Transport and metabolic profiling studies of amentoflavone in Caco-2 cells by UHPLC-ESI-MS/MS and UHPLC-ESI-Q-TOF-MS/MS

Neuroprotective potentials of Lead phytochemicals against Alzheimer's disease with focus on oxidative stress-mediated signaling pathways: Pharmacokinetic challenges, target specificity, clinical trials and future perspectives

BACKGROUND

Alzheimer's diseases (AD) and dementia are among the highly prevalent neurological disorders characterized by deposition of beta amyloid (Aβ) plaques, dense deposits of highly phosphorylated tau proteins, insufficiency of acetylcholine (ACh) and imbalance in glutamatergic system. Patients typically experience cognitive, behavioral alterations and are unable to perform their routine activities. Evidence also suggests that inflammatory processes including excessive microglia activation, high expression of inflammatory cytokines and release of free radicals. Thus, targeting inflammatory pathways beside other targets might be the key factors to control- disease symptoms and progression.

PURPOSE

This review is aimed to highlight the mechanisms and pathways involved in the neuroprotective potentials of lead phytochemicals. Further to provide updates regarding challenges associated with their use and their progress into clinical trials as potential lead compounds.

METHODS

Most recent scientific literature on pre-clinical and clinical data published in quality journals especially on the lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin was collected using SciFinder, PubMed, Google Scholar, Web of Science, JSTOR, EBSCO, Scopus and other related web sources.

RESULTS

Literature review indicated that the drug discovery against AD is insufficient and only few drugs are clinically approved which have limited efficacy. Among the therapeutic options, natural products have got tremendous attraction owing to their molecular diversity, their safety and efficacy. Research suggest that natural products can delay the disease onset, reduce its progression and regenerate the damage via their anti-amyloid, anti-inflammatory and antioxidant potentials. These agents regulate the pathways involved in the release of neurotrophins which are implicated in neuronal survival and function. Highly potential lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin regulate neuroprotective signaling pathways implicated in neurotrophins-mediated activation of tropomyosin receptor kinase (Trk) and p75 neurotrophins receptor (p75NTR) family receptors.

CONCLUSIONS

Phytochemicals especially phenolic compounds were identified as highly potential molecules which ameliorate oxidative stress induced neurodegeneration, reduce Aβ load and inhibit vital enzymes. Yet their clinical efficacy and bioavailability are the major challenges which need further interventions for more effective therapeutic outcomes.

Hypoglycemic effect and intestinal transport of phenolics-rich extract from digested mulberry leaves in Caco-2/insulin-resistant HepG2 co-culture model

Phenolics of mulberry (Morus alba L.) leaves (MLs) have potential anti-diabetic effects, but they may be chemically modified during gastrointestinal digestion so affect their biological activity. In this study, an in vitro digestion model coupled with Caco-2 monolayer and Caco-2/insulin-resistant HepG2 coculture model were used to study the transport and hypoglycemic effects of phenolics in raw MLs (U-MLs) and solid-fermented MLs (F-MLs). The results of LC-MS/MS analysis showed that the Papp (apparent permeability coefficient, 10-6cm/s) of phenolics in digested MLs ranged from 0.002 ± 0.00 (quercetin 3-O-glucoside) to 60.19 ± 0.67 (ferulic acid), indicating higher phenolic acids absorbability and poor flavonoids absorbability. The Papp values of phenolic extracts of F-MLs in Caco-2 monolayer were significantly higher (p > 0.05) than that of U-MLs. Digested phenolic extracts inhibited the activities of sucrase (60.13 ± 2.03 %) and maltase (82.35 ± 0.78 %) and decreased 9.28 ± 0.84 % of glucose uptake in Caco-2 monolayer. Furthermore, a decrease in the mRNA expression of glucose transporters SGLT1 (0.64 ± 0.18), GLUT2 (0.14 ± 0.02) and the sucrase-isomaltase (0.59 ± 0.00) was observed. In Caco-2/insulin-resistant HepG2 co-culture model, phenolic extracts regulated glucose metabolism by up-regulating the mRNA expressions of IRS1 (9.32-fold), Akt (17.07-fold) and GYS2 (1.5-fold), and down-regulating the GSK-3β (0.22-fold), PEPCK (0.49-fold) and FOXO1 (0.10-fold) mRNA levels. Both U-MLs and F-MLs could improve glucose metabolism, and the partial least squares (PLS) analysis showed that luteoforol and p-coumaric acid were the primary phenolics that strongly correlated with the hypoglycemic ability of MLs. Results suggested that phenolics of MLs can be used as dietary supplements to regulate glucose metabolism.

Total biflavonoids extraction from Selaginella chaetoloma utilizing ultrasound-assisted deep eutectic solvent: Optimization of conditions, extraction mechanism, and biological activity in vitro

In this study, the deep eutectic solvent based ultrasound-assisted extraction (DES-UAE) was investigated for the efficient and environmentally friendly extraction of Selaginella chaetoloma total biflavonoids (SCTB). As an extractant for optimization, tetrapropylaminium bromide-1,4-butanediol (Tpr-But) was employed for the first time. 36 DESs were created, with Tpr-But producing the most effective results. Based on response surface methodology (RSM), the greatest extraction rate of SCTB was determined to be 21.68 ± 0.78 mg/g, the molar ratio of HBD to HBA was 3.70:1, the extraction temperature was 57 °C, and the water content of DES was 22 %. In accordance with Fick's second rule, a kinetic model for the extraction of SCTB by DES-UAE has been derived. With correlation coefficients 0.91, the kinetic model of the extraction process was significantly correlated with the general and exponential equations of kinetics, and some important kinetic parameters such as rate constants, energy of activation and raffinate rate were determined. In addition, molecular dynamics simulations were used to study the extraction mechanisms generated by different solvents. Comparing the effect of several extraction methods on S.chaetoloma using ultrasound-assisted extraction and conventional methods, together with SEM examination, revealed that DES-UAE not only saved time but also enhanced SCTB extraction rate by 1.5-3 folds. SCTB demonstrated superior antioxidant activity in three studies in vitro. Furthermore, the extract could suppress the growth of A549, HCT-116, HepG2, and HT-29 cancer cells. Alpha-Glucosidase (AG) inhibition experiment and molecular docking studies suggested that SCTB exhibited strong inhibitory activity against AG and potential hypoglycemic effects. The results of this study indicated that a Tpr-But-based UAE method was suitable for the efficient and environmentally friendly extraction of SCTB, and also shed light on the mechanisms responsible for the increased extraction efficiency, which could aid in the application of S.chaetoloma and provide insight into the extraction mechanism of DES.

Biological analysis of constituents in Spatholobi Caulis by UFLC-MS/MS: Enhanced quantification and application to permeability properties study in Caco-2 cell monolayer model

Major chemical constituents in medicinal materials are often used as the marker compounds of traditional Chinese medicine (TCM) for treating various diseases. For spatholobi caulis (SPC), it contains a variety of flavones, phenolic acid esters, and lignans which exert many pharmacological effects. However, the absorption and permeability properties of these constituents of SPC are still unclear and require further investigation. Different types and major compounds of SPC were chosen as representative constituents to study their absorption and transepithelial transport characteristics in the human intestinal epithelium-like Caco-2 cell monolayer model. 35 constituents of SPC were evaluated by using ultra fast liquid chromatography combined with electrospray ionization triple quadrupole tandem mass spectrometry (UFLC-MS/MS) method, acetonitrile and water containing with 0.5 mM ammonium acetate were used as mobile phase, these analytes with good linear relationships (R² was within 0.9967-0.9998), precision (CV values were less than 10.23 %, LLOQ was less than 13.69 %), accuracy (Mean of inter- and intra-day were within 85.02 %-111.61 % and 85.50-112.97 %, respectively) and stability (The mean was within 85.07 %-113.93 %), among which 16 analytes showed good permeability, 5 analytes were considered to be poorly permeable compounds, and the other 14 analytes were assigned for the moderately absorbed compounds in Caco-2 cell monolayer model. The further results showed that the absorption mechanism of 7 well absorbed compounds, 8-O-methylretusin (1), genistein (7), spasuberol B (16), naringenin (18), isoliquiritigenin (19), 4-hydroxy-3-methoxy cinnamic acid methyl ester (23) and (+)-epipinoresinol (31) in SPC was mainly passive diffusion, their bidirectional transport rate was correlated with the concentration and transport time. The chemical structures of these compounds could affect the permeability properties on the cell monolayer. This study demonstrated the utility of Caco-2 cell monolayer model for evaluating the absorption properties and initial mechanisms of compounds in SPC in vitro, and provided important basis for predicting oral bioavailability of SPC compounds.

Mitochondrial dysfunction: A notable contributor to the progression of Alzheimer's and Parkinson's disease

Mitochondrial dysfunction remains a pivotal mechanism in manifold neurodegenerative diseases. Mitochondrial homeostasis within the cell is an essential aspect of cell biology. Mitochondria, the power-generating organelle of the cell, have a dominant role in several processes associated with genomic integrity and cellular equilibrium. They are involved in maintaining optimal cell functioning and ensuring guidance against possible DNA damage, which could lead to mutations and the onset of diseases. Conversely, system perturbations, which could be due to environmental factors or senescence, induce changes in the physiological balance and result in mitochondrial function impairment. As a result, we present a general overview of the pathological pathways involved in Alzheimer's and Parkinson's diseases caused by changes in mitochondrial homeostasis. The focal point of this review is on mitochondrial dysfunction being a significant condition in the onset of neuronal disintegration. We explain the pathways associated with the dysfunction of the mitochondria, which are common among the most recurring neurodegenerative diseases, including Alzheimer's and Parkinson's disease. Are mitochondrial dysfunctions an early event in the progression of neuropathological processes? We discovered that mtDNA mutation is a major contributor to the metabolic pathology of most neurological disorders, causing changes in genes important for physiological homeostasis. As a result, genetic changes in presenilin, Amyloid-, ABAD, DJ-1, PINK-1, PARKIN, alpha-synuclein, and other important controlling genes occur. Therefore, we suggest possible therapeutic solutions.

Multifaceted role of polyphenols in the treatment and management of neurodegenerative diseases

Neurodegenerative diseases (NDDs) are conditions that cause neuron structure and/or function to deteriorate over time. Genetic alterations may be responsible for several NDDs. However, a multitude of physiological systems can trigger neurodegeneration. Several NDDs, such as Huntington's, Parkinson's, and Alzheimer's, are assigned to oxidative stress (OS). Low concentrations of reactive oxygen and nitrogen species are crucial for maintaining normal brain activities, as their increasing concentrations can promote neural apoptosis. OS-mediated neurodegeneration has been linked to several factors, including notable dysfunction of mitochondria, excitotoxicity, and Ca²⁺ stress. However, synthetic drugs are commonly utilized to treat most NDDs, and these treatments have been known to have side effects during treatment. According to providing empirical evidence, studies have discovered many occurring natural components in plants used to treat NDDs. Polyphenols are often safer and have lesser side effects. As, epigallocatechin-3-gallate, resveratrol, curcumin, quercetin, celastrol, berberine, genistein, and luteolin have p-values less than 0.05, so they are typically considered to be statistically significant. These polyphenols could be a choice of interest as therapeutics for NDDs. This review highlighted to discusses the putative effectiveness of polyphenols against the most prevalent NDDs.

Evaluation on absorption risks of amentoflavone after oral administration in rats

The present study was aimed to systemically assess the absorption risks of amentoflavone (AMF). Physicochemical properties of AMF were evaluated using in vitro assays including water solubility and stability in both simulated gastric and intestinal fluids, as well as logD, pka and permeability studies in a monolayer Caco-2 model. The results together suggested that AMF was a compound with moderate intestinal absorption and the poor solubility was the key rate-limiting step for the oral absorption of AMF, and PVP-K30 were thus used as a solubilizer to improve its solubility and oral bioavailability. Furthermore, studies on pharmacokinetics and biliary excretion of AMF with tween 80 or PVP-K30 were performed after oral administration, and the results showed that the percentage of AMF conjugates in bile was determined up to be 96.73% and no AMF conjugates were detected in rat plasma. The above results revealed that the poor oral absorption of AMF may probably be attributed to the low solubility, high level of metabolism and hepatic first-pass effects. The relative bioavailability of AMF solubilized by PVP-K30 was about 2-fold than that of AMF suspended in 1% tween 80. The present study may help provide scientific insights to guide the rational design of AMF into more efficient formulation systems.

Analysis of Flavonoid Metabolites in Watercress (Nasturtium officinale R. Br.) and the Non-Heading Chinese Cabbage (Brassica rapa ssp. chinensis cv. Aijiaohuang) Using UHPLC-ESI-MS/MS

Flavonoids from plants play an important role in our diet. Watercress is a special plant that is rich in flavonoids. In this study, four important watercress varieties were compared with non-heading Chinese cabbage by ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS). A total of 132 flavonoid metabolites (including 8 anthocyanins, 2 dihydroflavone, 3 dihydroflavonol, 1 flavanols, 22 flavones, 11 flavonoid carbonosides, 82 flavonols, and 3 isoflavones) were detected. Flavonoid metabolites varied widely in different samples. Both the non-heading Chinese cabbage and the variety of watercress from Guangdong, China, had their own unique metabolites. This work is helpful to better understand flavonoid metabolites between the non-heading Chinese cabbage and the other four watercress varieties, and to provide a reliable reference value for further research.

Extensive metabolism of flavonoids relevant to their potential efficacy on Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disorder, the incidence of which is climbing with ever-growing aged population, but no cure is hitherto available. The epidemiological studies unveiled that chronic intake of flavonoids was negatively associated with AD risk. Flavonoids, a family of natural polyphenols widely distributed in human daily diets, were readily conjugated by phase II drug metabolizing enzymes after absorption in vivo, and glucuronidation could occur in 1 min following intravenous administration. Recently, as many as 191 metabolites were obtained after intragastric administration of a single flavonoid, indicating that other bioactive metabolites, besides conjugates, might be formed and account for the contradiction between efficacy of flavonoids in human or animal models and low systematic exposure of flavonoid glycosides or aglycones. In this review, metabolism of complete 68 flavonoid monomers potential for AD treatment, grouped in flavonoid O-glycosides, flavonoid aglycones, flavonoid C-glycosides, flavonoid dimers, flavonolignans and prenylated flavonoids according to their common structural elements, respectively, has been systematically retrospected, summarized and discussed, including their unequivocally identified metabolites, metabolic interconversions, metabolic locations, metabolic sites (regio- or stereo-selectivity), primarily involved metabolic enzymes or intestinal bacteria, and interspecies correlations or differences in metabolism, and their bioactive metabolites and the underlying mechanism to reverse AD pathology were also reviewed, providing whole perspective about advances on extensive metabolism of diverse potent flavonoids in vivo and in vitro up to date and aiming at elucidation of mechanism of actions of flavonoids on AD or other central nervous system (CNS) disorders.

Therapeutic Potential of Natural Products in Treating Neurodegenerative Disorders and Their Future Prospects and Challenges

Natural products derived from plants, as well as their bioactive compounds, have been extensively studied in recent years for their therapeutic potential in a variety of neurodegenerative diseases (NDs), including Alzheimer's (AD), Huntington's (HD), and Parkinson's (PD) disease. These diseases are characterized by progressive dysfunction and loss of neuronal structure and function. There has been little progress in designing efficient treatments, despite impressive breakthroughs in our understanding of NDs. In the prevention and therapy of NDs, the use of natural products may provide great potential opportunities; however, many clinical issues have emerged regarding their use, primarily based on the lack of scientific support or proof of their effectiveness and patient safety. Since neurodegeneration is associated with a myriad of pathological processes, targeting multi-mechanisms of action and neuroprotection approaches that include preventing cell death and restoring the function of damaged neurons should be employed. In the treatment of NDs, including AD and PD, natural products have emerged as potential neuroprotective agents. This current review will highlight the therapeutic potential of numerous natural products and their bioactive compounds thatexert neuroprotective effects on the pathologies of NDs.

Comprehensive Metabolomic Analysis Reveals Dynamic Metabolic Reprogramming in Hep3B Cells with Aflatoxin B1 Exposure

Hepatitis B virus (HBV) infection and aflatoxin B1 (AFB1) exposure have been recognized as independent risk factors for the occurrence and development of hepatocellular carcinoma (HCC), but their combined impacts and the potential metabolic mechanisms remain poorly characterized. Here, a comprehensive non-targeted metabolomic study was performed following AFB1 exposed to Hep3B cells at two different doses: 16 μM and 32 μM. The metabolites were identified and quantified by an ultra-performance liquid chromatography-mass spectrometry (UPLC-MS)-based strategy. A total of 2679 metabolites were identified, and 392 differential metabolites were quantified among three groups. Pathway analysis indicated that dynamic metabolic reprogramming was induced by AFB1 and various pathways changed significantly, including purine and pyrimidine metabolism, hexosamine pathway and sialylation, fatty acid synthesis and oxidation, glycerophospholipid metabolism, tricarboxylic acid (TCA) cycle, glycolysis, and amino acid metabolism. To the best of our knowledge, the alteration of purine and pyrimidine metabolism and decrease of hexosamine pathways and sialylation with AFB1 exposure have not been reported. The results indicated that our metabolomic strategy is powerful to investigate the metabolome change of any stimulates due to its high sensitivity, high resolution, rapid separation, and good metabolome coverage. Besides, these findings provide an overview of the metabolic mechanisms of the AFB1 combined with HBV and new insight into the toxicological mechanism of AFB1. Thus, targeting these metabolic pathways may be an approach to prevent carcinogen-induced cancer, and these findings may provide potential drug targets for therapeutic intervention.

Preparation of glass-ionomer cement containing ethanolic Brazilian pepper extract (Schinus terebinthifolius Raddi) fruits: chemical and biological assays

Plants may contain beneficial or potentially dangerous substances to humans. This study aimed to prepare and evaluate a new drug delivery system based on a glass-ionomer-Brazilian pepper extract composite, to check for its activity against pathogenic microorganisms of the oral cavity, along with its in vitro biocompatibility. The ethanolic Brazilian pepper extract (BPE), the glass-ionomer cement (GIC) and the composite GIC-BPE were characterized by scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and thermal analysis. The BPE compounds were identified by UPLC–QTOF–MS/MS. The release profile of flavonoids and the mechanical properties of the GIC-BPE composite were assessed. The flavonoids were released through a linear mechanism governing the diffusion for the first 48 h, as evidenced by the M_t/M_∞ relatively to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sqrt t$$\end{document}t, at a diffusion coefficient of 1.406 × 10^–6 cm² s⁻¹. The ATR-FTIR analysis indicated that a chemical bond between the GIC and BPE components may have occurred, but the compressive strength of GIC-BPE does not differ significantly from that of this glass-ionomer. The GIC-BPE sample revealed an ample bacterial activity at non-cytotoxic concentrations for the human fibroblast MRC-5 cells. These results suggest that the prepared composite may represent an alternative agent for endodontic treatment.

Systematic Strategy for Metabolites of Amentoflavone In Vivo and In Vitro Based on UHPLC-Q-TOF-MS/MS Analysis

Amentoflavone, a biflavonoid occurring in many edible supplements, possesses some bioactivities, including antioxidant, anti-inflammation, antitumor, and neuroprotective activities. In the present study, an ultrahigh-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF-MS/MS) method, combined with a three-step analytical strategy, was employed to identify metabolites in vivo (rat plasma, bile, urine, and feces) and in vitro (rat liver microsomes and rat intestine microsomes). A total of 39 metabolites in rats and nine metabolites in rat microsomes were elucidated by UHPLC-Q-TOF-MS/MS analysis, and the chemical structure of some isomers was further assigned by calculated Clog P values. Oxidation, internal hydrolysis, hydrogenation, methylation, sulfation, glucuronidation, glucosylation, O-aminomethylation, and degradation were the major metabolic pathways of amentoflavone. Noteworthy, O-aminomethylation and glucosylation could be considered as unique metabolic pathways of amentoflavone. This was the first report on metabolite identification of amentoflavone in vivo and in vitro, and the metabolic findings offer novel and valuable evidence for an in-depth understanding of the safety and efficacy of amentoflavone.