Role of Intestinal First-Pass Metabolism of Baicalein in its Absorption Process

Effects of baicalin pre-treatment on pentylenetetrazole-induced seizures: Insights from zebrafish larvae locomotor behavior and neuronal calcium imaging

Natural compounds are increasingly being studied for their potential neuroprotective effects against inflammatory neurological diseases. Epilepsy is a common neurological disease associated with inflammatory processes, and around 30% of people with epilepsy do not respond to traditional treatments. Some flavonoids, when taken along with antiseizure medications can help reduce the likelihood of drug-resistant epilepsy. Baicalin, a plant-based compound, has been shown to possess pharmacological properties such as anti-inflammatory, neuroprotective, anticonvulsant, and antioxidant activities. In this study, we tested the effect of baicalin on an established model of pharmacologically induced seizure in zebrafish using measures of both locomotor behavior and calcium imaging of neuronal activity. The results of our study showed that, at the tested concentration, and contrary to other studies in rodents, baicalin did not have an anti-seizure effect in zebrafish larvae. However, given its known properties, other concentrations and approaches should be explored to determine if it could potentially have other beneficial effects, either alone or when administered in combination with classic antiseizure medications.

Gut microbiota: a superior operator for dietary phytochemicals to improve atherosclerosis

Mounting evidence implicates the gut microbiota as a possible key susceptibility factor for atherosclerosis (AS). The employment of dietary phytochemicals that strive to target the gut microbiota has gained scientific support for treating AS. This study conducted a general overview of the links between the gut microbiota and AS, and summarized available evidence that dietary phytochemicals improve AS via manipulating gut microbiota. Then, the microbial metabolism of several dietary phytochemicals was summarized, along with a discussion on the metabolites formed and the biotransformation pathways involving key gut bacteria and enzymes. This study additionally focused on the anti-atherosclerotic potential of representative metabolites from dietary phytochemicals, and investigated their underlying molecular mechanisms. In summary, microbiota-dependent dietary phytochemical therapy is a promising strategy for AS management, and knowledge of "phytochemical-microbiota-biotransformation" may be a breakthrough in the search for novel anti-atherogenic agents.

Baicalin and lung diseases

Studies focusing on natural products have been conducted worldwide, and the results suggest that their natural ingredients effectively treat a wide range of illnesses. Baicalin (BIA) is a glycoside derived from the flavonoid baicalein present in Scutellaria baicalensis of the Lamiaceae family. Interestingly, BIA has been shown to protect the lungs in several animal models used in numerous studies. Therefore, we fully analyzed the data of the studies that focused on BIA's lung protective function against various injuries and included them in this review. Interestingly, BIA exhibits promising effects against acute lung injury, lung fibrosis, pulmonary embolism, and lung remodelling associated with COPD, LPS, and paraquat insecticide. BAI exhibits anticancer activity against lung cancer. Additionally, BIA potently attenuates lung damage associated with infections. BIA primarily exerts its therapeutic effects by suppressing inflammation, oxidative stress immune response, and apoptosis pathways. Nrf2/HO-1, PI3K/Akt, NF-κB, STAT3, MAPKs, TLR4, and NLRP3 are important targets in the pulmonary therapeutic effects of BIA on different lung disease models. Consequently, we recommend using it in future potential clinical applications, its contribution to treatment guidelines, and translating its promising effects to clinical practice in lung diseases.

Anti-CMV therapy, what next? A systematic review

Human cytomegalovirus (HCMV) is one of the main causes of serious complications in immunocompromised patients and after congenital infection. There are currently drugs available to treat HCMV infection, targeting viral polymerase, whose use is complicated by toxicity and the emergence of resistance. Maribavir and letermovir are the latest antivirals to have been developed with other targets. The approval of letermovir represents an important innovation for CMV prevention in hematopoietic stem cell transplant recipients, whereas maribavir allowed improving the management of refractory or resistant infections in transplant recipients. However, in case of multidrug resistance or for the prevention and treatment of congenital CMV infection, finding new antivirals or molecules able to inhibit CMV replication with the lowest toxicity remains a critical need. This review presents a range of molecules known to be effective against HCMV. Molecules with a direct action against HCMV include brincidofovir, cyclopropavir and anti-terminase benzimidazole analogs. Artemisinin derivatives, quercetin and baicalein, and anti-cyclooxygenase-2 are derived from natural molecules and are generally used for different indications. Although they have demonstrated indirect anti-CMV activity, few clinical studies were performed with these compounds. Immunomodulating molecules such as leflunomide and everolimus have also demonstrated indirect antiviral activity against HCMV and could be an interesting complement to antiviral therapy. The efficacy of anti-CMV immunoglobulins are discussed in CMV congenital infection and in association with direct antiviral therapy in heart transplanted patients. All molecules are described, with their mode of action against HCMV, preclinical tests, clinical studies and possible resistance. All these molecules have shown anti-HCMV potential as monotherapy or in combination with others. These new approaches could be interesting to validate in clinical trials.

Engineered production of bioactive polyphenolic O-glycosides

Polyphenolic compounds (such as quercetin and resveratrol) possess potential medicinal values due to their various bioactivities, but poor water solubility hinders their health benefits to humankind. Glycosylation is a well-known post-modification method to biosynthesize natural product glycosides with improved hydrophilicity. Glycosylation has profound effects on decreasing toxicity, increasing bioavailability and stability, together with changing bioactivity of polyphenolic compounds. Therefore, polyphenolic glycosides can be used as food additives, therapeutics, and nutraceuticals. Engineered biosynthesis provides an environmentally friendly and cost-effective approach to generate polyphenolic glycosides through the use of various glycosyltransferases (GTs) and sugar biosynthetic enzymes. GTs transfer the sugar moieties from nucleotide-activated diphosphate sugar (NDP-sugar) donors to sugar acceptors such as polyphenolic compounds. In this review, we systematically review and summarize the representative polyphenolic O-glycosides with various bioactivities and their engineered biosynthesis in microbes with different biotechnological strategies. We also review the major routes towards NDP-sugar formation in microbes, which is significant for producing unusual or novel glycosides. Finally, we discuss the trends in NDP-sugar based glycosylation research to promote the development of prodrugs that positively impact human health and wellness.

Autophagy Induction by Scutellaria Flavones in Cancer: Recent Advances

In parallel with a steady rise in cancer incidence worldwide, the scientific community is increasingly focused on finding novel, safer and more efficient modalities for managing this disease. Over the past decades, natural products have been described as a significant source of new structural leads for novel drug candidates. Scutellaria root is one of the most studied natural products because of its anticancer potential. Besides just describing the cytotoxic properties of plant constituents, their molecular mechanisms of action in different cancer types are equally important. Therefore, this review article focuses on the role of the Scutellaria flavones wogonin, baicalein, baicalin, scutellarein and scutellarin in regulating the autophagic machinery in diverse cancer models, highlighting these molecules as potential lead compounds for the fight against malignant neoplasms. The knowledge that autophagy can function as a dual-edged sword, acting in both a pro- and antitumorigenic manner, further complicates the issue, revealing an amazing property of flavonoids that behave either as anti- or proautophagic agents.

Tissue distribution and integrated pharmacokinetic properties of major effective constituents of oral Gegen-Qinlian decoction in mice

Gegen-Qinlian decoction (GQD) is a classic traditional Chinese medicine (TCM) formula. GQD is effective against colon or liver-related diseases including ulcerative colitis, non-alcoholic fatty liver, and type 2 diabetes. In this study, a liquid chromatography-tandem mass spectrometry method was developed, validated, and then applied to reveal the tissue distribution and integrated pharmacokinetic properties of major effective constituents of oral GQD in mice. The established method was quick, sensitive, and accurate enough to analyze GQD constituents in plasma and tissue homogenate samples quantitatively. According to their concentrations in the portal vein, systemic circulation, liver and colon samples of the mice after oral administration of GQD, the concentration-time curves of the constituents were respectively plotted. The results showed that daidzein, baicalin, and baicalein had relatively high exposure levels in the livers, while puerarin, berberine, epiberberine, coptisine, palmatine, jatrorrhizine, magnoflorine, glycyrrhizic acid, and glycyrrhetinic acid were enriched in the colons. Given that these constituents have significant biological activity, they could be regarded as the major effective constituents of GQD in treating colon or liver-related diseases, respectively. In addition, the integrated pharmacokinetic properties of GQD were studied. The GQD “integrated constituent” reached peak concentration at 4.0 h in the portal vein, the systemic circulation, the livers, and the colons, with half-lives of 1.5–4.1 h and mean retention time of 4.5–6.3 h, respectively. Furthermore, the concentration of the GQD “integrated constituent” in the colons was approximately 10 times higher than that in the livers, both of which were much higher than that in the systemic circulation, indicating its accumulation in these tissues, especially in the colons. In conclusion, the tissue distribution and integrated pharmacokinetic properties of oral GQD were revealed in the study. The results of the tissue distribution study would contribute to identifying the major target tissues and effective constituents of GQD, while the results of the integrated pharmacokinetic study would help to explain the pharmacokinetic properties of oral GQD as a whole.

Determination of human FaFg of polyphenols using allometric scaling

Certain polyphenols exhibit low permeability; precise prediction of their intestinal absorption is important for understanding internal exposure in humans. Intestinal availability, which represents the fraction of administered compounds that reach the portal blood (F_aF_g), is calculated by dividing bioavailability (F) by hepatic availability (F_h), and F is obtained from pharmacokinetic data from both intravenous (i.v.) and oral (p.o.) administration. However, human F_aF_g of polyphenols is hardly reported, as human i.v. data are extremely scarce. In this study, we developed an estimation method for F_aF_g of polyphenols in humans based on the extrapolation of rat clearance using allometric scaling (allometric scaling-based F_aF_g calculation method, AS- F_aF_gCM). First, for quercetin, for which human i.v. data have been reported, we compared the F_aF_g obtained by AS-F_aF_gCM with the traditional approach using human i.v. and p.o. data. Less than two-fold difference in FaFg values was observed between the two approaches. Next, we obtained F_aF_g of structurally diverse polyphenols (genistein, baicalein, resveratrol, and epicatechin) using AS-F_aF_gCM, demonstrating that all of them were poorly absorbable. Furthermore, to utilize the pharmacokinetic data of the total concentration, including aglycones and metabolites, we modified the AS-F_aF_gCM to focus on their excretion. The F_aF_g value of naringenin was obtained using modified AS-F_aF_gCM and was nearly equal to that of baicalein, a structural isomer of naringenin. This study provides quantitative information on the intestinal absorption of polyphenols using comprehensive estimation methods.

The pharmaceutical excipient PEG400 affect the absorption of baicalein in Caco-2 monolayer model by interacting with UDP-glucuronosyltransferases and efflux transport proteins

The bioavailability of drugs is often related to intestinal metabolism and transport mechanisms. In previous studies, pharmaceutical excipients were recognized as inert substances in clinical safety evaluations. However, a large number of studies have shown that pharmaceutical excipients regulate the metabolism and transport of drugs in the body and improve the bioavailability. The pharmaceutical excipient polyethylene glycol 400 (PEG400) as a good solubilizer and surfactant has the potential to improve the bioavailability of drugs. The combined action of UDP-glucuronosyltransferases (UGTs) and efflux transport proteins is responsible for the intestinal disposition and poor bioavailability of baicalein. Our aim is to study the effect of PEG400 on the absorption of baicalein on the Caco-2 monolayer, and confirm the interaction of PEG400 with UGTs (UGT1A8 and UGT1A9) and efflux transports. We initially found that baicalein in the Caco-2 monolayer would be metabolized into glucuronide conjugates BG and B6G under the action of UGT1A8 and UGT1A9 on the endoplasmic reticulum membrane, and then mainly excreted to different sides by acting of MRP and BCRP. The addition of PEG400 significantly accelerated the metabolism of B in Caco-2 cells and increased the penetration of BG and B6G. Furthermore, PEG400 also significantly decreased the efflux ratio of BG and B6G, which was the evidence of the interaction with the efflux transporters. In the in vitro intestinal microsome regeneration system, low concentration PEG400 decreased the K_m value of UGT1A8 and UGT1A9 (key enzymes that mediate the production of BG and B6G); high concentration PEG400 enhanced the V_max value of UGT1A8 and UGT1A9. In conclusion, our results determined that PEG400 interacted with some UGTs and efflux transporters, which were the main factors affecting the absorption of baicalein.

Baicalin inhibits APEC-induced lung injury by regulating gut microbiota and SCFA production

Baicalin is a plant-derived flavonoid from Scutellaria baicalensis Georgi with multiple bioactivities and has a protective effect against avian pathogenic Escherichia coli (APEC) infection. However, the underlying mechanism of baicalin against APEC infection is still unknown. Therefore, we aimed to explore whether the protective effects and mechanisms of baicalin on APEC-induced lung inflammation were related to the regulation of gut microbiota. The results showed that baicalin significantly reduced APEC colonization and pro-inflammatory cytokines production, and additionally recovered air-blood barrier integrity in the lungs after APEC challenge. However, depletion of gut microbiota significantly weakened the protective effects of baicalin against APEC infection as mentioned above. Furthermore, baicalin markedly restored the dysbiosis of gut microbiota induced by APEC as well as increased the abundance of short chain fatty acid (SCFA)-producing bacteria and the production of SCFAs including acetic acid, propionic acid and butyric acid, especially acetic acid. In addition, the concentrations of acetic acid and its receptor free fatty acid receptor 2 (FFAR2) were significantly upregulated in the lung tissues after baicalin treatment. In conclusion, gut microbiota played a key role in the pharmacological action of baicalin against APEC-induced lung inflammation. Baicalin remodeled the dysbiosis of gut microbiota caused by APEC and increased the production of SCFAs, especially acetic acid in the gut, and then the increased acetate may circulate to the lungs to activate FFAR2 to defend APEC infection. Together, our study suggested that baicalin inhibited APEC infection through remodeling the gut microbiota dysbiosis and increasing the SCFA production. Furthermore, baicalin may serve as an alternative antibiotic and a novel therapeutic drug to prevent or treat APEC infection.

Formulation and performance evaluation of polymeric mixed micelles encapsulated with baicalein for breast cancer treatment

The present study is aimed to formulate baicalein-loaded mixed micelles to enhance the solubility and oral bioavailability. Baicalein encapsulated D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) and pluronic F127 (F127) combined micelles were prepared and investigated for anticancer effect. The optimized formulation contains 25.04 ± 0.24 nm mean particle size of micelles with a zeta potential value of -4.01 ± 0.5 mV. The calculated entrapment efficiency percentage of baicalein within the micellar structure was 83.43 ± 0.13% and the in vitro release of baicalein from micelles displayed a sustained release profile at pH 7.4. The incorporation of baicalein within micelles core was also confirmed by FTIR analysis of formulation, which hardly represents the characteristic peak of baicalein, indicating successful entrapment of the drug. In vitro cell culture experiments revealed baicalein-loaded micelles significantly enhanced cellular uptake and cytotoxicity against MDAMB-231 cell lines in comparison to free baicalein. Additionally, as compared to free baicalein, baicalein micelles demonstrated greater apoptosis-inducing potential while the results of the cell cycle study exhibited arrest of cells at the G0/G1 phase of the cell cycle. Results of ROS (reactive oxygen species) and MMP (mitochondrial membrane potential) assay revealed the ROS-dependent mitochondrial-mediated apoptosis pathway utilized by developed formulation to inhibit cell proliferation. Thus, the developed nano micelles can serve as a potent carrier system for baicalein against breast cancer.

Effect of Coformer Selection on In Vitro and In Vivo Performance of Adefovir Dipivoxil Cocrystals

PURPOSE

This study aimed to improve the in vitro dissolution, permeability and oral bioavailability of adefovir dipivoxil (ADD) by cocrystal technology and clarify the important role of coformer selection on the cocrystal's properties.

METHODS

ADD was cocrystallized with three small molecules (i.e., paracetamol (PA), saccharin (SAC) and nicotinamide (NIC)), respectively. The obtained ADD-PA cocrystal was characterized by DSC, TGA, PXRD and FTIR. Comparative study on dissolution rates among the three ADD cocrystals were conducted in water and pH 6.8 phosphate buffer. Besides, effects of coformers on intestinal permeability of ADD were evaluated via in vitro Caco-2 cell model and in situ single-pass intestinal perfusion model in rats. Furthermore, in vivo pharmacokinetic study of ADD cocrystals was also compared.

RESULTS

Dissolution rates of ADD cocrystals were improved with the order of ADD-SAC cocrystal > ADD-PA cocrystal > ADD-NIC cocrystal. The permeability studies on Caco-2 cell model and single-pass intestinal perfusion model indicated that PA could enhance intestinal absorption of ADD by P-gp inhibition, while SAC and NIC did not. Further in vivo pharmacokinetic study showed that ADD-SAC cocrystal exhibited higher C_max (1.4-fold) and AUC_0-t (1.3-fold) of ADD than administration of ADD alone, and C_max and AUC_0-t of ADD-PA cocrystal were significantly enhanced by 2.1-fold and 2.2-fold, respectively, which was attributed to its higher dissolution and improved intestinal permeability.

CONCLUSION

Coformer selection had an important role on cocrystal's properties, and cocrystallization of ADD with a suitable coformer was an effective approach to enhance both dissolution and bioavailability of ADD.

Safety, tolerability, pharmacokinetics, and food effect of baicalein tablets in healthy Chinese subjects: A single-center, randomized, double-blind, placebo-controlled, single-dose phase I study

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellaria baicalensis (Huang-Qin in Chinese) is a dry root of the perennial herb Scutellaria baicalensis Georgi, which has been used extensively in current prescriptions. Scutellaria baicalensis is an herb high in flavonoids, and baicalein is the one flavonoid found in the highest amount in Scutellaria baicalensis.

AIM OF THE STUDY

Influenza virus could cause mild respiratory tract illness to severe pneumonia and even death. Baicalein has been proved to be one of the effective components against the influenza virus. However, there have been few reports on human trials of baicalein. The purpose of this study was to evaluate the safety of baicalein in vivo and analyze its pharmacokinetic characteristics.

MATERIALS AND METHODS

Three randomized studies were conducted to evaluate the pharmacokinetics (PK), safety, tolerability, and food effects of baicalein tablets. In the 7-month single-dose safety study, 60 subjects were enrolled and randomized to receive 100-800 mg baicalein tablets or placebo. In the single-dose PK study, 40 subjects were enrolled and randomized to receive 200 mg, 400 mg, 600 mg, 800 mg baicalein tablets. In the study of food effect on PK of baicalein, an additional 10 subjects were enrolled in the 400 mg group, this part of the trial lasted for 7 months. Blood and urine samples for PK analysis were collected at a pre-specified time. PK properties in both fasted and fed states were evaluated, as well as safety and tolerability.

RESULTS

Among the 80 subjects who were evaluable for the single-dose safety and tolerability, 56 adverse events (AEs) were observed in 32/80 subjects, of which 49 events were from 28/68 subjects in baicalein group and 7 events were from 4/12 subjects in placebo group. All AEs were mild and resolved without any medical intervention. The most common AEs were elevated high-sensitivity C-reactive protein (hs-CRP) level and high triglycerides. After a single administration of baicalein tablets (200 mg, 400 mg, 600 mg, or 800 mg), C_max were 280.44, 628.80, 845.20, 489.55 ng/mL; AUC_0-∞ were 2035.57, 2939.31, 4494.88, and 3754.43 h*ng/mL, respectively. And t_1/2z ranged from 7.80 to 14.91 h. The exposure of baicalein and its metabolites increased in a less than dose-proportional manner.

CONCLUSION

Baicalein tablets within the studied dose range were safe and well-tolerated in healthy Chinese subjects with no serious or severe adverse effects. Further investigation will be needed to assess the safety and efficacy in the target patients.

Simultaneous Determination of Four Bioactive Flavonoids in Rat Plasma by UPLC-MS/MS and Comparative Pharmacokinetic Study after Oral Administration of Danyikangtai Powder and Three Compatibilities

Background:

Danyikangtai powder, a Traditional Chinese Medicine (TCM) formula, shows promise to become a novel drug candidate for the simultaneous treatment of chronic cholecystitis and chronic pancreatitis. However, the pharmacokinetic behavior of Danyikangtai powder remains unclear.

Objective:

We investigated the comparative pharmacokinetics of four flavonoids in rats after oral administration of Danyikangtai powder and three compatibilities.

Materials and Methods:

The comparative pharmacokinetics was studied by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS). Chromatographic separation was performed on a Universil XB-C18 column with a gradient mobile phase containing 0.1% (v/v) aqueous formic acid and acetonitrile. All analytes and internal standard were quantitated in the multiple reaction monitoring modes with a positive electrospray ionization interface.

Results and Discussion:

Danyikangtai powder and Scutellariae radix have similar pharmacokinetic behaviors in rats after oral administration. However, the elimination of four flavonoids in rats after oral administration of Danyikangtai powder was accelerated, which was possibly related to the reduction of the potential hepatotoxicity of Scutellariae radix. The varying degrees of change in pharmacokinetic parameters after oral administration of different herb combinations suggested that herb–herb interactions occurred in vivo.

Conclusions:

This study will be helpful to reveal the safety, rational and mechanism of Danyikangtai powder formula compatibility, thereby providing pre-clinical research data for its new drug development and guidance for its rational clinical application.

Inhibitory effects of Coptidis Rhizoma on the intestinal absorption and metabolism of Scutellariae Radix

ETHNOPHARMACOLOGICAL RELEVANCE

The Scutellariae Radix (SR) and Coptidis Rhizoma (CR) herb couple is widely used in traditional Chinese medicine prescriptions for the treatment of diabetes mellitus due to its interaction and synergistic effect compared to either herb alone, but the underlying mechanism of interaction between these herbs is unclear. This study aimed to investigate the effects of CR on the metabolism and absorption of SR.

MATERIALS AND METHODS

After rats were treated with normal saline (NS group) or the CR extract (CR-treated group) for seven consecutive days, the intestinal flora was extracted from rat faeces for a co-incubation with the SR extract to investigate the metabolism of SR flavonoids, and a non-everted gut sac was prepared in vitro to evaluate the intestinal absorption of the SR extract. The components of the SR extract, the metabolites of the SR extract that was co-incubated with intestinal flora, and the dialysate acquired from non-everted gut sacs were identified and determined by an HPLC-MS/MS method. The absorption rate constant (Ka) and the apparent permeability (Papp) of each compound were calculated, and the effects of CR on the metabolism and absorption of flavonoids in SR were evaluated, by comparison the Ka and Papp between two groups using Student's t-test.

RESULTS

Twenty-nine flavonoids were detected and identified in the SR extract, including 16 glycosides and 13 aglycones. In the co-incubation with the intestinal flora, differences in metabolite classes were not observed between the NS group and CR-treated group; however, the metabolic rates of 17 flavonoids in the CR-treated group were significantly higher than the NS group. The Papp of 11 compounds (4 glycosides and 7 aglycones) across the gut sac were greater than 2 × 10-5 cm/s in both groups, while the Papp values of 7 compounds including wogonoside (WG) and other aglycones were significantly decreased in the CR-treated group.

CONCLUSION

Based on these results, CR decreased the metabolism and absorption of SR flavonoids, and exerted much greater inhibitory effects on aglycones than glycosides, which may be one of the potential mechanisms underlying the therapeutic effects of the combination of SR and CR on diabetes mellitus.

Study of Pharmaceutical Excipient PEG400 Alteration of Pharmacokinetics and Tissue Distribution of Main Flavonoids Metabolites of Baicalin

Background::

Polyethylene glycol 400 (PEG400), as a good traditional Chinese medicine solvent, diluent and solubilizer, is widely used as a main pharmaceutical excipient in traditional Chinese medicine compound preparations containing active ingredient baicalin. PEG400 could increase the solubility and release of baicalin in vivo, but it was unknown that PEG400 affected the absorption and distribution of baicalin or not.

Objective: :

At present, the effects of PEG400 on the pharmacokinetic characteristics and tissue distribution behaviors of the main flavonoid metabolites baicalin, baicalein 6-O-β-D-glucopyranoside (B6G) and baicalein after oral administration of baicalin were investigated by a rapid, efficient and sensitive ultra- high performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method. Moreover, we respectively studied the effects of PEG400 on the activities and protein expressions of two subtypes UDP-glucuronyltransferase 1 A8/A9 (UGT1A8 and UGT1A9) of UDP-glucuronosyltransferases (UGTs) in vitro and in vivo experiments to determine the partial mechanisms by which PEG400 altered the pharmacokinetics and tissue distribution behaviors of the three flavonoid metabolites.

Methods:

A rapid, efficient and sensitive ultra-high performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method and ELISA and so on.

Results:

The results showed that PEG400 significantly increased the Cmax and AUC0-t values (P < 0.05 or P < 0.01) of baicalin and B6G while baicalein could not be quantified due to its extremely low concentration (lower the LLOQ) in plasma. Baicalin, B6G and baicalein were mainly distributed in the stomach, small intestine, kidney and liver. PEG400 changed the distribution of three flavonoid metabolites in various tissues and also increased the activities and expressions of UGT1A8 and UGT1A9.

Conclusion::

In conclusion, PEG400 significantly altered the pharmacokinetic characteristics and tissue distribution behaviors of three flavonoid metabolites may partly result from PEG400 upregulated the activities and expressions of the drug biphasic metabolic enzymes UGT1A8 and UGT1A9, which provided a material basis and useful information to reveal the mechanism of action and clinical application of PEG400.

Anti-inflammatory and immunomodulatory effects of baicalin in cerebrovascular and neurological disorders

Inflammatory responses play an extraordinary role in the pathogenesis of cerebrovascular and neurological disorders. Baicalin is one of the important flavonoids, which is extracted from Scutellaria baicalensis Georgi. Recently, numerous in vivo and in vitro studies have shown that baicalin has salutary effects for anti-inflammatory and immunomodulatory and has been demonstrated to exert beneficial therapeutic properties in cerebrovascular and neurological diseases. In this review, we aim to discuss that baicalin exerts anti-inflammatory effects through multiple pathways and targets, thus affecting the production of a variety of inflammatory cytokines and neuroprotective process of neurological diseases; furthermore, the related targets of the anti-inflammatory effects of baicalin were analyzed via using the tools of network pharmacology, to provide theoretical basis and innovative ideas for the future clinical application of baicalin.

Nanocrystal technology for improving therapeutic efficacy of flavonoids

BACKGROUND

Bioflavonoids, secondary metabolites of plants, are beneficial in regulating human physiological mechanisms. Bioflavonoids majorly exist in the dietary intake of fruits, vegetables, legumes, pulses, etc. In addition to their cardio-protective and neuroprotective activities, they also possess prominent pharmacological effects including anti-oxidant, anti-inflammatory, anti-proliferative and anti-thrombogenic actions. However, therapeutic efficacy of the bioflavonoids is hampered by their lipophilic nature, low solubility and variable bioavailability which catch the eyes of formulation scientists.

PURPOSE

Nanocrystal formulations were studied for many bioflavonoids, although enough attention has not been given to their commercial exploitation, unlike drug nanocrystals. Nanocrystals of bioflavonoid can be prepared by top-down technique, bottom-up technique or combination of both. This review primarily focuses on nanocrystal technology for bioflavonoids, methods of production, critical process parameters, in vitro and in vivo studies conducted to evaluate the efficiency.

METHOD

The detailed literature survey was systematically carried out using different electronic databases. It includes Scopus, Web of Science, Medline via PubMed, EMBASE, and Google Scholar. Also up-to-date patent search was conducted to understand the prior art and available intellectual properties.

RESULT AND CONCLUSION

It was observed that several formulation and process parameters have an impact on flavonoids nanocrystals and their therapeutic efficacy. Also, clinical studies of flavonoid nanocrystals are barely done so far and thus, substantial safety and efficacy data is necessary for its commercial applications. Nevertheless, nanocrystals can be explored as a promising technology platform for improving overall therapeutic performance of flavonoids in future.

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.

Comparative pharmacokinetic study on phenolic acids and flavonoids in spinal cord injury rats plasma by UPLC-MS/MS after single and combined oral administration of danshen and huangqin extract

Chinese medicinal herbs danshen and huangqin have attracted attention in spinal cord injury (SCI) treatment. Purpose of this study was to investigate and compare the pharmacokinetic characteristics of 4 phenolic acids and 4 flavonoids in SCI rat plasma after orally administrate danshen, huangqin and combined extract of these two herbs (CDH). Thus, a rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for simultaneously quantitative determination of tanshinol, protocatechualdehyde, protocatechuic acid, salvianolic acid A, baicalein, baicalin, wogonin and wogonoside. After inducing a contusion injury by a weight-drop device, SCI rats were orally administrated a single dose (12.5 g/kg) of danshen, huangqin and CDH extracts, respectively. Then, blood samples at different time points were collected and analyzed. In CDH group, C_max and AUC of tanshinol, protocatechualdehyde and protocatechuic acid significantly declined, while those of salvianolic acid A enhanced. These changes were beneficial for danshen to treat SCI. As for flavonoids, double peaks were observed in huangqin group, while this phenomenon disappeared in CDH group. Concomitantly, C_max and AUC declined after administrated CDH. These alterations were due to influence of danshen active constituents on absorption and transportation process of flavonoids. Therefore, danshen and huangqin significantly influenced pharmacokinetic profile and parameters of each other, thus exert synergistic therapeutic effect in SCI treatment.

Enhancing the oral bioavailability of baicalein via Solutol® HS15 and Poloxamer 188 mixed micelles system

OBJECTIVES

To increase the solubility of baicalein (BAI) by preparing BAI-micelles (BAI-M) with Solutol HS15 (HS15) and Poloxamer 188 (F68), thereby improving its oral bioavailability.

METHODS

Baicalein micelles were prepared with HS15 and F68 by thin-film dispersion method and optimized by central composite design (CCD) approach. Physicochemical, in vitro release, Caco-2 cell transport and pharmacokinetic studies of BAI-M were performed.

KEY FINDINGS

The optimal formulation showed spherical shape by characterization of the transmission electron microscope with average small size (23.14 ± 1.46 nm) and high entrapment efficiency (92.78±0.98%) and drug loading (6.45±1.54%). The in vitro release study of BAI-M showed a significantly sustained release pattern compared with free BAI. Caco-2 cell transport study demonstrated that high permeability of BAI was achieved after loading it into micelles. Meanwhile, pharmacokinetics study of BAI-M showed a 3.02-fold increase in relative oral bioavailability compared with free BAI.

CONCLUSIONS

Based on our findings, we concluded that HS15 can be used as a carrier in this drug delivery system that includes F68, and BAI-M has great potential in improving solubility and oral bioavailability.

The Influence of Compatibility of Rhubarb and Radix Scutellariae on the Pharmacokinetics of Anthraquinones and Flavonoids in Rat Plasma

BACKGROUND AND OBJECTIVES

Rhubarb-Radix scutellariae is a classic herb pair, which is commonly used to clear away heat and toxin in clinic. The aim of this study was to investigate the influence of compatibility of Rhubarb and Radix scutellariae on the pharmacokinetic behaviors of anthraquinones and flavonoids in rat plasma.

METHODS

Eighteen rats were randomly divided into three groups, and were orally administered Rhubarb and/or Radix scutellariae extracts. A sensitive and rapid UPLC-MS/MS method was developed and validated to determine the concentrations of baicalin, baicalein, wogonside, wogonin, rhein, and emodin in rat plasma. The concentrations of phase II conjugates of flavonoid aglycones and anthraquinone aglycones were also determined after hydrolyzing the plasma with sulfatase.

RESULTS

Compared with administration of Radix scutellariae alone, co-administration of Rhubarb significantly decreased the first maximum plasma concentration (C _max1) of baicalin, wogonside, and the phase II conjugates of baicalein, wogonin to 46.40, 61.27, 41.49, and 20.50%, respectively. The area under the plasma concentration-time curve from time zero to infinity (AUC_0-∞) was significantly decreased from 82.60 ± 20.22 to 51.91 ± 7.46 μM·h for rhein and 276.83 ± 98.02 to 175.42 ± 86.82 μM·h for the phase II conjugates of wogonin after compatibility. The time to reach the first maximum plasma concentration (T _max1) of anthraquinones was shortened and the second peak of anthraquinones disappeared after compatibility.

CONCLUSIONS

Compatibility of Rhubarb and Radix scutellariae can significantly affect the pharmacokinetic behaviors of characteristic constituents of the two herbs. The cause of these pharmacokinetic differences was further discussed combined with the in vivo ADME (absorption, disposition, metabolism, and excretion) processes of anthraquinones and flavonoids.

Effects of Baicalein on Cortical Proinflammatory Cytokines and the Intestinal Microbiome in Senescence Accelerated Mouse Prone 8

Baicalein, a flavonoid derived from the roots of Scutellariae baicalensis Georgi, has shown health benefits for an array of human diseases including dementia. The senescence-accelerated mouse prone 8 (SAMP8) strain is extensively used as a senile dementia model. To further investigate the effects of baicalein in SAMP8 mice, behavioral testing, biochemical detection, and gut microbiota analysis were performed. The results demonstrated that treatment with baicalein ameliorated the senescence status of the SAMP8 mice, as manifested by reducing the grading score of senescence. Additionally, baicalein improved the cognitive functions of the SAMP8 mice, including spatial learning and memory abilities, object recognition memory, and olfactory memory. Furthermore, baicalein significantly inhibited the release of proinflammatory cytokines such as interleukin-6 (IL-6), interleukin-1 beta (IL-1β), and tumor necrosis factor-α (TNF-α) in the brain cortex of SAMP8 mice. Gut microbiota analysis revealed that treatment with baicalein markedly altered the abundance of six genera in SAMP8 mice. Correlation analysis indicated that the abundances of Mucispirillum, Bacteroides, and Sutterella were negatively correlated with cognitive abilities and that Christensenellaceae was positively correlated with cognition. Furthermore, the abundance of Christensenellaceae was negatively correlated with the levels of IL-6 and TNF-α, while [ Prevotella] was positively correlated with the levels of IL-1β and IL-6. In addition, Mucispirillum and Bacteroides were positively correlated with the level of IL-6 in the brain cortex. These data indicated that baicalein ameliorates senescence status and improves cognitive function in SAMP8 mice and that this effect might be attributable to suppression of cortical proinflammatory cytokines and modulation of the intestinal microbiome.

A nano-cocrystal strategy to improve the dissolution rate and oral bioavailability of baicalein

Baicalein (BE) is one of the main active flavonoids representing the variety of pharmacological effects including anticancer, anti-inflammatory and cardiovascular protective activities, but it's very low solubility, dissolution rate and poor oral absorption limit the therapeutic applications. In this work, a nano-cocrystal strategy was successfully applied to improve the dissolution rate and bioavailability of BE. Baicalein-nicotinamide (BE-NCT) nano-cocrystals were prepared by high pressure homogenization and evaluated both in vitro and in vivo. Physical characterization results including scanning electron microscopy, dynamic light scattering, powder X-ray diffraction and differential scanning calorimetry demonstrated that BE-NCT nano-cocrystals were changed into amorphous state with mean particle size of 251.53 nm. In the dissolution test, the BE-NCT nano-cocrystals performed 2.17-fold and 2.54-fold enhancement than BE coarse powder in FaSSIF-V2 and FaSSGF. Upon oral administration, the integrated AUC_0 − t of BE-NCT nano-cocrystals (6.02-fold) was significantly higher than BE coarse powder (1-fold), BE-NCT cocrystals (2.87-fold) and BE nanocrystals (3.32-fold). Compared with BE coarse powder, BE-NCT cocrystals and BE nanocrystals, BE-NCT nano-cocrystals possessed excellent performance both in vitro and in vivo evaluations. Thus, it can be seen that nano-cocrystal is an appropriate novel strategy for improving dissolution rate and bioavailability of poor soluble natural products such as BE.

The Relationship Between Endogenous β-Glucuronidase Activity and Biologically Active Flavones-Aglycone Contents in Hairy Roots of Baikal Skullcap

Here, we examine the relationship between contents of principal flavones in hairy roots of Scutellaria baicalensis with the activity of the β-glucuronidase (sGUS) enzyme during a culturing cycle. Using RP-HPLC, we show that the highest contents of aglycones, baicalin and wogonin is observed at the growth days 8, 14, and 71 and reach 45, 41, and 62% (based on the total weight of hairy roots of the Baikal skullcap), correspondingly. Their accumulation is accompanied by increase of the sGUS activity, which we determined fluorometrically. Moreover, the enzyme activity is characterized by significant and reasonable correlation only with the wogonin contents. Our results confirm a significant role of sGUS at the final steps of the metabolism in root-specific flavones of Baikal skullcap and suggest how one can optimize the conditions of culturing the hairy roots for biotechnological production of individual flavonoids. For example, at the culturing day 71 wogonin constituted over 80% of all flavones extracted from cells.

Liposome‑delivered baicalein induction of myeloid leukemia K562 cell death via reactive oxygen species generation

Baicalein (BL), a potential cancer chemopreventative flavone, has been reported to inhibit cancer cell growth by inducing apoptosis and causing cell cycle arrest in various human cancer cell models. Delivery of BL via nanoliposomes has been shown to improve its oral bioavailability and long-circulating property in vivo. However, the role of BL in the inhibition of human chronic myeloid leukemia (CML) K562 cell growth and its underlying mechanisms has yet to be elucidated. In the present study, BL was formulated into liposomes with different sizes to improve its solubility and stability. The cytotoxic and pro-apoptotic effects of free BL and liposomal BL were also evaluated. The results demonstrated that 100 nm liposomes were the most stable formulation when compared with 200 and 400 nm liposomes. Liposomal BL inhibited K562 cell growth as efficiently as free BL (prepared in DMSO), indicating that the liposome may be a potential vehicle to deliver BL for the treatment of CML. Flow cytometry analysis showed that there was significant (P<0.005) cell cycle arrest in the sub-G1 phase (compared with vehicle control), indicating cell apoptosis following 20 µM liposomal BL or free BL treatment of K562 cells for 48 h. The induction of cell apoptosis by all BL preparations was further confirmed through the staining of treated cells with Annexin V-fluorescein isothiocyanate/propidium iodide. A significant increase in reactive oxygen species (ROS) generation was observed in free BL and liposomal BL treated cells, with a higher level of ROS produced from those treated with free BL. This indicated that cell apoptosis induced by BL may be via ROS generation and liposome delivery may further extend the effect through its long-circulating property.

The Effects of Baicalin and Baicalein on Cerebral Ischemia: A Review

Ischemic stroke, producing a high mortality and morbidity rate, is a common clinical disease. Enhancing the prevention and control of ischemic stroke is particularly important. Baicalin and its aglycon baicalein are flavonoids extracted from Scutellaria baicalensis, an important traditional Chinese herb. In recent years, a growing body of evidences has shown that baicalin and baicalein could be effective in the treatment of cerebral ischemia. Pharmacokinetic studies have shown that baicalin could penetrate the blood-brain barrier and distribute in cerebral nuclei. Through a variety of in vitro and in vivo models of ischemic neuronal injury, numerous studies have demonstrated that baicalin and baicalein have salutary effect for neuroprotection. Especially, the studies on the pharmacological mechanism showed that baicalin and baicalein have several pharmacological activities, which include antioxidant, anti-apoptotic, anti-inflammatory and anti-excitotoxicity effects, protection of the mitochondria, promoting neuronal protective factors expression and adult neurogenesis effects and many more. This review focuses on the neuroprotective effects of baicalin and baicalein in ischemia or stroke-induced neuronal cell death. We aimed at collecting all important information regarding the neuroprotective effect and its pharmacological mechanism of baicalin and baicalein in various in vivo and in vitro experimental models of ischemic neuronal injury.

Efficient brain uptake of piperine and its pharmacokinetics characterization after oral administration

1. Piperine, the major biological active component in black pepper has been associated with miscellaneous pharmacological effects, especially on central nervous system. To correlate with its neurological activity, a comprehensive pharmacokinetic profile of piperine in brain, plasma and cerebrospinal fluid after oral administration in rats was investigated in this study. 2. It was noted that piperine could efficiently penetrate and homogeneously distribute into brain with similar pharmacokinetics profiles in each region. In addition, piperine concentrations in brain and plasma were found to be comparable with brain to plasma area under curve extrapolated to infinity (AUC_0→∞) ratios of 0.95 and 1.10 for total concentration and unbound concentrations, respectively. Piperine also demonstrated high affinity toward brain tissue (98.4-98.5%) and plasma protein (96.2-97.8%) leading to a brain distribution volume of 36.32 ± 1.40 ml/g brain. Moreover, its efficient membrane permeability (P _app values of 5.41  ±  0.40 × 10^{- 5} cm/s and 4.78  ±  0.16 × 10^{- 5} cm/s for basolateral to apical and apical to basolateral transport in Caco-2 monolayer model) and limited hepatic metabolism (Cl_int of 8.15 μl/min/mg) could also contribute to its quick and high extent brain exposure. 3. In summary, this study for the first time demonstrated high brain penetration potency of piperine could be resulted from its high brain tissue affinity and membrane permeability together with its limited liver metabolism.

Pharmacokinetics study of Erhuang decoction extracts in rats by HPLC-MS/MS

To study the pharmacokinetics of Erhuang decoction extracts, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established for the determination of effective substances in rat plasma. The extracts prepared by water extraction (WE) method were given to rats by oral administration. After collected from the orbital venous plexus, plasma was treated by protein precipitation method. Then, the concentration of index components, including baicalin, liquiritin, berberine, palmatine and glycyrrhetinic acid, were determined by HPLC-MS/MS. Gradient elution mode was used to the chromatographic separation with an Inertsil ODS-SP column (100 mm×2.1mm, 5μm), with acetonitrile and 0.1% formic acid containing 10mmolL^-1 ammonium acetate as the mobile phase. MS analysis was conducted by multiple reactions monitoring (MRM) with Electrospray Ionization (ESI). The extraction recoveries of the five active ingredients from plasma were greater than 86.04%, and the intra- and inter-day precisions were less than 16.57%. Results indicated that active ingredients in plasma of rats with oral administration of extracts showed certain difference in the pharmacokinetic parameters, which proved that the active ingredients were effectively absorbed. The established HPLC-MS/MS analytical method was sensitive and accurate, suitable for the pharmacokinetic study of active ingredients in Erhuang decoction.

Effects of Intestinal Microecology on Metabolism and Pharmacokinetics of Oral Wogonoside and Baicalin

Baicalin and wogonoside are two of the most abundant flavonoid glycosides in the root of Scutellaria baicalensis Georgi, which is a widely used peroral herbal medicine with anticancer, antiviral, antibacterial and anti-inflammatory properties. In the present study, the effects of intestinal microecology on the metabolism and pharmacokinetics of orally administered baicalin and wogonoside were investigated by UPLC-QTOF/MS measurement of the difference in metabolites between normal and antibiotic-pretreated rats. In the antibiotic-pretreated rats, the plasma concentration-time profile and pharmacokinetic parameters of the two flavonoid glycosides and their relevant aglycone forms were significantly changed compared with those in normal rats. Further, hydrolysis and glucuronidated metabolites were not detected in the cecum contents and urine samples from antibiotic-pretreated rats. These results suggested that intestinal microbiota may play a key role in the pharmacokinetics and metabolism of peroral baicalin and wogonoside. According to our findings, it is recommended that the root of S. baicalensis should not be co-administered with antibiotics in clinical use.

Dietary flavonoid aglycones and their glycosides: Which show better biological significance?

The dietary flavonoids, especially their glycosides, are the most vital phytochemicals in diets and are of great general interest due to their diverse bioactivity. The natural flavonoids almost all exist as their O-glycoside or C-glycoside forms in plants. In this review, we summarized the existing knowledge on the different biological benefits and pharmacokinetic behaviors between flavonoid aglycones and their glycosides. Due to various conclusions from different flavonoid types and health/disease conditions, it is very difficult to draw general or universally applicable comments regarding the impact of glycosylation on the biological benefits of flavonoids. It seems as though O-glycosylation generally reduces the bioactivity of these compounds - this has been observed for diverse properties including antioxidant activity, antidiabetes activity, anti-inflammation activity, antibacterial, antifungal activity, antitumor activity, anticoagulant activity, antiplatelet activity, antidegranulating activity, antitrypanosomal activity, influenza virus neuraminidase inhibition, aldehyde oxidase inhibition, immunomodulatory, and antitubercular activity. However, O-glycosylation can enhance certain types of biological benefits including anti-HIV activity, tyrosinase inhibition, antirotavirus activity, antistress activity, antiobesity activity, anticholinesterase potential, antiadipogenic activity, and antiallergic activity. However, there is a lack of data for most flavonoids, and their structures vary widely. There is also a profound lack of data on the impact of C-glycosylation on flavonoid biological benefits, although it has been demonstrated that in at least some cases C-glycosylation has positive effects on properties that may be useful in human healthcare such as antioxidant and antidiabetes activity. Furthermore, there is a lack of in vivo data that would make it possible to make broad generalizations concerning the influence of glycosylation on the benefits of flavonoids for human health. It is possible that the effects of glycosylation on flavonoid bioactivity in vitro may differ from that seen in vivo. With in vivo (oral) treatment, flavonoid glycosides showed similar or even higher antidiabetes, anti-inflammatory, antidegranulating, antistress, and antiallergic activity than their flavonoid aglycones. Flavonoid glycosides keep higher plasma levels and have a longer mean residence time than those of aglycones. We should pay more attention to in vivo benefits of flavonoid glycosides, especially C-glycosides.

Multiple-Ascending-Dose Pharmacokinetics and Safety Evaluation of Baicalein Chewable Tablets in Healthy Chinese Volunteers

BACKGROUND AND OBJECTIVES

Baicalein, a flavonoid isolated from the root of Scutellaria baicalensis Georgi, is a neuroprotective agent under development to treat Parkinson's disease. This study investigated the pharmacokinetics, safety and tolerability of baicalein after a multiple-ascending-dose protocol in healthy Chinese volunteers.

METHODS

In this single-center, double-blind, placebo-controlled, parallel-group study, participants were randomized to receive baicalein (n = 8 per dose regimen) or placebo (n = 2 per dose regimen). Dosing regimens were 200, 400, and 800 mg once daily on days 1 and 10, twice daily on days 3-9. Plasma, urine, and feces samples were assayed for baicalein and its predominant metabolite baicalin using validated HPLC-MS/MS methods. Pharmacokinetic parameters were computed using standard non-compartmental analysis. Dose proportionality was assessed with a method combining equivalence criterion and power model. Drug safety and tolerability were assessed by monitoring adverse events and laboratory parameters.

RESULTS

Thirty-three of 36 enrolled participants completed the study. A total of 44 adverse events occurred in 23 participants. A steady-state concentration of analytes in plasma was achieved on day 8 after repeated dosing. Analytes concentrations and exposure increased with increasing dose. The dose proportionality constant (β) for AUCss of baicalein and baicalin was 0.922 (90 % confidence interval, 0.650-1.195) and 0.942 (90 % confidence interval, 0.539-1.345), respectively. The accumulation index varied from 1.66 to 2.07 for baicalein and from 1.68 to 2.45 for baicalin.

CONCLUSION

In dose range of 200-800 mg, multiple-dose oral baicalein administration was safe and well tolerated, dose proportionality was inconclusive, and no serious accumulation of baicalein was observed.

An Agent-Based Approach to Dynamically Represent the Pharmacokinetic Properties of Baicalein

Baicalein, a typical flavonoid presented in Scutellariae radix, exhibits a unique metabolic profile during first-pass metabolism: parallel glucuronidation and sulfation pathways, with possible substrate inhibition in both pathways. In this project, we aimed to construct an agent-based model to dynamically represent baicalein pharmacokinetics and to verify the substrate inhibition hypothesis. The model consisted of three 3D spaces and two membranes: apical space (S1), intracellular space (S2), basolateral space (S3), apical membrane (M1), and basolateral membrane (M2). In silico enzymes (UDP-glucuronosyltransferases (UGTs) and sulfotransferases (SULTs)) and binder components were placed in S2. The model was then executed to simulate one-pass metabolism experiments of baicalein. With the implementation of a two-site enzyme design, the simulated results captured the preset qualitative and quantitative features of the wet-lab observations. The feasible parameter set showed that substrate inhibition happened in both conjugation pathways of baicalein. The simulation results suggested that the sulfation pathway was dominant at low concentrations and that SULT was more inclined to substrate inhibition than UGT. Cross-model validation was satisfactory. Our findings were consistent with a previously reported catenary model. We conclude that the mechanisms represented by our model are plausible. Our novel modeling approach could dynamically represent the metabolic pathways of baicalein in a Caco-2 system.

Hyaluronic acid-coated, prodrug-based nanostructured lipid carriers for enhanced pancreatic cancer therapy

CONTEXT

Gemcitabine (GEM) and Baicalein (BCL) are reported to have anti-tumor effects including pancreatic cancer. Hyaluronic acid (HA) can bind to over-expressed receptors in various kinds of cancer cells.

OBJECTIVE

The aim of this study is to develop prodrugs containing HA, BCL and GEM, and construct nanomedicine incorporate GEM and BCL in the core and HA on the surface. This system could target the cancer cells and co-deliver the drugs.

METHODS

GEM-stearic acid lipid prodrug (GEM-SA) and hyaluronic acid-amino acid-baicalein prodrug (HA-AA-BCL) were synthesized. Then, GEM and BCL prodrug-based targeted nanostructured lipid carriers (HA-GEM-BCL NLCs) were prepared by the nanoprecipitation technique. The in vitro cytotoxicity studies of the NLCs were evaluated on AsPC1 pancreatic cancer cell line. In vivo anti-tumor effects were observed on the murine-bearing pancreatic cancer model.

RESULTS

HA-GEM-BCL NLCs were effective in entering pancreatic cancer cells over-expressing HA receptors, and showed cytotoxicity of tumor cells in vitro. In vivo study revealed significant tumor growth inhibition ability of HA-GEM-BCL NLCs in murine pancreatic cancer model.

CONCLUSION

It could be concluded that HA-GEM-BCL NLCs could be featured as promising co-delivery, tumor-targeted nanomedicine for the treatment of cancers.

Pharmacokinetic-Pharmacodynamic Analysis on Inflammation Rat Model after Oral Administration of Huang Lian Jie Du Decoction

Huang-Lian-Jie-Du Decoction (HLJDD) is a classical Traditional Chinese Medicine (TCM) formula with heat-dissipating and detoxifying effects. It is used to treat inflammation-associated diseases. However, no systematic pharmacokinetic (PK) and pharmacodynamic (PD) data concerning the activity of HLJDD under inflammatory conditions is available to date. In the present study, the concentration-time profiles and the hepatic clearance rates (HCR) of 41 major components in rat plasma in response to the oral administration of a clinical dose of HLJDD were investigated by LC-QqQ-MS using a dynamic multiple reaction monitoring (DMRM) method. Additionally, the levels of 7 cytokines (CKs) in the plasma and the body temperature of rats were analyzed. Furthermore, a PK-PD model was established to describe the time course of the hemodynamic and anti-inflammatory effects of HLJDD. As one of the three major active constituents in HLJDD, iridoids were absorbed and eliminated more easily and quickly than alkaloids and flavonoids. Compared with the normal controls, the flavonoids, alkaloids and iridoids in inflamed rats exhibited consistently changing trends of PK behaviors, such as higher bioavailability, slower elimination, delays in reaching the maximum concentration (T_max) and longer substantivity. The HCR of iridoids was different from that of alkaloids and flavonoids in inflamed rats. Furthermore, excellent pharmacodynamic effects of HLJDD were observed in inflamed rats. The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-1β, IL-10, and macrophage inflammatory protein-2 (MIP-2) and body temperature significantly decreased after the administration of HLJDD. Based on PK-PD modeling with the three-phase synchronous characterization of time-concentration-effect, flavonoids exhibited one mechanism of action in the anti-inflammatory process, while iridoids and alkaloids showed another mechanism of action. Taken together, the results demonstrated that HLJDD may restrain inflammation synergistically via its major constituents (alkaloids, flavonoids and iridoids). A correlation between the exposure concentration of different types of compounds and their anti-inflammatory effects in the body was shown. This study provides a comprehensive understanding of the anti-inflammatory activity of HLJDD.

Role of Intestinal Microbiota in Baicalin-Induced Drug Interaction and Its Pharmacokinetics

Since many glycoside compounds in natural products are hydrolyzed by intestinal microbiota when administered orally, it is of interest to know whether their pharmacological effects are derived from the glycoside itself or from the aglycone form in vivo. An interesting example is baicalin versus baicalein, the aglycone of baicalin, which is contained in some herbs from Labiatae including Scutellaria baicalensis Georgi and Scutellaria lateriflora Linne. The herbs have been extensively used for treatment of inflammatory diseases in Asia. Although there have been numerous reports regarding the pharmacological effects of baicalin and baicalein in vivo and in vitro, some reports indicated that the glycoside form would hardly be absorbed in the intestine and that it should be hydrolyzed to baicalein in advance for absorption. Therefore, the role of metabolism by intestinal microbiota should also be considered in the metabolism of baicalin. In addition, baicalin contains a glucuronide moiety in its structure, by which baicalin and baicalein show complex pharmacokinetic behaviors, due to the interconversion between them by phase II enzymes in the body. Recently, concerns about drug interaction with baicalin and/or baicalein have been raised, because of the co-administration of Scutellaria species with certain drugs. Herein, we reviewed the role of intestinal microbiota in pharmacokinetic characteristics of baicalin and baicalein, with regards to their pharmacological and toxicological effects.

Metabolism and pharmacokinetics of 8-hydroxypiperidinylmethyl-baicalein (BA-j) as a novel selective CDK1 inhibitor in monkey

Cyclin-dependent kinase 1 (CDK1) is the only necessary CDK in the cell proliferation process and a new target in the research and development of anti-cancer drugs. 8-Hydroxypiperidinemethyl-baicalein (BA-j) is a Mannich base derivative of baicalein (BA) isolated from Scutellaria baicalensis, as a novel selective CDK1 inhibitor. 12 metabolites of BA-j in the monkey urine were identified by LC-MS-MS and (1)H NMR. The major metabolic pathways of BA-j, by capturing oxygen free radicals ((.)O2(-)) and releasing peroxides (H2O2), are degraded into active intermediate metabolite dihydroflavonol, then into main metabolite M179 by Shiff reaction, second metabolite M264 by sulfation, trace amount of metabolite M559 by glucuronidation UGT1A9, and without metabolism by CYP3A4. The metabolic process of BA-j by regulating intracellular reactive oxygen species (ROS) was related with BA-j selectively inducing apoptosis in cancer cells. Pharmacokinetics of 10mg/kg oral BA-j in monkey by HPLC-UV was best fitted to a two-compartment open model, with t1/2(β) of 4.2h, Cmax 25.4μM at 2h, and Vd 12.6L, meaning the drug distributing widely in body fluids with no special selectivity to certain tissues, and being able to permeate through the blood-brain barrier. The protein binding rate of BA-j was 91.8%. BA-j has excellent druggability for oral administration or injection, and it may be developed into a novel anti-cancer drug as a selective CDK1 inhibitor.

BA-j as a novel CDK1 inhibitor selectively induces apoptosis in cancer cells by regulating ROS

Cyclin-dependent kinase 1 (CDK1) is the only necessary CDK in cell proliferation and a novel target in the development of anticancer drugs. 8-Hydroxypiperidinemethyl-baicalein (BA-j) is a novel selective CDK1 inhibitor with broad spectrum anti-cancer activity (IC₅₀ 12.3 μM) and 2 tumor xenografts. Because of the differential mechanisms controlling redox-states in normal and cancer cells, BA-j can capture oxygen free radicals (^·O₂⁻) and selectively increase the level of H₂O₂ in cancer cells, thereby specifically oxidize and activate the intrinsic apoptosis pathway bypassing the extrinsic death receptor pathway, thus inducing apoptosis in cancer cells rather than in normal cells. BA-j is different from cytotoxic anticancer drugs which can activate both the intrinsic apoptosis pathway and the extrinsic death receptor pathway, and therefore harm normal cells while killing cancer cells. The molecular and biochemical mechanisms of reactive oxygen species (ROS) regulation suggest that BA-j may be developed into a novel anticancer agent.

The effects of baicalein and baicalin on mitochondrial function and dynamics: A review

Mitochondria play an essential role in cell survival by providing energy, calcium buffering, and regulating apoptosis. A growing body of evidence shows that mitochondrial dysfunction and its consequences, including impairment of the mitochondrial respiratory chain, excessive generation of reactive oxygen species, and excitotoxicity, play a pivotal role in the pathogenesis of different diseases such as neurodegenerative diseases, neuropsychiatric disorders, and cancer. The therapeutical role of flavonoids on these diseases is gaining increasing acceptance. Numerous studies on experimental models have revealed the favorable role of flavonoids on mitochondrial function and structure. This review highlights the promising role of baicalin and its aglycone form, baicalein, on mitochondrial function and structure with a focus on its therapeutic effects. We also discuss their chemistry, sources and bioavailability.