Role of tangeretin as a potential bioavailability enhancer for silybin: Pharmacokinetic and pharmacological studies

Intestinal absorption mechanism and nutritional synergy promotion strategy of dietary flavonoids: transintestinal epithelial pathway mediated by intestinal transport proteins

Dietary flavonoids exhibit a variety of physiological functions in regulating glucose and lipid metabolism, improving cardiovascular function, and enhancing stress resistance. However, poor intestinal absorption limits their health benefits. Previous studies on improving the absorption efficiency of flavonoids have focused on targeted release, enhanced gastrointestinal stability and prolonged retention time in digestive tract. But less attention has been paid to promoting the uptake and transport of flavonoids by intestinal epithelial cells through modulation of transporter protein-mediated pathways. Interestingly, some dietary nutrients have been found to modulate the expression or function of transporter proteins, thereby synergistically or antagonistically affecting flavonoid absorption. Therefore, this paper proposed an innovative regulatory strategy known as the "intestinal transport protein-mediated pathway" to promote intestinal absorption of dietary flavonoids. The flavonoid absorption mechanism in the intestinal epithelium, mediated by intestinal transport proteins, was summarized. The functional differences between the uptake transporter and efflux transporters during flavonoid trans-intestinal cellular transport were discussed. Finally, from the perspective of nutritional synergy promotion of absorption, the feasibility of promoting flavonoid intestinal absorption by regulating the expression/function of transport proteins through dietary nutrients was emphasized. This review provides a new perspective and developing precise dietary nutrient combinations for efficient dietary flavonoid absorption.

Bioactive Compounds Formulated in Phytosomes Administered as Complementary Therapy for Metabolic Disorders

Metabolic disorders (MDs), including dyslipidemia, non-alcoholic fatty liver disease, diabetes mellitus, obesity and cardiovascular diseases are a significant threat to human health, despite the many therapies developed for their treatment. Different classes of bioactive compounds, such as polyphenols, flavonoids, alkaloids, and triterpenes have shown therapeutic potential in ameliorating various disorders. Most of these compounds present low bioavailability when administered orally, being rapidly metabolized in the digestive tract and liver which makes their metabolites less effective. Moreover, some of the bioactive compounds cannot fully exert their beneficial properties due to the low solubility and complex chemical structure which impede the passive diffusion through the intestinal cell membranes. To overcome these limitations, an innovative delivery system of phytosomes was developed. This review aims to highlight the scientific evidence proving the enhanced therapeutic benefits of the bioactive compounds formulated in phytosomes compared to the free compounds. The existing knowledge concerning the phytosomes' preparation, their characterization and bioavailability as well as the commercially available phytosomes with therapeutic potential to alleviate MDs are concisely depicted. This review brings arguments to encourage the use of phytosome formulation to diminish risk factors inducing MDs, or to treat the already installed diseases as complementary therapy to allopathic medication.

Polymethoxylated flavonoids in citrus fruits: absorption, metabolism, and anticancer mechanisms against breast cancer

Polymethoxylated flavonoids (PMFs) are a subclass of flavonoids found in citrus fruits that have shown multifunctional biological activities and potential anticancer effects against breast cancer. We studied the absorption, metabolism, species source, toxicity, anti-cancer mechanisms, and molecular targets of PMFs to better utilize their anticancer activity against breast cancer. We discuss the absorption and metabolism of PMFs in the body, including the methylation, demethylation, and hydroxylation processes. The anticancer mechanisms of PMFs against breast cancer were also reviewed, including the estrogen activity, cytochrome P-450 enzyme system, and arylhydrocarbon receptor (AhR) inhibition, along with various molecular targets and potential anticancer effects. Although PMFs may be advantageous in the prevention and treatment for breast cancer, there is a lack of clinical evidence and data to support their efficacy. Despite their promise, there is still a long way to go before PMFs can be applied clinically.

Isoquercitrin attenuates the progression of non-alcoholic steatohepatitis in mice by modulating galectin-3-mediated insulin resistance and lipid metabolism

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is a global health problem with no effective treatment. Isoquercitrin (IQ) alters hepatic lipid metabolism and inhibits adipocyte differentiation. The underlying regulatory mechanisms of IQ in regulating insulin resistance (IR) and lipid metabolism remain unclear.

PURPOSE

This study was aimed at investigating the effects of IQ on NASH and deciphering whether the underlying mechanisms are via modulation of galectin-3 mediated IR and lipid metabolism.

METHODS

IR-HepG2 cell lines were used to demonstrate the ability of IQ to modulate galectin-3-mediated glucose disposal and lipid metabolism. A 20-week high-fat diet (HFD)-induced NASH model was established in C57BL/6J mice, and the protective effect of IQ on lipid disposal in the liver was verified. Further, the mRNA and protein levels of glucose and lipid metabolism were investigated, and lysophosphatidylcholine (LPC) and acylcarnitine (AC) profiling were performed to characterize the changes in endogenous substances associated with mitochondrial function and lipid metabolism in serum and cells. Furthermore, the pharmacokinetic features of IQ were explored in a rat model of NASH.

RESULTS

IQ restored liver function and ameliorated inflammation and lipid accumulationin NASH model mice. Notably, significant regulation of the proteins included fatty acid-generating and transporting, cholesterol metabolism enzymes, nuclear transcription factors, mitochondrial metabolism, and IR-related enzymes was noted to be responsible for the therapeutic mechanisms of IQ against experimental NASH. Serum lipid metabolism-related metabolomic assay confirmed that LPC and AC biosynthesis mostly accounted for the therapeutic effect of IQ in mice with NASH and that IQ maintained the homeostasis of LPC and AC levels.

CONCLUSION

This is the first study showing that IQ protects against of NASH by modulating galectin-3-mediated IR and lipid metabolism. The mechanisms responsible for liver protection and improved lipid metabolic disorder by IQ may be related to the suppression of IR and regulation of mitochondrial function and lipid metabolism. Galectin-3 down-regulation represents a potentially novel approach for the treatment and prevention of NASH.

Quercetin Enhances the Availability of 5-Heptadecylresorcinol by Inhibiting the Expression of P-gp

5-Heptadecylresorcinol (AR-C17), as the most important active monomer, is found in large quantities in wheat and triticale and plays a variety of health benefits, such as antidiabetic, anti-inflammatory, and antitumor. However, the low bioavailability of AR-C17 due to its low water solubility restricts its application. Moreover, the transport mechanism of AR-C17 is not fully understood. Here, we showed that the transport of AR-C17 in vitro was time- and concentration-dependent, and relatively higher temperature and lower pH obviously promoted the transport of AR-C17. Besides, transporters, especially P-glycoprotein (P-gp), markedly affected the transport of AR-C17 as well. Quercetin, a natural synergist in triticale bran (TB), was confirmed as an inhibitor of P-gp to promote the transport of AR-C17 in this study, and the bioavailability of AR-C17 reached the highest when the concentration ratio of quercetin to AR-C17 was 1:1.

Bovine Serum Albumin Nanoparticles Enhanced the Intranasal Bioavailability of Silybin in Rats

Silybin (SLB), an important flavonoid from silymarin, displays significant hepatoprotective, anticancer, antioxidant, and neuroprotective effects. However, its therapeutic efficacy is limited by its low solubility and bioavailability. To address these challenges, we engineered bovine serum albumin (BSA) nanoparticles (NP) loaded with SLB (BSA-NP/SLB) using the coacervation method. BSA-SLB NP exhibited a spherical shape, a mean size of 197 nm, a polydispersity index of 0.275, a zeta potential of -34 mV, and an entrapment efficiency of 67%. X-ray diffraction analysis indicated amorphization of SLB upon encapsulation. Formulation stability was upheld over 180 days. In vitro release assays demonstrated controlled diffusion-erosion release, with approximately 40% SLB released within 0.5 h and 100% over 12 h. Intranasal administration of BSA-NP/SLB in rats improved SLB bioavailability by fourfold compared to free SLB. These findings highlight the promising potential of intranasally administered BSA-NP/SLB as an alternative approach to enhance SLB bioavailability, paving the way for innovative therapeutic applications.

4'-OH as the Action Site of Lipids and MRP1 for Enhanced Transdermal Delivery of Flavonoids

To date, the transdermal delivery study mainly focused on the drug delivery systems' design and efficacy evaluation. Few studies reported the structure-affinity relationship of the drug with the skin, further revealing the action sites of the drugs for enhanced permeation. Flavonoids attained a considerable interest in transdermal administration. The aim is to develop a systematic approach to evaluate the substructures that were favorable for flavonoid delivery into the skin and understand how these action sites interacted with lipids and bound to multidrug resistance protein 1 (MRP1) for enhanced transdermal delivery. First, we investigated the permeation properties of various flavonoids on the porcine skin or rat skin. We found that 4'-OH (hydroxyl group on the carbon 4' position) rather than 7-OH on the flavonoids was the key group for flavonoid permeation and retention, while 4'-OCH₃ and -CH₂═CH₂-CH-(CH₃)₂ were unfavorable for drug delivery. 4'-OH could decrease flavonoids' lipophilicity to an appropriate log P and polarizability for better transdermal drug delivery. In the stratum corneum, flavonoids used 4'-OH as a hand to specifically grab the C═O group of the ceramide NS (Cer), which increased the miscibility of flavonoids and Cer and then disturbed the lipid arrangement of Cer, thereby facilitating their penetration. Subsequently, we constructed overexpressed MRP1 HaCaT/MRP1 cells by permanent transfection of human MRP1 cDNA in wild HaCaT cells. In the dermis, we observed that 4'-OH, 7-OH, and 6-OCH₃ substructures were involved in H-bond formation within MRP1, which increased the flavonoid affinity with MRP1 and flavonoid efflux transport. Moreover, the expression of MRP1 was significantly enhanced after the treatment of flavonoids on the rat skin. Collectively, 4'-OH served as the action site for increased lipid disruption and enhanced affinity for MRP1, which facilitate the transdermal delivery of flavonoids, providing valuable guidelines for molecular modification and drug design of flavonoids.

Changes in Disposition of Ezetimibe and Its Active Metabolites Induced by Impaired Hepatic Function: The Influence of Enzyme and Transporter Activities

Ezetimibe (EZE) is a selective cholesterol absorption inhibitor. Hepatic impairment significantly increases the systemic exposure of EZE and its main active phenolic glucuronide, EZE-Ph. Although changes in efflux transporter activity partly explain the changes in EZE-Ph pharmacokinetics, the causes of the changes to EZE and the effects of the administration route on EZE-Ph remain unclear. A carbon tetrachloride (CCl₄)-induced hepatic failure rat model was combined with in vitro experiments to explore altered EZE and EZE-Ph disposition caused by hepatic impairment. The plasma exposure of EZE and EZE-Ph increased by 11.1- and 4.4-fold in CCl₄-induced rats following an oral administration of 10 mg/kg EZE, and by 2.1- and 16.4-fold after an intravenous injection. The conversion of EZE to EZE-Ph decreased concentration-dependently in CCl₄-induced rat liver S9 fractions, but no change was observed in the intestinal metabolism. EZE-Ph was a substrate for multiple efflux and uptake transporters, unlike EZE. In contrast to efflux transporters, no difference was seen in the hepatic uptake of EZE-Ph between control and CCl₄-induced rats. However, bile acids that accumulated due to liver injury inhibited the uptake of EZE-Ph by organic anion transporting polypeptides (OATPs) (glycochenodeoxycholic acid and taurochenodeoxycholic acid had IC₅₀ values of 15.1 and 7.94 μM in OATP1B3-overexpressed cells). In conclusion, the increased plasma exposure of the parent drug EZE during hepatic dysfunction was attributed to decreased hepatic glucuronide conjugation, whereas the increased exposure of the metabolite EZE-Ph was mainly related to transporter activity, particularly the inhibitory effects of bile acids on OATPs after oral administration.

Solvent Free Twin Screw Processed Silybin Nanophytophospholipid: In Silico, In Vitro and In Vivo Insights

Silybin (SIL) is a polyphenolic phytoconstituent that is commonly used to treat liver disorders. It is difficult to fabricate an orally delivered SIL product due to its low oral bioavailability (0.95%). Therefore, the current research focusses on the development of a novel composition of a phospholipid complex, termed as nanophytophospholipid, of SIL by employing a unique, solvent-free Twin Screw Process (TSP), with the goal of augmenting the solubility and bioavailability of SIL. The optimised SIL-nanophytophospholipid (H6-SNP) was subjected to physicochemical interactions by spectrometry, thermal, X-ray and electron microscopy. The mechanism of drug and phospholipid interaction was confirmed by molecular docking and dynamics studies. Saturation solubility, in vitro dissolution, ex vivo permeation and preclinical pharmacokinetic studies were also conducted. H6-SNP showed good complexation efficiency, with a high practical yield (80%). The low particle size (334.7 ± 3.0 nm) and positively charged zeta potential (30.21 ± 0.3 mV) indicated the immediate dispersive nature of H6-SNP into nanometric dimensions, with good physical stability. Further high solubility and high drug release from the H6-SNP was also observed. The superiority of the H6-SNP was demonstrated in the ex vivo and preclinical pharmacokinetic studies, displaying enhanced apparent permeability (2.45-fold) and enhanced bioavailability (1.28-fold). Overall, these findings indicate that not only can phospholipid complexes be formed using solvent-free TSP, but also that nanophytophospholipids can be formed by using a specific quantity of lipid, drug, surfactant, superdisintegrant and diluent. This amalgamation of technology and unique composition can improve the oral bioavailability of poorly soluble and permeable phytoconstituents or drugs.

A review of recent progress in improving the bioavailability of nutraceutical-loaded emulsions after oral intake

Increasing awareness of the health benefits of specific constituents in fruits, vegetables, cereals, and other whole foods has sparked a broader interest in the potential health benefits of nutraceuticals. Many nutraceuticals are hydrophobic substances, which means they must be encapsulated in colloidal delivery systems. Oil-in-water emulsions are one of the most widely used delivery systems for improving the bioavailability and bioactivity of these nutraceuticals. The composition and structure of emulsions can be designed to improve the water dispersibility, physicochemical stability, and bioavailability of the encapsulated nutraceuticals. The nature of the emulsion used influences the interfacial area and properties of the nutraceutical-loaded oil droplets in the gastrointestinal tract, which influences their digestion, as well as the bioaccessibility, metabolism, and absorption of the nutraceuticals. In this article, we review recent in vitro and in vivo studies on the utilization of emulsions to improve the bioavailability of nutraceuticals. The findings from this review should facilitate the design of more efficacious nutraceutical-loaded emulsions with increased bioactivity.

Novel treatment for refractory rheumatoid arthritis with total glucosides of paeony and nobiletin codelivered in a self-nanoemulsifying drug delivery system

Patients with refractory rheumatoid arthritis (RA) remain a substantial clinical problem, while the overexpression of P-glycoprotein (P-gp) on their lymphocytes may contribute to resistance to anti-rheumatic drugs. This study aims to develop a novel treatment for refractory RA consisting of the combination of total glucosides of paeony (TGPs) and the P-gp inhibitor nobiletin (N), which are codelivered in a self-nanoemulsifying drug delivery system (SNEDDS). Based on the solubility, compatibility, and pseudoternary phase diagram tests, a nano-SNEDDS formulation composed of capryol 90-cremophor EL35-tcranscutol HP (CET) to codeliver TGP and N was developed, and this formulation increased the bioavailability of TGP by 435.04% (indicated with paeoniflorin). A modified adjuvant-induced arthritis (AIA) rat model was verified for the overexpression of P-gp in lymphocytes and resistance to methotrexate (MTX) treatment at the reported anti-inflammatory dosage. CET formulation not only increased the solubility and permeability of TGP but also inhibited the function and expression of P-gp, leading to enhanced bioavailability and intracellular concentration in the lymphocytes of AIA rats and consequently boosting the anti-arthritic effects of TGP. Moreover, TGP and N coloaded CET reduced the expression of P-gp in AIA rats partly by inhibiting the phosphorylated AKT and HIF-1α pathways. In summary, TGP-N coloaded SNEDDS is a novel and effective treatment for refractory RA.

Strategies and Mechanism in Reversing Intestinal Drug Efflux in Oral Drug Delivery

Efflux transporters distributed at the apical side of human intestinal epithelial cells actively transport drugs from the enterocytes to the intestinal lumen, which could lead to extremely poor absorption of drugs by oral administration. Typical intestinal efflux transporters involved in oral drug absorption process mainly include P-glycoprotein (P-gp), multidrug resistance proteins (MRPs) and breast cancer resistance protein (BCRP). Drug efflux is one of the most important factors resulting in poor absorption of oral drugs. Caco-2 monolayer and everted gut sac are sued to accurately measure drug efflux in vitro. To reverse intestinal drug efflux and improve absorption of oral drugs, a great deal of functional amphiphilic excipients and inhibitors with the function of suppressing efflux transporters activity are generalized in this review. In addition, different strategies of reducing intestinal drugs efflux such as silencing transporters and the application of excipients and inhibitors are introduced. Ultimately, various nano-formulations of improving oral drug absorption by inhibiting intestinal drug efflux are discussed. In conclusion, this review has significant reference for overcoming intestinal drug efflux and improving oral drug absorption.

Silybin phytosome attenuates cerebral ischemia-reperfusion injury in rats by suppressing oxidative stress and reducing inflammatory response: In vivo and in silico approaches

The present study was aimed to develop silybin phytosome (SIBP) and evaluate its effectiveness against cerebral ischemia-reperfusion (CIR) injury in rats. Initially, SIBP was prepared and characterized with Fourier transform-infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. Drug loading and entrapment efficiency of SIBP were also calculated. High-performance liquid chromatography was used to carry out bioavailability studies of SIBP. Adult Wistar rats were divided randomly into five groups. The CIR injury was induced after 14 days of pretreatment by occlusion of bilateral common carotid arteries for 30 min followed by 4 h of reperfusion. Biochemical estimation, histopathological studies, and in silico studies were carried out. Bioavailability studies revealed that SIB concentration was increased to twofolds in SIBP-treated rats. SIBP treatment significantly increases superoxide dismutase and glutathione levels while it decreases monoaldehyde, tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6) levels in both the hippocampus and cortex of the SIBP-treated CIR-injured rats. Histopathological studies reveal SIBP treatment alleviates cortex cell death and arrangement of CA1 neurons in CIR-injured rats. In silico studies against proteins (TNF-α and IL-6) involved in cerebral ischemia revealed that silybin (SIB) exhibits strong binding interaction with the target proteins when compared to thalidomide which was used as the positive control. Phytosome increase SIB bioavailability and SIBP treatment showed promising results when compared to treatment with SIB only. Based on our study, we conclude that phytosome is a suitable drug delivery agent to the brain for SIB as SIBP treatment was able to provide neuroprotective action against CIR injury.

Transport and Interactions of Co-incubated Bi-functional Flavonoids through Inhibiting the Function of P-Glycoprotein (P-gp) Using KB/Multidrug-Resistant (MDR) Cells and Rat Everted Gut Sacs

This study aims to evaluate the interaction of flavonoid-flavonoid by inhibiting the function of P-glycoprotein (P-gp). The cellular uptake of seven substrates and eleven co-incubated inhibitors was measured in KB/MDR cells. The effect of galangin or morin on the absorption of silibinin or wogonin was carried out in the rat everted gut sacs. Docking was performed to evaluate the interactions between inhibitors and P-gp. Most substrates were greatly enhanced by at least five co-incubated inhibitors. Conversely, the increased uptake of substrates coincided with a decrease or without affecting the uptake of inhibitors, implying a competitive/non-competitive inhibition on P-gp. The enhancement effect by galangin or morin on the transport of silibinin or wogonin was verified in everted gut sacs. Docking explained the inhibition of flavonoids on P-gp by competitively binding to the ATP site. These results provide a strategy for increasing the absorption of flavonoids by co-administration.

Systematic review of pharmacokinetics and potential pharmacokinetic interactions of flavonolignans from silymarin

Silymarin is an extract from the seeds (fruits) of Silybum marianum that contains flavonolignans and flavonoids. Although it is frequently used as a hepatoprotective agent, its application remains somewhat debatable, in particular, due to the low oral bioavailability of flavonolignans. Moreover, there are claims of its potential interactions with concomitantly used drugs. This review aims at a systematic summary and critical assessment of known information on the pharmacokinetics of particular silymarin flavonolignans. There are two known major reasons for poor systemic oral bioavailability of flavonolignans: (1) rapid conjugation in intestinal cells or the liver and (2) efflux of parent flavonolignans or formed conjugates back to the lumen of the gastrointestinal tract by intestinal cells and rapid excretion by the liver into the bile. The metabolism of phase I appears to play a minor role, in contrast to extensive conjugation and indeed the unconjugated flavonolignans reach low plasma levels after common doses. Only about 1%-5% of the administered dose is eliminated by the kidneys. Many in vitro studies tested the inhibitory potential of silymarin and its components toward different enzymes and transporters involved in the absorption, metabolism, and excretion of xenobiotics. In most cases, effective concentrations are too high to be relevant under real biological conditions. Most human studies showed no silymarin-drug interactions explainable by these suggested interferences. More interactions were found in animal studies, likely due to the much higher doses administered.

Anti-hepatitis B virus activity and hepatoprotective effect of des(rhamnosyl) verbascoside from Lindernia ruellioides in vitro

Although clinically approved hepatitis B virus (HBV) polymerase inhibitors (lamivudine-3TC, entecavir, etc.) serve as effective therapeutics, the virus can easily generate resistance to them. Therefore, the treatment of HBV infection remains a public health problem. Numerous studies have shown that natural products have prospective anti-HBV activity. The purpose of this study was to isolate and extract des(rhamnosyl) verbascoside from Lindernia ruellioides (Colsm.) Pennell and explore its anti-HBV and hepatoprotective effects. Anti-HBV activity was evaluated in HepG2.2.15 cells, a human hepatocellular carcinoma cell line with HBV-stable infection, and its protective effect was evaluated in HL-7702 cells, a normal human liver cell line. HepG2.2.15 cells maintained normal growth morphology within the selected concentration range of des(rhamnosyl) verbascoside. It also inhibited the expression of HBV antigens and HBV DNA in a dose- and time-dependent manner in vitro. Further, western blot experiments showed that it could downregulate HBV X protein (HBx) expression in a dose-dependent manner. In the H₂ O₂ -induced hepatocyte injury model, the cell-survival rate of the HL-7702 cells with the highest drug dose reached 85.25%, which was significantly improved compared with that of the model group. Most of the cells returned to normal morphology, showing polygonal or fusiform structures. Thus, it may be stated that des(rhamnosyl) verbascoside exhibits anti-HBV activity and hepatoprotective effects in vitro and may exert an anti-HBV effect via antigen inhibition, HBV DNA secretion, and HBx protein expression.

Enhanced Bioavailability and Efficacy of Silymarin Solid Dispersion in Rats with Acetaminophen-Induced Hepatotoxicity

We evaluated the bioavailability, liver distribution, and efficacy of silymarin-D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) solid dispersion (silymarin-SD) in rats with acetaminophen-induced hepatotoxicity (APAP) compared with silymarin alone. The solubility of silybin, the major and active component of silymarin, in the silymarin-SD group increased 23-fold compared with the silymarin group. The absorptive permeability of silybin increased by 4.6-fold and its efflux ratio decreased from 5.5 to 0.6 in the presence of TPGS. The results suggested that TPGS functioned as a solubilizing agent and permeation enhancer by inhibiting efflux pump. Thus, silybin concentrations in plasma and liver were increased in the silymarin-SD group and liver distribution increased 3.4-fold after repeated oral administration of silymarin-SD (20 mg/kg as silybin) for five consecutive days compared with that of silymarin alone (20 mg/kg as silybin). Based on higher liver silybin concentrations in the silymarin-SD group, the therapeutic effects of silymarin-SD in hepatotoxic rats were evaluated and compared with silymarin administration only. Elevated alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase levels were significantly decreased by silymarin-SD, silymarin, and TPGS treatments, but these decreases were much higher in silymarin-SD animals than in those treated with silymarin or TPGS. In conclusion, silymarin-SD (20 mg/kg as silybin, three times per day for 5 days) exhibited hepatoprotective properties toward hepatotoxic rats and these properties were superior to silymarin alone, which may be attributed to increased solubility, enhanced intestinal permeability, and increased liver distribution of the silymarin-SD formulation.

Cardioprotective Effect of Tangeretin by Inhibiting PTEN/AKT/mTOR Axis in Experimental Sepsis-Induced Myocardial Dysfunction

Sepsis aggregates undesirable immune response causing depression of ventricular myocardium and diastolic dysfunction. This present study examined the effect of a plant-derived flavone tangeretin (TG) on autophagy and reduction in myocardial dysfunction. The sepsis was induced by cecum ligation and puncture (CLP) in male Sprague-Dawley rats. Abnormal changes were seen in the heart after the sepsis induction. These abnormalities were analyzed based on the cardiac markers, namely Cardiac myosin light chain-1 (cMLC1) and Cardiac troponin I (cTnl), echocardiography, and plasma parameters, like Lactate dehydrogenase (LDH) and Creatinine kinase (CK). Microanatomy of the heart was studied using hematoxylin and eosin stained histopathological samples of cardiac tissue. Western blot technique was used to detect the nature and extent of protein with the amount of a specific RNA (gene expression) in the cardiac homogenate. Oxidative damage was analyzed using redox marker, reduced glutathione. This study successfully showed that TG attenuated sepsis-induced myocardial dysfunction by inhibiting myocardial autophagy via silencing the Phosphatase and tensin homolog (PTEN) expression and acting on the AKT/mTOR pathway. The present findings supported that TG is a novel cardioprotective therapeutic target for sepsis induced myocardial dysfunction.

Amorphous silibinin nanoparticles loaded into porous starch to enhance remarkably its solubility and bioavailability in vivo

In the present study, the silibinin (SLB) was loaded into porous starch (PS) in the form of nanoparticles (SNPS) by the liquid antisolvent precipitation (LAP) method, so as to improve its solubility and bioavailability. Firstly, the different experimental parameters on drug loading (DL) of the SLB in the LAP process were optimized through the single-factor experiments. Under the optimum conditions, the DL and the encapsulation efficiency (EE) of the SNPS were 9.49 ± 0.37 % and 89.93 ± 0.64 %, respectively. Compared with free SLB and SLB nanoparticles (SN), the SNPS had a higher solubility, and was about 180.81 ± 5.32 μg/mL in artificial gastric juice (AGJ) and was about 88.91 ± 4.14 μg/mL in artificial intestinal juice (AIJ), respectively. The in vitro release study demonstrated a slow and sustained ± release of SLB from the SNPS with the SN and free SLB as controls. The pharmacokinetic results showed that the Cmax and AUC(0-t) of the SNPS (87.71 ± 7.24 μg/L, 439.55 ± 8.76 μg/L*h) increased when compared with the SN (60.31 ± 8.98 μg/L, 206.51 ± 12.24 μg/L*h) and free SLB (26.08 ± 1.43 μg/L, 102.63 ± 7.15 μg/L*h), showing its ability to improve SLB's pharmacokinetic properties.

Path of Silibinin from diet to medicine: A dietary polyphenolic flavonoid having potential anti-cancer therapeutic significance

In the last few decades, targeting cancer by the use of dietary phytochemicals has gained enormous attention. The plausible reason and believe or mind set behind this fact is attributed to either lesser or no side effects of natural compounds as compared to the modern chemotherapeutics, or due to their conventional use as dietary components by mankind for thousands of years. Silibinin is a naturally derived polyphenol (a flavonolignans), possess following biochemical features; molecular formula C₂₅H₂₂O₁₀, Molar mass: 482.44 g/mol, Boiling point 793 °C, with strikingly high antioxidant and anti-tumorigenic properties. The anti-cancer properties of Silibinin are determined by a variety of cellular pathways which include induction of apoptosis, cell cycle arrest, inhibition of angiogenesis and metastasis. In addition, Silibinin controls modulation of the expression of aberrant miRNAs, inflammatory response, and synergism with existing anti-cancer drugs. Therefore, modulation of a vast array of cellular responses and homeostatic aspects makes Silibinin an attractive chemotherapeutic agent. However, like other polyphenols, the major hurdle to declare Silibinin a translational chemotherapeutic agent, is its lesser bioavailability. After summarizing the chemistry and metabolic aspects of Silibinin, this extensive review focuses on functional aspects governed by Silibinin in chemoprevention with an ultimate goal of summarizing the evidence supporting the chemopreventive potential of Silibinin and clinical trials that are currently ongoing, at a single platform.

Nano Porous Carbon Derived from Citrus Pomace for the Separation and Purification of PMFs in Citrus Processing Wastes

The by-product of citrus juice processing is a huge source of bioactive compounds, especially polymethoxyflavones (PMFs) and fibers. In this study, a method for the separation and purification of PMFs from citrus pomace was established based on citrus nanoporous carbon (CNPC) enrichment. Different biomass porous carbons were synthesized, their adsorption/desorption characteristics were evaluated, and the CNPCs from the peel of Citrus tangerina Tanaka were found to be best for the enrichment of PMFs from the crude extracts of citrus pomace. Using this method, six PMF compounds including low-abundant PMFs in citrus fruits such as 5,6,7,4'-tetramethoxyflavone and 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone can be simultaneously obtained, and the purities of these compounds were all higher than 95%, with the highest purity of nobiletin reaching 99.96%. Therefore, CNPCs have a great potential for the separation and purification of PMFs in citrus processing wastes, potentially improving the added value of citrus wastes. We also provide a method reference for disposing of citrus pomace in the future.

Evaluation of Mogroside V as a Promising Carrier in Drug Delivery: Improving the Bioavailability and Liver Distribution of Silybin

The objective of this work was to investigate the capacity of mogroside V (MOG-V), a food additive, as a novel carrier to improve the bioavailability and liver distribution of silybin (SLY). Solid dispersion particles (SDPs) of SLY/MOG-V were prepared utilizing the solvent evaporation method. The physicochemical characterizations of SDPs were evaluated by using dynamic light scattering (DLS), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) measurements. DLS results demonstrated the formation of nanoparticles (206 nm) of SDPs in water. DSC and PXRD analysis revealed that SLY was in amorphous form or molecularly dispersed in SDPs. SDPs also exhibited a major increase in both dissolution rate and saturation solubility, as evidenced by a 1931-fold improvement (2201 μg/mL) in solubility compared with pure SLY (1.14 μg/mL). The pharmacokinetic study in rats showed that oral absorption of SLY/MOG-V SDPs was dramatically increased. The mean value of AUC until 12 h for SLY/MOG-V SDPs (27,481 ng·min/mL) was 24.5-fold higher than that of pure SLY (1122 ng·min/mL). In vivo tissue distribution experiment in mice confirmed that the major distribution tissue was changed from lungs to liver after SLY was loaded into MOG-V. In addition, even orally administrated to mice at a high dose (4.2 g/kg), MOG-V exhibited no undesirable effect on the plasma glucose concentrations. Thus, MOG-V may have the applicability to serve as an ideal excipient for solubilization or as a novel liver targeting carrier for the delivery of SLY.

Metabolism, Transport and Drug-Drug Interactions of Silymarin

Silymarin, the extract of milk thistle, and its major active flavonolignan silybin, are common products widely used in the phytotherapy of liver diseases. They also have promising effects in protecting the pancreas, kidney, myocardium, and the central nervous system. However, inconsistent results are noted in the different clinical studies due to the low bioavailability of silymarin. Extensive studies were conducted to explore the metabolism and transport of silymarin/silybin as well as the impact of its consumption on the pharmacokinetics of other clinical drugs. Here, we aimed to summarize and highlight the current knowledge of the metabolism and transport of silymarin. It was concluded that the major efflux transporters of silybin are multidrug resistance-associated protein (MRP2) and breast cancer resistance protein (BCRP) based on results from the transporter-overexpressing cell lines and MRP2-deficient (TR-) rats. Nevertheless, compounds that inhibit the efflux transporters MRP2 and BCRP can enhance the absorption and activity of silybin. Although silymarin does inhibit certain drug-metabolizing enzymes and drug transporters, such effects are unlikely to manifest in clinical settings. Overall, silymarin is a safe and well-tolerated phytomedicine.

Liver Targeting Albumin-Coated Silybin-Phospholipid Particles Prepared by Nab™ Technology for Improving Treatment Effect of Acute Liver Damage in Intravenous Administration

In this study, a novel human serum albumin nanoparticle loading silybin-phospholipid complex (SLNPs) was developed for liver targeting after intravenous administration. The preparation of the drug delivery system consisted of two steps; initially, a silybin-phospholipid complex (SLC) was produced to improve the lipophilicity of SLB to then achieve enhanced encapsulation of SLB in albumin nanoparticles. FT-IR and XRD analysis confirmed the successful formation of SLC. The complex ratio of SLC in the first step was 99.6%. The encapsulation efficiency and drug loading of SLNPs in the second step were 96.2% and 5.6%, respectively. SLNPs were spherical and well-dispersed, with a zeta potential of approximately - 10 mV, and a mean particle size around 200 nm. An in vivo tissue distribution experiment and a pharmacodynamic experiment showed that, compared with SLB solution, SLNPs had an improved SLB accumulation in the liver. The hepatoprotective effect of SLNPs on CCl₄-induced acute liver damage was evaluated. CCl₄-damaged mice showed an increased enzymatic activity of ALT and AST; however, enzyme levels returned to near-normal levels in high-dose SLNP-treated mice. As SLNPs combine the enhanced oil solubility of SLC and the passive targeting of albumin nanoparticles, they possess great potential for the treatment of acute liver damage.

Ketoconazole pretreatment ameliorates carbon tetrachloride-induced acute liver injury in rats by suppressing inflammation and oxidative stress

Several studies have demonstrated the chemopreventive role of ketoconazole in animal models of liver injury. However, the underlying molecular mechanisms of this hepatoprotective effect are poorly understood. The present study assessed the potential of ketoconazole to enhance resistance to carbon tetrachloride-induced hepatotoxicity in vivo in a rat model. Ketoconazole pretreatment adult male rats were intraperitoneally injected with carbon tetrachloride for 24 hr and various hepatic parameters were analyzed. We observed decreased serum transaminases activity, reduced nuclear RelA/p65 expression, and suppressed production of pro-inflammatory cytokines in the liver tissue. Histopathological examination demonstrated ketoconazole pretreatment to extensively prevent liver injury. In addition, it significantly increased nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) protein expression, glutathione (GSH) to oxidized glutathione (GSSG) ratio, and antioxidant enzymes gene expression. These results suggest that ketoconazole pretreatment ameliorates carbon tetrachloride-induced acute liver injury in rats, signifying its anti-inflammatory and antioxidant functions.

Structure affinity relationship and docking studies of flavonoids as substrates of multidrug-resistant associated protein 2 (MRP2) in MDCK/MRP2 cells

This study was aimed to determine the relationship of flavonoid structures to their affinity for an important efflux transporter, multidrug-resistant associated protein 2 (MRP2). The cellular uptake (CU) of 35 flavonoids was investigated in MRP2 overexpression MDCK/MRP2 cells. Resulting data identified 8 flavonoids as MRP2 substrates based on their high CU_MK with MK-571 in MDCK/MRP2 cells. Also, three substrates showed better CU_MD in MDCK cells than did CU_MRP in MDCK/MRP2 cells. Docking analyses showed a good correlation (R = 0.926, p = 0.003) between efflux-fold of flavonoid substrates and their docking S_scoring with the MRP2 model, indicating consistency between in silico and in vitro approaches. A structure affinity relationship (SAR) study indicated that 3-OH, 5-OH, 6-OH, 3'-OH, and 4'-OCH₃ substituents were favourable while, 8-OCH₃, 2'-OH, 3'-OCH₃, 4'-OH and 5'-OH were unfavourable for flavonoid affinity to MRP2. Our study provides valuable information for dietary application of flavonoids with specific structures for high absorption.

Establishment and Use of Human Mouth Epidermal Carcinoma (KB) Cells Overexpressing P-Glycoprotein To Characterize Structure Requirements for Flavonoids Transported by the Efflux Transporter

This study was aimed to determine the mechanism for flavonoid poor absorption related to P-glycoprotein (P-gp). The cellular uptake (CU) of 40 flavonoids was investigated in P-gp overexpressing KB/multidrug-resistant (MDR) cells. A total of 9 flavonoids, including 5,7,3',4'-tetramethoxyflavone, with a significant ( p < 0.05) CU_KBE (2.90 ± 0.146 μmol/g) higher than CU_KBP (1.57 ± 0.129 μmol/g) were identified as P-gp substrates. Besides, 8 substrates, including tangeretin, showed a significant ( p < 0.05) CU_KB (9.72 ± 1.09 μmol/g) higher than its CU_KBP (7.36 ± 0.692 μmol/g). A total of 7 of 17 flavonoid substrates stimulated the P-gp efflux of rhodamine 123, and most substrates increased P-gp expression in KB/MDR cells. Docking analyses showed a good correlation ( R = 0.764; p < 0.01) between efflux fold and S_scoring of flavonoids to the P-gp model, indicating consistency between in silico and in vitro results. A structure-affinity relationship exhibited that 3-OH, 5-OH, 3'-OCH₃, and 4'-OCH₃ are crucial for flavonoids binding to P-gp. These results provide valuable information for finding a solution to improve the absorption of flavonoids.

Piperine enhances the bioavailability of silybin via inhibition of efflux transporters BCRP and MRP2

BACKGROUND

Although silybin serves as a well-known hepatoprotective agent with prominent anti-inflammatory, anti-oxidant and anti-fibrotic activities, its low bioavailability limits its application in the treatment of chronic liver diseases. However, novel formulation products with increased solubility were not sufficient to achieve pharmacologically meaningful concentrations of silybin in the clinical studies even used at high dosage.

HYPOTHESIS/PURPOSE

We hypothesized that inhibiting efflux transporter(s) and/or glucuronidation by piperine might enhance the bioavailability and efficacy of silybin.

METHODS

Pharmacokinetics of silybin given alone or in-combination with piperine was determined by a validated LC-MS method. A CCl₄ induced rat model of liver injury was prepared and verified for comparing the effects of silybin and combination treatment. To investigate the underlying mechanism, the inhibition effects of piperine on transportation of silybin were performed in Caco-2 and transfected MDCKII cell lines as well as sandwich-cultured rat hepatocytes (SCH). Human liver microsomes incubation was used for exploring the modulation effects of piperine on the phase-2 metabolism of silybin.

RESULTS

In the present study, we demonstrated for the first time that piperine as a bioenhancer increased the bioavailability of silybin (146%- 181%), contributing to a boosted therapeutic effect in CCl₄-induced acute liver-injury rat model. The underlying mechanisms involved that piperine enhanced the absorption of silybin by inhibiting the efflux transporters including MRP2 and BCRP but not MDR1 in Caco-2 and transfected MDCKII cell lines. Moreover, piperine could inhibit the biliary excretion of silybin and conjugated metabolites in sandwich-cultured rat hepatocytes. Notably, we found that piperine did not affect the phase-2 metabolism of silybin.

CONCLUSION

Efflux transporters play an important role in the pharmacokinetic behavior of flavolignans, and modulating these transporters by bioenhancer such as piperine could enhance the in vivo absorption of silybin, leading to more effective treatments.

Ginsenoside Rg5 overcomes chemotherapeutic multidrug resistance mediated by ABCB1 transporter: in vitro and in vivo study

Background

Multidrug resistance (MDR) to chemotherapy drugs remains a major challenge in clinical cancer treatment. Here we investigated whether and how ginsenoside Rg5 overcomes the MDR mediated by ABCB1 transporter in vitro and in vivo.

Methods

Cytotoxicity and colon formation as well as the intracellular accumulation of ABCB1 substrates were carried out in MDR cancer cells A2780/T and A549/T for evaluating the reversal effects of Rg5. The expressions of ABCB1 and Nrf2/AKT pathway were determined by Western blotting. An A549/T cell xenograft model was established to investigate the MDR reversal activity of Rg5 in vivo.

Results

Rg5 significantly reversed ABCB1-mediated MDR by increasing the intracellular accumulation of ABCB1 substrates without altering protein expression of ABCB1. Moreover, Rg5 activated ABCB1 ATPase and reduced verapamil-stimulated ATPase activity, suggesting a high affinity of Rg5 to ABCB1 binding site which was further demonstrated by molecular docking analysis. In addition, co-treatment of Rg5 and docetaxel (TXT) suppressed the expression of Nrf2 and phosphorylation of AKT, indicating that sensitizing effect of Rg5 associated with AKT/Nrf2 pathway. In nude mice bearing A549/T tumor, Rg5 and TXT treatment significantly suppressed the growth of drug-resistant tumors without increase in toxicity when compared to TXT given alone at same dose.

Conclusion

Therefore, combination therapy of Rg5 and chemotherapy drugs is a strategy for the adjuvant chemotherapy, which encourages further pharmacokinetic and clinical studies.

Baicalein Enhances the Oral Bioavailability and Hepatoprotective Effects of Silybin Through the Inhibition of Efflux Transporters BCRP and MRP2

Although hepatoprotective properties of silybin are well documented, the clinical therapeutic efficacy is limited by its low bioavailability due to absorption rates, extensive phase II metabolism, and biliary excretion. As our previous study indicated that metabolic enzymes may have limited effects on the pharmacokinetic (PK) behavior of silymarin, here, we intended to increase the oral bioavailability and bio-efficacy of silybin through the inhibition of active efflux. In Caco-2 and transfected MDCKII cell models, flavone baicalein significantly inhibited the efflux of silybin as a BCRP and MRP2 inhibitor. In addition, baicalein reduced the biliary excretion index (BEI) and biliary clearance of silybin conjugates in the sandwich-cultured rat hepatocyte (SCH) model, indicating the inhibition of baicalein in biliary excretion of conjugated silybin metabolites. PK study demonstrated that baicalein significantly increased the area under the curve (AUC) and C_max of silybin and its conjugates, suggesting enhanced absorption in vivo. Moreover, coadministration of silybin with baicalein boosted the liver protective, antioxidant, and anti-inflammatory effects of silybin in the carbon tetrachloride (CCl₄)-induced liver injury model in comparison with silybin given alone. In summary, efflux transporters play a critical role in the low bioavailability of silybin, while inhibition of breast cancer resistance protein (BCRP) and multi-drug resistance protein 2 (MRP2) by baicalein can significantly increase the absorption and bio-efficacy of silybin, which provides a new combination therapeutic approach for the treatment of chronic liver diseases.

Self-assembly and directed assembly of lipid nanocarriers for prevention of liver fibrosis in obese rats: a comparison with the therapy of bariatric surgery

Aim: Whether the obesity prevention by chemicals or surgeries in already obese patients is the better choice remains controversial. We aimed to compare the effect of orally silibinin-loaded nanocarriers and Roux-en-Y gastric bypass surgery on hepatic fibrosis in high-fat feeding-induced obese rats. Methodology: The developed nanocarriers included self-emulsifying drug delivery system (SNEDDS) and nanostructured lipid carriers (NLC). Results: A significant decrease in collagen production and lipid droplet formation was observed upon nanosystem and bariatric surgery than the rats treated with silibinin control suspension. Stage 3 fibrosis was present in 33% of the obese rats. This percentage could be minimized to 0% by SNEDDS and NLC. Following oral administration, SNEDDS and NLC resulted in 3.5- and 2.9-fold increase, respectively, in bioavailability compared with the reference suspension. Conclusion: Nanomedicine prevention provided a comparable efficiency to ameliorate liver steatosis as Roux-en-Y gastric bypass due to the improvement of silibinin dissolution and gastrointestinal permeation.

Determination of Tangeretin in Rat Plasma: Assessment of Its Clearance and Absolute Oral Bioavailability

Tangeretin (TAN) is a dietary polymethoxylated flavone that possesses a broad scope of pharmacological activities. A simple high-performance liquid chromatography (HPLC) method was developed and validated in this study to quantify TAN in plasma of Sprague-Dawley rats. The lower limit of quantification (LLOQ) was 15 ng/mL; the intra- and inter-day assay variations expressed in the form of relative standard deviation (RSD) were all less than 10%; and the assay accuracy was within 100 ± 15%. Subsequently, pharmacokinetic profiles of TAN were explored and established. Upon single intravenous administration (10 mg/kg), TAN had rapid clearance (Cl = 94.1 ± 20.2 mL/min/kg) and moderate terminal elimination half-life (t_{1/2 λz} = 166 ± 42 min). When TAN was given as a suspension (50 mg/kg), poor but erratic absolute oral bioavailability (mean value < 3.05%) was observed; however, when TAN was given in a solution prepared with randomly methylated-β-cyclodextrin (50 mg/kg), its plasma exposure was at least doubled (mean bioavailability: 6.02%). It was obvious that aqueous solubility hindered the oral absorption of TAN and acted as a barrier to its oral bioavailability. This study will facilitate further investigations on the medicinal potentials of TAN.