Pharmacokinetics and Relative Bioavailability of Flavonoids between Two Dosage Forms of Gegen-Qinlian-Tang in Rats

Bioactive Flavonoids: A Comprehensive Review on Pharmacokinetics and Analytical Aspects

Flavonoids are a diversified group of natural substances which were discovered to provide a variety of health benefits in human beings. Vegetables, fruits, wine and tea are the primary flavonoid dietary sources for humans and as the flavonoids are so closely connected to human dietary items and health, it is vital to explore the structural-activity connection. The arrangement, replacement of functional groups, and total number of hydroxyl groups around flavonoid's nucleus structure affect their biological activity, metabolism, and bioavailability. Various flavonoids have been proven to have hepatoprotective properties, that help in the prevention of coronary heart disease. Similarly, these flavonoids also possess anticancer, and anti-inflammatory activities. Flavonoids have been found to have a functional and structural link with their enzyme inhibitory action, that appears to have antiviral effect through acting as antioxidants, damaging cell membranes, blocking enzymes, activating mechanisms of host self-defense, and limiting virus penetration and attaching to cells. Identification, characterization, isolation, and biological role of flavonoids, as well as their uses on health advantages, are all major topics in research and development currently. This review represents a summary of various sources of flavonoids, class, subclass, their chemical structures, biological activities, the pharmacokinetics of flavonoids and various analytical, bioanalytical and electrochemical methods for determination of flavonoids from different matrices.

Energy metabolism and redox balance: How phytochemicals influence heart failure treatment

Heart Failure (HF) epitomizes a formidable global health quandary characterized by marked morbidity and mortality. It has been established that severe derangements in energy metabolism are central to the pathogenesis of HF, culminating in an inadequate cardiac energy milieu, which, in turn, precipitates cardiac pump dysfunction and systemic energy metabolic failure, thereby steering the trajectory and potential recuperation of HF. The conventional therapeutic paradigms for HF predominantly target amelioration of heart rate, and cardiac preload and afterload, proffering symptomatic palliation or decelerating the disease progression. However, the realm of therapeutics targeting the cardiac energy metabolism remains largely uncharted. This review delineates the quintessential characteristics of cardiac energy metabolism in healthy hearts, and the metabolic aberrations observed during HF, alongside the associated metabolic pathways and targets. Furthermore, we delve into the potential of phytochemicals in rectifying the redox disequilibrium and the perturbations in energy metabolism observed in HF. Through an exhaustive analysis of recent advancements, we underscore the promise of phytochemicals in modulating these pathways, thereby unfurling a novel vista on HF therapeutics. Given their potential in orchestrating cardiac energy metabolism, phytochemicals are emerging as a burgeoning frontier for HF treatment. The review accentuates the imperative for deeper exploration into how these phytochemicals specifically intervene in cardiac energy metabolism, and the subsequent translation of these findings into clinical applications, thereby broadening the horizon for HF treatment modalities.

Baicalin and baicalein in modulating tumor microenvironment for cancer treatment: A comprehensive review with future perspectives

Cancer is a leading cause of death worldwide. The burden of cancer incidence and mortality is increasing rapidly. New approaches to cancer prevention and treatment are urgently needed. Natural products are reliable and powerful sources for anticancer drug discovery. Baicalin and baicalein, two major flavones isolated from Scutellaria baicalensis Georgi, a multi-purpose traditional medicinal plant in China, exhibit anticancer activities against multiple cancers. Of note, these phytochemicals exhibit extremely low toxicity to normal cells. Besides their cytotoxic and cytostatic activities toward diverse tumor cells, recent studies demonstrated that baicalin and baicalein modulate a variety of tumor stromal cells and extracellular matrix (ECM) in the tumor microenvironment (TME), which is essential for tumorigenesis, cancer progression and metastasis. In this review, we summarize the therapeutic potential and the mechanism of action of baicalin and baicalein in the regulation of tumor microenvironmental immune cells, endothelial cells, fibroblasts, and ECM that reshape the TME and cancer signaling, leading to inhibition of tumor angiogenesis, progression, and metastasis. In addition, we discuss the biotransformation pathways of baicalin and baicalein, related therapeutic challenges and the future research directions to improve their bioavailability and clinical anticancer applications. Recent advances of baicalin and baicalein warrant their continued study as important natural ways for cancer interception and therapy.

The Role of Selective Flavonoids on Triple-Negative Breast Cancer: An Update

Among the many types of breast cancer (BC), Triple-Negative Breast Cancer (TNBC) is the most alarming. It lacks receptors for the three main biomarkers: estrogen, progesterone, and human epidermal growth factor, hence the name TNBC. This makes its treatment a challenge. Surgical procedures and chemotherapy, performed either alone or in combination, seem to be the primary therapeutic possibilities; however, they are accompanied by severe complications. Currently, the formulation of drugs using natural products has been playing an important role in the pharmaceutical industries, owing to the drugs’ increased efficacies and significantly lessened side effects. Hence, treating TNBC with chemotherapeutic drugs developed using natural products such as flavonoids in the near future is much warranted. Flavonoids are metabolic compounds largely present in all plants, vegetables, and fruits, such as blueberries, onions, (which are widely used to make red wine,) chocolates, etc. Flavonoids are known to have enormous health benefits, such as anticancer, antiviral, anti-inflammatory, and antiallergic properties. They are known to arrest the cell cycle of the tumor cells and induces apoptosis by modulating Bcl-2, Bax, and Caspase activity. They show a considerable effect on cell proliferation and viability and angiogenesis. Various studies were performed at both the biochemical and molecular levels. The importance of flavonoids in cancer treatment and its methods of extraction and purification to date have been reported as individual publications. However, this review article explains the potentiality of flavonoids against TNBC in the preclinical levels and also emphasizes their molecular mechanism of action, along with a brief introduction to its methods of extraction, isolation, and purification in general, emphasizing the fact that its quantum of yield if enhanced and its possible synergistic effects with existing chemotherapeutics may pave the way for better anticancer agents of natural origin and significantly lessened side-effects.

An insight into cytotoxic activity of flavonoids and sesquiterpenoids from selected plants of Asteraceae species

Cancer continues to be a disease that is difficult to cure and the current therapeutic regimen is associated with severe side effects and the issue of emerging drug resistance. According to the World Health Organization fact sheet 2017, cancer is the second major cause of morbidity and death and a 70% rise in new cases is expected over the next 20 years. The quest for new anticancer chemical entities is a thrust area identified by many government agencies and industry research and development groups. Nature-derived entities have played a very important role in therapeutics especially cancer Asteraceae is a large family consisting of around 1700 genera and more than 24,000 species. Several genera belonging to this family have ethnopharmacological uses such as cytotoxicity, antidiabetic, hepatoprotective and antioxidant. This review highlights the cytotoxic potential of structurally novel flavonoids and sesquiterpenes isolated from some selected species of Asteraceae plants native to Asia, Europe, parts of Africa and America. The existing literature suggests that sesquiterpenes and flavonoids from various species of Asteraceae represent a viable class of secondary metabolites with strong cytotoxic potential. These have demonstrated potent activity in cell cycle arrest, inhibition of neoangiogenesis and induction of apoptosis. The sesquiterpenoids exhibiting potent cytotoxic activity were found to contain an α- methylene-butyrolactone conjugated with an exomethylene group and the flavonoids obtained from various plant species of Blumea suggest that a dihydroxy ring system present in structure is essential for activity. Most of the published literature contains in vitro data of extracts/secondary metabolites with very few in vivo studies. Additionally, there is dearth of knowledge on mechanisms of cytotoxic activity and molecular targets impacted by the active secondary metabolites. This review hopes to fuel interest in researchers to take up detailed investigations on these scaffolds that could contribute significantly as potential leads in anticancer drug development.

Synthetic Biology towards Improved Flavonoid Pharmacokinetics

Flavonoids are a structurally diverse class of natural products that have been found to have a range of beneficial activities in humans. However, the clinical utilisation of these molecules has been limited due to their low solubility, chemical stability, bioavailability and extensive intestinal metabolism in vivo. Recently, the view has been formed that site-specific modification of flavonoids by methylation and/or glycosylation, processes that occur in plants endogenously, can be used to improve and adapt their biophysical and pharmacokinetic properties. The traditional source of flavonoids and their modified forms is from plants and is limited due to the low amounts present in biomass, intrinsic to the nature of secondary metabolite biosynthesis. Access to greater amounts of flavonoids, and understanding of the impact of modifications, requires a rethink in terms of production, more specifically towards the adoption of plant biosynthetic pathways into ex planta synthesis approaches. Advances in synthetic biology and metabolic engineering, aided by protein engineering and machine learning methods, offer attractive and exciting avenues for ex planta flavonoid synthesis. This review seeks to explore the applications of synthetic biology towards the ex planta biosynthesis of flavonoids, and how the natural plant methylation and glycosylation pathways can be harnessed to produce modified flavonoids with more favourable biophysical and pharmacokinetic properties for clinical use. It is envisaged that the development of viable alternative production systems for the synthesis of flavonoids and their methylated and glycosylated forms will help facilitate their greater clinical application.

Role of Flavonoids in Neurodegenerative Diseases: Limitations and Future Perspectives

BACKGROUND

Flavonoids, a group of natural dietary polyphenols, are known for their beneficial effects on human health. By virtue of their various pharmacological effects, like anti-oxidative, antiinflammatory, anti-carcinogenic and neuroprotective effects, flavonoids have now become an important component of herbal supplements, pharmaceuticals, medicinals and cosmetics. There has been enormous literature supporting neuroprotective effect of flavonoids. Recently their efficacy in various neurodegenerative diseases, like Alzheimer's disease and Parkinson diseases, has received particular attention.

OBJECTIVE

The mechanism of flavanoids neuroprotection might include antioxidant, antiapoptotic, antineuroinflammatory and modulation of various cellular and intracellular targets. In in-vivo systems, before reaching to brain, they have to cross barriers like extensive first pass metabolism, intestinal barrier and ultimately blood brain barrier. Different flavonoids have varied pharmacokinetic characteristics, which affect their pharmacodynamic profile. Therefore, brain accessibility of flavonoids is still debatable.

METHODS

This review emphasized on current trends of research and development on flavonoids, especially in neurodegenerative diseases, possible challenges and strategies to encounter using novel drug delivery system.

RESULTS

Various flavonoids have elicited their therapeutic potential against neurodegenerative diseases, however by using nanotechnology and novel drug delivery systems, the bioavailability of favonoids could be enhanced.

CONCLUSION

This study bridges a significant opinion on medicinal chemistry, ethanopharmacology and new drug delivery research regarding use of flavonoids in management of neurodegeneration.

Molecular elucidation of pancreatic elastase inhibition by baicalein

The serine protease, elastase exists in various forms and plays diverse roles in the human body. Pharmacological inhibition of elastase has been investigated for its therapeutic role in managing conditions such as diabetes, pneumonia and arthritis. Sivelestat, a synthetic molecule, is the only elastase inhibitor to have been approved by any major drug regulatory authority (PMDA, in this case) - but still has failed to attain widespread clinical usage owing to its high price, cumbersome administration and obscure long-term safety profile. In order to find a relatively better-suited alternative, screening was conducted using plant flavonoids, which yielded baicalein, a molecule that showed robust inhibition against Pancreatic Elastase inhibition (IC₅₀: 3.53 μM). Other than having a considerably lower IC₅₀than sivelestat, baicalein is also cheaper, safer and easier to administer. While MicroScale Thermophoresis validated baicalein-elastase interaction, enzyme-kinetic studies, molecular docking and molecular dynamic simulation revealed the mode of inhibition to be non-competitive. Baicalein exhibited binding to a distinct allosteric site on the enzyme. The current study demonstrates the elastase inhibition properties of baicalein in an in-vitro and in-silico environment.Communicated by Ramaswamy H. Sarma.

Design and Characterization of Chitosan-Graphene Oxide Nanocomposites for the Delivery of Proanthocyanidins

Introduction

In the last years, the utilization of phytomedicines has increased given their good therapeutic activity and fewer side effects compared to allopathic medicines. However, concerns associated with the biocompatibility and toxicity of natural compounds, limit the phytochemical therapeutic action, opening the opportunity to develop new systems that will be able to effectively deliver these substances. This study has developed a nanocomposite of chitosan (CS) functionalized with graphene oxide (GO) for the delivery of proanthocyanidins (PAs), obtained from a grape seed extract (Ext.).

Methods

The GO-CS nanocomposite was covalently bonded and was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM) and by dynamic light scattering (DLS). The loading and release of Ext. from the GO-CS nanocomposite were performed in simulated physiological, and the cytotoxicity of the raw materials (GO and Ext.) and nanocomposites (GO-CS and GO-CS-Ext.) was determined using a human kidney cell line (HEK 293).

Results

The chemical characterization indicated that the covalent union was successfully achieved between the GO and CS, with 44 wt. % CS in the nanocomposite. The GO-CS nanocomposite was thermostable and presented an average diameter of 480 nm (by DLS). The Ext. loading capacity was approximately 20 wt. %, and under simulated physiological conditions, 28.4 wt.% Ext. (g) was released per g of the nanocomposite. GO-CS-Ext. was noncytotoxic, presenting a 97% survival rate compared with 11% for the raw extract and 48% for the GO-CS nanocomposite at a concentration of 500 µg mL-1 after 24 hrs.

Conclusion

Due to π–π stacking and hydrophilic interactions, GO-CS was reasonably efficient in binding Ext., with high loading capacity and Ext. release from the nanocomposite. The GO-CS nanocomposite also increased the biocompatibility of PAs-rich Ext., representing a new platform for the sustained release of phytodrugs.

Wogonin glucuronidation in liver and intestinal microsomes of humans, monkeys, dogs, rats, and mice

Wogonin, one of the flavonoids isolated from Scutellaria baicalensis, exhibits some beneficial bioactivities, including anti-inflammatory and anticancer effects, and is metabolized into glucuronide by UDP-glucuronosyltransferase (UGT) enzymes in humans. In the present study, wogonin glucuronidation was examined in the liver and intestinal microsomes of humans, monkeys, dogs, rats, and mice using a kinetic analysis.The kinetics of wogonin glucuronidation by liver microsomes followed the biphasic model in all species examined. CL_int values (x-intercept) based on v versus V/[S] plots were rats > humans ≈ monkeys > mice > dogs. The kinetics of intestinal microsomes fit the Michaelis-Menten model for humans, monkeys, rats, and mice and the substrate inhibition model for dogs. CL_int values were rats > monkeys > mice > dogs > humans. The tissue dependence of CL_int values was liver microsomes > intestinal microsomes for humans, dogs, and rats, and liver microsomes ≈ intestinal microsomes for monkeys and mice.These results demonstrated that the metabolic abilities of UGT enzymes toward wogonin in the liver and intestines markedly differ among humans, monkeys, dogs, rats, and mice, and suggest that species differences are closely associated with the biological effects of wogonin.

Coptisine from Coptis chinensis exerts diverse beneficial properties: A concise review

Coptisine is a natural small-molecular compound extracted from Coptis chinensis (CC) with a history of using for thousands of years. This work aimed at summarizing coptisine's activity and providing advice for its clinical use. We analysed the online papers in the database of SciFinder, Web of Science, PubMed, Google scholar and CNKI by setting keywords as 'coptisine' in combination of 'each pivotal pathway target'. Based on the existing literatures, we find (a) coptisine exerted potential to be an anti-cancer, anti-inflammatory, CAD ameliorating or anti-bacterial drug through regulating the signalling transduction of pathways such as NF-κB, MAPK, PI3K/Akt, NLRP3 inflammasome, RANKL/RANK and Beclin 1/Sirt1. However, we also (b) observe that the plasma concentration of coptisine demonstrates obvious non-liner relationship with dosage, and even the highest dosage used in animal study actually cannot reach the minimum concentration level used in cell experiments owing to the poor absorption and low availability of coptisine. We conclude (a) further investigations can focus on coptisine's effect on caspase-1-involved inflammasome assembling and pyroptosis activation, as well as autophagy. (b) Under circumstance of promoting coptisine availability by pursuing nano- or microrods strategies or applying salt-forming process to coptisine, can it be introduced to clinical trial.

Pharmacokinetics of B-Ring Unsubstituted Flavones

B-ring unsubstituted flavones (of which the most widely known are chrysin, baicalein, wogonin, and oroxylin A) are 2-phenylchromen-4-one molecules of which the B-ring is devoid of any hydroxy, methoxy, or other substituent. They may be found naturally in a number of herbal products used for therapeutic purposes, and several have been designed by researchers and obtained in the laboratory. They have generated interest in the scientific community for their potential use in a variety of pathologies, and understanding their pharmacokinetics is important for a grasp of their optimal use. Based on a comprehensive survey of the relevant literature, this paper examines their absorption (with deglycosylation as a preliminary step) and their fate in the body, from metabolism to excretion. Differences among species (inter-individual) and within the same species (intra-individual) variability have been examined based on the available data, and finally, knowledge gaps and directions of future research are discussed.

Cancer chemoprevention through dietary flavonoids: what's limiting?

Flavonoids are polyphenols that are found in numerous edible plant species. Data obtained from preclinical and clinical studies suggest that specific flavonoids are chemo-preventive and cytotoxic against various cancers via a multitude of mechanisms. However, the clinical use of flavonoids is limited due to challenges associated with their effective use, including (1) the isolation and purification of flavonoids from their natural resources; (2) demonstration of the effects of flavonoids in reducing the risk of certain cancer, in tandem with the cost and time needed for epidemiological studies, and (3) numerous pharmacokinetic challenges (e.g., bioavailability, drug–drug interactions, and metabolic instability). Currently, numerous approaches are being used to surmount some of these challenges, thereby increasing the likelihood of flavonoids being used as chemo-preventive drugs in the clinic. In this review, we summarize the most important challenges and efforts that are being made to surmount these challenges.

Compound to Extract to Formulation: a knowledge-transmitting approach for metabolites identification of Gegen-Qinlian Decoction, a traditional Chinese medicine formula

Herbal medicines usually contain a large group of chemical components, which may be transformed into more complex metabolites in vivo. In this study, we proposed a knowledge-transmitting strategy for metabolites identification of compound formulas. Gegen-Qinlian Decoction (GQD) is a classical formula in traditional Chinese medicine (TCM). It is widely used to treat diarrhea and diabetes in clinical practice. However, only tens of metabolites could be detected using conventional approaches. To comprehensively identify the metabolites of GQD, a “compound to extract to formulation” strategy was established in this study. The metabolic pathways of single representative constituents in GQD were studied, and the metabolic rules were transmitted to chemically similar compounds in herbal extracts. After screening diversified metabolites from herb extracts, the knowledge was summarized to identify the metabolites of GQD. Tandem mass spectrometry (MSⁿ), fragment-based scan (NL, PRE), and selected reaction monitoring (SRM) were employed to identify, screen, and monitor the metabolites, respectively. Using this strategy, we detected 131 GQD metabolites (85 were newly generated) in rats biofluids. Among them, 112 metabolites could be detected when GQD was orally administered at a clinical dosage (12.5 g/kg). This strategy could be used for systematic metabolites identification of complex Chinese medicine formulas.

Targeting arachidonic acid pathway by natural products for cancer prevention and therapy

Arachidonic acid (AA) pathway, a metabolic process, plays a key role in carcinogenesis. Hence, AA pathway metabolic enzymes phospholipase A₂s (PLA₂s), cyclooxygenases (COXs) and lipoxygenases (LOXs) and their metabolic products, such as prostaglandins and leukotrienes, have been considered novel preventive and therapeutic targets in cancer. Bioactive natural products are a good source for development of novel cancer preventive and therapeutic drugs, which have been widely used in clinical practice due to their safety profiles. AA pathway inhibitory natural products have been developed as chemopreventive and therapeutic agents against several cancers. Curcumin, resveratrol, apigenin, anthocyans, berberine, ellagic acid, eugenol, fisetin, ursolic acid, [6]-gingerol, guggulsteone, lycopene and genistein are well known cancer chemopreventive agents which act by targeting multiple pathways, including COX-2. Nordihydroguaiaretic acid and baicalein can be chemopreventive molecules against various cancers by inhibiting LOXs. Several PLA₂s inhibitory natural products have been identified with chemopreventive and therapeutic potentials against various cancers. In this review, we critically discuss the possible utility of natural products as preventive and therapeutic agents against various oncologic diseases, including prostate, pancreatic, lung, skin, gastric, oral, blood, head and neck, colorectal, liver, cervical and breast cancers, by targeting AA pathway. Further, the current status of clinical studies evaluating AA pathway inhibitory natural products in cancer is reviewed. In addition, various emerging issues, including bioavailability, toxicity and explorability of combination therapy, for the development of AA pathway inhibitory natural products as chemopreventive and therapeutic agents against human malignancy are also discussed.

Berberine Sulfate Attenuates Osteoclast Differentiation through RANKL Induced NF-κB and NFAT Pathways

Osteoporosis, a metabolic bone disease, is characterized by an excessive formation and activation of osteoclasts. Anti-catabolic treatment using natural compounds has been proposed as a potential therapeutic strategy against the osteoclast related osteolytic diseases. In this study, the activity of berberine sulfate (an orally available form of berberine) on osteoclast differentiation and its underlying molecular mechanisms of action were investigated. Using bone marrow macrophages (BMMs) derived osteoclast culture system, we showed that berberine sulfate at the dose of 0.25, 0.5 and 1 μM significantly inhibited the formation of osteoclasts. Notably, berberine sulfate at these doses did not affect the BMM viability. In addition, we observed that berberine sulfate inhibited the expression of osteoclast marker genes, including cathepsin K (Ctsk), nuclear factor of activated T cells cytoplasmic 1 (NFATc1), tartrate resistant acid phosphatase (TRAcP, Acp5) and Vacuolar-type H+-ATPase V0 subunit D2 (V-ATPase d2). Luciferase reporter gene assay and Western blot analysis further revealed that berberine sulfate inhibits receptor for activation of nuclear factor ligand (RANKL)-induced NF-κB and NFAT activity. Taken together, our results suggest that berberine sulfate is a natural compound potentially useful for the treatment of osteoporosis.