Enhancement of oral bioavailability of quercetin by metabolic inhibitory nanosuspensions compared to conventional nanosuspensions

Carbon Monoxide-Releasing Activity of Plant Flavonoids

Flavonoids are naturally occurring compounds found in fruits, vegetables, and other plant-based foods, and they are known for their health benefits, such as UV protection, antioxidant, anti-inflammatory, and antiproliferative properties. This study investigates whether flavonoids, such as quercetin and 2,3-dehydrosilybin, can act as photoactivatable carbon monoxide (CO)-releasing molecules under physiological conditions. CO has been recently recognized as an important signaling molecule. Here, we show that upon direct irradiation, CO was released from both flavonoids in PBS with chemical yields of up to 0.23 equiv, which increased to almost unity by sensitized photooxygenation involving singlet oxygen. Photoreleased CO reduced cellular toxicity caused by high flavonol concentrations, partially restored mitochondrial respiration, reduced superoxide production induced by rotenone and high flavonol levels, and influenced the G0/G1 and G2/M phases of the cell cycle, showing antiproliferative effects. The findings highlight the potential of quercetin and 2,3-dehydrosilybin as CO-photoreleasing molecules with chemopreventive and therapeutic implications in human pathology and suggest their possible roles in plant biology.

Preparation and characterization of andrographolide nano-cocrystals using hummer acoustic resonance technology

Andrographolide (AG) is a diterpene lactone with significant anti-inflammatory and antitumor activities. However, the poor water solubility limits its clinical application. An andrographolide-salicylic acid (AG-SLA) nano-cocrystal delivery system was rapidly developed using hummer acoustic resonance (HAR) technology in this research. The formulation of the AG-SLA nano-cocrystal suspension and the process parameters for HAR technology were optimized in a high-throughput manner, with SDS-Tween 80 as the optimal composite stabilizer. Nano-cocrystal suspension of AG-SLA with an average particle size of 190 nm were successfully prepared, and then the optimal formulation were tenfold scaled up. Freeze-drying was adopted to solidify the nano-cocrystal and improve its stability. Various analytical techniques were used to characterize the particle size and solid state of the nano-cocrystals. The high-energy input from the HAR instrument induced partial amorphization of the nano-cocrystals, as confirmed by PXRD and DSC analyses. Saturation solubility experiments demonstrated that the solubility in pH 1.2 hydrochloric acid buffer and pH 6.8 phosphate buffer increased by 5.74 times and 6.82 times, respectively, compared to raw AG. In vitro dissolution tests indicated that the cumulative release over 120 min in pH 1.2 hydrochloric acid buffer and pH 6.8 phosphate buffer increased by 1.60 times and 1.88 times, respectively, compared to raw AG.

Therapeutic Potential of Natural Compounds to Modulate WNT/β-Catenin Signaling in Cancer: Current State of Art and Challenges

Targeted therapies and immunotherapies have improved the clinical outcome of cancer patients; however, the efficacy of treatment remains frequently limited due to low predictability of response and development of drug resistance. Therefore, novel therapeutic strategies for various cancer types are needed. Current research emphasizes the potential therapeutic value of targeting WNT/β-catenin dependent signaling that is deregulated in various cancer types. Targeting the WNT/β-catenin signaling pathway with diverse synthetic and natural agents is the subject of a number of preclinical studies and clinical trials for cancer patients. The usage of nature-derived agents is attributed to their health benefits, reduced toxicity and side effects compared to synthetic agents. The review summarizes preclinical studies and ongoing clinical trials that aim to target components of the WNT/β-catenin pathway across a diverse spectrum of cancer types, highlighting their potential to improve cancer treatment.

A Systematic Review: Quercetin-Secondary Metabolite of the Flavonol Class, with Multiple Health Benefits and Low Bioavailability

The main goal of this systematic review on the flavonol class secondary metabolite quercetin is to evaluate and summarize the existing research on quercetin's potential health benefits, therapeutic properties, and effectiveness in disease prevention and treatment. In addition to evaluating quercetin's potential for drug development with fewer side effects and lower toxicity, this type of review attempts to collect scientific evidence addressing quercetin's roles as an antioxidant, anti-inflammatory, antibacterial, and anticancer agent. In the first part, we analyze various flavonoid compounds, focusing on their chemical structure, classification, and natural sources. We highlight their most recent biological activities as reported in the literature. Among these compounds, we pay special attention to quercetin, detailing its chemical structure, physicochemical properties, and process of biosynthesis in plants. We also present natural sources of quercetin and emphasize its health benefits, such as its antioxidant and anti-inflammatory effects. Additionally, we discuss methods to enhance its bioavailability, analyzing the latest and most effective delivery systems based on quercetin.

Simple preparation and greatly improved oral bioavailability: The supersaturated drug delivery system of quercetin based on PVP K30

Quercetin, as a representative flavonoid, is widely present in daily diet and has been developed as a dietary supplement due to its beneficial physiological activities. However, the application of quercetin is limited due to its poor water solubility and extensive metabolism. So far, the nano-drug delivery systems designed to improve its bioavailability generally have the shortcomings of low drug loading content and difficulty in industrial production. In order to tackle these problems, quercetin supersaturated drug delivery system (QSDDS) was successfully prepared using solvent method, for which PVP K30 was employed as a crystallization and precipitation inhibitor to maintain the supersaturated state of quercetin in aqueous system. The obtained QSDDS, with a relative high drug loading content of 13%, could quickly disperse in water and form colloidal system with the mean particle size of about 200 nm, meanwhile induce the generation of supersaturated quercetin solution more than 12 h. In vivo pharmacokinetic study proved that QSDDS achieved a high absolute bioavailability of 36.05%, 10 times as that of physical quercetin suspension, which was dose-dependent with higher bioavailability at higher dose. Considering the simple preparation method, QSDDS provided a feasible strategy and a simple way to improve oral absorption of insoluble flavonoids.

Quercetin/Polyethyleneimine Modified Gold Nanoconjugates Inhibit Apoptosis and ROS Production Induced by Hydrogen Peroxide in DRG Sensory Neurons

The basis of most neurological syndromes is the accumulation of free radical molecules. Quercetin is a polyphenolic bioflavonoid molecule and it has a very strong antioxidant effect by maintaining oxidative balance. There are many difficulties in the clinical use of quercetin due to its hydrophobic structure, low solubility, instability, poor oral bioavailability, and limited tissue-barrier penetration. Its synergistic use in complex with gold nanoparticles (AuNPs) could overcome these problems. AuNPs have recently emerged as an attractive candidate for delivery applications of various biomolecules and drugs. The aim of this study was to synthesize two different sized gold nanoparticles (AuNP20 and AuNP50) modified with polyethyleneimine (PEI) and quercetin, evaluate their potential neuroprotective effects on the in vitro oxidative stress model using DRG primary sensory neurons. It was shown that the antioxidant and anti-apoptotic ability of the bioflavonoid was preserved after exposure to the designed quercetin modified AuNPs. The PEI surface coating increased the stability and biocompatibility of the AuNPs in both sizes. It also potentially enables additional surface functionalization. This study indicates that designed nanoparticles (AuNP-Q-PEI) with different sizes could be a useful potential platform for the treatment of neurodegenerative syndromes or cancer diseases.

Therapeutic potentials and targeting strategies of quercetin on cancer cells: Challenges and future prospects

BACKGROUND

Every cell in the human body is vital because it maintains equilibrium and carries out a variety of tasks, including growth and development. These activities are carried out by a set of instructions carried by many different genes and organized into DNA. It is well recognized that some lifestyle decisions, like using tobacco, alcohol, UV, or multiple sexual partners, might increase one's risk of developing cancer. The advantages of natural products for any health issue are well known, and researchers are making attempts to separate flavonoid-containing substances from plants. Various parts of plants contain a phenolic compound called flavonoid. Quercetin, which belongs to the class of compounds known as flavones with chromone skeletal structure, has anti-cancer activity.

PURPOSE

The study was aimed at investigating the therapeutic action of the flavonoid quercetin on various cancer cells.

METHODS

The phrases quercetin, anti-cancer, nanoparticles, and cell line were used to search the data using online resources such as PubMed, and Google Scholar. Several critical previous studies have been included.

RESULTS

Quercetin inhibits various dysregulated signaling pathways that cause cancer cells to undergo apoptosis to exercise its anticancer effects. Numerous signaling pathways are impacted by quercetin, such as the Hedgehog system, Akt, NF-κB pathway, downregulated mutant p53, JAK/STAT, G1 phase arrest, Wnt/β-Catenin, and MAPK. There are downsides to quercetin, like hydrophobicity, first-pass effect, instability in the gastrointestinal tract, etc., because of which it is not well-established in the pharmaceutical industry. The solution to these drawbacks in the future is using bio-nanomaterials like chitosan, PLGA, liposomes, and silk fibroin as carriers, which can enhance the target specificity of quercetin. The first section of this review covers the specifics of flavonoids and quercetin; the second section covers the anti-cancer activity of quercetin; and the third section explains the drawbacks and conjugation of quercetin with nanoparticles for drug delivery by overcoming quercetin's drawback.

CONCLUSIONS

Overall, this review presented details about quercetin, which is a plant derivative with a promising molecular mechanism of action. They inhibit cancer by various mechanisms with little or no side effects. It is anticipated that plant-based materials will become increasingly relevant in the treatment of cancer.

A Screen of Plant-Based Natural Products Revealed That Quercetin Prevents Pyroglutamylated Amyloid-β (Aβ3(pE)-42) Uptake in Astrocytes As Well As Resulting Astrogliosis and Synaptic Dysfunction

Two connected histopathological hallmarks of Alzheimer's disease (AD) are chronic neuroinflammation and synaptic dysfunction. The accumulation of the most prevalent posttranslationally modified form of Aβ1-42, pyroglutamylated amyloid-β (Aβ3(pE)-42) in astrocytes is directly linked to glial activation and the release of proinflammatory cytokines that in turn contribute to early synaptic dysfunction in AD. At present, the mechanisms of Aβ3(pE)-42 uptake to astrocytes are unknown and pharmacological interventions that interfere with this process are not available. Here we developed a simple screening assay to identify substances from a plant extract library that prevent astroglial Aβ3(pE)-42 uptake. We first show that this approach yields valid and reproducible results. Second, we show endocytosis of Aβ3(pE)-42 oligomers by astrocytes and that quercetin, a plant flavonol, is effective to specifically block astrocytic buildup of oligomeric Aβ3(pE)-42. Importantly, quercetin does not induce a general impairment of endocytosis. However, it efficiently protects against early synaptic dysfunction following exogenous Aβ3(pE)-42 application.

Plant Antioxidants: Therapeutic Potential in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are a global health problem. The mortality associated with them is one of the highest. Essentially, CVDs occur when the heart or blood vessels are damaged. Oxidative stress is an imbalance between the production of reactive oxygen species (free radicals) and antioxidant defenses. Increased production of reactive oxygen species can cause cardiac and vascular injuries, leading to CVDs. Antioxidant therapy has been shown to have beneficial effects on CVDs. Plants are a rich source of bioactive antioxidants on our planet. Several classes of these compounds have been identified. Among them, carotenoids and phenolic compounds are the most potent antioxidants. This review summarizes the role of some carotenoids (a/β-carotene, lycopene and lutein), polyphenols such as phenolic acids (caffeic, p-coumaric, ferulic and chlorogenic acids), flavonoids (quercetin, kaempferol and epigallocatechin gallate), and hydroxytyrosol in mitigating CVDs by studying their biological antioxidant mechanisms. Through detailed analysis, we aim to provide a deeper understanding of how these natural compounds can be integrated into cardiovascular health strategies to help reduce the overall burden of CVD.

Therapeutic Potential of Quercetin as an Antioxidant for Bone-Muscle-Tendon Regeneration and Aging

Quercetin (QC), a naturally occurring bioflavonoid found in various fruits and vegetables, possesses many potential health benefits, primarily attributed to its robust antioxidant properties. The generation of oxidative stress in bone cells is a key modulator of their physiological behavior. Moreover, oxidative stress status influences the pathophysiology of mineralized tissues. Increasing scientific evidence demonstrates that manipulating the redox balance in bone cells might be an effective technique for developing bone disease therapies. The QC antioxidant abilities in skeletal muscle significantly enhance muscle regeneration and reduce muscle atrophy. In addition, QC has been shown to have protective effects against oxidative stress, inflammation, apoptosis, and matrix degradation in tendons, helping to maintain the structural integrity and functionality of tendons. Thus, the antioxidant properties of QC might be crucial for addressing age-related musculoskeletal disorders like osteoporosis, sarcopenia, and tendon-related inflammatory conditions. Understanding how QC influences redox signaling pathways involved in musculoskeletal disorders, including their effect on bone, muscle, and tendon differentiation, might provide insights into the diverse advantages of QC in promoting tissue regeneration and preventing cellular damage. Therefore, this study reviewed the intricate relationship among oxidative stress, inflammation, and tissue repair, affected by the antioxidative abilities of QC, in age-related musculoskeletal tissues to improve the overall health of bones, muscles, and tendons of the skeletal system. Also, reviewing the ongoing clinical trials of QC for musculoskeletal systems is encouraging. Given the positive effect of QC on musculoskeletal health, further scientific investigations and controlled human intervention studies are necessary to explore the therapeutic potential to its optimum strength.

Quercetin nanocrystals for bioavailability enhancement: impact of different functional stabilizers on in vitro/in vivo drug performances

The purpose of this study was to investigate the impact of different functional stabilizers on in vitro/in vivo drug performances after oral administration of drug nanocrystals. Quercetin nanocrystals (QT-NCs) respectively stabilized by five types of functional stabilizers, including hydroxypropyl methyl cellulose E15 (HPMC E15), poloxamer 407 (P407), poloxamer 188 (P188), D-α-tocopherol polyethylene glycol succinate (TPGS), and glycyrrhizin acid (GL), were fabricated by wet media milling technique. The particle size, morphology, physical state, drug solubility, drug dissolution in vitro, and orally pharmacokinetic behaviors of all QT-NCs were investigated. All QT-NCs with similar particle size about 200 nm were obtained by controlling milling speed and milling time. No significant differences in particles shape and crystalline nature were found for QT-NCs stabilized by different functional stabilizers. But the solubility and dissolution of QT-NCs were significantly influenced by the different functional stabilizers. The AUC0∼t of all QT-NCs after oral administration was in the following order: QT-NCs/P188 ≈ QT-NCs/HPMC E15 > QT-NCs/GL > QT-NCs/P407 ≈ QT-NCs/TPGS, and the Cmax showed an order of QT-NCs/P407 > QT-NCs/P188 ≈ QT-NCs/GL > QT-NCs/HPMC E15 > QT-NCs/TPGS. Both of QT-NCs/P407 and QT-NCs/TPGS exhibited faster oral absorption with Tmax at 0.5 h and 0.83 h, respectively, while the other three QT-NCs (QT-NCs/P188, QT-NCs/GL and QT-NCs/HPMC E15) showed a relatively slow absorption with same Tmax at 5.33 h. The longest MRT0∼t (11.72 h) and t1/2z (32.22 h) were observed for QT-NCs/HPMC E15. These results suggested that the different functional stabilizers could significantly influence on drug solubility, drug dissolution in vitro and orally pharmacokinetic behavior of QT-NCs, and it is possible to alter the drug dissolution in vitro, oral absorption and drug retention in vivo by changing the type of functional stabilizers in NCs preparation.

Therapeutic Applications of Nanoformulated Resveratrol and Quercetin Phytochemicals in Colorectal Cancer-An Updated Review

Natural compounds such as polyphenols play several positive roles in maintaining the oxidative and inflammatory capacity of cells, which leads to their potential use as anticancer therapeutics. There is promising evidence for the in vitro and in vivo anticancer activity of many polyphenols, including resveratrol and quercetin, specifically in the treatment of colorectal cancer (CRC). There is a clear association between resveratrol and quercetin in interfering with the mechanistic pathways involved in CRC, such as Wnt, P13K/AKT, caspase-3, MAPK, NF-κB, etc. These molecular pathways establish the role of resveratrol and quercetin in controlling cancer cell growth, inducing apoptosis, and inhibiting metastasis. The major bottleneck in the progression of the use of resveratrol and quercetin as anticancer therapeutics is their reduced bioavailability in vivo because of their rapid metabolism in humans. Recent advancements in various nanotechnological formulations are promising for overcoming these bioavailability issues. Various nanoformulations of resveratrol and quercetin have shown an optimistic impact on reducing the solubility and improving the stability of resveratrol and quercetin in vivo. A combinatorial approach using nanoformulations of resveratrol with quercetin could potentially increase the impact of resveratrol in controlling CRC cell proliferation. This review discusses the mechanism of resveratrol and quercetin, the two bioactive polyphenolics, in colon cancer, with an emphasis on various types of nanoformulations of the two molecules targeting colon cancer. It also explores the synergistic effect of combining resveratrol and quercetin in various nanoformulations, targeting colon cancer. This research delves into the enhanced pharmacokinetics and potential chemotherapeutic benefits of these bioactive polyphenolics when used together in innovative ways.

Enhanced Anti-Inflammatory Activity of Tilianin Based on the Novel Amorphous Nanocrystals

Tilianin (Til), a flavonoid glycoside, is well-known for its therapeutic promise in treating inflammatory disorders. Its poor water solubility and permeability limit its clinical applicability. In order to overcome these restrictions, an antisolvent precipitation and ultrasonication technique was used to prepare amorphous tilianin nanocrystals (Til NCs). We have adjusted the organic solvents, oil-to-water ratio, stabilizer composition, and ultrasonic power and time by combining single-factor and central composite design (CCD) methodologies. The features of Til NCs were characterized using powder X-ray diffraction (PXRD), scanning calorimetry (DSC), and transmission electron microscopy (TEM). Specifically, the optimized Til NCs were needle-like with a particle size ranging from 90 to 130 nm. PVA (0.3%, w/v) and TPGS (0.08%, w/v) stabilized them well. For at least two months, these Til NCs stayed amorphous and showed an impressive stability at 4 °C and 25 °C. Remarkably, Til NCs dissolved almost 20 times faster in simulated intestinal fluid (SIF) than they did in crude Til. In RAW264.7 cells, Til NCs also showed a better cellular absorption as well as safety and protective qualities. Til NCs were shown to drastically lower reactive oxygen species (ROS), TNF-α, IL-1β, and IL-6 in anti-inflammatory experiments, while increasing IL-10 levels and encouraging M1 macrophages to adopt the anti-inflammatory M2 phenotype. Our results highlight the potential of amorphous Til NCs as a viable approach to improve Til's anti-inflammatory effectiveness, solubility, and dissolving rate.

Regulation of mitophagy and mitochondrial function: Natural compounds as potential therapeutic strategies for Parkinson's disease

Mitochondrial damage is associated with the development of Parkinson's disease (PD), indicating that mitochondrial-targeted treatments could hold promise as disease-modifying approaches for PD. Notably, natural compounds have demonstrated the ability to modulate mitochondrial-related processes. In this review article, we discussed the possible neuroprotective mechanisms of natural compounds against PD in modulating mitophagy and mitochondrial function. A comprehensive literature search on natural compounds related to the treatment of PD by regulating mitophagy and mitochondrial function was conducted from PubMed, Web of Science and Chinese National Knowledge Infrastructure databases from their inception until April 2023. We summarize recent advancements in mitophagy's molecular mechanisms, including upstream and downstream processes, and its relationship with PD-related genes or proteins. Importantly, we highlight how natural compounds can therapeutically regulate various mitochondrial processes through multiple targets and pathways to alleviate oxidative stress, neuroinflammation, Lewy's body aggregation and apoptosis, which are key contributors to PD pathogenesis. Unlike the single-target strategy of modern medicine, natural compounds provide neuroprotection against PD by modulating various mitochondrial-related processes, including ameliorating mitophagy by targeting the PINK1/parkin pathway, the NIX/BNIP3 pathway, and autophagosome formation (i.e., LC3 and p62). Given the prevalence of mitochondrial damage in various neurodegenerative diseases, exploring the exact mechanism of natural compounds on mitophagy and mitochondrial dysfunction could shed light on the development of highly effective disease-modifying or adjuvant therapies targeting PD and other neurodegenerative disorders.

Quercetin as a Promising Antiprotozoan Phytochemical: Current Knowledge and Future Research Avenues

Despite tremendous advances in the prevention and treatment of infectious diseases, only few antiparasitic drugs have been developed to date. Protozoan infections such as malaria, leishmaniasis, and trypanosomiasis continue to exact an enormous toll on public health worldwide, underscoring the need to discover novel antiprotozoan drugs. Recently, there has been an explosion of research into the antiprotozoan properties of quercetin, one of the most abundant flavonoids in the human diet. In this review, we tried to consolidate the current knowledge on the antiprotozoal effects of quercetin and to provide the most fruitful avenues for future research. Quercetin exerts potent antiprotozoan activity against a broad spectrum of pathogens such as Leishmania spp., Trypanosoma spp., Plasmodium spp., Cryptosporidium spp., Trichomonas spp., and Toxoplasma gondii. In addition to its immunomodulatory roles, quercetin disrupts mitochondrial function, induces apoptotic/necrotic cell death, impairs iron uptake, inhibits multiple enzymes involved in fatty acid synthesis and the glycolytic pathways, suppresses the activity of DNA topoisomerases, and downregulates the expression of various heat shock proteins in these pathogens. In vivo studies also show that quercetin is effective in reducing parasitic loads, histopathological damage, and mortality in animals. Future research should focus on designing effective drug delivery systems to increase the oral bioavailability of quercetin. Incorporating quercetin into various nanocarrier systems would be a promising approach to manage localized cutaneous infections. Nevertheless, clinical trials are needed to validate the efficacy of quercetin in treating various protozoan infections.

Management of Colorectal Cancer Using Nanocarriers-based Drug Delivery for Herbal Bioactives: Current and Emerging Approaches

Colorectal cancer (CRC) is a complex and multifactorial disorder in middle-aged people. Several modern medicines are available for treating and preventing it. However, their therapeutic uses are limited due to drawbacks, such as gastric perforation, diarrhea, intestinal bleeding, abdominal cramps, hair loss, nausea, vomiting, weight loss, and adverse reactions. Hence, there is a continuous quest for safe and effective medicines to manage human health problems, like CRC. In this context, herbal medicines are considered an alternative disease control system. It has become popular in countries, like American, European, and Asian, due to its safety and effectiveness, which has been practiced for 1000 years. During the last few decades, herbal medicines have been widely explored through multidisciplinary fields for getting active compounds against human diseases. Several herbal bioactives, like curcumin, glycyrrhizin, paclitaxel, chlorogenic acid, gallic acid, catechin, berberine, ursolic acid, betulinic acid, chrysin, resveratrol, quercetin, etc., have been found to be effective against CRC. However, their pharmacological applications are limited due to low bioavailability and therapeutic efficacy apart from their several health benefits. An effective delivery system is required to increase their bioavailability and efficacy. Therefore, targeted novel drug delivery approaches are promising for improving these substances' solubility, bioavailability, and therapeutic effects. Novel carrier systems, such as liposomes, nanoparticles, micelles, microspheres, dendrimers, microbeads, and hydrogels, are promising for delivering poorly soluble drugs to the target site, i.e., the colon. Thus, the present review is focused on the pathophysiology, molecular pathways, and diagnostic and treatment approaches for CRC. Moreover, an emphasis has been laid especially on herbal bioactive-based novel delivery systems and their clinical updates.

Preparation, characterization, and evaluation of the antitumor effect of kaempferol nanosuspensions

Kaempferol (KAE) is a naturally occurring flavonoid compound with antitumor activity. However, the low aqueous solubility, poor chemical stability, and suboptimal bioavailability greatly restrict its clinical application in cancer therapy. To address the aforementioned limitations and augment the antitumor efficacy of KAE, we developed a kaempferol nanosuspensions (KAE-NSps) utilizing D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) as a stabilizing agent, screened the optimal preparation process, and conducted a comprehensive investigation of their fundamental properties as well as the antitumor effects in the study. The findings indicated that the particle size was 186.6 ± 2.6 nm of the TPGS-KAE-NSps optimized, the shape of which was fusiform under the transmission electron microscope. The 2% (w/v) glucose was used as the cryoprotectant for TPGS-KAE-NSps, whose drug loading content was 70.31 ± 2.11%, and the solubility was prominently improved compared to KAE. The stability and biocompatibility of TPGS-KAE-NSps were favorable and had a certain sustained release effect. Moreover, TPGS-KAE-NSps clearly seen to be taken in the cytoplasm exhibited a stronger cytotoxicity and suppression of cell migration, along with increased intracellular ROS production and higher apoptosis rates compared to KAE in vitro cell experiments. In addition, TPGS-KAE-NSps had a longer duration of action in mice, significantly improved bioavailability, and showed a stronger inhibition of tumor growth (the tumor inhibition rate of high dose intravenous injection group was 68.9 ± 1.46%) than KAE with no obvious toxicity in 4T1 tumor-bearing mice. Overall, TPGS-KAE-NSps prepared notably improved the defect and the antitumor effects of KAE, making it a promising nanodrug delivery system for KAE with potential applications as a clinical antitumor drug.

Neuroprotective effect of quercetin and nano-quercetin against cyclophosphamide-induced oxidative stress in the rat brain: Role of Nrf2/ HO-1/Keap-1 signaling pathway

Quercetin (Qu) is a powerful flavanol antioxidant that is naturally found in plants and is part of the flavonoid family. Qu has a wide range of biological properties, such as neuroprotective, anti-cancer, anti-diabetic, anti-inflammatory, and radical scavenging capabilities. However, the in vivo application of Qu is limited by its poor water solubility and low bioavailability. These issues could be addressed by utilizing Qu nanoformulations. Cyclophosphamide (CP) is a potent chemotherapeutic agent that causes severe neuronal damage and cognitive impairment due to reactive oxygen species (ROS) overproduction. The present study aimed to explore the proposed neuroprotective mechanism of quercetin (Qu) and quercetin-loaded Chitosan nanoparticles (Qu-Ch NPs) against the brain oxidative damage induced by CP in male albino rats. For this aim, thirty-six adult male rats were randomly divided into six groups (n = 6). Rats were pretreated with Qu and Qu-Ch NPs orally in doses of 10 mg/kg bwt/day for 2 weeks, and CP (75 mg/kg bwt) was administered intraperitoneally 24 h before the termination of the experiment. After 2 weeks, some neurobehavioral parameters were evaluated, and then euthanization was done to collect the brain and blood samples. Results showed that CP induces neurobehavioral deteriorations and impaired brain neurochemical status demonstrated by a significant decrease in brain glutathione (GSH), serum total antioxidant capacity (TAC), and serotonin (5-HT) levels while malondialdehyde (MDA), nitric oxide (NO), Tumor necrosis factor α (TNFα), and choline esterase (ChE) concentrations increased significantly compared to the control group. Pretreatment with Qu and Qu-Ch NPs showed a significant anti-oxidative, anti-depressive, and neuroprotective effect through modification of the above-mentioned parameters. The results were further validated by assessing the expression levels of selected genes in brain homogenates and histopathological investigations were done to pinpoint the exact brain-altered regions. It could be concluded that Qu and Qu-Ch NPs can be useful neuroprotective adjunct therapy to overcome neurochemical damage induced by CP.

Nano Drug Delivery Strategies for an Oral Bioenhanced Quercetin Formulation

Quercetin, a naturally occurring flavonoid, has been credited with a wide spectrum of therapeutic properties. However, the oral use of quercetin is limited due to its poor water solubility, low bioavailability, rapid metabolism, and rapid plasma clearance. Quercetin has been studied extensively when used with various nanodelivery systems for enhancing quercetin bioavailability. To enhance its oral bioavailability and efficacy, various quercetin-loaded nanosystems such as nanosuspensions, polymer nanoparticles, metal nanoparticles, emulsions, liposomes or phytosomes, micelles, solid lipid nanoparticles, and other lipid-based nanoparticles have been investigated in in-vitro cells, in-vivo animal models, and humans. Among the aforementioned nanosystems, quercetin phytosomes are attracting more interest and are available on the market. The present review covers insights into the possibilities of harnessing quercetin for several therapeutic applications and a special focus on anticancer applications and the clinical benefits of nanoquercetin formulations.

Zein-based nanospheres and nanocapsules for the encapsulation and oral delivery of quercetin

In this study, the ability of zein nanospheres (NS) and zein nanocapsules containing wheat germ oil (NC) to enhance the bioavailability and efficacy of quercetin was evaluated. Both types of nanocarriers had similar physico-chemical properties, including size (between 230 and 250 nm), spherical shape, negative zeta potential, and surface hydrophobicity. However, NS displayed a higher ability than NC to interact with the intestinal epithelium, as evidenced by an oral biodistribution study in rats. Moreover, both types of nanocarriers offered similar loading efficiencies and release profiles in simulated fluids. In C. elegans, the encapsulation of quercetin in nanospheres (Q-NS) was found to be two twice more effective than the free form of quercetin in reducing lipid accumulation. For nanocapsules, the presence of wheat germ oil significantly increased the storage of lipids in C. elegans; although the incorporation of quercetin (Q-NC) significantly counteracted the presence of the oil. Finally, nanoparticles improved the oral absorption of quercetin in Wistar rats, offering a relative oral bioavailability of 26% and 57% for Q-NS and Q-NC, respectively, compared to a 5% for the control formulation. Overall, the study suggests that zein nanocarriers, particularly nanospheres, could be useful in improving the bioavailability and efficacy of quercetin.

Comparative Serum and Brain Pharmacokinetics of Quercetin after Oral and Nasal Administration to Rats as Lyophilized Complexes with β-Cyclodextrin Derivatives and Their Blends with Mannitol/Lecithin Microparticles

Quercetin (Que) is one of the most studied flavonoids with strong antioxidant properties ascribed to its ability to bind free radicals and inactivate them. However, the low solubility of the compound along with its inadequate absorption after oral administration limit its beneficial effects. Que's complexation with two different cyclodextrin (CD) derivatives (hydroxypropyl-β-CD and methyl-β-CD) via the neutralization/lyophilization method has been found to improve its physicochemical properties. Moreover, blends of the lyophilized powders with mannitol/lecithin microparticles (MLMPs) have been proposed as candidates for intranasal (IN) administration after in vitro and ex vivo evaluations. In this context, a comparative pharmacokinetic (PK) study of the IN vs oral administration of Que lyophilized powders and their blends with MLMPs (75:25 w/w) was performed on Wistar rats. The PK parameters estimated by a non-compartmental analysis using the sparse data methodology in Phoenix® 8.3 (Certara, Princeton, NJ, USA) illustrated the effectiveness of IN administration either in brain targeting or in reaching the bloodstream. Significant levels of the compound were achieved at both sites, compared to those after oral delivery which were negligible. These results favor the potential application of the prepared Que nasal powders for systemic and nose-to-brain delivery for the prevention and/or treatment of neuroinflammatory degenerative conditions, such as Parkinson's and Alzheimer's disease.

Flavonoids target different molecules of autophagic and metastatic pathways in cancer cells

Despite the success of cancer therapy, it has encountered a major obstacle due to the complicated nature of cancer, namely resistance. The recurrence and metastasis of cancer occur when anti-cancer therapeutic agents fail to eradicate all cancer cells. Cancer therapy aims to find the best agent that targets all cancer cells, including those sensitive or resistant to treatment. Flavonoids, natural products from our diet, show anti-cancer effects in different studies. They can inhibit metastasis and the recurrence of cancers. This review discusses metastasis, autophagy, anoikis in cancer cells, and their dynamic relationship. We present evidence that flavonoids can block metastasis and induce cell death in cancer cells. Our research suggests that flavonoids can serve as potential therapeutic agents in cancer therapy.

Impact of nanotechnology on the oral delivery of phyto-bioactive compounds

Nanotechnology is an advanced field that has remarkable nutraceutical and food applications. Phyto-bioactive compounds (PBCs) play critical roles in promoting health and disease treatment. However, PBCs generally encounter several limitations that delay their widespread application. For example, most PBCs have low aqueous solubility, poor biostability, poor bioavailability, and a lack of target specificity. Moreover, the high concentrations of effective PBC doses also limit their application. As a result, encapsulating PBCs into an appropriate nanocarrier may increase their solubility and biostability and protect them from premature degradation. Moreover, nanoencapsulation could improve absorption and prolong circulation with a high opportunity for targeted delivery that may decrease unwanted toxicity. This review addresses the main parameters, variables, and barriers that control and affect oral PBC delivery. Moreover, this review discusses the potential role of biocompatible and biodegradable nanocarriers in improving the water solubility, chemical stability, bioavailability, and specificity/selectivity of PBCs.

Quercetin and Its Nano-Formulations for Brain Tumor Therapy—Current Developments and Future Perspectives for Paediatric Studies

The development of efficient treatments for tumors affecting the central nervous system (CNS) remains an open challenge. Particularly, gliomas are the most malignant and lethal form of brain tumors in adults, causing death in patients just over 6 months after diagnosis without treatment. The current treatment protocol consists of surgery, followed using synthetic drugs and radiation. However, the efficacy of these protocols is associated with side effects, poor prognosis and with a median survival of fewer than two years. Recently, many studies were focused on applying plant-derived products to manage various diseases, including brain cancers. Quercetin is a bioactive compound derived from various fruits and vegetables (asparagus, apples, berries, cherries, onions and red leaf lettuce). Numerous in vivo and in vitro studies highlighted that quercetin through multitargeted molecular mechanisms (apoptosis, necrosis, anti-proliferative activity and suppression of tumor invasion and migration) effectively reduces the progression of tumor cells. This review aims to summarize current developments and recent advances of quercetin’s anticancer potential in brain tumors. Since all reported studies demonstrating the anti-cancer potential of quercetin were conducted using adult models, it is suggested to expand further research in the field of paediatrics. This could offer new perspectives on brain cancer treatment for paediatric patients.

Mechanistic insight into gel formation of co-amorphous resveratrol and piperine during dissolution process

Different from previous co-amorphous systems, co-amorphous resveratrol and piperine (namely RES-PIP CM) showed much lower dissolution in comparison to the original two crystalline drugs owing to its gel formation during dissolution. The purpose of this study is to investigate the mechanism of gel formation and seek strategies to eliminate such gelation. It was found that the dissolution performance of RES-PIP CM and the properties of formed gels were significantly affected by the medium temperature and stoichiometric ratio of components. Multiple characterization results confirmed that the gelation process underwent the decrease of T_g caused by water plasticization, and then entered into its supercooled liquid state with high viscosity, accompanied by self-assembly of molecules. Furthermore, the study answered the question that whether such gelation of RES-PIP CM could be eliminated by porous carrier materials. The materials, mesoporous silica (MES) and attapulgite (ATT), provided barrier and well separation between molecules and particles of RES-PIP CM by the pore steric hindrance, and impeded the self-assembly and aggregation, hence achieving the degelation and dissolution improvement. The present study highlights the importance of recognizing gelation potential of some co-amorphous formulations, and provides an effective strategy to eliminate gelation in developing high quality co-amorphous drug products.

The Chelating Ability of Plant Polyphenols Can Affect Iron Homeostasis and Gut Microbiota

In the past decades, many studies have widely examined the effects of dietary polyphenols on human health. Polyphenols are well known for their antioxidant properties and for their chelating abilities, by which they can be potentially employed in cases of pathological conditions, such as iron overload. In this review, we have highlighted the chelating abilities of polyphenols, which are due to their structural specific sites, and the differences for each class of polyphenols. We have also explored how the dietary polyphenols and their iron-binding abilities can be important in inflammatory/immunomodulatory responses, with a special focus on the involvement of macrophages and dendritic cells, and how they might contribute to reshape the gut microbiota into a healthy profile. This review also provides evidence that the axes “polyphenol–iron metabolism–inflammatory responses” and “polyphenol–iron availability–gut microbiota” have not been very well explored so far, and the need for further investigation to exploit such a potential to prevent or counteract pathological conditions.

Nanosuspension: A Formulation Technology for Tackling the Poor Aqueous Solubility and Bioavailability of Poorly Soluble Drugs

The poor water solubility of numerous novel drug candidates presents significant challenges, particularly in terms of oral administration. This limitation can result in various undesirable clinical implications, such as inter-patient variability, poor bioavailability, difficulties in achieving a safe therapeutic index, increased costs, and potential risks of toxicity or inefficacy. Biopharmaceutics Classification System (BCS) class II drugs face particular hurdles due to their limited solubility in the aqueous media of the gastrointestinal tract. In such cases, parenteral administration is often employed as an alternative strategy. To address these challenges, nanosuspension techniques offer a promising solution for enhancing drug solubility and overcoming oral delivery obstacles. This technique has the potential to bridge the gap between drug discovery and preclinical use by resolving problematic solubility. This literature review has delved into contemporary nanosuspension preparation technologies and the incorporation of stabilizing ingredients within the formulation. Furthermore, the manuscript explores nanosuspension strategies for both oral and parenteral/other delivery routes, and separate discussions have been presented to establish a suitable flow that addresses the challenges and strategies relevant to each administration method.

Quercetin Ameliorates Testicular Damage in Zucker Diabetic Fatty Rats through Its Antioxidant, Anti-Inflammatory and Anti-Apoptotic Properties

The aim of this study was to investigate the effects of quercetin (QUE) on the testicular architecture as well as markers of oxidative, inflammatory, and apoptotic profile of male gonads in Zucker diabetic fatty (ZDF) rats suffering from Type 2 diabetes mellitus in the absence or presence of obesity. QUE was administered orally at a dose of 20 mg/kg/day for 6 weeks. Morphometric analysis revealed that QUE treatment led to an improvement in testicular appearance, particularly in the case of Obese ZDF rats. Furthermore, a significant stabilization of the antioxidant capacity (p < 0.05), superoxide dismutase and catalase activity (p < 0.01), with a concomitant decrease in lipid peroxidation (p < 0.05) were observed in Obese ZDF animals exposed to QUE. Our data also indicate a significant decline in the levels of interleukin (IL)-1 (p < 0.05), IL-6 (p < 0.01) and tumor necrosis factor alpha (p < 0.001) following QUE supplementation to Obese ZDF rats in comparison with their respective control. Finally, a significant down-regulation of the pro-apoptotic BAX protein (p < 0.0001) was observed in Obese ZDF rats administered with QUE, while a significant Bcl-2 protein overexpression (p < 0.0001) was recorded in Lean ZDF animals when compared to their untreated control. As such, our results suggest that QUE is a potentially beneficial agent to reduce testicular damage in ZDF rats with Type 2 diabetes mellitus by decreasing oxidative stress, chronic inflammation, and excessive cell loss through apoptosis.

Advances on nanoformulation approaches for delivering plant-derived antioxidants: A case of quercetin

Oxidative stress has been implicated in tumorigenic, cardiovascular, neuro-, and age-related degenerative changes. Antioxidants minimize the oxidative damage through neutralization of reactive oxygen species (ROS) and other causative agents. Ever since the emergence of COVID-19, plant-derived antioxidants have received enormous attention, particularly in the Indian subcontinent. Quercetin (QCT), a bio-flavonoid, exists in the glycosylated form in fruits, berries and vegetables. The antioxidant potential of QCT analogs relates to the number of free hydroxyl groups in their structure. Despite presence of these groups, QCT exhibits substantial hydrophobicity. Formulation scientists have tested nanotechnology-based approaches for its improved solubilization and delivery to the intended site of action. By the virtue of its hydrophobicity, QCT gets encapsulated in nanocarriers carrying hydrophobic domains. Apart from passive accumulation, active uptake of such formulations into the target cells can be facilitated through well-studied functionalization strategies. In this review, we have discussed the approaches of improving solubilization and bioavailability of QCT with the use of nanoformulations.

Nanocrystals for controlled delivery: State of the art and approved drug products

INTRODUCTION

Controlled/extended-release formulations offer numerous benefits over conventional especially reduced side effects, improved therapeutic outcomes and high patient compliance. Controlled release nanocrystal is extremely versatile technology with several advantages such as very high drug loading, ease of manufacturing, avoidance of dose dumping, reproducible drug release. Usually, nanonization of drug is performed to improve dissolution rate, intrinsic solubility and thereby bioavailability. Most of the times, this is done for immediate release dosage forms where objective is quick onset of action. However, nanocrystals can also provide a sustained, reproducible plasma concentration profile for weeks to months based on tissue microenvironment, surface coating administration route.

AREAS COVERED

This review briefly describes the methods for producing nanocrystals, summarizes preclinical research and commercial products demonstrating tremendous potential of controlled release nanocrystals.

EXPERT OPINION

Lipophilic drugs are attractive candidates for the development of nanocrystal based controlled release formulations. However, constraint should be practiced while generalizing the technology for the controlled release purpose. Not all drugs fit in the requirement from the perspectives of physicochemical properties or pharmacokinetic requirements. Additionally, technologies should be explored which can convert the nanocrystal into its final dosage form for administration yet preserves the benefits of small particle size and controlled release.

Natural Kinase Inhibitors for the Treatment and Management of Endometrial/Uterine Cancer: Preclinical to Clinical Studies

Endometrial cancer (EC) is the sixth most prevalent type of cancer among women. Kinases, enzymes mediating the transfer of adenosine triphosphate (ATP) in several signaling pathways, play a significant role in carcinogenesis and cancer cells’ survival and proliferation. Cyclin-dependent kinases (CDKs) are involved in EC pathogenesis; therefore, CDK inhibitors (CDKin) have a noteworthy therapeutic potential in this type of cancer, particularly in EC type 1. Natural compounds have been used for decades in the treatment of cancer serving as a source of anticancer bioactive molecules. Many phenolic and non-phenolic natural compounds covering flavonoids, stilbenoids, coumarins, biphenyl compounds, alkaloids, glycosides, terpenes, and terpenoids have shown moderate to high effectiveness against CDKin-mediated carcinogenic signaling pathways (PI3K, ERK1/2, Akt, ATM, mTOR, TP53). Pharmaceutical regimens based on two natural compounds, trabectedin and ixabepilone, have been investigated in humans showing short and midterm efficacy as second-line treatments in phase II clinical trials. The purpose of this review is twofold: the authors first provide an overview of the involvement of kinases and kinase inhibitors in the pathogenesis and treatment of EC and then discuss the existing evidence about natural products’ derived kinase inhibitors in the management of the disease and outline relevant future research.

Self-gelation involved in the transformation of resveratrol and piperine from a co-amorphous system into a co-crystal system

Self-gelation of co-amorphous system promotes the transformation into its co-crystal system during dissolution.