Pentafluorophenyl Trifluoroacetate

Netilmicin is a semi-synthetic aminoglycoside antibiotic used against a broad spectrum of Gram-negative bacteria. A reversed-phase high-performance liquid chromatographic method has been developed to determine the composition of netilmicin sulfate and to estimate its related substances without pre- or post-column derivatization. A UV detector cannot be used to detect low levels of known and unknown related substances of netilmicin, as it has only a weak UV chromophore. A charged aerosol detector was used instead to obtain the high sensitivity that was necessary for the intended purpose of the method. This method can separate all related substances of netilmicin. A (10 cm x 4.6 mm) pentafluorophenyl high-performance liquid chromatographic column from Restek was used with a mobile phase consisting of (A) pentafluoropropionic acid-water-acetonitrile (0.1:96:4, v/v/v) and (B) trifluoroacetic acid-water-acetonitrile (1:96:4, v/v/v).

This study describes the biophysical and immunomodulatory features of a cyclic peptide termed C1 which consists of alternating d-, l-amino acids and is capable of inhibiting IL-2 production in vitro and reducing the induction and extent of T-cell mediated inflammation in animal models. Solid-state nuclear magnetic resonance demonstrates that the peptide orders the lipid bilayer, suggesting a transmembrane orientation, and this is supported by surface plasmon resonance indicating strong binding affinity of C1 to model membranes. In vitro cell viability and proliferation assays show that C1 does not disrupt the integrity of cell surface membranes. Permeation studies of C1 and analogs across human epidermis cells show that the stability and skin permeability are enhanced by cyclization. Treatment with C1 in an asthma and in an arthritis animal model resulted in a suppressed immune response. Cyclization may be a useful means of enhancing biological linear peptide activity and improving delivery.

Liquid chromatography-mass spectrometry (LC-MS) is considered today as a mainstay tool for the structure characterization of minor components like impurities (IMPs) and degradation products (DPs) in drug substances and products. A multi-step systematic strategy for the purpose involves high resolution mass and multi-stage mass studies on both the drug and IMPs/DPs, followed by comparison of their fragmentation profiles. Its successful application requires consideration of many practical aspects at each step. The same are critically discussed in this review.

Gentamicin sulfate is a potent broad spectrum aminoglycoside antibiotic which is used as an active pharmaceutical ingredient (API) against both Gram-positive and Gram-negative bacteria. A reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed and validated to determine the composition of gentamicin sulfate and to estimate its related substances (without any pre- or post-column derivatization) in a pharmaceutical cream. As gentamicin has a weak UV chromophore, it is not possible to detect low levels of known and unknown related substances of gentamicin using a UV detector. In this method, a Charged Aerosol Detector (CAD) was used to obtain high sensitivity that was necessary for the intended purpose of the method. This method can separate all the analogues of gentamicin including all known and unknown related substances of the API. A short (5cmx4.6mm) pentafluorophenyl HPLC column from Restek (Allure PFP) was used with an ion-pair gradient mobile phase consisting of (A) heptafluorobutyric acid:water:acetonitrile (0.