The present invention provides a cationic lipid which is able to be used for nucleic acid delivery to the cytoplasm. A cationic lipid according to the present invention is, for example, a compound represented by formula (1a) or a pharmaceutically acceptable salt thereof. (In formula (1a), each of L1 and L2 independently represent an alkylene group having 3-10 carbon atoms; each of R1 and R2 independently represent an alkyl group having 4-22 carbon atoms or an alkenyl group having 4-22 carbon atoms; X1 represents a single bond or -CO-O-; and ring P represents one of formulae (P-1) to (P-5).)(In formulae (P-1) to (P-5), R3 represents an alkyl group having 1-3 carbon atoms.)
The present invention provides a cationic lipid which is able to be used for nucleic acid delivery to the cytoplasm. A cationic lipid according to the present invention is, for example, a compound represented by formula (1a) or a pharmaceutically acceptable salt thereof. (In formula (1a), each of L
1
and L
2
independently represent an alkylene group having 3-10 carbon atoms; each of R
1
and R
2
independently represent an alkyl group having 4-22 carbon atoms or an alkenyl group having 4-22 carbon atoms; X
1
represents a single bond or —CO—O—; and ring P represents one of formulae (P-1) to (P-5).)(In formulae (P-1) to (P-5), R
3
represents an alkyl group having 1-3 carbon atoms.)