4. Conclusion
The rice bran extract prepared by scCO2
gave lower yields, but higher
unsaturated fatty acid contents (gamma linolenic acid, linoleic acid
and oleic acid and more total phenolic contents in the form of gallic
acid than those from the ethanolic maceration.
The extracts from both methods showed no significant difference
of antioxidative, tyrosinase inhibition and cell proliferation activity
on the 30th passage aged normal human skin fibroblasts.
All extracts gave no cytotoxicity and the stimulation effects of the
extracts on collagen synthesis of the aged human skin fibroblasts
were anticipated.
The physical characteristics including the
vesicular size, morphology, phase transition temperature and the
microviscosity of the niosomes entrapped and not entrapped with
the extracts prepared by scCO2 technique were not significant different
from those by the chloroform film method.
The morphology of all niosomes were in unilamellar structure investigated by TEM. For all niosomes, the phase transition (gel-liquid) temperature at about 80 ◦C and the gradual decreasing trend of the vesicular membrane microviscosity
when the temperature increased were observed.
The supercritical carbon dioxide fluid (scCO2) appeared to be a suitable alternative technique for the preparation of the rice bran extract and the preparation of niosomes entrapped with the extract because of not only
its environmental friendly, but also its less step requirement as
well.