Patent ID: 7407947

Claim:
A sterol derivative according to formula (1): Amphoteric substance -Y- spacer -X- sterol (1), wherein: said amphoteric substance comprises a first portion having a cationic charge with a pKa value between about 4 and about 8.5 and a second portion of anionic charge with a pKa value between about 3 and about 7; said first portion of said amphoteric substance is selected from the group consisting of piperazines, imidazoles, morpholines, purines, and pyrimidines; said second portion of said amphoteric substance comprises a carboxyl group; said spacer is a linear or branched C 1-8 alkyl comprising 0-2 ethylenically unsaturated bonds; said linking group X is selected from the group consisting of —(C═O)—O—, —(C═O)—NH— and —NH—(C═O)—O—; said linking group Y is selected from the group consisting of —O—(C═O), —NH—(C═O), —(C═O)—O— and —(C═O)—NH—; said sterol is selected from the group consisting of cholesterol, sitosterol, campesterol, desmosterol, fucosterol, 22-ketosterol, 20-hydroxysterol, stigmasterol, 22-hydroxycholesterol, 25 -hydroxycholesterol, lanosterol, 7-dehydrocholesterol, dihydrocholesterol, 19-hydroxycholesterol, 5α-cholest-7-en-3β-ol, 7-hydroxycholesterol, epicholesterol, ergosterol, and dehydroergosterol; and said sterol derivative has an isoelectric point between about 4.5 and about 8.5.