The thin-layer chromatographic (TLC) behaviour of liposomes containing
inositol phosphates (IPs) was studied. The liposomes contained differ
ent concentrations of D-myo-inositol 1,4,5-trisphosphate (IP3), D-myo-
inositol 1,2,6-trisphosphate (alpha-trinositol, PP 56, a novel Perstor
p Pharma derivative), D-myo-inositol 1,3,4,5-tetrakisphosphate (IP4),
D-myo-inositol 1,3,4,5,6-pentakisphosphate (IP5) and D-myo-inositol 1,
2,3,4,5,6-hexakisphosphate (IP6). Migration of all liposome batches wa
s compared to that of control liposomes (containing only triple-distil
led water), and to that of free phosphatidylcholine (PC); the same amo
unt of lipid was used in all situations. Thin-layer chromatography was
performed on silica gel as adsorbent. As solvent we used an n-buthano
l:ethanol: water mixture in a 4:3:3 volume ratio. Significant differen
ces were found between PC and all liposome batches, as well as between
control liposomes and the ones containing IP3, alpha-trinositol, IP4,
or IP5, in various concentrations. Liposomes containing IP6 migrate c
ompletely differently compared not only to phosphatidylcholine and con
trol liposomes, but also to the ones containing other IPs (<10(-3) M).
Unlike the other IPs studied, liposome-entrapped IP6 elicits dose-ind
ependent contractions of the isolated rat aorta. This suggests that li
posomes loaded with IP6 undergo, during or after their preparation, ph
ysico-chemical alterations that eventually change their drug-delivery
capacity.