Self-emulsifying drug delivery system of (R)-α-lipoic acid to improve its stability and oral absorption.

The present study was designed to develop a self-emulsifying drug delivery system (SEDDS) of (R)-α-lipoic acid (RLA) to improve the physicochemical and nutraceutical properties of RLA. RLA/SEDDS was prepared using medium-chain triglycerides, Tween 80, and polyethylene glycol 400 as oil, surfactant, and co-surfactant, respectively. The preferable composition of SEDDS was selected according to a pseudo-ternary phase diagram for improved emulsification properties, and its physicochemical and pharmacokinetic properties were evaluated. RLA/SEDDS showed the immediate formation of fine micelles with a mean droplet size of approximately 260 nm when introduced into aqueous media. In simulated gastric fluid, this system could significantly improve the dissolution behavior of RLA and prevent the degradation of RLA, possibly due to the encapsulation of RLA into the emulsion structure. Following the oral administration of RLA/SEDDS (10 mg RLA/kg) in rats, systemic exposure to RLA and dihydrolipoic acid (DHLA), a reduced form of RLA, increased by 7- and 3-fold, respectively. The improved dissolution and gastric stability of RLA could contribute to enhancing systemic exposure to RLA and DHLA after oral administration. From these findings, RLA/SEDDS might be an efficacious dosage option for improving the oral bioavailability as well as nutraceutical properties of RLA.

Effects of alpha-lipoic acid on the behavior, serum indicators, and bone quality of broilers under stocking density stress.

The objective of present study was to investigate the effects of alpha-lipoic acid (ALA) dietary supplementation on the behavior, physiological and oxidant stress indicators, and bone quality in broilers under high stocking density (HSD) stress. A total of one thousand eight hundred 22-day-old Arbor Acres male broiler chicks were randomly allocated to 18 pens (2.97 × 2.03 m) in 3 groups: 14 birds/m2 (NSD, normal stocking density) or 18 birds/m2 (HSD) or 18 birds/m2 plus 300 mg/kg ALA dietary supplement (HSD + ALA, high stocking density + alpha-lipoic acid). Each treatment had 6 replicates, and the experiment lasted 3 wk. The HSD group was significantly lower than the NSD group (P < 0.05) in the frequency of eating, walking, and preening behavior. The alkaline phosphatase activity and serum calcium content were significantly higher, and the parathyroid hormone (PTH) level was significantly lower in the HSD group than in the NSD group (P < 0.05). When compared with the NSD group, the HSD group showed an increase (P < 0.05) in serum heterophil/lymphocyte ratio (H/L ratio), corticosterone (CORT), malondialdehyde (MDA) content, and catalase (CAT) activity, whereas a decrease (P < 0.05) in total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) concentrations. The HSD group was also significantly lower (P < 0.05) than the NSD group in the tibia and femur breaking strength, bone mineral density, and BMC. Importantly, the addition of ALA into the diets of the HSD group enabled the HSD + ALA group to recover to the levels of NSD group (P > 0.05) in the standing and preening behavior, alkaline phosphatase activity, PTH concentration, H/L ratio, CAT, T-AOC, MDA, SOD, and GSH-Px. These results indicate that the increase of stocking density lowered the bone quality, increased the physiological and oxidative stress indicators, and modified the behavior of broilers, whereas ALA dietary supplementation could counteract the reduction in the performance and physiological responses of broilers under high-density environmental stress.

Gastrointestinal Tolerability and Absorption of R- Versus R,S-Lipoic Acid in Progressive Multiple Sclerosis: A Randomized Crossover Trial.

We compared the gastrointestinal (GI) tolerability and assessed for bioequivalent absorption of R-lipoic acid (LA) in people with progressive multiple sclerosis (MS) in a single-center, double-blind, randomized crossover trial. Participants randomly assigned to formulation sequence took 600 mg of R-LA or 1200 mg of a 1:1 racemic R,S-LA mixture in single daily doses for 7 to 10 days, underwent a washout of at least 7 days, and then took the other form of LA for 7 to 10 days. At the end of each period on LA, GI symptoms were assessed with GI questions from the Monitoring of Side Effects Scale. Serum LA concentrations were measured before and 60, 90, 120, 180, and 240 minutes after the first and last day's dose of each form of LA to derive an area under the plasma concentration-time curve (AUC) and maximum serum concentration (Cmax ). Twenty participants enrolled (12 women; 15 secondary progressive MS, 5 primary progressive MS; mean age, 59.6 years). Two withdrew early due to symptoms while taking R,S-LA, and one withdrew early while taking R-LA. The mean GI Monitoring of Side Effects Scale score was 1.7 points lower on R-LA than on R,S-LA (P = .069), and there were fewer reports of each GI side effect when taking the R-LA than the R,S-LA (31 vs 60; P = .025). The AUC and Cmax for R-LA were bioequivalent for the 2 formulations (90% confidence intervals 97.4% to 99.3% for AUC and 93.4% to 98.2% for Cmax ). This study supports that in people with progressive MS, there is better GI tolerability and bioequivalent serum absorption of R-LA when 600 mg of R-LA is taken as R-LA alone than when taken in a 1:1 racemic R,S-LA mixture.

A Simplified Method for Simultaneous Determination of α-Lipoic Acid and Low-Molecular-Mass Thiols in Human Plasma.

α-Lipoic acid, glutathione, cysteine, and cysteinylglycine can be applied as therapeutic agents in civilization diseases such as diabetes mellitus, cardiovascular diseases, and cancers. On the other hand, a higher concentration of homocysteine can result in health problems and has been indicated as an independent risk factor for cardiovascular disease and accelerated atherosclerosis. Here, the first simplified HPLC-UV assay that enables simultaneous determination of α-lipoic acid and low-molecular-mass thiols in plasma, reduces the number of steps, shortens the total time of sample preparation, and limits the amount of single-use polypropylene laboratory materials is described. The assay is based on reversed-phase high performance liquid chromatography with UV detection and simultaneous reduction of disulfide bound with tris(2-carboxyethyl)phosphine and the selective pre-column derivatization of the thiol group with 1-benzyl-2-chloropyridinium bromide. Linearity in the detector responses for plasma samples were observed in ranges: 0.12-5.0 nmol mL-1 for α-lipoic acid; 2.0-20.0 nmol mL-1 for glutathione, cysteinylglycine, and homocysteine; and 40.0-400.0 for cysteine. The LODs for α-lipoic acid and low-molecular-mass thiols were 0.08 and 0.12 nmol mL-1, respectively, while LOQs were 0.12 and 0.16 nmol mL-1, respectively. The usefulness of the proposed method has been proven by its application to real samples.

Insights on the Use of α-Lipoic Acid for Therapeutic Purposes.

α-lipoic acid (ALA, thioctic acid) is an organosulfur component produced from plants, animals, and humans. It has various properties, among them great antioxidant potential and is widely used as a racemic drug for diabetic polyneuropathy-associated pain and paresthesia. Naturally, ALA is located in mitochondria, where it is used as a cofactor for pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase complexes. Despite its various potentials, ALA therapeutic efficacy is relatively low due to its pharmacokinetic profile. Data suggests that ALA has a short half-life and bioavailability (about 30%) triggered by its hepatic degradation, reduced solubility as well as instability in the stomach. However, the use of various innovative formulations has greatly improved ALA bioavailability. The R enantiomer of ALA shows better pharmacokinetic parameters, including increased bioavailability as compared to its S enantiomer. Indeed, the use of amphiphilic matrices has capability to improve ALA bioavailability and intestinal absorption. Also, ALA's liquid formulations are associated with greater plasma concentration and bioavailability as compared to its solidified dosage form. Thus, improved formulations can increase both ALA absorption and bioavailability, leading to a raise in therapeutic efficacy. Interestingly, ALA bioavailability will be dependent on age, while no difference has been found for gender. The present review aims to provide an updated on studies from preclinical to clinical trials assessing ALA's usages in diabetic patients with neuropathy, obesity, central nervous system-related diseases and abnormalities in pregnancy.

The Effect of 600 mg Alpha-lipoic Acid Supplementation on Oxidative Stress, Inflammation, and RAGE in Older Adults with Type 2 Diabetes Mellitus.

Alpha-lipoic acid (ALA) has been used as a dietary supplement at different doses in patients with diabetes mellitus type 2 (T2DM) due to its antioxidant, anti-inflammatory, and hypoglycemic effects. However, the reports on the effects of ALA are controversial. For this reason, the purpose of the present study was to determine the effect of 600 mg/day of ALA on the markers of oxidative stress (OxS) and inflammation and RAGE in older adults with T2DM. A quasiexperimental study was carried out with a sample of 135 sedentary subjects (98 women and 37 men) with a mean age of 64 ± 1 years, who all had T2DM. The sample was divided into three groups: (i) experimental group (EG) with 50 subjects, (ii) placebo group (PG) with 50 subjects, and control group (CG) with 35 subjects. We obtained the following measurements in all subjects (pre- and posttreatment): glycosylated hemoglobin (HbA1c), receptor for advanced glycation end products (RAGE), 8-isoprostane, superoxide dismutase (SOD), glutathione peroxidase (GPx), total antioxidant status (TAS), and inflammatory (CRP, TNF-α, IL-6, IL-8, and IL-10) markers. Regarding the effect of ALA on HbA1c, a decrease was observed in the EG (baseline 8.9 ± 0.2 vs. posttreatment 8.6 ± 0.3) and the PG (baseline 8.8 ± 0.2 vs. posttreatment 8.4 ± 0.3) compared to the CG (baseline 8.8 ± 0.3 vs. six months 9.1 ± 0.3) although the difference was not statistically significant (p < 0.05). There was a statistically significant decrease (p < 0.05) in the blood concentration of 8-isoprostane in the EG and PG with respect to the CG (EG: baseline 100 ± 3 vs. posttreatment 57 ± 3, PG: baseline 106 ± 7 vs. posttreatment 77 ± 5, and CG: baseline 94 ± 10 vs. six months 107 ± 11 pg/mL). Likewise, a statistically significant decrease (p < 0.05) in the concentration of the RAGE was found in the EG (baseline 1636 ± 88 vs. posttreatment 1144 ± 68) and the PG (baseline 1506 ± 97 vs. posttreatment 1016 ± 82) compared to CG (baseline 1407 ± 112 vs. six months 1506 ± 128). A statistically significant decrease was also observed in all markers of inflammation and in the activity of SOD and GPx in the CG with respect to the EG and PG. Our findings suggest that the administration of ALA at a dose of 600 mg/day for six months has a similar effect to that of placebo on oxidative stress, inflammation, and RAGE in older adults with T2DM. Therefore, higher doses of ALA should be tried to have this effect. This trial is registered with trial registration number ISRCTN13159380.

Enhanced bioavailability of alpha-lipoic acid by complex formation with octenylsuccinylated high-amylose starch.

An aqueous dispersion of alpha-lipoic acid (ALA) using octenylsuccinic anhydride-modified high-amylose starch (OS) was prepared, and thermal stability and cellular bioavailability of ALA were compared with those prepared using native high-amylose starch (HA) and beta-cyclodextrin (ß-CD). The ALA was homogeneously dispersed via the encapsulation of V-type amylose helices. In comparison with HA and ß-CD, OS exhibited a higher ALA absorption in Caco-2 cells, indicating the OS facilitated the intestinal epithelial transport of ALA. Oral administration of the encapsulated ALA in-vivo resulted in a higher maximum ALA plasma concentration and extended the terminal half-life by 30-40%. The area under the plasma concentration vs. time for the administration of ALA complexed by OS was 50% larger than that by HA, indicating the effectiveness of OS in enhancing the oral bioavailability of ALA. These results indicate that OS is an efficient carrier for ALA in oral delivery and bioavailability.

Potential cause-effect relationship between insulin autoimmune syndrome and alpha lipoic acid: Two case reports.

OBJECTIVES: Insulin autoimmune syndrome (IAS) or Hirata disease is a rare cause of autoimmune hypoglycemia with apparent high insulin levels and anti-insulin autoantibodies and was first described by Hirata in Japan in 1970. IAS cases are usually related to exposure to sulfhydryl-containing drugs, which stimulate the production of insulin autoantibodies. Among sulfhydryl-containing compounds, alpha lipoic acid (ALA) has recently emerged as a cause of IAS. After the first observations of ALA-induced IAS were reported in Japan in 2006, an increasing number of cases related to ALA administration have been described. An Italian group recently reported on six cases of IAS of which one was associated with HLA-DRB1*04:06 and the remaining five with HLA-DRB1*04:03. This suggests that the latter is potentially involved in the genetic susceptibility of people of European descent to IAS. METHODS: Here, we describe two new cases of IAS in women that were triggered by ALA. RESULTS: Both cases are associated with HLA-DRB1*04:03 and confirm the evidence that HLA-DRB1*04:03 rather than HLA-DRB1*04:06 is specifically related to IAS susceptibility in Europeans. CONCLUSIONS: Case reports of ALA-induced hypoglycemic episodes highlight the need for greater care in prescribing ALA supplementation as well as the identification of specific and personalized therapeutic targets.

The issue of HPLC determination of endogenous lipoic acid in human plasma.

Lipoic acid (LA) is used extensively as a therapeutic agent for the treatment of various diseases. Many methods have been reported for the determination of LA plasma levels and its metabolites after its supplementation, but available information concerning endogenous plasma levels is still scarce. Studies which directly focused on determining the endogenous plasma levels provided highly controversial results, <4.9 nmol/L or 143.7-197.0 nmol/L. The main aim of this study was to verify the levels of free LA in the plasma of 40 individuals (17 women, 23 men). This group was nonsupplemented with LA and met the conditions for incorporation into the blood donors register. We measured the levels of LA using an HPLC method with very sensitive coulometric detection after previous sample preparation including deproteination and solid-phase extraction with a Phenyl cartridge. Our limit of detection was 1.85 nmol/L and was better than the values reported in studies that directly focused on determining the endogenous plasma levels of LA: 2.4 and 4.9 nmol/L respectively. However, the levels of free LA in the plasma of nonsupplemented voluntary blood donors were not detectable in all cases. The presented results of our study show that endogenous concentrations of LA are <1.85 nmol/L.

Lipoic Acid Stimulates cAMP Production in Healthy Control and Secondary Progressive MS Subjects.

Lipoic acid (LA) exhibits antioxidant and anti-inflammatory properties; supplementation reduces disease severity and T lymphocyte migration into the central nervous system in a murine model of multiple sclerosis (MS), and administration in secondary progressive MS (SPMS) subjects reduces brain atrophy compared to placebo. The mechanism of action (MOA) of LA's efficacy in suppression of MS pathology is incompletely understood. LA stimulates production of the immunomodulator cyclic AMP (cAMP) in vitro. To determine whether cAMP could be involved in the MOA of LA in vivo, we performed a clinical trial to examine whether LA stimulates cAMP production in healthy control and MS subjects, and whether there are differences in the bioavailability of LA between groups. We administered 1200 mg of oral LA to healthy control, relapsing remitting MS (RRMS) and SPMS subjects, and measured plasma LA and cAMP levels in peripheral blood mononuclear cells (PBMCs). There were no significant differences between the groups in pharmacokinetic (PK) parameters. Healthy and SPMS subjects had increased cAMP at 2 and 4 h post-LA treatment compared to baseline, while RRMS subjects showed decreases in cAMP. Additionally, plasma concentrations of prostaglandin E2 (PGE2, a known cAMP stimulator) were significantly lower in female RRMS subjects compared to female HC and SPMS subjects 4 h after LA ingestion. These data indicate that cAMP could be part of the MOA of LA in SPMS, and that there is a divergent response to LA in RRMS subjects that may have implications in the efficacy of immunomodulatory drugs. This clinical trial, "Defining the Anti-inflammatory Role of Lipoic Acid in Multiple Sclerosis," NCT00997438, is registered at https://clinicaltrials.gov/ct2/show/record/NCT00997438 .

Nutritional Interventions that Slow the Age-Associated Decline in Renal Function in a Canine Geriatric Model for Elderly Humans.

OBJECTIVE: To determine the effects of feeding traditional and renal protective foods (RPF) supplemented with functional food bioactives on glomerular filtration rate (GFR), lean body percent (LB%), and selected circulating biomarker and metabolite concentrations in a geriatric dog model. DESIGN: Randomized block design and cross-sectional study. SETTING: Hill's Pet Nutrition, Inc. dog colony. PARTICIPANTS: Eighty-one geriatric dogs (mean age, 10.4; range, 7.9-14.2 years) and 30 mature-adult dogs (mean age, 5.0; range, 3.3-6.9 years). INTERVENTION: Geriatric dogs were fed one of three foods (n = 27 per group) for 6 months: a traditional RPF (control) that was energy dense and mildly protein-restricted, or control food supplemented with increasing amounts of functional food bioactives: fish oil, lipoic acid, fruits and vegetables, and higher quality protein sources [functional foods one (FF1) and two (FF2)]. Geriatric dogs were compared before and after the feeding trial with mature adult dogs. MEASUREMENTS: Renal function was assessed by GFR, LB% was determined by dual energy x-ray absorptiometry, and circulating biomarkers and metabolites were measured in blood. RESULTS: Before the feeding trial, GFR (+28.2%), LB% (+18.6%), and serum total protein (+10.0%) were higher in mature versus healthy geriatric dogs (all P<0.001). Geriatric dogs consuming all three foods increased (P<0.001) GFR over time; group averages ranged from 13.0-16.9%. Dogs fed the highest supplemented level of bioactives (FF2) had lower (P<0.001) symmetric dimethylarginine (SDMA) concentrations (-14.3%). Feeding functional foods did not alter body weight, but increased (P<0.001) serum protein concentration (+6.7%). CONCLUSION: Supplementation with functional food bioactives can temporarily reverse the age-associated decline in renal function and serum total protein.

Plasma Metabolic Profiles in Women are Menopause Dependent.

Menopause is an endocrinological transition that greatly affects health and disease susceptibility in middle-aged and elderly women. To gain new insights into the metabolic process of menopause, plasma metabolic profiles in 115 pre- and post-menopausal women were systematically analyzed by ultra-performance liquid chromatography/mass spectrometry in conjunction with univariate and multivariate statistical analysis. Metabolic signatures revealed considerable differences between pre- and post-menopausal women, and clear separations were observed between the groups in partial least-squares discriminant analysis score plots. In total, 28 metabolites were identified as potential metabolite markers for menopause, including up-regulated acylcarnitines, fatty acids, lysophosphatidylcholines, lysophosphatidylethanolamines, and down-regulated pregnanediol-3-glucuronide, dehydroepiandrosterone sulfate, p-hydroxyphenylacetic acid and dihydrolipoic acid. These differences highlight that significant alterations occur in fatty acid ß-oxidation, phospholipid metabolism, hormone metabolism and amino acid metabolism in post-menopausal women. In conclusion, our plasma metabolomics study provides novel understanding of the metabolic profiles related to menopause, and will be useful for investigating menopause-related diseases and assessing metabolomic confounding factors.

Effects of α-lipoic acid and eicosapentaenoic acid in overweight and obese women during weight loss.

OBJECTIVE: To evaluate the potential body weight-lowering effects of dietary supplementation with eicosapentaenoic acid (EPA) and α-lipoic acid separately or combined in healthy overweight/obese women following a hypocaloric diet. METHODS: This is a short-term double-blind placebo-controlled study with parallel design that lasted 10 weeks. Of the randomized participants, 97 women received the allocated treatment [Control, EPA (1.3 g/d), α-lipoic acid (0.3 g/d), and EPA+α-lipoic acid (1.3 g/d+0.3 g/d)], and 77 volunteers completed the study. All groups followed an energy-restricted diet of 30% less than total energy expenditure. Body weight, anthropometric measurements, body composition, resting energy expenditure, blood pressure, serum glucose, and insulin and lipid profile, as well as leptin and ghrelin levels, were assessed at baseline and after nutritional intervention. RESULTS: Body weight loss was significantly higher (P<0.05) in those groups supplemented with α-lipoic acid. EPA supplementation significantly attenuated (P<0.001) the decrease in leptin levels that occurs during weight loss. Body weight loss improved lipid and glucose metabolism parameters but without significant differences between groups. CONCLUSIONS: The intervention suggests that α-lipoic acid supplementation alone or in combination with EPA may help to promote body weight loss in healthy overweight/obese women following energy-restricted diets.

Simultaneous determination of the endogenous free α-lipoic acid and dihydrolipoic acid in human plasma and erythrocytes by RP-HPLC coupled with electrochemical detector.

A highly sensitive, precise, and accurate reversed-phase high performance liquid-chromatography/electrochemical detection method for simultaneous determination of the endogenous free α-lipoic acid and dihydrolipoic acid in biological matrices is presented. The two analytes are extracted from samples with acetonitrile-10% m-phosphoric acid solution(aqueous) (50:50 v/v). To determine the total lipoic acid, samples are treated with tris(2-carboxyethyl)phosphine solution in phosphate buffer: pH 2.5 with 85% o-phosphoric acid prior to deproteination. The two analytes are separated on a C18 (150 × 4.6 mm, 5 µm) analytical column using acetonitrile-50 mM phosphate buffer: pH 2.5 with 85% o-phosphoric acid (35:65 v/v) as the isocratic mobile phase pumped at a flow rate of 2.0 ml/min at the column oven temperature of 35 °C. The column eluents are monitored at a potential of 0.9 V. These analytes are efficiently resolved in <7 min.

Determination of newly synthesized lipoic acid-niacin dimer in rat plasma by UPLC/electrospray ionization tandem mass spectrometry: assay development, validation and application to a pharmacokinetic study.

A simple, sensitive and specific ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method was developed to determine the newly synthesized compound lipoic acid-niacin dimer (N2L) in plasma. Plasma samples were precipitated by methanol using tetrahydropalmatine as internal standard. Chromatographic separation was achieved on an Acquity BEH C18 (2.1 × 50 mm i.d., 1.7 µm) column; the mobile phase contains methanol and buffer solution (water with 0.5% formic acid and 10 mmol/L ammonium acetate). Multiple reaction monitoring (m/z 353.9 → 148.6 for N2L and m/z 356.0 → 192.0 for internal standard) was performed for detection and quantification. The method was validated to be rapid, specific, accurate and precise over the concentration range of 1-750 ng/mL; N2L was not stable on the bench-top or during freeze-freeze-thaw cycles in plasma, but was stable in the stock solution and after preparation in the autosampler for 24 h. The utility of the assay was confirmed by pharmacokinetic study of N2L in rats.

Mutations in human lipoyltransferase gene LIPT1 cause a Leigh disease with secondary deficiency for pyruvate and alpha-ketoglutarate dehydrogenase.

BACKGROUND: Synthesis and apoenzyme attachment of lipoic acid have emerged as a new complex metabolic pathway. Mutations in several genes involved in the lipoic acid de novo pathway have recently been described (i.e., LIAS, NFU1, BOLA3, IBA57), but no mutation was found so far in genes involved in the specific process of attachment of lipoic acid to apoenzymes pyruvate dehydrogenase (PDHc), α-ketoglutarate dehydrogenase (α-KGDHc) and branched chain α-keto acid dehydrogenase (BCKDHc) complexes. METHODS: Exome capture was performed in a boy who developed Leigh disease following a gastroenteritis and had combined PDH and α-KGDH deficiency with a unique amino acid profile that partly ressembled E3 subunit (dihydrolipoamide dehydrogenase / DLD) deficiency. Functional studies on patient fibroblasts were performed. Lipoic acid administration was tested on the LIPT1 ortholog lip3 deletion strain yeast and on patient fibroblasts. RESULTS: Exome sequencing identified two heterozygous mutations (c.875C > G and c.535A > G) in the LIPT1 gene that encodes a mitochondrial lipoyltransferase which is thought to catalyze the attachment of lipoic acid on PDHc, α-KGDHc, and BCKDHc. Anti-lipoic acid antibodies revealed absent expression of PDH E2, BCKDH E2 and α-KGDH E2 subunits. Accordingly, the production of 14CO2 by patient fibroblasts after incubation with 14Cglucose, 14Cbutyrate or 14C3OHbutyrate was very low compared to controls. cDNA transfection experiments on patient fibroblasts rescued PDH and α-KGDH activities and normalized the levels of pyruvate and 3OHbutyrate in cell supernatants. The yeast lip3 deletion strain showed improved growth on ethanol medium after lipoic acid supplementation and incubation of the patient fibroblasts with lipoic acid decreased lactate level in cell supernatants. CONCLUSION: We report here a putative case of impaired free or H protein-derived lipoic acid attachment due to LIPT1 mutations as a cause of PDH and α-KGDH deficiencies. Our study calls for renewed efforts to understand the mechanisms of pathology of lipoic acid-related defects and their heterogeneous biochemical expression, in order to devise efficient diagnostic procedures and possible therapies.

Age and gender dependent bioavailability of R- and R,S-α-lipoic acid: a pilot study.

Lipoic acid (LA) shows promise as a beneficial micronutrient toward improving elder health. Studies using old rats show that (R)-α-LA (R-LA) significantly increases low molecular weight antioxidants that otherwise decline with age. Despite this rationale for benefiting human health, little is known about age-associated alterations in absorption characteristics of LA, or whether the commercially available racemic mixture of LA (R,S-LA) is equally as bioavailable as the naturally occurring R-enantiomer. To address these discrepancies, a pilot study was performed to establish which form of LA is most effectively absorbed in older subjects relative to young volunteers. Young adults (average age=32 years) and older adults (average age=79 years) each received 500 mg of either R- or R,S-LA. Blood samples were collected for 3h after supplementation. After a washout period they were given the other chiral form of LA not originally ingested. Results showed that 2 out of 6 elder males exhibited greater maximal plasma LA and area under the curve for the R-form of LA versus the racemic mixture. The elder subjects also demonstrated a reduced time to reach maximal plasma LA concentration following R-LA supplementation than for the racemic mixture. In contrast, young males had a tendency for increased bioavailability of R,S-LA. Overall, bioavailability for either LA isoform was much more variable between older subjects compared to young adults. Plasma glutathione levels were not altered during the sampling period. Thus subject age, and potential for varied response, should be considered when determining an LA supplementation regimen.

Glycemic and oxidative status of patients with type 2 diabetes mellitus following oral administration of alpha-lipoic acid: a randomized double-blinded placebo-controlled study.

Despite well-controlled blood glucose levels, diabetic complications still inevitably take place via several mechanisms including excessive generation of free radicals in patients who suffer from diabetes mellitus (DM). A randomized double-blind placebo-controlled clinical trial to investigate the effectiveness of oral supplementation of DL-alpha-lipoic acid (ALA) on glycemic and oxidative status in DM patients was conducted. Thirty eight outpatients with type 2 DM were recruited and randomly assigned to either placebo or treatment in various doses of ALA (300, 600, 900, and 1200 mg/day) for 6 months. Following the treatment, all subjects were evaluated for glucose status and oxidative biomarkers. Results showed that fasting blood glucose, HbA1c trended to decrease in a dose-dependent manner. Increase of urinary PGF2α-Isoprostanes (F2α-IsoP) was noted in placebo but not ALA-treated groups, indicating possible suppressing action of ALA on lipid peroxidation in DM subjects. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) levels, however, were similar in both placebo and ALA groups as well as urinary microalbumin and serum creatinine. Safety evaluation was monitored and treatment was found to be well tolerated despite some minor side effects. Results from this study reflected the benefits of ALA in glucose status with slight efficiency on oxidative stress-related deterioration in DM patients.

Determination of lipoic acid, Trolox methyl ether and tocopherols in human plasma by liquid-chromatography and ion-trap tandem mass spectrometry.

A method for the simultaneous determination of lipoic acid and/or Trolox methyl ether, along with α-, γ- and δ-tocopherol was developed using liquid chromatography-tandem mass spectrometry with negative electrospray ionization (HPLC-ESI-MS/MS) in an ion-trap mass spectrometer. Detection and quantification were accomplished by a multiple reaction monitoring method, using specific transitions from precursor ion to product ion for each analyte. Chromatographic separation was achieved in a 12 min run using a C(18) -bonded phase and methanol-aqueous ammonium acetate elution gradient. Linear correlations of the chromatographic peak area (r.u. × s(-1) ) to the injected amount (ng) gave the slope values (r.u. × s(-1) × ng(-1) ) 2.34 × 10(4) for α-tocopherol, 5.05 × 10(4) for γ-tocopherol, 1.27 × 10(5) for δ-tocopherol, 8.86 × 10(5) for lipoic acid and 1.23 × 10(5) for Trolox methyl ether. The lower limit of quantification ranged between 0.02 and 1.22 ng for Trolox methyl ether and lipoic acid. MS(3) experiments of γ- and δ-tocopherol suggest ion-radical reactions and dependence of the tocopherol fragmentation pattern on the phenolic ring methylation degree. The method is shown to be applicable to measurement of these metabolites in human serum after extraction.

Single dose bioavailability and pharmacokinetic study of a innovative formulation of α-lipoic acid (ALA600) in healthy volunteers.

AIM: α-Lipoic acid is an important micronutrient with several pharmacological as well as antioxidant properties. The present study was aimed to examine the human bioavailability, pharmacokinetics (PK) and tolerability of an innovative oral formulation (ALA600) containing racemic α-lipoic acid 600 mg. METHODS: After a single 600-mg oral administration in healthy volunteers, blood samples were collected up to 8 hours post dosing, and plasma α-lipoic acid concentrations were determined by Liquid Chromatography-Mass Spectrometry (LC-MS) detection. RESULTS: The PK data revealed a short time to reach plasma peak oncentrations (50.8± 4.2 min) with a C(max) of 6.86±1.29 µg/mL. The C(max) implying that the new pharmaceutical form positively influences absorption and absorption time. The AUC value of 5.65±0.79 µg/mL*h is the more reliable measure of new formulation bioavailability. The half-life and MRT values further show that new formulation is absorbed consistently and rapidly and is eliminated efficiently. These PK data appear to promote further refinement of present formulation. Should the authors compare the obtained data with the recent published data, the new formulation of α-lipoic acid tends to show an improvement of C(max) value (2.5-5.4 times) and AUC (1.8 times). CONCLUSION: ALA600 formulation is characterized by rapid absorption, high bioavailability, brief half-life and low toxicity. These PK parameters could significantly increase clinical use of lipoic acid with improvement of the therapeutic effects at the cellular level and might also prove to be the most suitable formulation for chronic administration such as peripheral neuropathies.