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Natural substances present in herbal preparations should be carefully used because they can give toxic or therapeutic effects despite of their amount or the way of administration. The safety of products of vegetable origin must be assessed before commercialisation by monitoring the active ingredients and their metabolites. This study was therefore designed to identify and quantify arbutin and its metabolite hydroquinone, naturally present in Arctostaphylos uva-ursi (L.) Spreng plant in rat plasma, after an acute and subacute administration of aqueous arbutin solution in Wistar rats. For this purpose a reversed-phase high-performance liquid chromatography coupled with photodiode array detection was developed to assess the pharmacokinetic of arbutin and hydroquinone in plasma of female rats treated with aqueous arbutin solutions. The detection (arbutin: 0.0617 μg/ml and hydroquinone 0.0120 μg/ml) and quantification (arbutin: 0.2060 μg/ml and hydroquinone: 0.0400 μg/ml) limits were determined. At the arbutin concentration level of 10.7 μg/ml repeatability was 13.33% and its recovery 93.4±6.93%, while at the hydroquinone concentration level of 10.6 μg/ml repeatability was 11.66% and its recovery 92.9±7.75%. Furthermore the method was fully validated and the obtained data indicate that the new method provides good performances. [ABSTRACT FROM AUTHOR]

Human acyl protein thioesterases (APTs) catalyze the depalmitoylation of S-acylated proteins attached to the plasma membrane, facilitating reversible cycles of membrane anchoring and detachment. We previously showed that a bacterial APT homologue, FTT258 from the gram-negative pathogen Francisella tularensis, exists in equilibrium between a closed and open state based on the structural dynamics of a flexible loop overlapping its active site. Although the structural dynamics of this loop are not conserved in human APTs, the amino acid sequence of this loop is highly conserved, indicating essential but divergent functions for this loop in human APTs. Herein, we investigated the role of this loop in regulating the catalytic activity, ligand binding, and protein folding of human APT1, a depalmitoylase connected with cancer, immune, and neurological signaling. Using a combination of substitutional analysis with kinetic, structural, and biophysical characterization, we show that even in its divergent structural location in human APT1 that this loop still regulates the catalytic activity of APT1 through contributions to ligand binding and substrate positioning. We confirmed previously known roles for multiple residues (Phe72 and Ile74) in substrate binding and catalysis while adding new roles in substrate selectivity (Pro69), in catalytic stabilization (Asp73 and Ile75), and in transitioning between the membrane binding β-tongue and substrate-binding loops (Trp71). Even conservative substitution of this tryptophan (Trp71) fulcrum led to complete loss of catalytic activity, a 13°C decrease in total protein stability, and drastic drops in ligand affinity, indicating that the combination of the size, shape, and aromaticity of Trp71 are essential to the proper structure of APT1. Mixing buried hydrophobic surface area with contributions to an exposed secondary surface pocket, Trp71 represents a previously unidentified class of essential tryptophans within α/β hydrolase structure and a potential allosteric binding site within human APTs., (© 2024 Wiley Periodicals LLC.)

Introduction: Turmeric is the common name for the rhizome of Curcuma longa L. In the recent years, food supplements containing turmeric have been marketed and widely used by an increasing number of consumers. Spontaneous reports of suspected adverse reactions to food supplements are collected within the Phytovigilance system., Methods: An ad hoc multidisciplinary group investigated the suspected cases of hepatotoxicity reported to the Italian Phytovigilance system associated with the assumption of turmeric food supplements with the methodology specific to pharmacovigilance as well as for the evaluation of the quality and safety of food supplements., Results: A cluster of 28 spontaneous reports of acute hepatitis, mostly with cholestasis, associated with turmeric products were sent to the Italian Phytovigilance system in the first six months of 2019. In all cases, except one, the causality assessment was at least possible. The suspected products were collected and analysed for the presence of drugs, heavy metals, aflatoxins, pesticides, synthetic dyes and pyrrolizidine alkaloids., Conclusion: On the basis of the results of all the activities performed by multidisciplinary group, regulatory intervention was taken. This study highlights the importance of developing an integrated evaluation approach for the evaluation of the adverse effects associated with the use of food supplements.

Background: HDL-C plasma levels are modulated by dietary fatty acid (FA), but studies investigating dietary supplementation in FA gave contrasting results. Saturated FA increased HDL-C levels only in some studies. Mono-unsaturated FA exerted a slight effect while poly-unsaturated FA mostly increased plasma HDL-C., Aims: This study presents two aims: i) to investigate the relationship between HDL-C levels and plasma FA composition in a Sicilian population following a "Mediterranean diet", ii) to investigate if FA that resulted correlated with plasma HDL-C levels in the population study and/or very abundant in the plasma were able to affect HDL catabolism in an "in vitro" model of cultured hepatoma cells (HepG2)., Results: plasma HDL-C levels in the population correlated negatively with myristic acid (C14:0, β = -0.24, p < 0.01), oleic acid (C18:1n9, β = -0.22, p < 0.01) and cis-11-Eicosenoic (C20:1n9, β = -0.19, p = 0.01) and positively with palmitoleic acid (C16:1, β = +0.19, p = 0.03). HepG2 cells were conditioned with FA before evaluating HDL binding kinetics, and only C14:0 increased HDL binding by a non-saturable pathway. After removal of heparan sulphate proteoglycans (HSPG) by heparinases HDL binding dropped by 29% only in C14:0 conditioned cells (p < 0.05). C14:0 showed also the highest internalization of HDL-derived cholesteryl esters (CE, +32% p = 0.01 vs. non-conditioned cells)., Conclusions: C14:0 was correlated with decreased plasma HDL-C levels in a Mediterranean population. C14:0 might reduce HDL-C levels by increasing HDL trapping to cell surface HSPG and CE stripping from bound HDL. Other mechanisms are to be investigated to explain the effects of other FA on HDL metabolism., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Backgrounds and Aims: Adrenal insufficiency (AI) has been reported in patients with stable cirrhosis. A lack of substrates has been suggested as a possible contributing pathogenic mechanism leading to glucocorticoid deficiency in these subjects. To better explore this hypothesis, we studied lipoproteins in cirrhotics with and without AI., Methods: A total of 81 cirrhotic patients and 30 normal volunteers were enrolled. The severity of liver disease was graded by Child-Pugh score. Total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglyceride (TG), and apolipoprotein AI (Apo-AI) levels were evaluated. HDL subfractions were measured by gradient gel electrophoresis. Adrenal function was assessed by the Low-Dose Short Synacthen Test., Results: Cirrhotic patients showed a significant reduction of TC, HDL, LDL, TG, and Apo-AI levels compared with controls. HDL3 was significantly lower, while HDL2 was higher, in cirrhotics compared with the controls. AI was observed in 26 patients. TC, TG, HDL, and Apo-AI were significantly reduced in cirrhotics with AI compared with those with normal adrenal function. HDL2 and HDL3 did not differ between these two groups. Delta cortisol was related to TC (r = 0.30, p < 0.01), TG (r = 0.22, p = 0.05), and Apo-AI (r = 0.37, p < 0.001). Multivariate analysis revealed that Apo-AI and HDL were independently associated with AI., Conclusion: Our study shows that TC, TG, HDL, and Apo-AI are reduced in cirrhotics with AI. In particular, because both HDL and Apo-AI play a primary role in providing substrates for steroidogenesis to adrenal cells, this deficiency may contribute to the pathogenesis of AI in these patients.