Microemulsion of seal oil markedly enhances the transfer of a hydrophobic radiopharmaceutical into acetylated low density lipoprotein

Diets Enriched in Fish-Oil or Seal-Oil have Distinct Effects on Lipid Levels and Peroxidation in BioF1B Hamsters

Aim:

Fish-oil omega-3 polyunsaturated fatty acids (n-3 PUFAs) are mostly esterified to the sn-2 position of triglycerides, while in seal-oil triglycerides, these are mostly esterified to the sn-1 and -3 positions. We investigated whether fish-oil and seal-oil feeding has a different effect on the regulation of lipid metabolism and oxidative stress in BioF₁B hamsters.

Methods:

BioF₁B hamsters were fed high fat diets rich in fish-oil or seal-oil for 4 weeks, and fasted for 14 hours prior to blood and tissue collection.

Results:

Plasma and hepatic lipids and lipid peroxidation levels were significantly lower in seal-oil-fed hamsters as compared to those fed fish-oil. There was a selective hindrance of clearance of lipids in fish-oil-fed hamsters as reflected by higher levels of plasma apoB48.

Conclusion:

Differences in the fatty acid composition and positional distribution of n-3 PUFAs in triglycerides of fish-oil and seal-oil are suggested to trigger metabolic differences.

Squalene emulsions for parenteral vaccine and drug delivery

Squalene is a linear triterpene that is extensively utilized as a principal component of parenteral emulsions for drug and vaccine delivery. In this review, the chemical structure and sources of squalene are presented. Moreover, the physicochemical and biological properties of squalene-containing emulsions are evaluated in the context of parenteral formulations. Historical and current parenteral emulsion products containing squalene or squalane are discussed. The safety of squalene-based products is also addressed. Finally, analytical techniques for characterization of squalene emulsions are examined.

The effect of seal oil on paclitaxel induced cytotoxicity and apoptosis in breast carcinoma MCF-7 and MDA-MB-231 cell lines

Some studies have suggested that omega-3 polyunsaturated fatty acids (PUFAs) have an inhibitory effect on the growth of cancer cells and therefore have the potential to increase the efficacy of cancer chemotherapeutic drugs. Considering that omega-3 PUFAs are present abundantly in harp seal oil, we investigated the effect of seal oil on the cytotoxicity and apoptosis induced by paclitaxel in 2 breast cancer cell lines, MCF-7 and MDA-MB-231, respectively. Cytotoxicity evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that the concentration of paclitaxel that is required for 50% inhibition of cell growth in the presence of seal oil was significantly lower than that of paclitaxel alone. Apoptosis assessment based on morphological changes and DNA fragmentation results indicated that more cells treated with paclitaxel in combination with seal oil underwent apoptosis than with paclitaxel alone. Western blot analysis showed that the expression of B cell lymphoma-2 (Bcl-2) protein, an apoptosis inhibitory protein, in both cell lines was decreased more significant by paclitaxel in combination with seal oil than by paclitaxel alone. In addition, seal oil alone was found to induce apoptosis in both cell lines tested, which appeared to be due to the increased intracellular lipid peroxides produced. It is therefore concluded that paclitaxel in combination with seal oil demonstrated enhanced cytotoxicity and apoptosis in MCF-7 and MDA-MB-231 cells compared to paclitaxel alone, and the use of seal oil may be beneficial in the treatment of breast cancer.

Preparation and physical characterization of a novel marine oil emulsion as a potential new formulation vehicle for lipid soluble drugs

Emulsions often contain vegetable oils such as soybean oil. In this study, a 10% (w/w) of marine mammal oil emulsion was prepared. The effect of a group of emulsifying agents on the stability of the 10% of seal oil emulsion was examined. The emulsifying agents studied were hydrogenated castor oil coated with various polyoxyethylene derivatives. It was found that 2.5% of HCO-40 resulted in the most stable seal oil emulsion. The size of the emulsified droplets defined by their diameters was found to be around 240-270 nm. The initial zeta-potential and pH value of the emulsion were found to be around -27 mV and 3.5, respectively, which decreased over time, to about -31 mV and 2.4, respectively. This is believed to be a result of the hydrolysis of triacylglycerides into free fatty acids in the emulsion. The effect of various amounts of Crodasinic LS-30, a negatively charged surfactant, and Incroqal Behenyl TMS, a positively charged surfactant, on the emulsion was investigated. It was shown that Crodasinic LS-30 had very little effect on the particle size, zeta-potential and pH, while the effect of Incroquat Benhenyl TMS was found to be dependent upon the concentration of the surfactant used.

Ex vivo evaluation of a novel polyiodinated compound for early detection of atherosclerosis

Atherosclerosis is a primary cause of heart disease and stroke; it is the underlying cause of about 50% of all deaths in Western countries. It is known that early detection of atherosclerotic lesions would significantly reduce the risk of mortality. The objective of this study was to develop a radioimaging method for early detection of atherosclerotic plaques. A novel polyiodinated cholesterol analog, cholesteryl 1,3-diiopanoate glyceryl ether (C2I, patent pending), was synthesized and radiolabeled with 125I. 125I-C2I was incorporated into acetylated low-density lipoprotein (AcLDL), which is considered to be an atherosclerotic plaque-seeking carrier. 125I-C2I was also prepared as a chylomicron-like emulsion. Transgenic mice deficient in apoE and low-density lipoprotein receptors (LDLR), known as apoE/LDLR double knockout, were used as an animal model of early atherosclerosis. 125I-C2I/AcLDL or 125I-C2I emulsion was injected into the apoE/LDLR knockout mice via the tail vein, and the mice were killed humanely 24 h after injection. Various tissues including aorta were removed and radioactivity was determined. The aorta samples were also imaged to determine the accumulation of radioactivity from C2I. The images were compared to the atherosclerotic lesions revealed by histological studies. It was found that both 125I-C2I/AcLDL and 125I-C2I emulsion resulted in accumulation of radioactivity at the site of early atherosclerotic lesions, and they therefore may be useful for early detection of atherosclerosis.

Diethyl ether fraction of Labrasol having a stronger absorption enhancing effect on gentamicin than Labrasol itself

In our previous study, we had reported that Labrasol has a good gastrointestinal (GI) absorption enhancing effect on poorly absorbable drugs. In order to improve further absorption enhancing effect of Labrasol on gentamicin (GM), which is a representative water-soluble, poorly absorbable drug, Labrasol was fractionated with hexane, diethyl ether, ethyl acetate and water. The absorption enhancing effect of each fraction of Labrasol and Labrasol alone were evaluated in vivo using rats. Each test formulation of GM was administered into the rat colon at a dose of 5.0 mg/kg and plasma GM concentrations were measured by a HPLC method. Among the four fractions of Labrasol and Labrasol, diethyl ether fraction showed the strongest absorption enhancing effect on GM. When the doses of diethyl ether fraction were 1.0, 0.5 and 0.1 ml/kg, the Cmax values were 8.95 +/- 1.46, 8.02 +/- 2.14 and 7.41 +/- 1.25 microg/ml, respectively. Moreover, AUC(0-6) values were also maintained at high level, i.e. 27.28 +/- 5.90, 20.32 +/- 3.79 and 19.61 +/- 2.09 microg h/ml. Based on the AUC(0-6) values obtained with each fraction, the rank order of absorption enhancing effect on GM was diethyl ether > ethyl acetate=hexane > aqueous fraction.

Enhanced delivery of AZT to macrophages via acetylated LDL

It is known that infected macrophages play an important role in HIV pathogenesis acting as a reservoir for dissemination of the virus to various organs. Enhanced and/or specific delivery of anti-HIV agents to infected cells is expected to improve their therapeutic index by increasing efficacy and reducing toxicity. Acetylated low density lipoproteins (AcLDL) are known to be taken up by macrophages via scavenger receptors and appear to be good carriers for targeting drug molecules to macrophages. This study investigated the delivery of 3'-azido-3'-deoxythymidine (AZT), an anti-HIV agent, to macrophages using AcLDL. Since the incorporation of AZT into AcLDL was found to be low, several derivatives of AZT including 5'-O-13-oxamyristate-AZT (5'-O-oxaMyr-AZT) have been synthesized as prodrugs. The prodrugs were incorporated into AcLDL using two different methods, namely the contact method and the microemulsion method. Our results demonstrated that the microemulsion method was more effective. The physicochemical properties of the AcLDL/prodrug complex were evaluated by electrophoresis and electron microscopy (EM). Incubation of the complex with plasma resulted in little distribution of the incorporated drug molecules from AcLDL to other components of the plasma, suggesting that the complex was quite stable. Cellular uptake studies using J774.A and U937 demonstrated that AcLDL/prodrug was taken up about 10 times more than AZT. The presence of excess AcLDL was found to inhibit the cellular uptake of AcLDL/5'-O-oxaMyr-AZT by macrophages while excess high density lipoprotein (HDL) or low density lipoprotein (LDL) was found to have little effect, suggesting that the AcLDL/prodrug complex is taken up into macrophages via the scavenger receptor.