Contribution of Biotransformations Carried Out by the Microbiota, Drug-Metabolizing Enzymes, and Transport Proteins to the Biological Activities of Phytochemicals Found in the Diet

The consumption of dietary phytochemicals has been associated with several health benefits and relevant biological activities. It is postulated that biotransformations of these compounds regulated by the microbiota, Phase I/II reactions, transport proteins, and deconjugating enzymes contribute not only to their metabolic clearance but also, in some cases, to their bioactivation. A number of factors (age, genetics, sex, physiopathological conditions, and the interplay with other dietary phytochemicals) modulating metabolic activities are important sources and contributors to the interindividual variability observed in clinical studies evaluating the biological activities of phytochemicals. In this review, we discuss all the processes that can affect the bioaccessibility and beneficial effects of these bioactive compounds. Herein, we argue that the role of these factors must be further studied to correctly understand and predict the effects observed following the intake of phytochemicals. This is, in particular, with regard to in vitro investigations, which have shown great inconsistency with preclinical and clinical studies. The complexity of in vivo metabolic activity and biotransformation should therefore be considered in the interpretation of results in vitro and their translation to human physiopathology.

Cyclodextrin Complexation for Enhanced Stability and Non-invasive Pulmonary Delivery of Resveratrol-Applications in Non-small Cell Lung Cancer Treatment

Pulmonary drug delivery is a noninvasive therapeutic approach that offers many advantages including localized drug delivery and higher patient compliance. As with all formulations, the low aqueous solubility of a drug often poses a challenge in the formulation development. Thus, strategies such as cyclodextrin (CD) complexation have been utilized to overcome this challenge. Resveratrol (RES), a natural stilbene, has shown abundant anti-cancer properties. Due to many drawbacks of conventional chemotherapeutics, RES has been proposed as an emerging alternative with promising pharmacological effects. However, RES has limited therapeutic applications due to low water solubility, chemical stability, and bioavailability. This study was aimed at developing an inhalable therapy that would increase the aqueous solubility and stability of RES by complexation with sulfobutylether-β-cyclodextrin (SBECD). Phase solubility profiles indicated an optimal stoichiometric inclusion complex at 1:1 (SBECD:RES) ratio for formulation considerations. Physiochemical characterizations were performed to analyze CD-RES. Stability studies at pH 7.4 and in plasma indicated significant improvement in RES stability after complexation, with a much longer half-life. The mass median aerodynamic diameter (MMAD) of CD-RES was 2.6 ± 0.7 μm and fine particle fraction (FPF) of 83.4 ± 3.0% are suitable for pulmonary delivery and efficient deposition. Lung cancer was selected as the respiratory model disease, owing to its high relevance as the major cause of cancer deaths worldwide. Cell viability studies in 5 non-small-cell-lung-cancer (NSCLC) cell lines suggest CD-RES retained significant cytotoxic potential of RES. Taken together, CD-RES proves to be a promising inhalation treatment for NSCLC.

Efflux excretion of bisdemethoxycurcumin-O-glucuronide in UGT1A1-overexpressing HeLa cells: Identification of breast cancer resistance protein (BCRP) and multidrug resistance-associated proteins 1 (MRP1) as the glucuronide transporters

Bisdemethoxycurcumin (BDMC) was a natural curcuminoid with many bioactivities present in turmeric (Curcuma longa L.). However, the disposition mechanisms of BDMC via uridine 5'-diphospho-glucuronosyltransferase (UGT) metabolism still remain unclear. Therefore, we aimed to determine the potential efflux transporters for the excretion of BDMC-O-glucuronide. Herein, chemical inhibition assays (Ko143, MK571, dipyridamole, and leukotriene C4) and biological inhibition experiments including stable knocked-down of breast cancer resistance protein (BCRP), multidrug resistance-associated proteins (MRPs) transporters were both performed in a HeLa cell line stably overexpressing UGT1A1 established previously. The results indicated that Ko143 (5 and 20 μM) caused a marked reduction in excretion rate (18.4-55.6%) and elevation of intracellular BDMC-O-glucuronide (28.8-48.1%), whereas MK-571 (5 and 20 μM) resulted in a significant decrease in excretion rate (6.2-61.6%) and increase of intracellular BDMC-O-glucuronide (maximal 27.1-32.6%). Furthermore, shRNA-mediated silencing of BCRP transporter led to a marked reduction in the excretion rate (21.1-36.9%) and an obvious elevation of intracellular glucuronide (24.9%). Similar results were observed when MRP1 was partially silenced. In addition, MRP3 and MRP4 silencing both displayed no obvious changes on the excretion rate and intracellular levels of glucuronide. In conclusion, chemical inhibition and gene silencing results both indicated that generated BDMC-O-glucoside were excreted primarily by the BCRP and MRP1 transporters. © 2018 BioFactors, 44(6):558-569, 2018.

Sulfation disposition of liquiritigenin in SULT1A3 overexpressing HEK293 cells: The role of breast cancer resistance protein (BCRP) and multidrug resistance-associated protein 4 (MRP4) in sulfate efflux of liquiritigenin

This study aimed to investigate the cellular disposition of liquiritigenin via the sulfonation pathway and the role of efflux transporters in liquiritigenin sulfate excretion. The sulfonation disposition of liquiritigenin was investigated using SULT1A3 overexpressed HEK293 cells (HEK-SULT1A3 cells). Liquiritigenin generated one mono-sulfate metabolite (7-O-sulfate) in HEK-SULT1A3 cell lysate. And the sulfonation followed the Michaelis-Menten kinetic (V_max = 0.84 nmol/min/mg and K_m = 7.12 μM). Expectedly, recombinant SULT1A3 (hSULT1A3) showed a highly similar kinetic profile with cell lysate. Furthermore, 7-O-sulfate was rapidly generated and excreted in HEK-SULT1A3 cells. Ko143 (a BCRP-selective inhibitor) at 20 μM significantly decreased the excretion rate of liquiritigenin sulfate (>42.5%, p < 0.001). Moreover, the pan-MRPs inhibitor MK-571 at 20 μM essentially abolished the liquiritigenin sulfate effluxion, resulting in the marked reduction of excretion rate (>97.4%, p < 0.001). Furthermore, knockdown of BCRP led to moderate reduction in sulfate excretion (15.9%-16.9%, p < 0.05). Silencing of MRP4 caused significant decreased in sulfate excretion (20.2%-32.5%, p < 0.01). In conclusion, one sulfate metabolite was generated from liquiritigenin in HEK-SULT1A3 cells. BCRP and MRP4 should be the key factors for the cellular excretion of liquiritigenin sulfate.

Cellular Pharmacokinetic Model-Based Analysis of Genistein, Glyceollin, and MK-571 Effects on 5 (and 6)-Carboxy-2',7'-Dichloroflourescein Disposition in Caco-2 Cells

Pharmacokinetic modeling was used to describe 5 (and 6)-carboxy-2',7'-dichloroflourescein (CDF) disposition in Caco-2 cells following CDF or CDFDA (CDF diacetate) dosing. CDF transcellular flux was modeled by simple passive diffusion. CDFDA dosing models were based on simultaneous fitting of CDF levels in apical, basolateral, and intracellular compartments. Predicted CDF efflux was 50% higher across the apical versus the basolateral membrane. This difference was similar following apical and basolateral CDFDA dosing, despite intracellular levels being 3-fold higher following basolateral dosing, thus supporting nonsaturable CDF efflux kinetics. A 3-compartment catenary model with intracellular CDFDA hydrolysis described CDF disposition. This model predicted that apical CDF efflux was not altered in the presence of MK-571, and that basolateral membrane clearance was enhanced to account for reduced intracellular CDF in the presence of this multidrug resistance-associated protein (MRP) inhibitor. Similar effects were predicted for glyceollin, while genistein exposure had no predicted effects on CDF efflux. These modulator effects are discussed in the context of model predicted intracellular CDF concentrations relative to reports of CDF affinity (measured by Km) for MRP2 and MRP3. This model-based analysis confirms the complexity of efflux kinetics and suggests that other transporters may have contributed to CDF efflux.

Differential Proteomics Analysis of Colonic Tissues in Patients of Slow Transit Constipation

Objective. To investigate and screen the different expression of proteins in STC and normal group with a comparative proteomic approach. Methods. Two-dimensional electrophoresis was applied to separate the proteins in specimens from both 5 STC patients and 5 normal controls. The proteins with statistically significant differential expression between two groups were identified by computer aided image analysis and matrix assisted laser desorption ionization tandem time of flight mass spectrometry (MALDI-TOF-MS). Results. A total of 239 protein spots were identified in the average gel of the normal control and 215 in patients with STC. A total of 197 protein spots were matched and the mean matching rate was 82%. There were 14 protein spots which were expressed with statistically significant differences from others. Of those 14 protein spots, the expression of 12 spots increased markedly, while that of 2 spots decreased significantly. Conclusion. The proteomics expression in colonic specimens of STC patients is statistically significantly different from that of normal control, which may be associated with the pathogenesis of STC.