JPH02129119A - Liposome preparation - Google Patents

Abstract

PURPOSE:To obtain a liposome preparation physiological activity such as anti- thrombus, anti-asthma, antitumor action, etc., containing a highly unsaturated fatty acid derivative. CONSTITUTION:<=30%(W/V), preferably 60-100%(W/W) at least one of compounds shown by the formula (R1 is oleoyl or palmitoyl: R2 is eicosapentaenoyl or docosahexaenoyl) is used and pharmaceutically manufactured by ultrasonic treatment, reversed phase evaporation or injection to give the aimed substance. The preparation can be administered orally or parenterally, is especially effective as injection and drop. A dose is properly 0.01-200mg calculated as active ingredient/kg weight per adult daily. Since the substance is pharmaceutically manufactured into liposome, a large amount of the preparation can be administered as a highly concentrated aqueous solution to abdominal cavity and vein.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a liposome preparation comprising a highly unsaturated fatty acid derivative and to novel pharmaceutical uses. The liposome preparation comprising the highly unsaturated fatty acid derivative of the present invention has physiological activities such as antithrombotic, antiasthmatic, and antitumor effects.

(Prior art) Phospholipids consist of a lipid bilayer membrane in water with a diameter of 0.05 mm.
It is known to form molecular aggregates called ~10-liposomes. Liposomes are a type of microcapsule material that encapsulates drugs and enzymes, and rather function to encapsulate and assist in transporting physiologically active drugs. It has also been known for some time that phospholipids themselves are effective against arteriosclerosis, neurosis, liver dysfunction, cholelithiasis, respiratory distress in premature infants, inflammation, and the like. 1000 for biological membranes
It is said that more than one type of phospholipid exists, and the biological activities exhibited by these phospholipids are gradually being clarified.

Recently, it has been reported that plant-derived phosphatidylinositol exhibits cytotoxicity specifically to cancer cells, that lysophosphatidylcholine, which has blood-letting properties, exhibits macrophage activating ability, and that platelet activating factor has platelet activating effects and macrophage activation. It has been found that this drug induces various reactions in vivo, such as blood pressure and blood pressure lowering effects.

(Problems to be Solved by the Invention) Regarding phospholipids with a specific structure that have physiological activity, the present inventors have discovered that leukotrienes, which play an important role in asthma, allergies, inflammation, myocardial infarction, and gastrointestinal diseases, are produced from arachidonic acid. A specific inhibitor of 5-lipoxygenase, which is an enzyme produced by 5-lipoxygenase (patented in 1988, antiallergic agent), and an anticancer agent that shows strong differentiation-inducing activity against teratoma cells and erythroblastic leukemia cells (patented in 1982) -318616
We found that it is effective as an anticancer drug.

The main component of these phospholipids is phosphatidylcholine, which has an oleoyl group or valmitoyl group at the 5n-1 position and an eicosapentaenoyl group or docosahexaenoyl group at the 5n-2 position. Therefore, these phosphatidylcholines were mainly dissolved in a solvent that does not cause cytotoxicity to cells, such as ethanol, and their physiological activities were confirmed.

In terms of formulation, due to the characteristics of these substances, they are processed into intravenous injections dissolved in ethanol and enteric-coated capsules.

Enteric-coated capsules are made by molding these compounds into granules together with lactose and cellulose, which are used as a base material to float and flow in a fluidized bed, and then coated with a coating base material consisting of cellulose and phthalate to form enteric-coated granules. . Therefore, the content of the target compound in the enteric-coated capsule formulation is low;
Its absorption also occurs through the intestinal tract. If the dose is increased to make the target compound exert its physiological activity more strongly in the body,
This formulation involves continuous high N uptake of the coated substrate. Therefore, there is a need for a dosage form that does not involve the ingestion of a large amount of such coated substrates, and that allows for a more efficient dosage and for a larger amount to be taken into the target site.

Injections and infusions are prepared by dividing these compounds into several hundred times the amount of glucose, dissolving them in ethanol before use, and adding a large amount of physiological saline to the solution. Therefore, the content of the target compound in the injection/infusion preparation is very low relative to the total amount, and there are concerns about the safety of the ethanol used for long-term parenteral administration to living organisms. Therefore, we attempted to reduce the amount of ethanol used in injections and infusions (and increase the content of the target compound in the main rules), but no sufficient effect was obtained.

In addition, phospholipids are insoluble in water and difficult to form into a solution, and even when made into an emulsion using an emulsifier, the concentration increases, making it difficult to use as an injection, and the medicinal efficacy is also reduced.

Therefore, there is a need for a highly concentrated preparation that solves the problem of continuous ingestion of a large amount of solvent and coated substrate due to high dosages, and allows for more uptake into the target area.

An object of the present invention is to provide a high-concentration liposome preparation that is a dosage form that can efficiently administer large amounts of phosphatidylcholine containing highly unsaturated fatty acids that exhibit physiological effects.

(Failure to solve the problem) The present invention relates to general formula (I): CH, -OR.

CH-OR, (1) CHt PO4-(CHz)zN''(CHi)z (wherein, R3 is an oleoyl group or a valmitoyl group, and R
2 is a liposome preparation containing at least one compound represented by the following formula (eicosapentaenoyl group or docosahexaenoyl group).

Examples of the compounds included in the above general formula (1) include the following.

5n-1-oleoyl-5n-2-eicosapentaenoyl-3n-3-glycerophosphocholine (1), 5n-1-valmitoyl-3n-2-eicosapentaenoyl-3n-3-glycerophosphocholine Choline (2), 5n-1-oleoyl-3n-2-docosahexaenoyl-3n-3-glycerophosphocholine (3), 5n-2-valmitoyl-3n-2-docosahexaenoyl-5n-3 - Glycerophosphocholine (4), a mixture (5) of (1) and (2), a mixture (6) of (3) and (4), a mixture (7) of (1) and (3).

The above compound is disclosed in Japanese Patent Application No. 62-318617 and Japanese Patent Application No. 62-318617.
No. 318616, obtained by the method described in JP-A No. 61-12919.

That is, the above-mentioned phosphatidylcholines are synthesized using a method combining chemical synthesis using glycerophosphocholine with a natural structure as a starting material and biochemical reactions using various phospholipases, and reverse-phase partition column chromatography using phosphatidylcholine in phospholipids from egg yolks and egg whites. It can be produced by a graphical isolation method. In particular, the compound of type (1) can be obtained by selecting the origin of the phospholipid as a starting material and the fatty acid species used in the acylation reaction.

We have found that suitable for high doses of compounds of general formula (I),
We investigated a dosage form that would allow greater uptake into the target area.

The physiologically active compound of general formula (1) used by the present inventors was a phosphatidylcholine group. In the course of examining these dosage forms containing a high content of phosphatidylcholine, it was found that all of the constituent fatty acids of the -format (1) compound have 14 or more carbon atoms. Carbon number 14
Phosphatidylcholine, which has two fatty acids of more than It was assumed that the body was removed, forming closed vesicles and becoming liposomes. In fact, the compound of form (1) formed liposomes with a high concentration of 50 μ/- or more in aqueous solutions and phosphate buffers, and its stability was also excellent.

In general, liposomes of phosphatidylcholine having an unsaturated fatty acid group have a rapid transfer of liposome membrane components into cells and exchange of lipid components between liposomes and cell membranes. Liposomes with compounds are suitable for exerting the biological activity of these compounds.

Phosphatidylcholines are easily hydrolyzed by heat, pH 1 enzymes, etc., and phosphatidylcholines having unsaturated fatty acid groups are particularly susceptible to autooxidation. Therefore, when liposomes are formed using the compound of form (1), vitamin E or vitamin E ester can be added thereto as an antioxidant. These substances also have a stabilizing effect in plasma. In addition, all steps were performed under an inert gas stream, and the obtained liposomes were analyzed using the lipid peroxide determination method using potentiometric titration (Hara, Hase Yo, Lead powder, Toya, Yukagaku, 34, 2).
83.1985), good results can be obtained by adjusting the amount to 20 meq/kg or less.

Commercially available phosphatidylcholines for liposomes include naturally occurring egg yolk lecithin, soybean lecithin, hydrogenated soybean lecithin, and synthetic products such as dipalmitoylphosphatidylcholine and dioleoylphosphatidylcholine, but these phosphatidylcholines have relatively low phase transition temperatures. Because of its high temperature, it is heated at 70 to 80°C during liposome formation. However, the compound of general formula (I) of the present invention has a highly open unsaturated fatty acid in its structure, and therefore has a very low phase transition temperature. Therefore, when these compounds are used alone, liposomes are easily formed at temperatures below 20°C, and there is no need for heating at all. In addition, when liposome formation is carried out by maintaining the temperature at 70 to 80°C, an extruder (extrusion molding machine) is used to
Mole unilamellar vesicles (small unilamellar vesicles) vesicle fusion occurs after preparation (small unilamellar liposomes), resulting in decreased stability. However, when liposomes are formed after adding sterols such as cholesterol or cholestane as a membrane-forming agent in order to stabilize these liposomes, the stability is poor at temperatures below 20°C, and the stability is poor at 70-80°C. It was good. Particularly in the case of cholesterol addition, -form (r
) is suitably 1 part or less of cholesterol per 2 parts of the compound.

The stability of liposomes in plasma and serum is better when vitamin E and cholesterol are added, and especially when cholesterol is added, distribution to the liver and lungs is suppressed, resulting in a high blood concentration and Disappearance is delayed. Therefore, - liposome formation with compounds of form (1) allows for greater uptake of these into the target site and provides a dosage form containing them in high concentration, making it possible to carry out continuous high doses. becomes possible.

As a method for producing a liposome preparation using the compound of general formula (1) used in the present invention, an ultrasonic treatment method, a reverse phase evaporation method, an injection method, etc. can be adopted. Liposomes are broadly classified into multilayer type, small single-layer model, large single-layer model, reversed phase evaporation injection molding, and giant type according to their morphology. The liposomes can be in any form.

In the liposome preparation of the present invention, it is advantageous to use the compound of formula (1) in an amount of 30% (w/w) or more, preferably 60 to 100%, as one of the constituent components. When preparing liposomes, - as a film forming agent other than the compound of format (1),
It is preferable to add sterols such as cholesterol and cholestane, which do not affect the physiological activity of this compound, and vitamin E as an antioxidant, but stearylamine and dicetyl phosphate, which affect the charge of the lipid bilayer membrane, are preferable. , phosphatidic acid, and other charged substances are not preferred for exerting the physiological activity of the compound of general formula (1).

Although there are no particular limitations on the liposome preparation method of the present invention, the ultrasonication method mainly used is as follows. That is, under a nitrogen stream, the compound of form (1) and other membrane stabilizers and antioxidants if necessary are weighed out onto the inner wall of an eggplant flask containing glass beads, and lipid-based substances such as hexane, chloroform, and ethanol are added. It is dissolved in a solvent, and then the solvent is distilled off under a nitrogen stream to form a thin film.

Purified water, physiological saline, phosphate buffer, etc. are added to this flask, and the resulting mixture is shaken, preferably ultrasonically, while maintaining it at room temperature or around 70°C to obtain a liposome dispersion. . The resulting dispersion is passed through a 0.2- to 0.05-tnn filter using an extruder to adjust the particle size of liposomes.

This dispersion can be used as it is, or it can be pulverized by freeze-drying.

Liposomes prepared according to the above preparation method may change in particle size during preparation or storage due to differences in the composition of the membrane-forming agent, etc., so confirm liposome formation by fluorescence microscopy using fluorescent lipids. went. In addition, regarding the physiological activity of the prepared liposomes, the antiallergic effect was 5.
- The lipoxygenase inhibition rate and anticancer activity were determined by measuring the differentiation induction rate of erythroblastic leukemia cells. As a result, it was confirmed that even if the compound represented by the -format (1) was processed into a liposome preparation, its physiological activity was not completely lost.

The liposome preparation of the present invention can be administered either orally or parenterally, and particularly can be used as an injection or a drip. Although the dosage depends on the symptoms, the appropriate amount for adults is 0.01 to 200 μg/kg body weight of the active ingredient per day.

(Effect of the invention) The liposome preparation provided by the present invention has antithrombotic,
Since phosphatidylcholine having an acyl group containing eicosapentaenoic acid or docosahexaenoic acid, which exhibits physiological activities such as anti-asthma and anti-tumor effects, is used, the liposome-like endoplasmic reticulum itself has a strong medicinal effect. Conventionally, substances that could only be processed into injections/infusions by adding glucose and dissolving them in ethanol, or into enteric-coated capsules by adding various excipients, are now formulated into liposomes, allowing for high concentrations. It is now possible to administer large amounts into the peritoneal cavity or vein as an aqueous solution.

(Example) Hereinafter, the present invention will be explained in more detail by showing production examples, formulation examples, acute toxicity test examples, and pharmacological test examples of the compounds used in the present invention.

Hereinafter, the compounds (11, (2), (3), (4), (
Some specific manufacturing methods of 5), (6), and (7) will be shown as manufacturing examples.

[Manufacturing example]

Production Example 1 Compound (1) 1-oleoyl-3 in dehydrated chloroform 50-
- Glycerylphosphorylcholine 776 mg (1,49 mmol), eicosapene citric anhydride 960 ■ (1,
64 mmol) and 203 nv (1,66 mmol) of N,N-dimethyl-4-aminopyridine were added, and the mixture was reacted for 24 hours with stirring at room temperature.

After the reaction, N, N-dimethyl=4- in the reaction mixture
To remove aminopyridine, 25 ml of acidic cation exchange resin (manufactured by Rohm & Haas, registered trademark Amberlite 200C) and basic anion exchange resin (
A glass column with a diameter of 3.0 cm and a length of 50 cm was filled with 50 ml of a mixture of equal amounts of Amberlite IRC-50 (registered trademark) and Amberlite TRA-93 (manufactured by Rohm & Haas), and was then flushed with chloroform. did.

This treated solution was subjected to silica gel thin layer chromatography (developing solvent was chloroform:methanol:water=65:25:
4. As a result of analysis using iodine), Rf (If 0.
The purple coloration of 1 to 0.3 (indicating a complex of N,N-dimethyl-4-aminopyridine and acid anhydride) completely disappeared.

Chloroform was distilled off under reduced pressure, and the residue was eluted using chloroform soom1 using a glass column with a diameter of 1.5 cm and a length of 50 cm packed with 20-silica gel, and the fraction 1 (Fl), chloroform:
Using methanol-10:1.500-? Using fraction 2 (pz), chloroform:methanol=5:1.1500-? The extracted material was designated as fraction 3 (F3).

F,, F,,F3 were subjected to silica gel thin layer chromatography (developing solvent was chloroform:methanol:water=65
:25:4, color development is iodine) As a result of analysis, the target product 1-oleoyl-2-eicosapentaenoyl-3 was detected.
- Glycerophosphocholine was contained in F3.

The solvent of F was distilled off under reduced pressure to obtain 70 mg of ■-oleoyl-2eicosapentaenoyl-3-glycerophosphocholine.

The obtained 1-oleoyl-2-eicosapentaenoyl-3-glycerophosphocholine was analyzed using the direct introduction method of FAB-MS, and the molecular ion of this compound was 8.
06 ((M+H)°) was clearly observed. Further, 1-oleoyl-3-glycerylphosphorylcholine, which is an unreacted raw material, was not observed.

Production Example 2 Compound (2) In 50 ml of dehydrated chloroform, 1000 μl of 1-valmitoyl-3-glycerylphosphorylcholine (2,0
2 mmol), eicosapene citric anhydride 2300 m
g (3,92 mmol), and N,N-dimethyl 4-
500 mg (4.10 mmol) of aminopyridine was added, and the mixture was reacted for 24 hours with stirring at room temperature.

After the reaction was completed, the product was purified according to Production Example 1. As a result, 1
-Valmitoyl-2-eicosapentaenoyl-3-glycerophosphocholine 563 mg was obtained (yield 35.8
%).

Production Example 3 Compound (3) In 50 ml of dehydrated chloroform, 1-oleoyl-
3-glycerylphosphorylcholine 776mg (1,4
9 mmol), docosahexaenoic anhydride 1, 047
(1,64 mmol), and N,N-dimethyl-4-
203 mg (1.66 mmol) of aminopyridine was added, and the mixture was reacted for 24 hours with stirring at room temperature.

After the reaction was completed, the product was purified according to Production Example 1. As a result,■
-Oleoyl-2-docosahexaenoyl-3-glycerophosphocholine 773 mg (yield 62.5%).

Production Example 4 Compound (5) Immediately after egg collection, 300 g of fertilized rainbow trout eggs were mixed with chloroform/methanol (2/1, vol/vol).
? The mixture was placed in a pot at 1.21 p.m. and subjected to high-speed shear extraction using a homomixer for 30 minutes. The filtered wet cake was mixed with 0.4 of the above solvent.
7! The extraction operation was performed twice, 0.61 g of chloroform and 0.61 g of distilled water were added to the total filtrate, and the chloroform layer was collected and solvent removed to obtain 20.2 g of total lipids.

Pour the obtained total lipids into 250ml of water-cooled acetone! The mixture was extracted for 10 minutes with stirring, and the precipitate was collected. This operation was repeated four times to obtain 10.4 g of phospholipid fraction.

Divide the total amount of phospholipids into four equal parts and perform silica gel column chromatography (Fujigel CG-3, Mito Chemical, diameter 5cm).
m, length 40 cm column (700 cc),
Chloroform/methanol (4/1, vol/vol)
Phospholipids that elute before phosphatidylcholine are removed using a mixed eluent system, and chloroform/methanol (
Elute with an eluent system of 3/2, vol/vol) mixture, T
LC (developing solvent: chloroform/methanol/water, 65
/25/4, vol/vol/vol) and Rf value 0.
Fractions in which a single spot was observed between 20 and 0.30 (phosphatidylcholine) were collected. The same operation was repeated four times to obtain 2.7 g of phosphatidylcholine.

Then, the obtained phosphatidylcholine was added to 1% wt/v
ol in methanol, a fully automated large-scale preparative liquid chromatography HLC-837 manufactured by Tosoh was equipped with an ODS packed column (2 inches in diameter, 60 cm in length), and methanol was flowed at 40 mff1/min as an eluent.
5rn1 sample solution was injected per batch. A huge main peak appeared around the elution time of 100 minutes, and four minor peaks were detected before and three minor peaks were detected after. From the fractions corresponding to each peak, 1 to 15 μl fractions were collected per batch.

As a result of measuring the fatty acid composition of phosphatidylcholine in each fraction, it was found that the peak immediately before the main peak was a component mainly composed of eicosabencitric acid. This fraction was recovered at 5 μm per batch, and FAB-
MS confirmed that the molecular weight was 780 (CM+H)'') and 806 ((M+H)''), and the fatty acid composition was 40.6% eicosaben citric acid and 17% oleic acid.
．． 3%, palmitic acid 23.9%, and the amount of eicosapene citric acid at the 5n-2 position by phospholipase A2 treatment was 78.6%.

Using a portion of the methanol solution of the raw material, 10 batches were made to obtain the compounds (I-balmitoyl-2eicosapentaenoyl-3-glycerophosphocholine and 1-oleoyl-2-eicosapentaenoyl-3). -glycerophosphocholine) 43■ was isolated.

[Formulation example]

Formulation Example I Under a nitrogen stream, compound +1120 and ammonium 8-anilino-1-naphthalenesulfonate (0.32 mg of fluorescent material to confirm liposome formation) were each added to a 20-sized eggplant flask containing a large number of glass beads. After weighing and dissolving in chloroform, evaporate under nitrogen stream in an evaporator.
The solvent was distilled off. Physiological saline 2- was added to this residue and thoroughly shaken using a portex mixer (20 minutes, room temperature) to give a suspension of 2.0 to 0.05.
The particle size was adjusted using an extruder equipped with a filter with a pore size of 11111.

The resulting suspension becomes a transparent solution with the fluorescence characteristic of a solution that has formed liposome-like endoplasmic reticulum, and observation using a fluorescence microscope using this as a sample shows that the particle size is 0.
Closed endoplasmic reticulum (liposomes) having a shape of around 1×m were confirmed. The amount of lipid peroxide in the obtained liposome (potentiometric titration method) was 20 meq/kg.

Formulation Example 2 Under nitrogen flow, compound + 314 omg and cholesterol 5 were placed in a 20rn1 eggplant flask containing many glass beads.
After weighing out 0.32 cm of ammonium 8-anilino-1-naphthalenesulfonate and dissolving them in chloroform, the solvent was distilled off using an evaporator under a nitrogen stream.

Add phosphate buffer 2- to this residue, shake thoroughly using a portex mixer (20 minutes, 70°C), and pass the resulting suspension through a filter with a pore size of 2.0 to 0.05°C. The particle size was adjusted using the attached extruder.

The resulting suspension becomes a transparent solution with the fluorescence characteristic of a solution that has formed liposome-like endoplasmic reticulum, and observation using a fluorescence microscope using this as a sample shows that the particle size is 0.
A closed endoplasmic reticulum (liposome) having a shape of around 1 tlfn was confirmed. The amount of lipid peroxide in the obtained liposome (potentiometric titration method) was 15 meq/kg.

Formulation Example 3 Under a nitrogen stream, the compound (51100 μ, cholesterol 10
■, α-tocopherol 10■ and 8-anilino-1-
0.32 mg of ammonium naphthalene sulfonate was weighed out and dissolved in chloroform, and then the solvent was distilled off using an evaporator under a nitrogen stream. Add 2 ml of purified sterile water to this residue and mix it with a Portex mixer (20 minutes, 7 ml).
The resulting suspension was thoroughly shaken at 0° C.), and the particle size of the resulting suspension was adjusted using an extruder equipped with a filter having a bore size of 2.0 to 0.05.

The resulting suspension becomes a transparent solution with the fluorescence characteristic of solutions that have formed liposome-like endoplasmic reticulum, and observation using a fluorescence microscope using this as a sample shows that the particle size is 0.
Closed endoplasmic reticulum (liposomes) with a shape of around 1 cape were confirmed. The amount of lipid peroxide in the obtained liposome (potentiometric titration method) was 13 meq/kg.

[Acute toxicity test]

One 5-week-old male and female ICR mouse weighing 25-32 g
The liposome preparation of Formulation Example 2 was intraperitoneally administered to a group of 10 animals at a single dose of 5000 mg/kg. The animals were observed for 14 days after administration, and no abnormalities were observed in terms of mortality or general condition, and the weight of both males and females increased steadily. No abnormalities were observed in the autopsy results 14 days after administration. When the liposome formulation of Formulation Example 2 was intraperitoneally administered to ICR mice, the minimum lethal dose was 5000 mg for both male and female mice.
/ kg or more. The liposome formulation of Formulation Example 2 used in this test was one in which the fluorescent substance among the constituent components was removed.

Pharmacological test examples Test example 1 5-lipoxygenase activity measurement method (antiallergic)
RB L (rat basophylic leu
kemia cell) ■ cells were cultured in MEN medium in the presence of 10% fetal bovine serum. After culturing, R
After collecting BL-1 cells, they were washed with phosphate buffer. After washing, phosphate buffer was added and cells were disrupted using a sonicator.

The solution containing the destroyed cells was heated at 600×G and 10,000×G.
The supernatant was used as an enzyme solution.

This enzyme exhibited stable activity for more than 6 months at -80°C. After finally adding 2mM calcium chloride solution to 0.5ml of this enzyme, 0.2μC of IC-arachidonic acid was added.
The product was extracted and isolated and identified by TLC. Activity measurement was expressed as conversion activity from 14C-arachidonic acid.

Using the liposome preparation of Formulation Example 1.2.3 and Compounds (1) and (5), a test for the inhibitory effect on 5-lipoxygenase activity was conducted according to the above test example, and the results were given as ID,
. (50% inhibition value).

Test results, ID,. (μM) Compound (1) 3, Compound +5) 12 Formulation Example 1 1
7. Formulation Example 25 Formulation Example 3 15 From the above results, the 5-lipoxygenase activity inhibitory effect of the compound represented by general formula (1) maintains its excellent activity without change even when processed into a lipotum preparation. Ta.

Test Example 2 Friend leukemia cells (mouse erythroblastic leukemia cells, B8
A test was conducted on cells). HAM's F-12 medium (
(manufactured by GIBCO) with 15% fetal bovine serum and 60 μ/l
of kanamycin and 2.5X10'cell
B8 cells were inoculated at a concentration of 1/ml, and a predetermined amount of the test compound was added thereto (final volume: 5 ml).

After culturing at 37°C for 7 days in 8.0% carbon dioxide gas, the cells were stained using Orkin's benzidine staining method.
The number of stained cells, that is, the number of cells that began to produce hemoglobin due to differentiation into red blood cells, was measured, and the differentiation induction rate was determined from the ratio to the total cells.

Using Formulation Example I, the liposome preparation of 2.3, and Compounds (1) and (5), the differentiation-inducing activity of Friend's leukemia tI cells was investigated by the above test method, and the results were expressed as differentiation induction rate.

Test results Added concentration 40 n/ml Compound (1)
22%, Compound (5) 24% Formulation example 123%
, Formulation example 218% Formulation example 325% From the above results, the effect of the compound represented by general formula (1) on inducing differentiation of erythroblastic leukemia cells remains unchanged even when processed into a liposome preparation. was holding it.

Note that the liposome formulations of Formulation Examples 1.2.3 used in this test were those in which the fluorescent substance among the constituent components was excluded.

Claims (1)

[Claims] General formula (I): ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 is an oleoyl group or a palmitoyl group, and R_2 is an eicosapentaenoyl group or a docosa At least one of the compounds represented by (which is a hexaenoyl group)
Liposomal formulation containing seeds as a component.