Journal of Pharmaceutical Analysis

Screening primary racemic amines for enantioseparation by derivatized polysaccharide and cyclofructan columns☆

Yeeun Lim, Zachary S. Breitbach, Daniel W. Armstrong, Alain Berthod

2016, 6(6): 345-355.

Abstract(124) PDF(1)

Abstract:
It is a challenge to separate the enantiomers of native chiral amines prone to deleterious silanol interactions. A set of 39 underivatized chiral primary amines was screened for enantiomeric separation. Seven recently introduced commercial chiral columns were tested. They included six polysaccharide based chiral stationary phases (CSP) with bonded derivatives, ChiralPak? IA, IB, IC, ID, IE and IF columns and a cyclofructan derivatized CSP, Larihc? CF6-P column. Both the normal phase (NP) mode with heptane/alcohol mobile phases and the polar organic (PO) mode with acetonitrile/alcohol were evaluated. It was found that the cyclofructan based CSP demonstrated the highest success rate in separating primary amines in the PO mode with only one chiral amine not resolved. It is shown that, when screening the columns, there is no standard optimal condition;an excellent mobile phase composition for one column may be poorly suited to another one. Although butylamine was a good mobile phase additive for the polysaccharide columns in both PO and NP modes, it was detrimental to the enantio-recognition capability of the cyclofructan column. Triethylamine was the appropriate silanol screening agent for this latter column.

Comparison of ESI-and APCI-LC-MS/MS methods:A case study of levonorgestrel in human plasma☆

Rulin Wang, Lin Zhang, Zunjian Zhang, Yuan Tian

2016, 6(6): 356-362.

Abstract(93) PDF(2)

Abstract:
Electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) techniques for liquid chromatography–tandem mass spectrometry (LC–MS/MS) determination of levonorgestrel were evaluated. In consideration of difference in ionization mechanism, the two ionization sources were compared in terms of LC conditions, MS parameters and performance of method. The sensitivity for detection of levonorgestrel with ESI was 0.25 ng/mL which was lower than 1 ng/mL with APCI. Matrix effects were evaluated for levonorgestrel and canrenone (internal standard, IS) in human plasma, and the results showed that APCI source appeared to be slightly less liable to matrix effect than ESI source. With an overall consideration, ESI was chosen as a better ionization technique for rapid and sensitive quantification of levonorgestrel. The optimized LC–ESI–MS/MS method was validated for a linear range of 0.25–50 ng/mL with a correlation coefficient≥0.99. The intra-and inter-batch precision and accuracy were within 11.72%and 6.58%, respectively. The application of this method was demonstrated by a bioequivalence study following a single oral administration of 1.5 mg levonorgestrel tablets in 21 Chinese healthy female volunteers.

Structural characterization of monoterpene indole alkaloids in ethanolic extracts of Rauwolfia species by liquid chromatography with quadrupole time-of-flight mass spectrometry

Sunil Kumar, Awantika Singh, Vikas Bajpai, Mukesh Srivastava, Bhim Pratap Singh, Brijesh Kumar

2016, 6(6): 363-373.

Abstract(85) PDF(0)

Abstract:
Rauwolfia species (Apocynaceae) are medicinal plants well known worldwide due to its potent bioactive monoterpene indole alkaloids (MIAs) such as reserpine, ajmalicine, ajmaline, serpentine and yohimbine. Reserpine, ajmalicine and ajmaline are powerful antihypertensive, tranquilizing agents used in hypertension. Yohimbine is an aphrodisiac used in dietary supplements. As there is no report on the comparative and comprehensive phytochemical investigation of the roots of Rauwolfia species, we have developed an efficient and reliable liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for ethanolic root extract of Rauwolfia species to elucidate the fragmentation pathways for dereplication of bioactive MIAs using high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (HPLC–ESI–QTOF–MS/MS) in positive ion mode. We identified and established diagnostic fragment ions and fragmentation pathways using reserpine, ajmalicine, ajmaline, serpentine and yohimbine. The MS/MS spectra of reserpine, ajmalicine, and ajmaline showed C-ring-cleavage whereas E-ring cleavage was observed in serpentine via Retro Diels Alder (RDA). A total of 47 bioactive MIAs were identified and characterized on the basis of their molecular formula, exact mass measurements and MS/MS analysis. Reserpine, ajmalicine, ajmaline, serpentine and yohimbine were unambiguously identified by comparison with their authentic standards and other 42 MIAs were tentatively identified and characterized from the roots of Rauwolfia hookeri, Rauwolfia micrantha, Rauwolfia serpentina, Rauwolfia verticillata, Rauwolfia tetraphylla and Rauwolfia vomitoria. Application of LC–MS followed by principal component analysis (PCA) has been successfully used to discriminate among six Rauwolfia species.

The impact of storage conditions upon gentamicin coated antimicrobial implants☆

Nicholas D. Mullins, Benjamin J. Deadmana, Humphrey A. Moynihan, Florence O. McCarthy, Simon E. Lawrence, Jonathan Thompson, Anita R. Maguire

2016, 6(6): 374-381.

Abstract(87) PDF(0)

Abstract:
A systematic approach was developed to investigate the stability of gentamicin sulfate (GS) and GS/poly (lactic-co-glycolic acid) (PLGA) coatings on hydroxyapatite surfaces. The influence of environmental factors (light, humidity, oxidation and heat) upon degradation of the drug in the coatings was investigated using liquid chromatography with evaporative light scattering detection and mass spectrometry. GS coated rods were found to be stable across the range of environments assessed, with only an oxidizing atmosphere resulting in significant changes to the gentamicin composition. In contrast, rods coated with GS/PLGA were more sensitive to storage conditions with compositional changes being detected after storage at 60 °C, 75%relative humidity or exposure to light. The effect of γ-irradiation on the coated rods was also investigated and found to have no significant effect. Finally, liquid chromatography–mass spectrometry analysis revealed that known gentamines C1, C1a and C2 were the major degradants formed. Forced degradation of gentamicin coatings did not produce any unexpected degradants or impurities.

Optimization of microwave-assisted extraction of bioactive alkaloids from lotus plumule using response surface methodology☆

Wei Xiong, Xianqiang Chen, Guangping Lv, Dejun Hu, Jing Zhao, Shaoping Li

2016, 6(6): 382-388.

Abstract(115) PDF(0)

Abstract:
In this work, a fast and efficient microwave-assisted extraction (MAE) method was developed to extract main bioactive alkaloids from lotus plumue. To optimize MAE conditions, three main factors were selected using univariate approach experiments, and then central composite design (CCD). The optimal extraction conditions were as follows: methanol concentration of 65%, microwave power of 200 W, and extraction time of 260 s. A high performance liquid chromatography–diode array detector (HPLC–DAD) method was established to quantitatively analyze these phytochemicals in different lotus plumule samples and in different part of lotus. Chromatographic separation was carried out on an Agilent Zorbax Extend-C18 column (4.6 mm×150 mm, 3.5 μm). Gradient elution was applied with the mobile phase constituted with 0.1%triethylamine in water (A) and acetonitrile (B): 40%?70% B at 0?8 min, 70%?100% B at 8–9 min, 100% B for 2 min, and then equilibrated with 40%B for 2 min.

Wound healing activity of Delonix elata stem bark extract and its isolated constituent quercetin-3-rhamnopyranosyl-(1-6) glucopyranoside in rats☆

Pradeepa Krishnappa, Krishna Venkatarangaiah, Venkatesh, Santosh Kumar Shimoga Rajanna, Rebijith Kayattukandy Balan

2016, 6(6): 389-395.

Abstract(86) PDF(1)

Abstract:
Delonix elata L. is a Ceasalpinaceae species and is traditionally used in India for treatment of skin diseases, liver diseases and rheumatic problems. However, systematic evaluation of its wound healing activity is lacking. Thus, in the present study, we aimed to assess the wound healing activity of D. elata stem bark extract (DSE) and its isolated constituent quercetin-3-rhamnopyranosyl-(1-6) glucopyranoside (QRPG) in rats. The formulations effects on wound healing were assessed by the wound contraction rate, epithelialization period, tensile strength, content of the hydroxyproline, hexosamine and uronic acid in granulation tissue, histopathological studies and Col 1α(I) expression level in wound tissue by reverse transcription polymerase chain reaction (RT-PCR) study. The topical application of DSE ointment caused faster epithelialization, significant wound contraction (100%), and better tensile strength (710.5 ± 10.5 g/cm2), while QRPG showed wound epithelialization with 98.2%contraction, better than that of the control group (78.18%). The biochemical analysis of granulation tissue revealed that DSE and QRPG significantly increased hydroxyproline, hexosamine and uronic acid content. A significant increase in the expression of Col 1α(I) was observed in the wound tissue of DSE and QRPG treated rats. DSE and QRPG were shown to enhance wound healing by increasing collagen synthesis through up-regulation of Col 1α(I), thus validating ethnomedicinal uses.

Development of an HPLC-UV assay method for the simultaneous quantification of nine antiretroviral agents in the plasma of HIV-infected patients

Nitin Charbe, Sara Baldelli, Valeria Cozzi, Simone Castoldi, Dario Cattaneo, Emilio Clementi

2016, 6(6): 396-403.

Abstract(72) PDF(0)

Abstract:
A new method using high-performance liquid chromatography coupled with ultra violet detection (HPLC–UV) was developed and validated for the simultaneous quantification of atazanavir, dolutegravir, darunavir, efavirenz, etravirine lopinavir, raltegravir, rilpivirine and tipranavir in human plasma. For the first time we reported here the development and validation of an HPLC–UV assay to quantify the frequently administered 9 antiretroviral compounds including dolutegravir and rilpivirine. A simple solid phase extraction procedure was applied to 500 μL aliquots of plasma. The chromatographic separation of the drugs and internal standard (quinoxaline) was achieved with a gradient of acetonitrile and sodium acetate buffer on a C18 reverse-phase analytical column with a 25 min analytical run time. Calibration curves were optimised according to the therapeutic range of drug concentrations in patients, and the coefficient of determination (r2) was higher than 0.99 for all analytes. Mean intraday and interday precisions (RSD) for all compounds were less than 15.0%, and the mean accuracy (%deviation from nominal concentration) was also found to be less than 15.0%. Extraction recovery range was between 80%and 120%for all drugs analysed. The solid phase extraction and HPLC–UV method enable a specific, sensitive, and reliable simultaneous determination of nine antiretroviral agents in plasma. Good extraction efficiency and low limit of HPLC–UV quantification make this method suitable for use in clinical trials and therapeutic drug monitoring.

Determination of pKa values of alendronate sodium in aqueous solution by piecewise linear regression based on acid-base potentiometric titration

Jing Ke, Hanfei Dou, Ximin Zhang, Dushimabararezi Serge Uhagaze, Xiali Ding, Yuming Dong

2016, 6(6): 404-409.

Abstract(88) PDF(1)

Abstract:
As a mono-sodium salt form of alendronic acid, alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups. The dissociation constants of alendronate sodium were determined in this work by studying the piecewise linear relationship between volume of titrant and pH value based on acid-base potentiometric titration reaction. The distribution curves of alendronate sodium were drawn according to the determined pKa values. There were 4 dissociation constants (pKa1=2.43, pKa2=7.55, pKa3=10.80, pKa4=11.99, respectively) of alendronate sodium, and 12 existing forms, of which 4 could be ignored, existing in different pH environments.

CdS nanocrystals as fluorescent probe for detection of dolasetron mesylate in aqueous solution:Application to biomedical analysis

Samadhan P. Pawar, Laxman S. Walekar, Uttam R. Kondekar, Dattatray B. Gunjal, Anil H. Gore, Prashant V. Anbhule, Shivajirao R. Patil, Govind B. Kolekar

2016, 6(6): 410-416.

Abstract(75) PDF(0)

Abstract:
A simple and straightforward method for the determination of dolasetron mesylate (DM) in aqueous solution was developed based on the fluorescence quenching of 3-Mercaptopropionic acid (MPA) capped CdS quantum dots (QDs). The structure, morphology, and optical properties of synthesized QDs were characterized by using UV-Vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. Under the optimum conditions, the MPA-CdS QDs fluorescence probe offered good sensitivity and selectivity for detecting DM. The probe provided a highly specific selectivity and a linear detection of DM in the range of 2–40 μg/mL with detection limit (LOD) 1.512 μg/mL. The common excipients did not interfere in the proposed method. The fluorescence quenching mechanism of CdS QDs is also discussed. The developed sensor was applied to the quantification of DM in urine and human serum sample with satisfactory results.

Journal of Pharmaceutical Analysis

2016, 6(6): 417-418.

Abstract(113) PDF(0)

Abstract:

2016 Vol. 6, No. 6