Isomeric effects of anti-diabetic α-lipoic acid with γ-cyclodextrin

Characterization and pharmacokinetic evaluation of microcomposite particles of alpha lipoic acid/hydrogenated colza oil obtained in supercritical carbon dioxide

The work reported here is an extension of our previous findings in which supercritical composite particles (SCP) of alpha lipoic acid (ALA) masked with hydrogenated colza oil (HCO) named as ALA/HCO/SCP were obtained by the modified particles from gas-saturated solutions (PGSS) process in supercritical carbon dioxide in order to obscure the unpleasant taste and odor of ALA. The masking effect on ALA/HCO/SCP was compared with the widely used mechano-chemically masked formulation of ALA and HCO named as MC-50F. In the present study, ALA/HCO/SCP particles were found to have a significant improvement in regard to bitterness, numbness, and smell compared to ALA bulk powders suggesting they were well coated. The pharmacokinetic parameters for ALA/HCO/SCP and ALA bulk powder gave similar values but were significantly different from those of MC-50F. The amount of ALA absorbed into the body, in the administered ALA/HCO/SCP, was comparable to that absorbed by ALA bulk powder, whereas about half portion of ALA of the MC-50F was not absorbed, because the ALA/HCO/SCP particles were small enough and the particles of MC-50F were relatively large and had smaller specific surface area. Therefore, this study suggested a newly masked candidate may offer functional particles with maintained efficacy.

In Vivo Effect of Bis(Maltolato)Zinc(II) Complex on Akt Phosphorylation in Adipose Tissues of Mice

The risk of serious complication gradually increases as diabetes mellitus (DM) progresses. Thus, strategies for the prevention and delay of symptom progression are urgently needed. Previously, we synthesized zinc (Zn) complexes estimated to have a high bioavailability and evaluated their insulin-like anti-DM effects. However, in vivo studies of the effects of Zn compounds on the insulin signaling pathway and the molecular mechanisms underlying the anti-diabetic activities of Zn complexes were unresolved. In this study, we evaluated the effect of bis(maltolato)zinc(II) complex [Zn(mal)₂] on male ICR mice (6-week-old) that received intraperitoneal (i.p.) injection of [Zn(mal)₂]. The liver, skeletal muscle, and adipose tissues were collected from mice under anesthesia with isoflurane 40 or 90 min after i.p. injection. The [Zn(mal)₂]-treatment did not affect Akt phosphorylation in the liver or skeletal muscle. In contrast, in adipose tissues, [Zn(mal)₂]-treatment showed increased Akt phosphorylation at 40 min and 90 min after injection (p < 0.01 vs. control). The Zn distribution in the organs was evaluated using inductively coupled plasma mass spectrometry. Notably, high Zn accumulation was observed in the adipose tissue (4.5 ± 2.7 μg Zn/g wet weight), and this value was about six times higher than in the control mice (p < 0.01). Based on the observed organ-specific distribution of [Zn(mal)₂], we suggest that it does not directly promote glycogen synthesis in the liver but may impact the insulin signaling pathway in adipose tissues. Our results may contribute to the clinical use of zinc compounds for the treatment of diabetes.

The effect of alpha-lipoic acid supplementation on anthropometric indices and food intake in patients who experienced stroke: A randomized, double-blind, placebo-controlled clinical trial

Background:

Stroke as a devastating condition is a major cause of death worldwide. It is accountable for long-term disability with high personal and social cost in adults. Alpha-lipoic acid (ALA) is an eight-carbon, sulfur-containing compound with antioxidant properties which reduces body weight, changes other anthropometric indices, and regulates food intake by suppressing appetite and increasing metabolism This study was designed to evaluate the possible effects of ALA supplementation on anthropometric indices and dietary intake in patients with stroke.

Materials and Methods:

In this randomized, double-blind, placebo-controlled clinical trial, 67 patients with stroke were randomly allocated to two groups (taking a 600 mg ALA supplement or placebo daily for 12 weeks). Weight, waist circumference, energy, carbohydrate, protein, and fat intake were measured, and body mass index (BMI) was calculated before and after intervention. Dietary intake and statistical analyses were carried out using Nutritionist IV and SPSS (version 16; SPSS Inc., Chicago, IL, USA) software, respectively.

Results:

Primary features were similar in the intervention and placebo groups (P > 0.05). Waist circumference (P < 0.001), energy, carbohydrate, protein, and fat intake (P < 0.001) decreased significantly, after the intervention period, in ALA group compared with placebo. While no significant change was observed in weight (P = 0.26) and BMI (P = 0.56) in ALA supplementation group compared with placebo.

Conclusion:

Results of this trial indicated that 12-week supplementation with 600 mg ALA can decrease waist circumference and food intake (energy, carbohydrate, protein, and fat) in patients with stroke.

Investigation of Enantioselective Membrane Permeability of α-Lipoic Acid in Caco-2 and MDCKII Cell

α-Lipoic acid (LA) contains a chiral carbon and exists as two enantiomers (R-α-lipoic acid (RLA) and S-α-lipoic acid (SLA)). We previously demonstrated that oral bioavailability of RLA is better than that of SLA. This difference arose from the fraction absorbed multiplied by gastrointestinal availability (F_a × F_g) and hepatic availability (F_h) in the absorption phase. However, it remains unclear whether F_a and/or F_g are involved in enantioselectivity. In this study, Caco-2 cells and Madin–Darby canine kidney strain II cells were used to assess the enantioselectivity of membrane permeability. LA was actively transported from the apical side to basal side, regardless of the differences in its steric structure. Permeability rates were proportionally increased in the range of 10–250 µg LA/mL, and the permeability coefficient did not differ significantly between enantiomers. Hence, we conclude that enantioselective pharmacokinetics arose from the metabolism (F_h or F_g × F_h), and definitely not from the membrane permeation (F_a) in the absorption phase.