Nanoemulsions can be produced using simple methods and compounds from natural sources. They can increase
water dispersibility and bioavailability and optimise active ingredient dispersion in particular skin layers.
Lipophilic compounds of the vitamin E family (tocopherols and tocotrienols) are well-known for their high
antioxidant activity and capacity to protect the skin from oxidative stress. In this context, oil-in-water (o/w)
nanoemulsions with and without α-tocopherol (Vitamin E, VE) were formulated with two emulsifier alternatives,
Quillaja saponin (QS), and a combination of QS with Tribulus terrestris (QSTT) (50/50, w/w). The emulsions were
evaluated concerning stability, microstructure, droplet size, colour attributes, encapsulation efficiency, UV
photostability, antioxidant activity, and in vitro permeation studies to assess the delivery potential. Results
showed highly stable systems, with round-shape droplets of 80–121 nm size. QS and QSTT samples’ colours were
close to white and light brownish, respectively. The topical nano cream had the capacity to entrap VE, producing
a protective effect from UV degradation, and very significant antioxidant activity, with IC50 values around 0.01
%wt. The skin permeation profiles showed the efficiency of the formulations in the delivery of VE, with permeabilities
between 64 and 74 μg/cm2, while the control sample showed no VE permeation.
The authors are grateful to the Foundation for Science and Technology
(FCT, Portugal) for financial support through national funds
FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/
2020), SusTEC (LA/P/0007/2021), LSRE-LCM (UIDB/50020/2020 and
UIDP/00690/2020), and ALiCE (LA/P/0045/2020). FCT for the PhD
research grants of T.B. Schreiner (2020.05564.BD) and G. Colucci
(2021.05215.BD). National funding by FCT, P.I., through the institutional
scientific employment program contract of A. Santamaria-Echart.
