Insight into glycyrrhetinic acid: the role of the hydroxyl group on liver targeting.

Two kinds of glycyrrhetinic acid-modified chitosan/poly(ethylene glycol) nanoparticles (CTS/PEG-GA NPs) were prepared by an ionic gelation process in which the liver targeting ligand glycyrrhetinic acid (GA) was introduced into the nanoparticles at the C(30)-carboxyl group (CTS/PEG-GA(c) NPs) or the C(3)-hydroxyl group (CTS/PEG-GA(h) NPs). Their characteristics, especially their ability to target the liver, were compared. The results showed that both the CTS/PEG-GA(c) NPs and the CTS/PEG-GA(h) NPs are remarkably targeted to the liver. The accumulation in the liver is 51.3% and 56.5% of the injected dose for the CTS/PEG-GA(c)(4.60%) NPs (the subscript number denotes the GA content as weight percent in nanoparticles) and the CTS/PEG-GA(h)(4.57%) NPs at 3 h after injection, respectively. This is nearly 2.6-2.8 times higher than that obtained with the CTS/PEG NPs. According to our results, there is no significant difference between the CTS/PEG-GA(c) NPs and the CTS/PEG-GA(h) NPs in their ability to target the liver, when they were formed under identical conditions. This indicated that the C(3)-hydroxyl group in GA has little influence on the targeting ability.