated 138%, 149% and 145%, while choline chloride: fructose (5:2): H₂O (35%) NDES mixture demonstrated 243%, 225% and 238% of the total alkaloidal extraction capacity of ethanol, methanol and water, respectively at 50 °C for extraction time 1 h using ultrasonication for all experiments. Furthermore, Box-Behnken response surface design combined with the overall desirability value were successfully employed to optimize and study the individual and interactive effect of process variables such as extraction temperature, time and surfactant %, for Genapol X-80, and sonication extraction temperature, time and water concentration, for choline chloride: fructose: H₂O NDES mixture, on the alkaloidal yield from C. powellii. It was evident that parameters interacting together can act in synergism if adjusted properly according to the optimized conditions to obtain maximum alkaloids extractability. It is for the first time that the efficiency of micelle-mediated extraction has been compared to that of natural deep eutectic solvents for the extraction of alkaloids and the results thoroughly discussed.