Acute preexercise supplementation of combined carnosine and anserine enhances initial maximal power of Wingate tests in humans.

Classic in vitro experiments (Severin's phenomenon) demonstrated that acute carnosine supplementation may potentiate muscle contractility. However, upon oral ingestion, carnosine is readily degraded in human plasma by the highly active serum carnosinase-1 (CN1). We developed a novel strategy to circumvent CN1 by preexercise ingestion of combined carnosine (CARN) and anserine (ANS), the methylated analog with similar biochemical properties but more resistant to CN1. First, in vitro hydrolysis was tested by adding carnosine and anserine to human plasma, alone or in combination. Second, five subjects were supplemented with 25 mg/kg anserine or 25 mg/kg of each anserine and carnosine to test in vivo bioavailability. Third, two double-blind, placebo-controlled, crossover studies investigated the effect of preexercise ANS + CARN (20 mg/kg body wt of each) supplementation on performance during a single all-out Wingate test following 6-min high-intensity cycling (study A) or three repeated Wingate tests (study B). In vitro experiments demonstrated slower degradation of anserine versus carnosine, which was further slowed by simultaneously adding carnosine. In vivo bioavailability of plasma anserine was more prominent [2.5-fold increased area under the curve (AUC)] when ANS + CARN versus ANS was ingested. Study A showed significantly higher (+6% ± 11%; P = 0.04) power in the first 5 s of the Wingate test following ANS + CARN (12.8 ± 2.4 W/kg) versus placebo (12.1 ± 2.2 W/kg). Study B demonstrated increased peak power (+3%) throughout three consecutive Wingate tests (ANS + CARN 10.5 ± 0.6 W/kg vs. placebo 10.2 ± 9.9 W/kg). These experiments reveal a novel acute nutritional method to effectively raise plasma anserine and carnosine by high-dose combined supplementation. This approach led to improved initial cycling power, revealing a new nutritional strategy to increase exercise performance.NEW & NOTEWORTHY Current results reveal that carnosine and anserine competitively bind to the highly active carnosinase enzyme in human plasma. Acute combined carnosine and anserine supplementation is therefore described as novel strategy to raise plasma anserine and carnosine. We report that indices of maximal exercise/muscle power during the initial stage of a Wingate test were significantly improved by preexercise 20-25mg/kg body wt anserine and carnosine supplementation, pointing toward a novel acute nutritional strategy to improve high-intensity exercise performance.

Pharmacokinetic profile of bilberry anthocyanins in rats and the role of glucose transporters: LC-MS/MS and computational studies.

The aim of the present investigation was to better understand the pharmacokinetic profile of bilberry (Vaccinium Myrtillus) anthocyanins and the role of glucose transporters (sGLT1 and GLUT2) on their absorption. In particular, the absorption of 15 different anthocyanins contained in a standardized bilberry extract (Mirtoselect®) was measured in rats by a validated LC-ESI-MS/MS approach. The plasma concentration peak (Cmax) of 11.1ng/mL was reached after 30min and fasting condition significantly increased the bioavailability of anthocyanins by more than 7 fold in respect to fed rats. Glucose co-administration did not interfere with the overall anthocyanin uptake. Bioavailability of each anthocyanin was then estimated by comparing the relative content in plasma vs extract. The 15 anthocyanins behaved differently in term of bioavailability and both the aglycone and the sugar moiety were found to affect the absorption. For instance, arabinoside moiety was detrimental while cyanidin enhanced bioavailability. Computational studies permitted to rationalize such results, highlighting the role of glucose transporters (sGLT1 and GLUT2) in anthocyanins absorption. In particular a significant correlation was found for the 15 anthocyanins between sGLT1 and GLUT2 recognition and absorption.

Human serum albumin cysteinylation is increased in end stage renal disease patients and reduced by hemodialysis: mass spectrometry studies.

The aim of the present work was to monitor the covalent modifications of human serum albumin (HSA) in end stage renal diseases (ESRD) non-diabetic patients, before and after hemodialysis (HD), by direct infusion electrospray mass spectrometry (ESI-MS). Human serum samples were collected from healthy subjects (n = 10, 20-60 yr) and age-matched ESRD patients (n = 8) before and after HD, purified by affinity chromatography and analyzed by a triple-quadrupole mass spectrometer. The deconvoluted spectra from healthy subjects were all characterized by three peaks attributed to non-glycated mercaptoalbumin (HSA-SH) and to the corresponding adducts with cysteine (HSA-Cys) and glucose (HSA-Glc); relative contents: mercaptoalbumin in both glycated and non-glycated form, HSA-SHt (74 ± 6%), HSA-Cys (26 ± 5%) and HSA-Glc (24 ± 3%). HSA isolated from ESRD patients before HD was characterized by a significant reduction of HSA-SHt (42 ± 7%), and by a concomitant increase of the HSA-Cys adduct (58 ± 7%). Hemodialysis significantly reduced the cysteinylated form (37 ± 7%) and restored HSA-SHt (63 ± 8%) in all the ESRD patients. The mechanism of thiol oxidation and cysteinylation was then studied by mass spectrometry, using LQQCPF as a model peptide and H(2)O(2) as an oxidizing agent.