Effects of morin on the pharmacokinetics of etoposide in 7,12-dimethylbenz[a]anthracene-induced mammary tumors in female Sprague-Dawley rats

Human Cytochrome P450 Cancer-Related Metabolic Activities and Gene Polymorphisms: A Review

BACKGROUND

Cytochromes P450 (CYPs) are heme-containing oxidoreductase enzymes with mono-oxygenase activity. Human CYPs catalyze the oxidation of a great variety of chemicals, including xenobiotics, steroid hormones, vitamins, bile acids, procarcinogens, and drugs.

FINDINGS

In our review article, we discuss recent data evidencing that the same CYP isoform can be involved in both bioactivation and detoxification reactions and convert the same substrate to different products. Conversely, different CYP isoforms can convert the same substrate, xenobiotic or procarcinogen, into either a more or less toxic product. These phenomena depend on the type of catalyzed reaction, substrate, tissue type, and biological species. Since the CYPs involved in bioactivation (CYP3A4, CYP1A1, CYP2D6, and CYP2C8) are primarily expressed in the liver, their metabolites can induce hepatotoxicity and hepatocarcinogenesis. Additionally, we discuss the role of drugs as CYP substrates, inducers, and inhibitors as well as the implication of nuclear receptors, efflux transporters, and drug-drug interactions in anticancer drug resistance. We highlight the molecular mechanisms underlying the development of hormone-sensitive cancers, including breast, ovarian, endometrial, and prostate cancers. Key players in these mechanisms are the 2,3- and 3,4-catechols of estrogens, which are formed by CYP1A1, CYP1A2, and CYP1B1. The catechols can also produce quinones, leading to the formation of toxic protein and DNA adducts that contribute to cancer progression. However, 2-hydroxy- and 4-hydroxy-estrogens and their O-methylated derivatives along with conjugated metabolites play cancer-protective roles. CYP17A1 and CYP11A1, which are involved in the biosynthesis of testosterone precursors, contribute to prostate cancer, whereas conversion of testosterone to 5α-dihydrotestosterone as well as sustained activation and mutation of the androgen receptor are implicated in metastatic castration-resistant prostate cancer (CRPC). CYP enzymatic activities are influenced by CYP gene polymorphisms, although a significant portion of them have no effects. However, CYP polymorphisms can determine poor, intermediate, rapid, and ultrarapid metabolizer genotypes, which can affect cancer and drug susceptibility. Despite limited statistically significant data, associations between CYP polymorphisms and cancer risk, tumor size, and metastatic status among various populations have been demonstrated.

CONCLUSIONS

The metabolic diversity and dual character of biological effects of CYPs underlie their implications in, preliminarily, hormone-sensitive cancers. Variations in CYP activities and CYP gene polymorphisms are implicated in the interindividual variability in cancer and drug susceptibility. The development of CYP inhibitors provides options for personalized anticancer therapy.

Consideration of Fractional Distribution Parameter fd in the Chen and Gross Method for Tissue-to-Plasma Partition Coefficients: Comparison of Several Methods

PURPOSE

The tissue-to-plasma partition coefficient (K_p) describes the extent of tissue distribution in physiologically-based pharmacokinetic (PBPK) models. Constant-rate infusion studies are common for experimental determination of the steady-state K_p,ss, while the tissue-plasma concentration ratio (C_T/C_p) in the terminal phase after intravenous doses is often utilized. The Chen and Gross (C&G) method converts a terminal slope C_T/C_p to K_p,ss based on assumptions of perfusion-limited distribution in tissue-plasma equilibration. However, considering blood flow (Q_T) and apparent tissue permeability (f_upPS_in) in the rate of tissue distribution, this report extends the C&G method by utilizing a fractional distribution parameter (f_d).

METHODS

Relevant PBPK equations for non-eliminating and eliminating organs along with lung and liver were derived for the conversion of C_T/C_p values to K_p,ss. The relationships were demonstrated in rats with measured C_T/C_p and K_p,ss values and the model-dependent f_d for 8 compounds with a range of permeability coefficients. Several methods of assessing K_p were compared.

RESULTS

Utilizing f_d in an extended C&G method, our estimations of K_p,ss from C_T/C_p were improved, particularly for lower permeability compounds. However, four in silico methods for estimating K_p performed poorly across tissues in comparison with measured K_p values. Mathematical relationships between K_p and K_p,ss that are generally applicable for eliminating organs with tissue permeability limitations necessitates inclusion of an extraction ratio (ER) and f_d.

CONCLUSION

Since many different types/sources of K_p are present in the literature and used in PBPK models, these perspectives and equations should provide better insights in measuring and interpreting K_p values in PBPK.

Challenges and potential for improving the druggability of podophyllotoxin-derived drugs in cancer chemotherapy

Covering: up to 2020As a main bioactive component of the Chinese, Indian, and American Podophyllum species, the herbal medicine, podophyllotoxin (PTOX) exhibits broad spectrum pharmacological activity, such as superior antitumor activity and against multiple viruses. PTOX derivatives (PTOXs) could arrest the cell cycle, block the transitorily generated DNA/RNA breaks, and blunt the growth-stimulation by targeting topoisomerase II, tubulin, or insulin-like growth factor 1 receptor. Since 1983, etoposide (VP-16) is being used in frontline cancer therapy against various cancer types, such as small cell lung cancer and testicular cancer. Surprisingly, VP-16 (ClinicalTrials NTC04356690) was also redeveloped to treat the cytokine storm in coronavirus disease 2019 (COVID-19) in phase II in April 2020. The treatment aims at dampening the cytokine storm and is based on etoposide in the case of central nervous system. However, the initial version of PTOX was far from perfect. Almost all podophyllotoxin derivatives, including the FDA-approved drugs VP-16 and teniposide, were seriously limited in clinical therapy due to systemic toxicity, drug resistance, and low bioavailability. To meet this challenge, scientists have devoted continuous efforts to discover new candidate drugs and have developed drug strategies. This review focuses on the current clinical treatment of PTOXs and the prospective analysis for improving druggability in the rational design of new generation PTOX-derived drugs.

Overview of Morin and Its Complementary Role as an Adjuvant for Anticancer Agents

The Global cancer incidence and mortality data released by the World Health Organization proposes that out of 18.1 million new cancer cases diagnosed, 9.8 million deaths occurred globally in 2018. Cancer is one of the major health burdens among non-communicable diseases globally responsible for impeding life expectancy in the present century. Disrupting hallmarks of cancer (such as prolonged inflammation, increased growth signal, tissue invasion and metastasis, unlimited proliferation and evasion of apoptosis) with dietary agents is of considerable focus for cancer prevention and therapy. In the last decade, a significant contribution has been provided in finding many plant-derived natural agents that can be identified as promising molecular cancer therapeutics. Our focus in this review is on one such natural dietary agent, Morin (3,5,7,2',4'-pentahydroxyflavone): a bioflavonoid. Morin exerts strong pharmacological properties against a multitude of cancer (liver cancer, cervical cancer, melanoma, breast cancer, prostate, and colon cancer). Recent progress has also been made in examining the potential of morin as a natural dietary agent for fostering the pharmacological effects of other well-known anticancer agents. This review provides an overview of morin and its derivatives in combination with anticancer agents for cancer prevention and therapy.

No Synergistic Effect of Silibinin and Morin in a Kainic Acid-Induced Epileptic Mouse Model

Temporal lobe epilepsy (TLE) is the most common form of localization-related epilepsy, with the highest prevalence rate in adulthood. Recently, we reported the beneficial effects of the individual treatment with flavonoids such as silibinin and morin in kainic acid (KA)-treated mouse model for TLE. In this study, we investigated whether there is a synergistic effect of co-treatment with silibinin and morin on the susceptibility to seizure, the frequency of spontaneous recurrent seizures (SRSs), and granule cell dispersion in the dentate gyrus, which could be partially controlled by treatment with each flavonoid in the animal model for TLE. Unfortunately, we did not observe any synergistic effect against the susceptibility of seizure and SRS induced by KA treatment. However, the combination of these flavonoids showed similar antiepileptic effects compared with treatment with each one individually. Therefore, although silibinin and morin are not suitable for combination therapy, our results still suggest that these flavonoids can be used as potent therapeutic compounds for preventing epileptic seizures.

UHPLC-UV Analysis of Morin and Structurally Related Flavonoids with Potential Anticancer Activity

Background:

Flavonoids as secondary metabolites of plants fulfill various functions in cell protection. They are of a considerable scientific interest because of their potentially medical use due to their anticancer, chemoprotective, antimicrobial, antiallergic, anti-inflammatory and antiviral activities. </P><P> Objective: The study aimed to develop a new UHPLC-UV method for morin and 2 other structurally related flavonoids - naringenin and kaempferol as the structural similarity of huge numbers of flavonoids does not limit their various biological functions and activities.

Methods:

Separation of morin and 2 other structurally related flavonoids - naringenin and kaempferol - was achieved by using BEH C18 (1.7 µm, 2.1 x 50 mm) analytical column (Waters® Acquity UPLC) and a mobile phase composed of 0.05%v/v Formic acid in water and acetonitrile in proportion of 77:23 v/v and pumped at a flow rate of 0.4 ml/min. Column temperature was set at 25 ºC and samples were analyzed (3 µl injection volume) at a wavelength of 340 nm. Waters® Xevo G2-S QToF coupled with Waters® Acquity UPLC system with binary Solvent Manager (I-Class) via electrospray ionization (ESI) interface was used to confirm the identity of the peaks in biological samples.

Results:

A rapid and simple UHPLC-UV separation of morin, kaempferol and naringenin is documented including methods validation. The developed method was applied to measuring morin, kaempferol and naringenin in human plasma after a solid phase extraction. Additionally, stability of morin in tissue culture medium was verified. The extraction method and UHPLC-UV elution conditions described provide a practical means to analyze morin, kaempferol and naringenin in biological matrices.

Conclusion:

The developed method is fast and highly sensitive. Moreover, the flavonoids used were stable in human plasma for more than 10 days.

Morin exerts cytoprotective effects against oxidative stress in C2C12 myoblasts via the upregulation of Nrf2-dependent HO-1 expression and the activation of the ERK pathway

In the present study, we investigated the cytoprotective efficacy of morin, a natural flavonoid, against oxidative stress and elucidated the underlying mechanisms in C2C12 myoblasts. Our results indicated that morin treatment prior to hydrogen peroxide (H2O2) exposure significantly increased cell viability and prevented the generation of reactive oxygen species. H2O2-induced comet-like DNA formation and γH2AX phosphorylation were also markedly suppressed by morin with a parallel inhibition of apoptosis in C2C12 myoblasts, suggesting that morin prevented H2O2-induced cellular DNA damage. Furthermore, morin markedly enhanced the expression of heme oxygenase-1 (HO-1) associated with the induction and phosphorylation of nuclear factor-erythroid 2-related factor 2 (Nrf2) and the inhibition of Kelch-like ECH-associated protein 1 (Keap1) expression. Notably, these events were eliminated by transient transfection with Nrf2‑specific small interfering RNA. Additional experiments demonstrated that the activation of the Nrf2/HO-1 pathway by morin was mediated by the extracellular signal‑regulated kinase (ERK) signaling cascade. This phenomenon was confirmed with suppressed Nrf2 phosphorylation and consequently diminished HO-1 expression in cells treated with a pharmacological inhibitor of ERK. Collectively, these results demonstrated that morin augments the cellular antioxidant defense capacity through the activation of Nrf2/HO‑1 signaling, which involves the activation of the ERK pathway, thereby protecting C2C12 myoblasts from H2O2-induced oxidative cytotoxicity.

Korean red ginseng extract enhances paclitaxel distribution to mammary tumors and its oral bioavailability by P-glycoprotein inhibition

1. Drug efflux by P-glycoprotein (P-gp) is a common resistance mechanism of breast cancer cells to paclitaxel, the primary chemotherapy in breast cancer. As a means of overcoming the drug resistance-mediated failure of paclitaxel chemotherapy, the potential of Korean red ginseng extract (KRG) as an adjuvant chemotherapy has been reported only in in vitro. Therefore, we assessed whether KRG alters P-gp mediated paclitaxel efflux, and therefore paclitaxel efficacy in in vitro and vivo models. 2. KRG inhibited P-gp protein expression and transcellular efflux of paclitaxel in MDCK-mdr1 cells, but KRG was not a substrate of P-gp ATPase. In female rats with mammary tumor, the combination of paclitaxel with KRG showed the greater reduction of tumor volumes, lower P-gp protein expression and higher paclitaxel distribution in tumors, and greater oral bioavailability of paclitaxel than paclitaxel alone. 3. From these results, KRG increased systemic circulation of oral paclitaxel and its distribution to tumors via P-gp inhibition in rats and under the current study conditions.

Pharmacokinetics of YJC-10592, a novel chemokine receptor 2 (CCR-2) antagonist, in rats

YJC-10592, a novel chemokine receptor 2 (CCR-2) antagonist, was developed for treating asthma and atopic dermatitis. We studied the pharmacokinetic characteristics of YJC-10592 after intravenous (5, 10 and 20 mg/kg) and oral (100 and 200 mg/kg) administration of the drug to rats. Tissue distribution of YJC-10592 was also evaluated after intravenous administration of YJC-10592, 10 mg/kg, to rats. The pharmacokinetics of YJC-10592 was dose-dependent from 20 mg/kg after intravenous administration to rats. The values of the area under the plasma concentration-time curve from time zero to infinity (AUC) of YJC-10592 were dose-dependent from 20 mg/kg and the time-averaged total body (CL) and nonrenal (CLNR) clearances of YJC-10592 were significantly lower at dose of 20 mg/kg, suggesting that saturable metabolism may be involved. The absolute bioavailability (F) of YJC-10592 was generally low (<2.55 %) for both oral doses due to incomplete absorption and low urinary excretion. YJC-10592 had a great affinity to all rat tissues studied except brain, which was supported by a relatively high value of the apparent volume of distribution at steady state (V ss) (890-1385 mL/kg). In conclusion, YJC-10592 showed dose-dependent pharmacokinetics and low F value due to slower elimination and incomplete absorption.

Recent trends in preclinical drug-drug interaction studies of flavonoids--Review of case studies, issues and perspectives

Because of health benefits that are manifested across various disease areas, the consumption of herbal products and/or health supplements containing different kinds of flavonoids has been on the rise. While the drug-drug interaction potential between flavonoids and co-ingested drugs still remain an issue, opportunities exist for the combination of flavonoids with suitable anti-cancer drugs to enhance the bioavailability of anti-cancer drugs and thereby reduce the dose size of the anti-cancer drugs and improve its therapeutic index. In recent years, scores of flavonoids have undergone preclinical investigation with variety of drugs encompassing therapeutic areas such as oncology (etoposide, doxorubicin, paclitaxel, tamoxifen etc.), immunosuppression (cyclosporine) and hypertension (losartan, felodipine, nitrendipine etc.). The review provides examples of the recent trends in the preclinical investigation of 14 flavonoids (morin, quercetin, silibinin, kaempferol etc.) with various co-administered drugs. The relevance of combination of flavonoids with anti-cancer drugs and a framework to help design the in vitro and in vivo preclinical studies to gain better mechanistic insights are discussed. Also, concise discussions on the various physiological factors that contribute for the reduced bioavailability of flavonoids along with the significant challenges in the data interpretation are provided.

Computed tomography-guided screening of surfactant effect on blood circulation time of emulsions: application to the design of an emulsion formulation for paclitaxel

PURPOSE

In an effort to apply the imaging techniques currently used in disease diagnosis for monitoring the pharmacokinetics and biodisposition of particulate drug carriers, we sought to use computed tomography (CT) scanning methodology to investigate the impact of surfactant on the blood residence time of emulsions.

METHODS

We prepared the iodinated oil Lipiodol emulsions with different compositions of surfactants and investigated the impact of surfactant on the blood residence time of emulsions by CT scanning.

RESULTS

The blood circulation time of emulsions was prolonged by including Tween 80 or DSPE-PEG (polyethylene glycol 2000) in emulsions. Tween 80 was less effective than DSPE-PEG in terms of prolongation effect, but the blood circulating time of emulsions was prolonged in a Tween 80 content-dependent manner. As a proof-of-concept demonstration of the usefulness of CT-guided screening in the process of formulating drugs that need to be loaded in emulsions, paclitaxel was loaded in emulsions prepared with 87 or 65% Tween 80-containing surfactant mixtures. A pharmacokinetics study showed that paclitaxel loaded in 87% Tween 80 emulsions circulated longer in the bloodstream compared to those in 65% Tween 80 emulsions, as predicted by CT imaging.

CONCLUSIONS

CT-visible, Lipiodol emulsions enabled the simple evaluation of surfactant composition effects on the biodisposition of emulsions.