Design of composite microparticle systems based on pectin and waste material of propolis for modified l-alanyl-l-glutamine release and with immunostimulant activity.

Catabolic conditions like acquired immunodeficiency syndrome, cancer, and burn can cause immunosuppression. Amino acids such as alanine and glutamine are essential for the activity of the immune system. Propolis is immunostimulant and the waste of propolis extraction has been reused with technological and therapeutic purposes. Therefore, this study describes the association of propolis byproduct extract (BPE) with pectin to prepare spray-dried microparticles containing the dipeptide l-alanyl-l-glutamine as stimulant systems of neutrophils. The use of a factorial design allowed selecting the best formulation, which was characterized by morphology, size, and entrapment efficiency analyses. In addition, the systems were characterized by thermal and X-ray diffraction analysis, Fourier-transform infrared spectroscopy, in vitro drug release, and in vitro cytotoxicity and stimulation test of neutrophils. Small well-structured microparticles with good entrapment efficiency values were achieved. Thermal stability of formulation was observed, and it was proved that pectin, BPE and l-alanyl-l-glutamine were dispersed throughout the matrix. The drug was released from the microparticles during 24 h governed by swelling and diffusion. The drug-loaded formulations showed a significant stimulating effect on neutrophils. These structures could increase the activity of immune cells, and other in vitro and in vivo studies should be performed in the future.

Physicochemical and preclinical pharmacokinetic and toxicological evaluation of LK-423--a new phthalimido-desmuramyl-dipeptide derivative with immunomodulating activity.

INTRODUCTION: LK-423 is a new phthalimido-desmuramyl-dipeptide derivative with immunomodulating activity. As optimized delivery to the site of action appears crucial for further preclinical development of LK-423, the aim of this study was to perform a physicochemical and preclinical pharmacokinetic and toxicological evaluation. METHODS: The solubility, partition coefficient, permeability, and stability profile were determined. Pharmacokinetics were evaluated in rats following intravenous and oral application of LK-423, and in dogs after intravenous administration and oral administration of microcapsules, designed for colon-specific delivery of LK-423 based on pH-, time-, and enzyme-controlled release mechanisms. Additionally, the acute and subchronic toxicity was examined. RESULTS AND DISCUSSION: LK-423 is hydrophilic, sparingly to slightly soluble, and poorly permeable. Stability profile in aqueous solution is pH dependent. A pharmacokinetic study following intravenous application to rats and dogs revealed that LK-423 is rapidly eliminated with a short terminal phase half-life, and high plasma clearance, as well as a limited distribution to the peripheral tissue. Oral bioavailability of LK-423 is low, presumably due to low permeability. Debris of insoluble microcapsule coating in feces and obtained plasma concentration profiles confirm that LK-423 microcapsules are a promising approach for local treatment of inflammatory diseases of the large intestine. Acute and a subchronic toxicity results indicate that LK-423 is a safe and nontoxic drug under the applied experimental conditions.

Safety studies of l-alanyl-l-glutamine (l-AG).

The safety of l-alanyl-l-glutamine (l-AG) derived by fermentation using a recombinant Escherichia coli strain containing the l-amino acid alpha-ligase gene from Bacillus subtilis, was assessed in acute and subchronic toxicity studies in the rat. l-AG was tested in vitro in a bacterial reverse mutation assay and in a chromosome aberration assay. l-AG was not acutely toxic when administered to Sprague-Dawley rats by gavage at 2000mg/kg bw. In a 14-day range-finding study, l-AG at up to 5% in the diet was without effect. In the 13-week dietary study, there were no toxicologically significant differences between the treated groups (1.0, 3.0 and 5.0% l-AG) and the controls (0% and 5% l-AG produced via a different method) with respect to body weight gain, feed consumption, feed efficiency, or the results of ophthalmological, haematological, clinical chemistry, and urinalysis evaluations. Three of 10 high-dose males had mild testicular changes, however, these were of exactly the same nature and severity as those that occur spontaneously, and were considered unlikely to be treatment-related. The NOAEL in both males and females was established as the highest dose tested at 3129 and 3601mg/kg bw/day, respectively (5.0% in the diet). There was no evidence of genotoxicity of l-AG in the Ames assay or in the in vitro CHL cell chromosome aberration study.

Differential regulation and substrate preferences in two peptide transporters of Saccharomyces cerevisiae.

Dal5p has been shown previously to act as an allantoate/ureidosuccinate permease and to play a role in the utilization of certain dipeptides as a nitrogen source in Saccharomyces cerevisiae. Here, we provide direct evidence that dipeptides are transported by Dal5p, although the affinity of Dal5p for allantoate and ureidosuccinate is higher than that for dipeptides. Allantoate, ureidosuccinate, and to a lesser extent allantoin competed with dipeptide transport by reducing the toxicity of the peptide Ala-Eth and decreasing the accumulation of [(14)C]Gly-Leu. In contrast to the well-studied di/tripeptide transporter Ptr2p, whose substrate specificity is very broad, Dal5p preferred to transport non-N-end rule dipeptides. S. cerevisiae W303 was sensitive to the toxic peptide Ala-Eth (non-N-end rule peptide) but not Leu-Eth (N-end rule peptide). Non-N-end rule dipeptides showed better competition with the uptake of [(14)C]Gly-Leu than N-end rule dipeptides. Similar to the regulation of PTR2, DAL5 expression was influenced by the addition of Leu and by the CUP9 gene. However, DAL5 expression was downregulated in the presence of leucine and the absence of CUP9, whereas PTR2 was upregulated. Toxic dipeptide and uptake assays indicated that either Ptr2p or Dal5p was predominantly used for dipeptide transport in the common laboratory strains S288c and W303, respectively. These studies highlight the complementary activities of two dipeptide transport systems under different regulatory controls in common laboratory yeast strains, suggesting that dipeptide transport pathways evolved to respond to different environmental conditions.

Toxicity of the novel anti-peptic ulcer agent polaprezinc in beagle dogs.

A preliminary dose-range finding study, two 13-week studies and a 52-week study were performed in beagle dogs with polaprezinc (catena-(S)-[mu-[Na-(3-aminopropionyl)histidinato (2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7, Z-103), a novel anti-peptic ulcer agent, as part of a safety evaluation program. In the preliminary single-dose study, treatment-related findings were confined to one animal treated with 200 mg/kg and consisted in emesis and mucosal lesions in the stomach and upper small intestine. Based on these data, dosages were selected for the main 13-week study (0, 50, 120 and 300 mg/kg/day) and additional 13-week study (0, 8 and 20 mg/kg/day). The dosages for the 52-week study were 8, 20 and 50 mg/kg/day. In the 13-week studies, dosages of 50 mg/kg/day and above resulted in emesis, mild diarrhea and salivation; reduced food consumption and associated reduction in body weight gain for high dosed females; increased blood alkaline phosphatase and decreased urinary specific gravity; histopathological changes in the kidney of the high dosed group in males and females. These changes were no longer apparent following the withdrawal period. In the 52-week study, similar but milder and transient results were noted at the high dose of 50 mg/kg/day. From these results, the no-effect dose level was estimated to be 20 mg/kg b.w./day.

[Characteristics of the mechanism of action of complex copper (II) compounds with alpha-amino acids]. / Nekotorye osobennosti mekhanizma deistviia kompleksnykh soedinenii nedi (II) s al'fa-aminokislotami.

There was no direct inhibition of DNA synthesis in ascites hepatoma 22A cells after intraperitoneal injection of single doses of copper (II) complexes with amino acids into tumor-bearing C3HA mice. Meanwhile cis-dichlorodiamine platinum (II) (DDP) as well as sarcolysine showed such inhibition. Copper (II) complexes with alpha-amino acids displayed as significant superoxide dismutase-like activity at concentrations corresponding to therapeutic doses of these compounds. The complexes of copper (II) combined with DDP give an additive antitumor effect in solid tumors of mice.

Hypothalamic morphology following ingestion of aspartame or MSG in the neonatal rodent and primate: a preliminary report.

Neonatal mice received oral doses of monosodium glutamate (MSG) at levels of 0.25, 0.5m 1.0, 2.0, and 4.0 g/kg or aspartame at levels of 0.5, 1.0, 1.5, and 2.0 g/kg. Hypothalamic lesions were encountered at dose levels equal to or exceeding 0.5 g/kg (MSG) and 1.0 g/kg (aspartame). Aspartame administration resulted in a much smaller hypothalamic lesion than did equal dosages of MSG. Infant monkeys received MSG (1-4 g/kg) or aspartame (2 g/kg) by stomach tube. Hypothalamic morphology remained normal at both the microscopic and ultrastructural level. Thus, in contrast to the neonatal rodent, the neonatal primate is able to cope either metabolically or at the level of the blood-brain barrier with excessive amino acid loads.