Biocatalytic Synthesis And Characterization Of Novel Functional Lipids

Funcional lipids are receiving increasing attention due to their biocompatibility, special functions and tailor-made multi-applications. This work devoted to biocatalytic synthesis and characterization of novel functional lipids for different applications. The main results include three parts.1. Preparation of 1,3-oleic-2-palmitic acid triglyceride (OPO) via enzymatic catalyzed-acidolysis. The methods for analysis of fatty acid composition, distribution and triglyceride composition using GC, HPLC and GC-MS have been developed. The fatty acid composition, distribution and triglyceride composition of camellia oil which is an edible vegetable oil in Zhejiang have been analyzed. High oleic acid mixture (～76%) was obtained through saponification from camellia oil. OPO was synthesized by sn-1,3 regiospecific lipases-catalyzed acidolysis of tripalmitin (PPP) with oleic acid. The reaction conditions of two immobilized lipase, Lipozyme TL IM and Lipozyme RM IM catalyzed synthesis of OPO was optimised. The reuse ability of the two lipases were also investigated. Based on the optimised reaction conditions, the synthesis were able to scale up to 20 folder of the production of OPO from palm stearin and oleic acid prepared from camellia oil.2. Biosynthsis of a group of ultra-long chain amphiphilic lipids using Novozym 435. This group of compounds are behenic acid sugar alcohol monoesters with behenic acid (22:0) as an acyl representative and sugar alcohols altered from ethylene glycol to glycerol, erythritol, pentaerythritol, arabitol, xylitol and sorbitol. The synthetic compounds were conformed by 1H NMR, FT-IR and MS. The thermal properties of the synthetic compounds were characterized by DSC analysis. The molecular packing of the synthetic compounds were investigated by Temp-Ramp-FT-IR. The resluts indicated the thermostability of the compounds are largely governed by hydrophobic interactions among the alkanyl chains, while the polar heads may determine the packing patterns. The synthetic compounds show surface activity and improved resistance to PPL (porcine pancreatic lipase)-mediated in vitro lipolysis. Systemic mapping of structure-property-function relationship of the compounds revealed the potential of the compounds for multi-applications.3. Then we focus on examining the potential of this group of compounds as new excipients for developing surfactant-free solid lipid nanoparticles (SF-SLN) by emulsification-diffusion method. The results indicated the head groups have great influence on forming of the nanoparticles. Two compounds, arabitol mono-behenate and sorbitol mono-behenate, were successful made into SF-SLN. Lipophilic drug, fenofibrate was chosen as modelling drug. The SF-SLNs encapsulated with 10% fenofibrate show small particle size and narrow particle distribution. SF-SLNs also show highly stably during storage and long-term in vitro drug release which could be explained by the strong association of the lipophilic drug with hydrophobic alkyl chain of the amphiphilic compounds. Multiple imaging techniques were used to investigated the particles structures which show the SF-SLN are vesicles. This SF-SLN system has the potential for in vivo application.