Disclosed herein is an ophthalmic formulation comprising a compound of formula (I) wherein le is a linear or branched C.sub.9-C.sub.33 alkyl or a linear or branched C.sub.9-C.sub.33 alkenyl with 1 to 4 double bonds; R.sup.2 is a linear or branched C.sub.9-C.sub.19 alkyl or a linear or branched C.sub.9-C.sub.19 alkenyl with 1 to 4 double bonds; and an ophthalmologically acceptable carrier.

Provided is a high-concentration and high-purity eicosapentaenoic acid-containing composition. A method for producing an eicosapentaenoic acid alkyl ester-containing composition, the method includes: (1) bringing a raw oil that contains an eicosapentaenoic acid alkyl ester into contact with an aqueous solution that contains a silver salt, and then collecting an aqueous layer; (2) adding an organic solvent to the aqueous layer, and then collecting an organic solvent layer; and (3) subjecting the organic solvent layer to vacuum distillation at a temperature of 180 to 188° C. and a tower top vacuum degree of 0.7 Pa or below, to recover the eicosapentaenoic acid alkyl ester from the organic solvent layer.

Provided is a high-concentration and high-purity eicosapentaenoic acid-containing composition. A method for producing an eicosapentaenoic acid alkyl ester-containing composition, the method includes: (1) bringing a raw oil that contains an eicosapentaenoic acid alkyl ester into contact with an aqueous solution that contains a silver salt, and then collecting an aqueous layer; (2) adding an organic solvent to the aqueous layer, and then collecting an organic solvent layer; and (3) subjecting the organic solvent layer to vacuum distillation at a temperature of 180 to 188° C. and a tower top vacuum degree of 0.7 Pa or below, to recover the eicosapentaenoic acid alkyl ester from the organic solvent layer.

Provided is a high-concentration and high-purity eicosapentaenoic acid-containing composition. A method for producing an eicosapentaenoic acid alkyl ester-containing composition, the method includes: (1) bringing a raw oil that contains an eicosapentaenoic acid alkyl ester into contact with an aqueous solution that contains a silver salt, and then collecting an aqueous layer; (2) adding an organic solvent to the aqueous layer, and then collecting an organic solvent layer; and (3) subjecting the organic solvent layer to vacuum distillation at a temperature of 180 to 188° C. and a tower top vacuum degree of 0.7 Pa or below, to recover the eicosapentaenoic acid alkyl ester from the organic solvent layer.

Methods for preparing isotopically modified 1,4-diene systems from non-isotopically modified 1,4-dienes involve selective oxidation of one or more bis-allylic position(s), or the preparation of isotopically modified 1,4-diene systems via trapping pi-allylic complexes with a source of deuterium or tritium. Such methods are useful for preparing isotopically modified polyunsaturated lipid including polyunsaturated fatty acids and polyunsaturated fatty acid derivatives.

Methods for preparing isotopically modified 1,4-diene systems from non-isotopically modified 1,4-dienes involve selective oxidation of one or more bis-allylic position(s), or the preparation of isotopically modified 1,4-diene systems via trapping pi-allylic complexes with a source of deuterium or tritium. Such methods are useful for preparing isotopically modified polyunsaturated lipid including polyunsaturated fatty acids and polyunsaturated fatty acid derivatives.

The present invention relates to a process for preparing a 3-isopropenyl-6-heptenal compound of the following formula (2): wherein R.sup.1 represents a hydrogen atom or a methyl group, the process comprising: subjecting a 3-isopropenyl-6-heptenoate ester compound of the following formula (1): wherein R.sup.1 is as defined above, and R.sup.2 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, to a reduction reaction with a reducing agent to form the 3-isopropenyl-6-heptenal compound (2).

##STR00001##

The present invention relates to a process for preparing a 3-isopropenyl-6-heptenal compound of the following formula (2): wherein R.sup.1 represents a hydrogen atom or a methyl group, the process comprising: subjecting a 3-isopropenyl-6-heptenoate ester compound of the following formula (1): wherein R.sup.1 is as defined above, and R.sup.2 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, to a reduction reaction with a reducing agent to form the 3-isopropenyl-6-heptenal compound (2).

##STR00001##

The present invention relates to a process for preparing a 3-isopropenyl-6-heptenal compound of the following formula (2): wherein R.sup.1 represents a hydrogen atom or a methyl group, the process comprising: subjecting a 3-isopropenyl-6-heptenoate ester compound of the following formula (1): wherein R.sup.1 is as defined above, and R.sup.2 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, to a reduction reaction with a reducing agent to form the 3-isopropenyl-6-heptenal compound (2).

##STR00001##

The present invention relates to lipid comprising docosapentaenoic acid and/or docosahexaenoic acid wherein the docosapentaenoic acid and/or docosahexaenoic acid may be preferentially esterified at the sn-2 position of triacylglycerol, and processes for producing and using the lipid.