68 HAIR CARE


colorimetrically at 595 nm. The antioxidant potential of samples is determined using a ferrous iron standard curve and results are expressed as Fe2+


equivalents (µM). Data


are submitted to t test of student for paired and unpaired data and reported as mean ± SD.


Results of FRAP assay on hair locks Data show that the pretreatment of hair locks with olive fruit extract increases antioxidant defence by 50% (comparison with the cleansed control, p<0.001). Even after UV exposure, it boosts the pool of antioxidants (+ 19%, p<0.05). The results obtained for the treated hair locks were statistically different from the results obtained for the untreated hair locks (*** p<0.001). These data highlight that olive fruit


extract strengthens the antioxidant defences of hair, make it more resilient towards several kinds of oxidative threats.


Protective activity of olive fruit extract from straightening iron- induced damage Study design Human hair locks are washed using a neutral shampoo, dabbed with a paper towel and dried with a hair dryer. Ten (n=10) brown hair locks are treated with active formula (tested concentration of olive fruit extract: 0.75%) and ten (n=10) with placebo formula. The test products are applied on dry hair locks and then submitted to thermal stress (230°C) using a hair straightener. The amount of products applied on


hair locks is 600 mg and products are distributed all over the hair locks. Thermal oxidative damage is quantified


through ‘protein carbonyl content assay’. Carbonyl content is determined by the derivatization of protein carbonyl groups with 2,4-dinitrophenylhydrazine (DNPH) leading to the formation of stable dinitrophenyl (DNP) hydrazone adducts, which can be detected spectrophotometrically at 375 nm, proportional to the carbonyls present. Protein carbonylation, a harmful


irreversible oxidative protein modification, is considered a major hallmark of oxidative stress and molecular damage. It is a type of protein oxidation that can be promoted by reactive oxygen, metal catalysed oxidation, or glycation/glycoxidation. Data are submitted to two-way t-test of


Student and reported as mean ± SE in nmol/mg hair.


Results Data show that hair locks pre-treated with the active formula produced less carbonylated proteins than hair locks pre-


PERSONAL CARE EUROPE 500 *** 400 300 200 100 0 T0


T0 is the protein carbonyl content before product application and HM + UV exposure, THM+UV is the protein carbonyl content after product application and HM+UV exposure (HM= heavy metals)


THM+UV nOLEA-HT 10 n Placebo Figure 5: Results of protein carbonyl assay before and after exposure to heavy metals and UV.


treated with placebo (+59,2% VS +111,6% = 52,4% lower production). Therefore, olive fruit extract is effective in protecting the hair protein structure from the carbonylation induced by straightening iron.


Qualitative evaluation of hair locks with scanning electron microscopy (SEM) Study design Hair ultra-structure is qualitatively analysed by means of Scanning Electronic Microscopy (SEM) in order to examine the morphological changes of cuticle layers on the hair surface after thermal treatment. The test products are applied on dry hair locks and then submitted to thermal stress (230°C) using a hair straightener. Hence, pieces of hair are taken from the middle of each lock and analysed. The pieces are placed in a specific sample holder (stub) and fixed by means of a small quantity of adhesive.


Results Hereafter, we report two set of pictures acquired (Fig 4). In the first column on the left, there are two untreated hair locks, where the cuticle layer is intact. The middle column reports two hair locks pre- treated with active formula, while the column on the right shows two hair locks pre-treated with the placebo formula. After heating, the cuticle scales remain


flatter on the hair tresses treated with 0.75% of olive fruit extract, whereas hair locks treated with placebo lost, almost completely, the cuticle. These pictures point out that olive fruit


extract, thanks to its strong antioxidant activity, is able to prevent the degradation of cuticle layers.


Protective activity of olive fruit extract from environmental pollution Study design Human hair locks are washed using a neutral shampoo, dabbed with a paper towel and dried with a hair dryer. Ten (n=10) brown hair locks are treated with active formula and ten (n=10) with placebo formula. Tested concentration of olive fruit


extract: 0.75% The test products (600 mg) are applied


on dry hair locks and concurrently treated with a solution containing: Fe 100 ppb, Cu 100 ppb, Zn 100 ppb. Hair locks are left to stand for 24 hours,


and then are exposed to UV radiation using a solar simulator. The UV dose applied to the hair locks is 3600 KJ*m-2. The chosen dose corresponds at about 5 hours exposure to the sun at European latitudes. Oxidative stress is quantified through


protein carbonyl content assay. Data are submitted to two-way t-test of Student and reported as mean ± SE in nmol/mg hair.


Results After treatment with heavy metals (Fe, Cu, Zn) and UV, in comparison with placebo, active formula produced a lower amount of carbonylated proteins (+ 103,5% VS 139,9% = 36,4% lower production). Olive fruit extract has demonstrated to be effective in protecting the hair protein structure from the carbonylation induced by photocatalysis reactions. These data corroborate the antioxidant and chelating properties of olive fruit extract.


Conclusion Since hair is constantly exposed to sun radiation, air particulate and beauty rituals


September 2020 *** ***p< 0.001 intragroup statistical analysis *p< 0.05 intergroup statistical analys 600 *


nmol/mg hair


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