Performance comparison of chlorinated chiral stationary phases in supercritical fluid chromatography for separation of selected pyrrolidone derivatives / 药物分析学报

The effects of two chlorinated chiral stationary phases, namely, Lux Cellulose-2 and Lux i-Cellulose-5, flow-rate, percentage of co-solvent and chemical structures of the compounds on retention and reso-lution were studied within this article. In this work a backpressure of 150 bar, a temperature of 40 ℃ and 10％ of methanol as co-solvent were chosen as operating conditions. The optimum flow-rate was 2 mL/min. The percentage of co-solvent was studied between 7.5％ and 15％. We have observed that 15％ of methanol gave the best results for most of the compounds. For all the derivatives, the Lux Cellulose-2 provided better resolutions going from 1.50 to 3.59 compared with Lux i-Cellulose-5.

S-(+)- and R-(-)-linalool: a comparison of the in vitro anti-Aeromonas hydrophila activity and anesthetic properties in fish

ABSTRACT Linalool is the main compound of many essential oils and occurs in two isomeric forms: S-(+)- and R-(-)-linalool. This study aimed to determine if linalool isomers have different antimicrobial and anesthetic properties in fish. For this purpose, these compounds were previously isolated from Lippia alba (Mill.)N. E. Brown and Ocimum americanum L. essential oils. Antimicrobial effects were evaluated through the microdilution test against Aeromonas hydrophila, an important fish disease etiologic agent. Induction time until sedation, anesthesia and recovery time were determined in silver catfish (Rhamdia quelen) through bath exposure (60, 180, 300 or 500 μL L-1). The results showed different biological properties for the isomers being S-(+)-linalool the only active against A. hydrophila at 3.2 mg mL-1. The sedation was induced without differences between the compounds, however R-(-)-linalool promoted faster anesthesia. There were no differences regarding the recovery time of the animals exposed to the linalool isomers. Although both S-(+)- and R-(-)-linalool can be used for sedative purposes, their use in A. hydrophila infection is inadvisable due to the high effective concentration. Considering anesthesia as the main objective, the R-(-)-linalool demonstrated clear advantages at lower concentration.

S, R-Isomer Separation of Hydrochloride Palonosetron by RP-HPLC with HP-β-CD as Chiral Additive / 中国药师

Objective: To establish an HPLC method for the separation of optical isomers of palonosetron hydrochloride by RP-HPLC with HP-β-cyclodextrin ( HP-β-CD) as the chiral additive. Methods:The optimal separation process was performed on a Shi-seido CAPACELL PAK C18 VG 120 (250 mm × 4. 6 mm,5μm) column,the mobile phase was triethylamine (TEA) with HP-β-CD at different concentrations, the pH value was adjusted by acetic acid, the detection wavelength was 240nm, and the column temperature was 30℃. Results:The mobile phase was 0. 5% TEA (1% HP-β-CD, adjusting pH to 5. 5 with acetic acid)-acetonotirile (85∶15);the detection wavelength was 240nm, and the flow rate was 0. 5 ml·min-1 . The S, R-Isomer of palonosetron hydrochloride could be well separated. Conclusion:The method can be used as the optical isomer quality control for palonosetron hydrochloride.

Determination of tirofiban hydrochloride enantiomers by chiral HPLC / 中国药学杂志

OBJECTIVE: To develop a chiral HPLC method for the determination of enantiomers of tirofiban hydrochloride.

Efectos de los isómeros en la práctica clínica / Isomers effects in clinical practice

Las isoformas estructurales de los medicamentos actúan de manera diferente en el organismo y se precisa un conocimiento básico para conocer sus efectos. El presente artículo tiene por objetivo presentar una revisión general sobre la estereoquímica de los agentes farmacológicos, cuya acción no siempre es la que desea el clínico, debido a que sus formas espaciales difieren a pesar de que estructuralmente sean idénticas. Para la realización del trabajo se realizó una revisión de la literatura mediante base de datos Embase y Medline. La farmacodinímica es la acción que ejercen los medicamentos en el organismo; sin embargo aún falta conocerse muchos efectos químicos producidos por sus propiedades espaciales, mientras que la farmacogénetica puede ser un gran aporte para aclarar el origen de muchas respuestas disímiles entre individuos, a pesar que los compuestos sean similares desde el punto de vista molecular.

The drugs structural isoforms work differently in the body and require a basic understanding for their effects. This articles aims to present a comprehensive review on the stereochemistry of pharmacological agents whose actions are not always desired by the clinician because, even though they are structurally identical, their spatial configuration differ. To carry out this work, a review of the literature by database Embase and medline has been made. Pharmacodynamics is the action exerted by drugs in the body, but we still need to know many chemical effects produced by their spatial properties, in the meanwhile pharmacogenetics may be an important contribution to clarify the origin many dissimilar response between individuals, although compounds are similar from the molecular standpoint of view.

Stereoisomerism(Chirality) of Psychotropic Drugs / 대한정신약물학회지

Many psychotropic drugs are marketed and prescribed as a racemate form in a mixture of the stereoisomers. A chiral center or a center of unsaturation of carbon atoms in the chemical structures creates various stereoisomers of the psychotropic drugs, including antidepressants such as fluoxetine and venlafaxine, etc. The stereochemical significances of enantiomers on the pharmacokinetics and pharmacodynamics of several psychotropic drugs and their relationships with pharmacogenetic polymorphisms were reviewed. The single enantiomer drugs will be increasing more in the market shares replacing the racemic drugs by chiral switching, which is driven by the development of the analytical and preparative resolution techniques and will be of much benefit to the treatment from low dosages, simple dose-response curve, few adverse reactions, and so on.

Study on Pharmacokinetics and Relative Bioavailability of Racemic Benzeneacetic Acid of Chirality Sus-tained Release Tablet in Human Body / 中国药房

OBJECTIVES:To study the pharmacokinetics of racemic benzeneacetic acid of chirality(RBAC)sustained re-lease tablet in human body of healthy volunteers,and to evaluate the bioequiavailability of RBAC and benzeneacetic acid of chirality(BAC)sustained release tablet.METHODS:18healthy volunteers studies were administered with multidoses of RBAC or BAC by randomized crossover and own control,the plasma concentrations of RBAC and BAC were determined by RP-HPLC,the pharmacokinetic parameters were calculated and ANOVA and two&one side t tests were carried out as well.RESULTS:The pharmacokinetic parameters of RBAC and BAC were respectively as follows:t 1/2 were(8.14?1.95)h and(8.81?2.27)h;t max were(3.44?0.62)h and(3.44?0.70)h;C ss max were(3.69?0.50)mg/L and(3.68?0.76)mg/L,AUC 0～t were(23.49?2.53)(mg?h)/L and(22.48?2.59)(mg?h)/L;DF were(138.21%?23.10)%and(134.53%?28.14)%;C ss were(1.96?0.21)mg/L and(1.85?0.22)mg/L;The relative bioavailability of RBAC to BAC was(102.45?8.07)%.CON-CLUSION:RBAC and BAC were bioequivalent.

X-ray studies on crystalline complexes involving amino acids and peptides: Part XVIII. Crystal structure of a new form of L-arginine D-glutamate and a comparative study of amino acid crystal structures containing molecules of the same and mixed chirality.

The new form of L-arginine D-glutamate is monoclinic, P2l, with a = 9·941(1), b = 4·668(2), c= 17·307(1) Å, ß = 95·27(1)°, and Ζ = 2. In terms of composition, the new form differs from the old form in that the former is a monohydrate whereas the latter is a trihydrate. The structure has been solved by the direct methods and refined to R = 0·085 for 1012 observed reflections. The conformation of the arginine molecule is the same in both the forms whereas that of the glutamate ion is different. The change in the conformation of the glutamate ion is such that it facilitates extensive pseudosymmetry in the crystals. The molecules arrange themselves in double-layers stabilised by head-to-tail sequences involving main chains, in both the forms. However, considerable differences exist between the two forms in the interface, consisting of side chains and water molecules, between double-layers. A comparative study of the relationship between the crystal structures of L and DL amino acids on the one hand and that between the structures of LL and LD amino acid-amino acid complexes on the other, provides interesting insights into amino acid aggregation and the effect of chirality on it. The crystal structures of most hydrophobic amino acids are made up of double-layers and those of most hydrophilic amino acids contain single layers, irrespective of the chiralities of the amino acids involved. In most cases, the molecules tend to appropriately rearrange themselves to preserve the broad features of aggregation patterns when the chirality of half the molecules is reversed as in the structures of DL amino acids. The basic elements of aggregation in the LL and the LD complexes, are similar to those found in the crystals of L and DL amino acids. However, the differences between the LL and the LD complexes in the distribution of these elements are more pronounced than those between the distributions in the structures of L and DL amino acids.