Transdermal Delivery Systems for Ibuprofen and Ibuprofen Modified with Amino Acids Alkyl Esters Based on Bacterial Cellulose

The potential of bacterial cellulose as a carrier for the transport of ibuprofen (a typical example of non-steroidal anti-inflammatory drugs) through the skin was investigated. Ibuprofen and its amino acid ester salts-loaded BC membranes were prepared through a simple methodology and characterized in terms of structure and morphology. Two salts of amino acid isopropyl esters were used in the research, namely L-valine isopropyl ester ibuprofenate ([ValOiPr][IBU]) and L-leucine isopropyl ester ibuprofenate ([LeuOiPr][IBU]). [LeuOiPr][IBU] is a new compound; therefore, it has been fully characterized and its identity confirmed. For all membranes obtained the surface morphology, tensile mechanical properties, active compound dissolution assays, and permeation and skin accumulation studies of API (active pharmaceutical ingredient) were determined. The obtained membranes were very homogeneous. In vitro diffusion studies with Franz cells were conducted using pig epidermal membranes, and showed that the incorporation of ibuprofen in BC membranes provided lower permeation rates to those obtained with amino acids ester salts of ibuprofen. This release profile together with the ease of application and the simple preparation and assembly of the drug-loaded membranes indicates the enormous potentialities of using BC membranes for transdermal application of ibuprofen in the form of amino acid ester salts.

Electron-induced ionization of undeuterated and deuterated benzoic acid isopropyl esters and nicotinic acid isopropyl esters: Some implications for the mechanism of the McLafferty rearrangement

Electron ionization mass spectra, ionization, and appearance energies and bond energies (as dissociation energies) are reported for benzoic acid-1-methyl-ethyl ester (BAIPE), benzoic acid-1-deutero-1-methyl-ethyl ester (BAIPED1), benzoic acid-2,2,2-trideutero-1-trideuteromethyl-ethyl ester (BAIPED6) as well as nicotinic acid-1-methyl-ethyl ester (NAIPE), nicotinic acid-1-deutero-1-methyl-ethyl ester (NAIPED1), and nicotinic acid-2,2,2-trideutero-1-trideuteromethyl-ethyl ester (NAIPED6). Ionization energies of 9.39 eV for BAIPE, 9.40 eV for BAIPED1, 9.26 eV for BAIPED6 as well as 9.70 eV for NAIPE, 9.79 eV for NAIPED1, and 9.65 eV for NAIPED6 were determined. A gas-phase formation enthalpy of [Formula: see text] = (−4.10 ± 0.1) eV for BAIPE is calculated as well as [Formula: see text] = (−3.35 ± 0.1) eV for NAIPE. Molecular ions show two main fragmentation pathways. The first is a classical McLafferty rearrangement, characterized by the transfer of one γ-hydrogen atom from the isopropyl ester chain leading to the ions of the corresponding acid and neutral propene. The second is the double hydrogen transfer from the ester chain leading to the formation of the protonated acid and a C3H5√ allyl radical. For BAIPE, both hydrogen atoms originate from the methyl groups of the aliphatic chain with a probability of ≥98%, whereas the C-1-hydrogen is transferred with a probability of ≤2%. For NAIPE, both hydrogen atoms originate from the methyl groups of the aliphatic chain with a probability of 90%. Experimental proton affinities of PA = (8.75 ± 0.2) eV for benzoic acid and PA = (8.43 ± 0.2) eV for nicotinic acid are derived. For the protonation of the carbonyl group, B3LYP DFT calculations yielded PA = 8.66 eV for benzoic acid and PA = 8.41 eV for nicotinic acid. The overall fragmentation mechanism is explained with the initial formation of a 1,5-distonic ion by transfer of the first hydrogen. For the transfer of the second hydrogen, an intermediate ion/neutral complex is formulated.

Synthesis of Isopropyl Esters from Jatropha Curcas Oil at Short Time Reaction

The searching of environmentally friendly materials that have potential to replacement mineral oil is currently being considered a top priority research topic in the fuel and energy sector. This paper presents the influence of ultrasound-assisted transesterification of jatropha oil to isopropyl ester and the optimum condition. The transesterification was performed by using isopropyl alcohol as solvent in the presence of ultrasound operating frequency constant at 35 kHz. The isopropyl ester content of product was 97.80 % under the the reaction temperature of 60 °C, isopropyl alcohol to jatropha oil molar ratio of 8 : 1 within the reaction time of 15 minutes.

Development of Phosphonate Monoesters Building Units in Metal-Organic Frameworks

The use of predictable coordination geometries and the development of new ligands has allowed supramolecular chemists to design a plethora of new materials. Among these are metal-organic frameworks (MOFs), which are composed of ligands coordinating to metal atoms or clusters to generate a framework with potential porosity. MOFs exemplify supramolecular design strategy as their extended structure and tunable properties allow them to be applied for various applications.1 To date, many MOFs utilize carboxylates as the coordinating group since they have well studied coordination geometries and thus predictable framework topologies. Though there are examples of carboxylate-based MOFs possessing water stability, most do not possess this key feature, hindering their application in industrial settings. Phosphonate monoesters (PMEs) have been investigated as a means to impart water stability to a MOF by kinetically shielding the linker-metal bond with the ester moiety.2 Unfortunately, phosphonate monoesters have relatively unexplored coordination geometries, with most studies focusing on chlodronic acid and its derivatives, which do not typically form porous materials. In an attempt to establish building units based on PMEs, 1,4-benzenediphosphonate monoester ligands have been synthesized, coordinated to Cu(II), and characterized. It was found that while the methyl and ethyl analogues form similar 3-D structures with poor water stability,3 the isopropyl analogue forms a layered material possessing water stability. The isopropyl analogue contains chains of Cu-PME, with the isopropyl esters lying directly above and below the Cu atoms, kinetically shielding this bond from water. This water stable building unit was predicted to generate a porous framework with non-linear ligands. To test this hypothesis, 1,3,5-benzenetriphosphonate monoisopropyl ester was synthesized and coordinated to Cu(II). Unfortunately, no single crystal of sufficient quality has been produced, though a predicted and refined structure matches well to various characterization techniques. As predicted, this material is porous and does not degrade in harsh humid conditions (353K and 90% relative humidity).