Analogues of phospholipids: synthesis and biological evaluation of a series of 3-phosphocholine glyceric acid derivatives

Valcavi, U; Aveta, Raffaele; Brandt, Alex; Gb, Corsi; Pascucci, G; Solinas, Francesca

doi:10.1016/0223-5234(90)90116-k

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“…Nucleophilic attack of the hydroxyl group at the nearby carbonyl group generates a five-membered ring intermediate, which can either turn back to the original structure or result in transesterification and therefore change in copolymer molecular structure to a thermodynamically more stable ester (Figure ). This process causes a shift of the proton peaks at 3.8 ppm (CH 2 ) and 5.2 ppm (CH, coinciding with CH of lactide) for the HMG units in the original structure to 4.0–4.5 ppm for the transesterified product (hydrogens at positions 1 and 2; see Figure ) …”

Section: Discussionmentioning

confidence: 99%

Mechanistic Studies on the Degradation and Protein Release Characteristics of Poly(lactic-co-glycolic-co-hydroxymethylglycolic acid) Nanospheres

et al. 2013

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The purpose of this study was to gain mechanistic insights into the effect of different formulation parameters on the degradation and release behavior of protein-loaded nanoparticulate carrier systems based on an aliphatic polyester with pendant hydroxyl groups, poly(lactic-co-glycolic-hydroxymethyl glycolic acid) (pLGHMGA). Bovine serum albumin (BSA) was used as a model protein. BSA-loaded pLGHMGA nanospheres of 400-700 nm were prepared using a solvent evaporation method using pLGHMGA of different molecular weights and different compositions. Also, the concentration of pLGHMGA in the organic phase was varied. The nanospheres showed a continuous mass loss accompanied by continuous decrease in number average molecular weight, which indicates that the degradation of the nanospheres is by bulk degradation with a rapid release of water-soluble low molecular weight fragments. On the basis of NMR analysis, it is concluded that intramolecular transesterification precedes extensive hydrolysis of the polymer and degradation of the nanospheres. BSA-loaded freeze-dried nanospheres showed a significant burst release of 40-50% of the BSA loading. In contrast, nonfreeze-dried samples showed a small burst of around 10-20%, indicating that freeze-drying induced pore formation. Nonlyophilized nanospheres prepared from pLGHMGA with 64/18/18 lactic/glycolic/hydroxymethylglycolic acid (L/G/HMG) ratio showed a relatively fast release of BSA for the next 30 days. Nanospheres prepared from a more hydrophobic pLGHMGA (74/13/13, L/G/HMG) showed a two-phase release. Circular dichroism analysis showed that the secondary structure of the released protein was preserved. This study shows a correlation between release behavior and particle erosion rate, which can be modulated by the copolymer composition.

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Section: Discussionmentioning

confidence: 99%