In Vivo Modulation of Rat Liver Microsomal Cytochrome P450 Activity by Antimalarial, Anti-HIV, and Antituberculosis Plant Medicines

Quantitative protein profiling of phenobarbital-induced drug metabolizing enzymes in rat liver by liquid chromatography mass spectrometry using formalin-fixed paraffin-embedded samples

Administration of a compound can induce drug-metabolizing enzymes (DMEs) in the liver. DME induction can affect various parameters in toxicology studies. Therefore, evaluation of DME induction is important for interpreting test compound-induced biological responses. Several methods such as measurement of hepatic microsomal DME activity using substrates, electron microscopy, or immunohistochemistry have been used; however, these methods are limited in throughput and specificity or are not quantitative. Liquid chromatography mass spectrometry (LC/MS)-based protein analysis can detect and quantify multiple proteins simultaneously per assay. Studies have shown that formalin-fixed paraffin-embedded (FFPE) samples, which are routinely collected in toxicology studies, can be used for LC/MS-based protein analysis. To validate the utility of LC/MS using FFPE samples for quantitative evaluation of DME induction, we treated rats with a DME inducer, phenobarbital, and compared the protein expression levels of 13 phase-I and 11 phase-II DMEs between FFPE and fresh frozen hepatic samples using LC/MS. A good correlation between data from FFPE and frozen samples was obtained after analysis. In FFPE and frozen samples, the expression of 6 phase-I and 8 phase-II DMEs showed a similar significant increase and a prominent rise in Cyp2b2 and Cyp3a1 levels. In addition, LC/MS data were consistent with the measurement of microsomal DME activities. These results suggest that LC/MS-based protein expression analysis using FFPE samples is as effective as that using frozen samples for detecting DME induction.

Toward a better understanding of metabolic and pharmacokinetic characteristics of low-solubility, low-permeability natural medicines

Today, it is very challenging to develop new active pharmaceutical ingredients. Developing good preparations of well-recognized natural medicines is certainly a practical and economic strategy. Low-solubility, low-permeability natural medicines (LLNMs) possess valuable advantages such as effectiveness, relative low cost and low toxicity, which is shown by the presence of popular products on the market. Understanding the in vivo metabolic and pharmacokinetic characteristics of LLNMs contributes to overcoming their associated problems, such as low absorption and low bioavailability. In this review, the structure-based metabolic reactions of LLNMs and related enzymatic systems, cellular and bodily pharmacological effects and metabolic influences, drug-drug interactions involved in metabolism and microenvironmental changes, and pharmacokinetics and dose-dependent/linear pharmacokinetic models are comprehensively evaluated. This review suggests that better pharmacological activity and pharmacokinetic behaviors may be achieved by modifying the metabolism through using nanotechnology and nanosystem in combination with the suitable administration route and dosage. It is noteworthy that novel nanosystems, such as triggered-release liposomes, nucleic acid polymer nanosystems and PEGylated dendrimers, in addition to prodrug and intestinal penetration enhancer, demonstrate encouraging performance. Insights into the metabolic and pharmacokinetic characteristics of LLNMs may help pharmacists to identify new LLNM formulations with high bioavailability and amazing efficacy and help physicians carry out LLNM-based precision medicine and individualized therapies.