Patent ID: 7598421

Claim:
A lipid of general formula (I) or (II): wherein X 1 and X 2 are —O—; R 1 and R 2 for formula I are the same or different and are straight or branched, saturated or unsaturated C 7 to C 24 hydrocarbyl groups which are unsubstituted or substituted by one or more substituents selected from the group consisting of hydroxy, halogen and OR′, wherein R′ is a C 1 to C 6 hydrocarbyl group and R 1 and R 2 for formula II are the same or different and are straight or branched unsaturated C 7 to C 24 hydrocarbyl groups or straight or branched saturated C 18 to C 24 hydrocarbyl groups, which are unsubstituted or substituted by one or more substituents selected from the group consisting of hydroxy, halogen and OR′, wherein R′ is a C 1 to C 6 hydrocarbyl group; R 5 is —N + (R 3 ) 2 —R 6 ; R 6 is either: (a) -[A-Y] n R 4 wherein: each Y is the same or different and is —N + (R 4 ) 2 —; each A is the same or different and is a C 1-20 alkylene group which is unsubstituted or substituted by one or more substituents selected from the group consisting of hydroxy, halogen, —OR′, —C(O)OH, —CN, —NR′R″, and —C(O)R′ wherein R′ and R″ are the same or different and are C 1-6 hydrocarbyl; and n is an integer of from 1 to 10; or (b) —[B—O] m B-Q wherein: each B is the same or different and is a C 1-10 alkylene group which is unsubstituted or substituted by one or more substituents selected from the group consisting of hydroxy, halogen, —OR′, —C(O)OH, —CN, —NR′R″ and —C(O)R′ wherein R′ and R″ are the same or different and are C 1-6 hydrocarbyl; m is an integer of from 1 to 10; and Q is selected from the group consisting of —N + (R 3 ) 3 , —OH, —OR′, —OC(O)R′ and halogen, wherein R′ is as defined above; and each R 3 and each R 4 is the same or different and is a straight or branched, saturated or unsaturated C 1 to C 10 hydrocarbyl group which is unsubstituted or substituted by one or more substituents selected from the group consist of hydroxy, halogen, —OR′, —C(O)OH, —CN, —NR′R″, and —C(O)R′ wherein R′ and R″ are the same or different and are C 1 to C 6 hydrocarbyl.