Development of paraben-free hydrogel based on plant extracts for topical application
Conference Paper
Overview
Overview
abstract
Historically, medicinal preparations are derived from plants and their employment in
dermatological and cosmetic products is increasing [1]. Topical application of products containing
compounds with free radical scavenging properties protects tissues from oxidative damage [2].
The skin is an important protective barrier between the environment and the inner milieu, being
highly exposed to oxidative stress, either from exogenous as well as endogenous sources [3]. The
antioxidant potential of herbal extracts or pure isolated compounds have been extensively studied,
but very few reports are available on the antioxidant properties of final formulations in which they
have been included. In the present study, aqueous and ethanolic extracts from the flower buds of
hawthorn (Crataegus monogyna Jacq.) were incorporated into hydrosoluble gels. Gels have been
largely used in cosmetic products and as a dermatologic base, as they are easily dispersed, nonoily
and can carry hydrosoluble active principles. Gel consistency was optimized when carbopol
940 was added at 1%. The prepared formulations presented a light green colour, a non-greasy
texture and were promptly absorbed by the skin. Since the inclusion of parabens is nowadays
poorly accepted by the consumers, imidazolidinyl urea was included as the antimicrobial
component. Regarding pH evaluation, there were no significant alterations during the 90 days of
observation, with values ranging between 5.5 and 6.5. The antioxidant activity of the prepared
hydrogels was assessed and compared with a blank formulation (with all the components used in
the hydrogel formulation, except the extract) and also with the results obtained for the extracts
alone, at the same concentration (1 00 jlg/ml). The antioxidant activity measured in each
hydrosoluble gel is very close to the value obtained for the isolated extract, in what regards
inhibition of lipid peroxidation using thiobarbituric acid reactive substances (TBARS) and Beta carotene
bleaching inhibition, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and
reducing power. Hydrogels prepared with ethanolic extracts showed higher antioxidant activity
than aqueous extracts, unless in Beta carotene bleaching inhibition assay. In general, it became evident that the inclusion of extracts in the prepared hydrosoluble gels caused very limited losses in their bioactivity.
