Degradation of copolymers obtained by ring-opening polymerization of glycolide and -caprolactone: A high resolution NMR and ESI-MS study

Electrospray ionization-mass spectrometry (ESI-MS) and proton nuclear magnetic resonance (¹H NMR) have been used to investigate the hydrolytic degradation of copolymers obtained by bulk ring-opening copolymerization of glycolide and -caprolactone with monomer ratios ranging from 70/30 to 30/70. NMR allows changes of the average sequence distribution and composition of the components to be followed. In contrast, ESI-MS is able to reveal the detailed chemical structures of various sequences despite the molecular weight limit of 2000 Da. Combination of ESI-MS with NMR can thus provide information to describe microstructure changes during degradation. The distribution of various oligomers shown in the form of planar projections is of great interest for the design of biodegradable system aimed at medical applications.     

Reverse-Phase High-Performance Liquid-Chromotographic DAD Method for Simultaneous Determination of Five Isoflavones in Millettia nitida var. hirsutissima

Abstract

A reverse-phase high-performance liquid-chromatographic photodiode array detection (DAD) method has been developed and validated for the simultaneous determination of five isoflavones in Millettia nitida var. hirsutissima: hirsutissimiside B, sphaerobioside, lanceolarin, formononetin, and afromosin. The method utilized a C₁₈ column (4 µm, 250 × 4.6 mm) with an acetonitrile and aqueous H₃PO₄ gradient and ultraviolet detection at 259 nm. The recovery of the method is 94.1–105.9%, and linearity (r > 0.9996) is obtained for all the isoflavones.     

New alkylamides from pericarps of Zanthoxylum bungeanum

Two new unsaturated alkylamides(2E,7E,9E)-N-(2-hydroxy-2-methylpropyl)-6,11-dioxo-2,7,9-dodecatrienamide(1) and (2E,6E,8E)-N-(2-hydroxy-2-methylpropyl)-10-oxo-2,6,8-decatrienamide(2) together with six known compounds(3-8) have been isolated from the pericarps of Zanthoxylum bungeanum.Their structures were elucidated on the basis of extensive spectroscopic analysis,including MS,IR,1D and 2D NMR experiments.     

Release behaviors of porous poly(butylene succinate)/poly(epsilon-caprolactone) microcapsules containing indomethacin

The biodegradable poly(butylene succinate)/poly(epsilon-caprolactone) (PBS/PCL) microcapsules containing indomethacin were prepared by emulsion solvent evaporation method. The morphologies, thermal properties, and release behaviors of PBS/PCL microcapsules were investigated. As a result, the microcapsules exhibited porous and spherical form in the presence of gelatin as a surfactant. From the DSC result, the PBS/PCL microcapsules showed the two exothermic peaks meaning the melting points of PCL and PBS. The results of FT-IR and DSC proved that the PBS and PCL were mixed so that the PBS/PCL microcapsules were composed of two wall-forming materials. And the release rate of indomethacin from the microcapsules was decreased with increasing the PCL content. It was noted that an addition of PCL on the PBS led to the decrease of pore size in the PBS/PCL microcapsules.