Enrichment of Artemia nauplii in vitamin A, vitamin C and methionine using liposomes

Several types of liposomes were used to enrich Artemia nauplii in vitamin A, vitamin C and free methionine. In a first experiment, unilamellar liposomes formulated with krill phospholipid extract and retinyl palmitate demonstrated their capability to enhance the retinol content of Artemia nauplii. Furthermore, the increase in retinol was related to the amount of retinyl palmitate included in the liposomes as vitamin A source. These findings yield the possibility of using such vesicles to bioencapsulate simultaneously both vitamin A and essential fatty acids present in the krill phospholipid extract. A second enrichment was carried out with unilamellar liposomes composed of soybean phosphatidylcholine and loaded with sodium ascorbate as vitamin C source. Our results did not show that vitamin C content in the nauplii could be increased using unilamellar liposomes. This was most likely due to the degradation of the vitamin C during enrichment as well as the ascorbate leakage. Finally, a third experiment assessed enrichment in free methionine using liposomes of different lamellarity (unilamellar or multilamellar) and composed of either soybean phosphatidylcholine or dipalmitoyl phosphatidylcholine, both combined with cholesterol as a membrane stabilizer. Results indicated that multilamellar liposomes represent a useful tool to deliver methionine to Artemia nauplii. Enhanced protection given by their multiple bilayers in comparison to unilamellar liposomes could account for the higher ability displayed by multilamellar vesicles for free methionine bioencapsulation.