• Archives of Pharmacal Research
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• v.10 no.2
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• pp.94-99
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• 1987

By using the former equation (8), we modified the equation which can show the dissimilar osmotic behavior of liposome with composition change. The slope of the new equation was presented as the ratio of osmotically active volume (V$_{act}$= ) to the total volume (V$_{totel}$= $_{acl}$+ V$_{dead}$ ; V$_{dead}$ is osmotically inactive volume) of loposomes, we defined is as a Z-value, which can elucidate the dissimilarity of the osmotic activity of multilamellar liposomes with the change of phospholipid composition and the differences of physicochemical properties of liposomes. Z-value was applied for studying the physico-chemical properties of liposomal membrane. The factor that affects on the Z-value was not the lipid concentration of liposome stock dispersion but the lipid composition of liposomal membrane. As the content of dicetylphosphate, the negative charged phospholipid, was increased, the osmotic activity, represented by Z-value, of multilamellar liposome was decreased. Using the hypertonic conditions (shrinking region), Z-value steadily increased and reached a maximum at 10 mole percent cholesterol with increasing the cholesterol content.

• Bulletin of the Korean Chemical Society
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• v.17 no.3
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• pp.239-244
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• 1996

Mastoparan B (MP-B) that is a novel MP isolated from the hornet Vespa basalis, was studied as compared with MP, in terms of interaction with phospholipid bilayer and antimicrobial activity. MP-B has more hydrophilic amino acid residues in hydrophilic face of amphiphilic α-helical structure than MP. The both peptides exhibited considerably different effect on interaction with lipid bilayers, e.g. their conformation in the presence of acidic and neutral liposomes, dye-release ability from encapsulated liposomes, but on the whole the interaction mode was similar. On antimicrobial activity, MP had a strong activity against Gram-positive bacteria but no against Gram negative ones. Contrary to this, MP-B had a strong activity against Gram-positive and potent against Gram-negative ones. Since both peptides have almost same residues on the hydrophobic side, such more hydrophilic surface on the molecule seems to lead to the subtle change in its interaction with membranes, resulting in the alternation in its biological activity.

• Journal of Pharmaceutical Investigation
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• v.34 no.4
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• pp.305-310
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• 2004

This study was to prepare the anionic liposomes which were to release anticancer drug (doxorubicin) at the hyperthermia temperature $({\sim}42^{\circ}C)$ and to stabilize in bovine serum solution at $37^{\circ}C$. The vesicle size and zeta potential of liposomes in Tris-HCl buffered solution (pH 7.4) were measured by an electrophoretic light scattering spectrophotometer. To estimate the stability of liposomes, liposome size was measured in bovine serum solution at $37^{\circ}C$ for 72 h. The release of doxorubicin from liposome was determined by measuring the fluorescence intensity using fluorescence spectrophotometry with temperature and time. The size of liposomes was from 120 to 160 nm and zeta potential was from $-33.3{\pm}2.4$ to $-75.6{\pm}6.9\;mV$. Anionic liposome was stabilized in bovine serum solution at $37^{\circ}C$ within 72 h. Additionally, the release transition temperature of doxorubicin from liposomes was increased by increasing mole % of anionic phospholipid.

• Journal of Life Science
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• v.12 no.2
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• pp.144-150
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• 2002

This experiment was designed to investigate the antioxidant effects of Chrysanthemum coronarium L. (CC) fractions on the liposomal phospholipid membranes. The sample CC was extracted and fractionated into five different types, methanol (CCMM), hexane (CCMH), ethylacetate (CCMEA), butanol (CCMB), and aqueous (CCMA) fractions. The antioxidant activities of CC fractions in oxidized dilinoleoylphosphatidylcholine (DLPC) liposomes were examined by spectrophotometry measuring conjugated dienes. The oxidation indices of five CC fractions exhibited weaker antioxidant activities than that of BHT in oxidized DLPC liposomes, however, showing much similar antioxidant activities of $\alpha$-tocopherol in the oxidized DLPC liposomes, which is known as a potent antioxidant. Among CC fractions, CCMM and CCMA in oxidized DLPC liposomes showed rather effective than $\alpha$-tocopherol after 2 h. These results strongly indicate that bioactive substances in CC fractions have a kind of function as potent antioxidants against biomembrane oxidation.

• Archives of Pharmacal Research
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• v.18 no.2
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• pp.84-89
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• 1995

The complexation and physical characteristics of egg phosphatidylcholine (PC) liposome containing amphotericin B(AmB) were investigated through circular dichrosim(CD) spectra, the size distribution, the turbidity change, and the calcein release. CD spectra of AmB-containing egg PC mxture exhibited a positive peak around 330 nm indicative of complexation of AmB and four negative peaks. The positive peak increased up to $2.2{\;}millidegree/{\mu}g$ AmB as AmB contents increased up to 12% (w/w), suggesting that AmB-phospholipid complexation was promoted by the antibiotics. The effective diameter of liposomesa by dynamic light scattering decreased from 450 nm to 220 nm as the amount of AmB in liposomes increased from o to 30% (w/w). The complexation may be responsible for the reduction in size. On the other hand, at around 1 mN deoxycholate (DOC), the reltive turbidities of 5 and 10% (w/w) AmB-containing liposome suspension were less than 1 probably due to the soblubilization of the complex, while those of pure PC liposome suspension were larger than 1 at the same concentration. Deoxycholate-induced release of liposomes, indicating the intercalation of the drug into the bilayers. Therefore, it is concluded that in AmB/eggPC/water system, AmB-phospholipid complexcoexists with AmB-containing liposomes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.3
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• pp.506-510
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• 2002

The effect of antioxidant activity of Platycodon grandiflorum (PG) on the liposomal phospholipid membrane was investigated by spectrophotometry. Membrane oxidation causes damage to the membrane fluidity and permeability. It brings further destruction to the sustenance of biological homeostasis. In addition, it is related to several diseases, aging and carcinogenesis. The sample PG was extracted and fractionated to five different types; butanol (PGMB), ethylacetate (PGMEA), ethylether (PGMEE), hexane (PGMH) and methanol (PGMM). The oxidation indices of PGMEA and PGMEE fractions in oxidized dilinoleoylphosphatidylcholine (DLPC) liposomes had stronger antioxidant activities than that of ${\alpha}$-tocopherol and were similar to antioxidant activities compared with butylated hydroxy toluene (BHT), a well-known potent antioxidant, in oxidized DLPC liposomes. The oxidation indices of PGMM extract, PGMB and PGMH fractions exhibited weak antioxidant activity compared with ${\alpha}$-tocopherol in oxidized DLPC liposomes. The oxidation indiex of PGMEE fractions added with vitamin C showed even strong antioxidant activity in the oxidized DLPC liposomes. The oxidation activity of BHT with vitamin C also proved to be stronger than BHT without vitamin C. Therefore vitamin C evidently helps to improve the effect of antioxidant in DLPC liposomes. These results indicate that potentially bioactive substances in PGMEE fraction has a function as potent antioxidant against phospholipid membrane oxidation.

• BMB Reports
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• v.35 no.4
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• pp.358-363
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• 2002

Chemical and photochemical processes during storage and preparation rapidly degrade retinol, the most active form of vitamin A. therefore, the efficacy of incorporation into liposomes in order to modulate the kinetics of retinol degradation was investigated. Retinol was readily incorporated into multilamellar liposomes that were prepared form soybean phosphatidylcholine; the extent of the incorporation was 98.14±0.93% at pH 9.0 at a ratio of 0.01 : 1 (wt:wt) retinol : phospholipid. It was only marginally lower at higher retinol concentrations. The pH of the hydration buffer had a small effect. The incorporation efficiency ranged from 99.25±0.47% at pH 3 to 97.45±1.13% at pH 11. The time course of the retinol degradation in the aqueous solution in liposomes was compared to that of free retinol and free retinol with α-tocopherol under a variety of conditions of pH(3, 7, and 11), temperature(4, 25, 37, and 50℃), and light exposure(dark, visible, and UV). The retinol that was incorporated into the liposomes degraded significantly slower than the free retinol or retinol with α-tocopherol at pH 7 and 11. At pH 3, where the free retinol degrades rapidly, the degradation kinetics were similar in liposomes and the presence of α-tocopherol. At pH 7.0 and 4℃ in the light, for example, free aqueous retinol was completely degraded within 2 days, while only 20% of the retinol in the liposomes were degraded after 8 days. In general, the protective effect of the liposome incorporation was greater at low temperatures, at neutral and high pH, and in the dark. The results suggest that protection is greater in the solid, gel phase than in the fluid liquid crystalline phase lipids. These results indicate that the incorporation into liposomes can extend the shelf-life of retinol under a variety of conditions of temperature, pH, and ambient light conditions.

• Journal of Photoscience
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• v.8 no.3_4
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• pp.123-126
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• 2001

We have attempted to determine the Germanium ion (G $e^{4+}$) effect on the human body by observing the formation of artificial lipid membrane and photolysis in the mineral water containing G $e^{4+}$ ion. The artificial lipid membrane is prepared by using the phospholipid in the Germanium water and the formation efficiency of the liposomes is compared with those obtained in the plain mineral water without G $e^{4+}$ ion. This work shows that the liposomes are formed in the Germanium water better than in the non-Germanium water. The liposomes can be photolyzed by superoxide anion ( $O_{2-}$$^{.}$) produced in the presence of some peptide such as NAT (N-acethyl-L-tryptophan). However, this is inhibited by superoxide dismutase (SOD), and it was found that the activity of SOD on the inhibition of the liposomes oxidative damage is higher in the Germanium water than in the non-Germanium water. It is concluded that the G $e^{4+}$ ion in mineral water helps the formation of new cell as well as elevation of SOD activity for the lipid oxidation.n.

• Journal of Pharmaceutical Investigation
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• v.31 no.1
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• pp.43-47
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• 2001

Sterically stabilized liposomes (SSL) have been introduced for longer circulation in blood than conventional liposomes (CL). However, there are a couple of problems in SSL preparation due to the instability of phospholipid and the degradation of drug in aqueous conditions. To solve these problems, it is necessary to go through lyophilization process. Therefore, in this study, effects of lyophilization on SSL were evaluated for physical characteristics changes upon rehydration of lyophilized SSL such as the particle size, efficiency of drug entrapment, turbidity and drug release. SSL containing streptozocin, a water-soluble anticancer drug as a model compound, were prepared with DSPC and DSPE-PEG 2000. The size was controlled to 100 nm by extrusion with polycarbonate membrane, and sucrose was used as a cryoprotectant for lyophilization at the 1:3 (lipid:sucrose) ratio. Upon rehydration of lyophilized SSL, the average size was in the range of $50{\sim}200\;nm$ which is adequate for longer circulation in blood, and the encapsulation efficiency was kept as its initial state. Rehydrated SSL were not adsorbed to rat plasma protein and revealed a similar drug release profile to that of fresh SSL before lyophilization. Therefore, lyophilization could be introduced efficiently to overcome aqueous instability problems of SSL.

• Archives of Pharmacal Research
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• v.15 no.4
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• pp.309-316
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• 1992

The effects of lipid peroxidation on the fluidity of the lipid bilayers of the human erythrocyte ghosts and egg-lecithin phospholipid liposomes have been studied. For the measurements of the peroxidation extent and the fluidity of the membranes, the thiobarbituric acid-reactive substances and the fluorescence depolarization of 1, 6-diphynyl-1, 3, 5-hexatriene labelled into the membrane were employed, respectively. The lipid peroxidation was performed in hypoxanthine/xanthine oxidase/ferrous ion, and hydrogen peroxide/ferrous ion systems. The results of these experiments show that both of the xanthine oxidase and hydrogen peroxide systems effectively. The lipid peroxidation decreased the fluidity of the membranes, especially at the very early stage of the peroxidation reaction. The decrease in the fluidity of membrane by the lipid peroxidation has been ascribed to the alteration of the polyunsaturated acyl chains of lipids and cross linkages among the membrane components. However, under drastic condition of lipid peroxidation, tdhe fluidity of the membrane rather increased possibly due to the deterioration of the membrane integrity by the peroxidation. Morphological change of the erythrocyte on peroxidation has also been observed.