Non-alcoholic fatty liver disease (NAFLD) is a spectrum of liver disorders. It is defined by the presence of steatosis in more than 5 % of hepatocytes with little or no alcohol consumption. Insulin resistance, the metabolic syndrome or type 2 diabetes and genetic variants of PNPLA3 or TM6SF2 seem to play a role in the pathogenesis of NAFLD. The pathological progression of NAFLD follows tentatively a ‘three-hit’ process namely steatosis, lipotoxicity and inflammation. The presence of steatosis, oxidative stress and inflammatory mediators like TNF-α and IL-6 have been implicated in the alterations of nuclear factors such as CAR, PXR, PPAR-α in NAFLD. These factors may results in altered expression and activity of drug metabolizing enzymes (DMEs) or transporters. Existing evidence suggests that the effect of NAFLD on CYP3A4, CYP2E1 and MRP3 are more consistent across rodent and human studies. CYP3A4 activity is down-regulated in NASH whereas the activity of CYP2E1 and the efflux transporter MRP3 are up-regulated. However, it is not clear how the majority of CYPs, UGTs, SULTs and transporters are influenced by NAFLD either in vivo or in vitro. The alterations associated with NAFLD could be a potential source of drug variability in patients and could have serious implications for the safety and efficacy of xenobiotics. In this review, we summarize the effects of NAFLD on the regulation, expression and activity of major drug metabolizing enzymes and transporters. We also discuss the potential mechanisms underlying these alterations.

Oseltamivir is the main medicine recommended by the World Health Organization in anticipation of next influenza pandemic. This anti-influenza viral agent is an ester prodrug, and the antiviral activity is achieved by its hydrolytic metabolite: oseltamivir carboxylate. In this study, we report that the hydrolytic activation is catalyzed by carboxylesterase human carboxylesterase (HCE) 1. Liver microsomes rapidly hydrolyzed oseltamivir, but no hydrolysis was detected with intestinal microsomes or plasma. The overall rate of the hydrolysis varied among individual liver samples and was correlated well with the level of HCE1. Recombinant HCE1 but not HCE2 hydrolyzed this prodrug and produced similar kinetic parameters as the liver microsomes. Several HCE1 natural variants differed from the wildtype enzyme on the hydrolysis of oseltamivir. In the presence of antiplatelet agent clopidogrel, the hydrolysis of oseltamivir was inhibited by as much as 90%

Oxytocin (OT) is a potential treatment for multiple neuropsychiatric disorders. Since OT is a peptide, delivery by the intranasal (IN) route is the preferred method in clinical studies. Although studies have shown increased cerebrospinal fluid (CSF) OT levels following IN administration, this does not clearly demonstrate that the peripherally administered OT is entering the CSF. For example, it has been suggested that peripheral delivery of OT could lead to central release of endogenous OT. It is also unknown whether the IN route provides for more efficient entry of the peptide into the CSF compared to the IV route which requires blood brain barrier (BBB) penetration. To address these questions, we developed a sensitive and specific quantitative mass spectrometry assay that distinguishes labelled (d5-deuterated) from endogenous (d0) OT. We administered d5-oxytocin (80 IU) to 6 nonhuman primates via IN and IV routes as well as IN saline as a control condition. We measured plasma and CSF concentrations of administered and endogenous OT before (t=0) and after (t=10, 20, 30, 45, 60 minutes) d5-oxytocin dosing. We demonstrate CSF penetrance of d5, exogenous OT delivered by IN and IV administration. Peripheral administration of d5-OT did not lead to increased d0, endogenous OT in the CSF. This suggests that peripheral administration of OT does not lead to central release of endogenous OT. We also did not find that IN administration offered an advantage compared to IV administration with respect to achieving greater CSF concentrations of OT.

BACKGROUND AND PURPOSEPatients with diabetes mellitus require pharmacotherapy with numerous medications. However, the effect of diabetes on drug biotransformation is not well understood. Our goal was to investigate the effect of diabetes on liver cytochrome P450 3As, the most abundant phase I drug-metabolizing enzymes in humans. EXPERIMENTAL APPROACHHuman liver microsomal fractions (HLMs) were prepared from diabetic (n = 12) and demographically matched nondiabetic (n = 12) donors, genotyped for CYP3A4*1B and CYP3A5*3 polymorphisms. Cytochrome P450 3A4, 3A5 and 2E1 mRNA expression, protein level and enzymatic activity were compared between the two groups. KEY RESULTSMidazolam 1′-or 4-hydroxylation and testosterone 6b-hydroxylation, catalyzed by P450 3A, were markedly reduced in diabetic HLMs, irrespective of genotype. Significantly lower P450 3A4 protein and comparable mRNA levels were observed in diabetic HLMs. In contrast, neither P450 3A5 protein level nor mRNA expression differed significantly between the two groups. Concurrently, we have observed increased P450 2E1 protein level and higher chlorzoxazone 6-hydroxylation activity in diabetic HLMs. CONCLUSIONS AND IMPLICATIONSThese studies indicate that diabetes is associated with a significant decrease in hepatic P450 3A4 enzymatic activity and protein level. This finding could be clinically relevant for diabetic patients who have additional comorbidities and are receiving multiple medications. To further characterize the effect of diabetes on P450 3A4 activity, a well-controlled clinical study in diabetic patients is warranted. Abbreviations1′-OH MDZ, 1′-hydroxymidazolam; 4-OH MDZ, 4-hydroxymidazolam; 6-OH CZ, 6-hydroxychlorzoxazone; 6b-OH TST, 6b hydroxytestosterone; CZ, chlorzoxazone; HLM, human liver microsomes; Ksi, substrate inhibition constant; MDZ, midazolam; P450 3A, cytochrome P450 3A subfamily; P450, cytochrome P450 (also termed haeme-thiolate P450); rP450, recombinant cytochrome P450; STZ, streptozotocin-induced diabetes model; TBARS, thiobarbituric acid reactive substances; TST, testosterone BJP British Journal of Pharmacology

Certain bacteria use cell-to-cell chemical communication to coordinate community-wide phenotypic expression, including swarming motility, antibiotic biosynthesis, and biofilm production. Here we present a marine gram-positive bacterium that secretes secondary metabolites capable of quenching quorum sensing-controlled behaviors in several gram-negative reporter strains. Isolate C42, a Halobacillus salinus strain obtained from a sea grass sample, inhibits bioluminescence production by Vibrio harveyi in cocultivation experiments. With the use of bioassay-guided fractionation, two phenethylamide metabolites were identified as the active agents. The compounds additionally inhibit quorum sensing-regulated violacein biosynthesis by Chromobacterium violaceum CV026 and green fluorescent protein production by Escherichia coli JB525. Bacterial growth was unaffected at concentrations below 200 g/ml. Evidence is presented that these nontoxic metabolites may act as antagonists of bacterial quorum sensing by competing with N-acyl homoserine lactones for receptor binding.Taxonomically diverse marine bacteria have proven to be a rich resource for the discovery of structurally unique and bioactive secondary metabolites (5). Given the intense microbial competition for resources such as space and nutrients, it is probable that many excreted metabolites help mediate microbe-microbe interactions. Various antibiotics have been implicated as chemical defenses for marine bacteria, thus suggesting a role for the biosynthesis of toxic metabolites. For example, a pelagic Alteromonas species produces the antibiotic 2-n-pentyl-4-quinolinol, capable of influencing bacterial community structure on particles (25), and production of the antibiotic andrimid by a marine Vibrio species prevents colonization of surfaces by the particle specialist Vibrio cholerae (26).Though not yet widely studied, the secretion of nontoxic molecules could also play important roles in antagonistic marine microbial interactions. Quorum sensing pathways of competing bacteria are potential targets for such nontoxic chemical defenses. Bacterial communication is facilitated by the production and subsequent recognition of small signaling molecules (autoinducers) and can regulate important phenotypes, including bioluminescence, biofilm formation, swarming motility, antibiotic biosynthesis, and virulence factor production (3, 7, 15). Gram-negative bacteria commonly use N-acyl homoserine lactones (AHL) as signaling molecules, which bind their cognate receptor proteins to activate gene expression (10). These autoinducers share a conserved L-homoserine lactone moiety, and the length and sites of oxidation on the acyl chain dictate the species specificity (37). In contrast, gram-positive bacteria generally accomplish quorum sensing using posttranslationally modified peptides as autoinducers. For example, Staphylococcus aureus uses cyclic oligopeptides to regulate virulence factor production (11).Here we report the production of nontoxic secondary metabolites by a marine gram-pos...