Lipids, lipid complexes and use thereof

1. A method for transferring a pharmaceutically active compound into a cell or across a membrane or cell membrane, comprising the following steps:

providing the cell or the membrane;

providing a compound according to formula (I),

wherein R 1 and R 2 are each and independently an alkyl group;

n is any integer between 1 and 4;

R 3 is an acyl selected from the group consisting of lysyl, ornithyl, 2,4-diaminobutyryl,

histidyl and an acyl moiety according to formula (II),

wherein m is any integer from 1 to 3 and

Y − is a pharmaceutically acceptable anion;

providing the pharmaceutically active compound; and

contacting the cell or the membrane with the pharmaceutically active compound and said compound of formula (I).

2. The method according to claim 1 , wherein said compound of formula (I) is provided in the form of a composition comprising a carrier and said compound of formula (I).

3. The method according to claim 1 , wherein the method further comprises detecting the pharmaceutically active compound in the cell and/or beyond the membrane.

4. A method of delivering a reagent to a cell, comprising contacting said cell with a compound according to formula (I),

wherein R 1 and R 2 are each and independently an alkyl group;

n is any integer between 1 and 4;

R 3 is an acyl selected from the group consisting of lysyl, ornithyl, 2,4-diaminobutyryl,

histidyl and an acyl moiety according to formula (II),

wherein m is any integer from 1 to 3 and

Y − is a pharmaceutically acceptable anion and a reagent selected from the group consisting of a peptide, a protein, an oligonucleotide, a polynucleotide and a nucleic acid.

5. The method according to claim 4 , wherein said cell is a human cell.

6. The method according to claim 5 , wherein said cell is an endothelial cell.