UEA I-bearing nanoparticles for brain delivery following intranasal administration.

Surface engineering of nanoparticles with lectins opened a novel pathway to improve the brain uptake of agents loaded by biodegradable PEG-PLA nanoparticles following intranasal administration. Ulex europeus agglutinin I (UEA I), specifically binding to l-fucose, which is largely located in the olfactory epithelium, was selected as a promising targeting ligand and conjugated onto the PEG-PLA nanoparticles surface with an optimized protocol relying on maleimide-mediated covalent binding technique. The in vivo results in rats suggested that UEA I modification at the nanoparticles surface facilitated the absorption of a fluorescent marker--6-coumarin associated with the nanoparticles into the brain following intranasal administration with significant increase in the area under the concentration-time curve (about 1.7 times) in different brain tissues compared with that of coumarin incorporated in the unmodified ones. UEA I-conjugation also elevated the brain-targeting efficiency of nanoparticles. Inhibition experiment of specific sugar suggested that the interactions between the nasal mucosa and the lectinised nanoparticles were due to the immobilization of carbohydrate-binding pockets on the surface of the nanoparticles. Distribution profiles of UEA I-modified nanoparticles indicated their higher affinity to the olfactory mucosa than to the respiratory one. Therefore, the UEA I-modified nanoparticles might serve as potential carriers for brain drug delivery, especially for mental therapeutics with multiple biological effects.

Lectin-conjugated PEG-PLA nanoparticles: preparation and brain delivery after intranasal administration.

In order to improve the absorption of nanoparticles in the brain following nasal administration, a novel protocol to conjugate biorecognitive ligands-lectins to the surface of poly (ethylene glycol)-poly (lactic acid) (PEG-PLA) nanoparticles was established in the study. Wheat germ agglutinin (WGA), specifically binding to N-acetyl-D-glucosamine and sialic acid, both of which were abundantly observed in the nasal cavity, was selected as a model lectin. The WGA-conjugated nanoparticles were prepared by incorporating maleimide in the PLA-PEG molecular and taking advantage of its thiol group binding reactivity to conjugate with 2-iminothialane thiolated WGA. Coupling of WGA with the PEG-PLA nanoparticles was confirmed by the existence of gold-labeled WGA-NP under TEM. The retention of biorecognitive activity of WGA after the covalent coupling procedure was confirmed by haemagglutination test. The resulting nanoparticles presented negligible nasal ciliatoxicity and the brain uptake of a fluorescent marker-coumarin carried by WGA functionized nanoparticles was about 2 folds in different brain tissues compared with that of coumarin incorporated in the unmodified ones. Thus, the technique offered a novel effective noninvasive system for brain drug delivery, especially for brain protein and gene delivery.

Determination of apovincaminic acid in human plasma by high-performance liquid chromatography using solid-phase extraction and ultraviolet detection.

A new, simple and rapid high-performance liquid chromatography (HPLC) method with UV detection has been developed for the determination of apovincaminic acid in human plasma. Apovincaminic acid and internal standard were isolated from plasma samples by solid-phase extraction with OASIS HLB cartridges. The chromatographic separation was accomplished on a reversed-phase C(18) column and UV detection was set at 311 nm. The calibration curves were linear in the concentration range of 2.4-240.0 ng/ml, and the limits of quantification was 2.4 ng/ml. The precision and accuracy ranged from 0.84 to 8.54% and 91.5 to 108.3%, respectively. The developed method was subsequently applied to study the pharmacokinetics of apovincaminic acid in a group of 20 human subjects at a single oral dose of 10mg of vinpocetine tablet.

Quantification of lipoic acid in plasma by high-performance liquid chromatography-electrospray ionization mass spectrometry.

A sensitive and specific liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) method has been developed and validated for the identification and quantification of lipoic acid (LA) in human plasma. LA and the internal standard, naproxen, were extracted from a 500 microl plasma sample by one-step deproteination using acetonitrile. Chromatographic separation was performed on a Zorbax SB-C(18) Column (100 mmx3.0mm i.d. with 3.5 microm particle size) with the mobile phase consisting of acetonitrile and 0.1% acetic acid (pH 4, adjusted with ammonia solution) (65:35, v/v), and the flow rate was set at 0.3 ml/min. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via electrospray ionization (ESI) source. The method was linear over the concentration range of 5-10,000 ng/ml for LA. The intra- and inter-day precisions were less than 7% and accuracy ranged from -7.87 to 9.74% at the LA concentrations tested. The present method provides a relatively simple and sensitive assay with short turn-around time. The method has been successfully applied to a clinical pharmacokinetic study of LA in 10 healthy subjects.

Characterization of biosynthetic genes of ascamycin/dealanylascamycin featuring a 5'-O-sulfonamide moiety in Streptomyces sp. JCM9888.

Ascamycin (ACM) and dealanylascamycin (DACM) are nucleoside antibiotics elaborated by Streptomyces sp. JCM9888. The later shows broad spectrum inhibition activity to various gram-positive and gram-negative bacteria, eukaryotic Trypanosoma and is also toxic to mice, while ascamycin is active against very limited microorganisms, such as Xanthomonas. Both compounds share an unusual 5'-O-sulfonamide moiety which is attached to an adenosine nucleoside. In this paper, we first report on the 30 kb gene cluster (23 genes, acmA to acmW) involved in the biosynthesis of these two antibiotics and a biosynthetic assembly line was proposed. Of them, six genes (AcmABGKIW) are hypothetical genes involved in 5'-O-sulfonamide formation. Two flavin adenine dinucleotide (FAD)-dependent chlorinase genes acmX and acmY were characterized which are significantly remote from acmA-W and postulated to be required for adenine C2-halogenation. Notably gene disruption of acmE resulted in a mutant which could only produce dealanylascamycin but was blocked in its ability to biosynthesize ascamycin, revealing its key role of conversion of dealanylascamycin to ascamycin.