| Cinnamomum camphora seed kernel is rich in oil, and the oil consists of medium chain fatty acids (MCFA), up to90%of total fatty acids are capric acid (C10:0,53.27%) and lauric acid (C12:0,39.93%), respectively. Oil with such high amount of medium-chain triglycerides (MCT) can be used as a special energy source for patients after surgery, infection, skin burn, AIDS, cancer and diabetic mellitus, and also for those with fat malabsorption and fatty diarrhea due to their metabolic properties. However, Cinnamomum camphora seed oil (CCSO) cannot be used as cooking oil due to its low smoke point, hydrophobic polarity, and unfavorable smell.Liposome, because of their biphasic character, can act as carriers for both lipophilic and hydrophilic drugs. Liposomes are taken as the delivery media of CCSO in order to enhance its bioavailability as well as prolong the residence time of the drugs in the blood, making the drugs release slowly in intestine.The standard curve of oil mass and the peak area of capric acid or lauric acid were established to determine encapsulation efficiency (EE). The regression equations were as follows:for C10:0, y=1924x+48.984, R2=0.9995, for C12:0y=1317.7x+27.723, R2=0.9996. The results showed that the peak areas were both well linearly related to CCSO concentration. Formula were verified that EE could be calculated by peak area ratio method with a good recovery rates and high precision. The shell of liposome was broken by chloroform and methanol with volume ratio of1:1. N-hexane was added to extract the free and total CCSO using refrigerated high-speed centrigugator with5min. Recording to the relationship of peak area and the mass of CCSO to calculate EE.The method is simple and original. For saturated oil that has no ultraviolet absorption is a useful method.The dynamic high pressure microfluidization (DHPM) combined with thin film dispersion method were utilized to prepare CCSO liposome. Using EE and particle size as the evaluation indices, the optimum condition of the impacting factors was studied. Response surface methodology was used to optimize the preparation conditions. The optimum preparation conditions were prepared as follows, concentration of soybean lecithin,3g/100mL; the ratio of lecithin to CCSO,3:1(m/m); lecithin to cholesterol,6.7:1(m/m). phosphate buffer solution as the aqueous phase, pH7.0,0.01mol/L; Tween80,24.2%of the mass of lecithin; and temperature,35℃. Under these conditions, the EE was maintained to (91.8±3.7)%. The mean diameter was (107±8.6) nm by conducting Micro-jet twice at120Mpa.Taking shape, size distribution reconstruction effects and EE as indices, the effects of pre-freezing temperature, pre-freezing time, total freeze-dried time, types of cryoprotectants and the mass ratio of cryoprotectant to lecithin were investigated. The suitable preparation conditions of liposome were as follows:pre-freezing tempera are,-80℃; pre-freezing time,5h; total freeze-dried time,36h; trehalose as suitable cryoprotectant; the ratio of sucrose to soybean lecithin (w/w),2:1. Under these conditions, the EE of CCSO liposome was87.2%with a mean particle size of138.1nm. The results showed that the freeze-dried CCSO liposome had better physical stability with little changes in particle size. The exothermic peak of freeze-dried product was86.42℃.In addition, the changes of particle size and morphology of liposome before and after lyophilization were studied. The morphology of the liposome before and after lyophilization were both small unilamellar vesicles with uniform size and regular shape. But reconstructed CCSO liposome has a thicker biofilm. The60d limb-placing test was conducted. Using appearance, EE, particle size, pH, the amount of leakage and malondialdehyde content as indicators, the results showed that both products had good physical and chemical stability. Release of CCSO were controlled in simulate gastric (SGF) and intestine (SIF).The rate of vitro releasing was low in SGF and became higher in SIF because of the enzyme species. The pancrelipase in the intestine can accelerate the decomposition of CCSO liposome. |
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