It is commonly observed that hydrophobic molecules alone cannot self-assemble into stable nanoparticles, requiring amphiphilic or ionic materials to support nanoparticle stability and function in vivo. We report herein newly self-assembled nanomedicines through entirely different mechanisms. We present proof-of-concept methodology and results in support of our hypothesis that disulfide-induced nanomedicines (DSINMs) are promoted and stabilized by the insertion of a single disulfide bond into hydrophobic molecules, in order to balance the competition between intermolecular forces involved in the self-assembly of nanomedicines. This hypothesis has been explored through diverse synthetic compounds, which include four first-line chemotherapy drugs (paclitaxel, doxorubicin, fluorouracil, and gemcitabine), two small-molecule natural products and their derivatives, as well as a fluorescent probe. Such an unprecedented and highly reproducible system has the potential to serve as a synthetic platform for a wide array of safe and effective therapeutic and diagnostic nanomedicine strategies.

Uridine-disphosphate glucuronosyl transferase (UGT) enzymes catalyze the formation of glucuronide conjugates of Phase II metabolism. Methods for absolute quantification of UGT1A1 and UGT1A6 were previously established utilizing stable isotope peptide internal standards with LC-MS/MS. The current method expands upon this by quantifying eight UGT1A isoforms by nanobore HPLC coupled with a linear ion trap-time of flight mass spectrometer platform. Recombinant enzyme digests of each of the isoforms were used to determine assay linearity and detection limits. Enzyme expression level in human liver, kidney and intestinal microsomal protein was determined by extrapolation from spiked stable isotope standards. Intraday and Interday variability was <25% for each of the enzyme isoforms. Enzyme expression varied from 3 pmol/mg protein to 96 pmol/mg protein in liver and intestinal microsomal protein digests. Expression levels of UGT1A7, 1A8 and 1A10 were below detection limits (<1 pmol/mg protein) in HLMs. In kidney microsomes the expression of UGT1A3 was below detection limits, but levels of UGT1A4, 1A7, 1A9 and 1A10 protein were higher relative to liver, suggesting that renal glucuronidation could be a significant factor in renal elimination of glucuronide conjugates. This novel method allows quantification of all nine UGT1A isoforms, many previously not amenable to measurement with traditional methods such as immunologically based assays. Quantitative measurement of proteins involved in drug disposition, such as the UGTs, significantly improves the ability to evaluate and interpret in vitro and in vivo studies in drug development.

Targeted quantitative proteomics using heavy isotope dilution techniques is increasingly being utilized to quantify proteins, including UGT enzymes, in biological matrices. Here we present a multiplexed method using nanoLC-MS/MS and multiple reaction monitoring (MRM) to quantify 14 UGT1As and UGT2Bs in liver matrices. Where feasible, we employ two or more proteotypic peptides per protein, with only four proteins quantified with only one proteotypic peptide. We apply the method to analysis of a library of 60 human liver microsome (HLM) and matching S9 samples. Ten of the UGT isoforms could be detected in liver, and the expression of each was consistent with mRNA expression reported in the literature. UGT2B17 was unusual in that ∼30% of liver microsomes had no or little (<0.5 pmol/mg protein) content, consistent with a known common polymorphism. Liver S9 UGT concentrations were approximately 10-15% those of microsomes. The method was robust, precise, and reproducible and provides novel UGT expression data in human liver that will benefit rational approaches to evaluate metabolism in drug development.

Renal metabolism by UDP-glucuronosyltransferase (UGT) enzymes is central to the clearance of many drugs. However, significant discrepancies about the relative abundance and activity of individual UGT enzymes in the normal kidney prevail among reports, whereas glucuronidation in tumoral kidney has not been examined. In this study, we performed an extensive profiling of glucuronidation metabolism in normal (n = 12) and tumor (n = 14) kidneys using targeted mass spectrometry quantification of human UGTs. We then correlated UGT protein concentrations with mRNA levels assessed by quantitative polymerase chain reaction and with conjugation activity for the major renal UGTs. Beyond the wide interindividual variability in expression levels observed among kidney samples, UGT1A9, UGT2B7, and UGT1A6 are the most abundant renal UGTs in both normal and tumoral tissues based on protein quantification. In normal kidney tissues, only UGT1A9 protein levels correlated with mRNA levels, whereas UGT1A6, UGT1A9, and UGT2B7 quantification correlated significantly with their mRNA levels in tumor kidneys. Data support that posttranscriptional regulation of UGT2B7 and UGT1A6 expression is modulating glucuronidation in the kidney. Importantly, our study reveals a significant decreased glucuronidation capacity of neoplastic kidneys versus normal kidneys that is paralleled by drastically reduced UGT1A9 and UGT2B7 mRNA and protein expression. UGT2B7 activity is the most repressed in tumors relative to normal tissues, with a 96-fold decrease in zidovudine metabolism, whereas propofol and sorafenib glucuronidation is decreased by 7.6-and 5.2-fold, respectively. Findings demonstrate that renal drug metabolism is predominantly mediated by UGT1A9 and UGT2B7 and is greatly reduced in kidney tumors.

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Although organic anion transporting polypeptide (OATP)-mediated hepatic uptake is generally conserved between rodents and humans at a gross pharmacokinetic level, the presence of three major hepatic OATPs with broad overlap in substrate and inhibitor affinity, and absence of rodent-human orthologs preclude clinical translation of single-gene knockout/knockin findings. At present, changes in pharmacokinetics and tissue distribution of pravastatin, atorvastatin, simvastatin, and carboxydichlorofluorescein were studied in oatp1a/1b-knockout mice lacking the three major hepatic oatp isoforms, and in knockout mice with liver-specific knockin of human OATP1B1 or OATP1B3. Relative to wild-type controls, oatp1a/1b-knockout mice exhibited 1.6-to 19-fold increased intravenous and 2.1-to 115-fold increased oral drug exposure, due to 33%-75% decreased clearance, 14%-60% decreased volume of distribution, and £74-fold increased oral bioavailability, with the magnitude of change depending on the contribution of oatp1a/1b to pharmacokinetics. Hepatic drug distribution was 4.2-to 196-fold lower in oatp1a/1b-knockout mice; distributional attenuation was less notable in kidney, brain, cardiac, and skeletal muscle. Knockin of OATP1B1 or OATP1B3 partially restored control clearance, volume, and bioavailability values (24%-142% increase, £47% increase, and £77% decrease vs. knockout, respectively), such that knockin pharmacokinetic profiles were positioned between knockout and wild-type mice. Consistent with liver-specific humanization, only hepatic drug distribution was partially restored (1.3-to 6.5-fold increase vs. knockout). Exposure and liver distribution changes in OATP1B1-humanized versus knockout mice predicted the clinical impact of OATP1B1 on oral exposure and contribution to human hepatic uptake of statins within 1.7-fold, but only after correcting for human/humanized mouse liver relative protein expression factor (OATP1B1 = 2.2, OATP1B3 = 0.30).

UGT enzymes catalyze the formation of glucuronic acid conjugates. Specifically selected representative stable isotope (C(13), N(15)) labeled peptide internal standards of each enzyme were employed to quantify UGTs 1A1 and 1A6 by LC-MS/MS using isotope dilution techniques. Inter day variability (n=5) for human liver microsomes was

Background: Little is known concerning the enantioselective disposition of 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) in humans. In addition, the potential of utilizing the stereochemical composition of an analyte in biological media for forensic purposes requires investigation. Methods: The enantiomers of MDMA and its demethylated metabolite, 3,4-methylenedioxyamphetamine (MDA), present in plasma and urine extracts were derivatized with (−)-(R)-α-methoxy-α-trifluoromethylphenylacetyl chloride and analyzed by gas chromatography–mass spectrometry and gas chromatography, respectively. The enantioselective disposition of MDMA and MDA was determined following oral administration of racemic MDMA (40 mg) to eight male volunteers. Results: The plasma concentrations of (R)-MDMA exceeded those of the S-enantiomer [ratio R:S of the area under the curve (AUC), 2.4 ± 0.3], and the plasma half-life of (R)-MDMA (5.8 ± 2.2 h) was significantly longer than that of the S-enantiomer (3.6 ± 0.9 h). The majority of the recovered material in urine was excreted within 24 h after dosing, with the recovery of (R)-MDMA (21.4% ± 11.6%) being significantly greater than that of (S)-MDMA (9.3% ± 4.9%), and with (S)- and (R)-MDA accounting for 1.4% ± 0.5% and 1.0% ± 0.3% of the dose, respectively. Mathematical modeling of plasma enantiomeric composition vs sampling time demonstrated the applicability of using stereochemical data for the prediction of time elapsed after drug administration. Conclusions: Analytical methods for determining the enantiomeric composition of MDMA and MDA in plasma and urine were developed. The disposition of MDMA in humans is stereoselective, with the more active S-enantiomer having a reduced AUC and shorter half-life than (R)-MDMA. The determination of stereochemical composition may be applicable for forensic purposes.