to increase the entrapment efficiency of liposomes. The
liposome containing SPC: CHOL (4:1) had 61%
entrapment while the formulations with added DP or
DA (0.25 molar ratio) had entrapment efficiency of 65%
or 71%, respectively (Table 3). It was found that the
most suitable liposome formulation with the highest
entrapment efficacy (83%) and smallest particle size
(332 mm) was composed of SPC: Tween 80: DA (84: 16:
2.5) by weight ratios. This formulation was therefore
selected for further studies of its stability, skin
permeation and skin irritation. The stability test of
liposomes was performed for 2 months at 4°C under
light protection. Its entrapment efficiency and particle
size were evaluated during storage, and compared to
the data for freshly prepared liposomes (Fig. 2 and 3).
Fig. 2 depicts that, no significant change in the particle
size of liposomes was observed after one month
storage. However, after 2 months, the particle size of
liposomes was slightly larger (~13%) due to the
coalescence effects. Fig. 3 illustrates that entrapment
efficiency of the Roselle liposome decreased about 10%
after 2 months under the testing conditions.
The in vitro skin permeation study of the
Roselle liposomes was evaluated, comparing the data
to the results from an identical study antioxidant
constituent in aqueous solutions of the extract. The
studies were performed by measuring the antioxidant
activity of the fluid in the receptor compartment of the
modified Franz-diffusion cell at various time points from
0.5 to 12 hours. The active ingredients from the extract