60 SCALP CARE
5.0
4.50 4.0 3.50 3.0 2.50 2.0
Untreated control
Positive control
0.50% 1% Yeast Ferment Extract 2%
(***)
(***) >-50%
Statistic: Mean ± SEM; n=4 One Way ANOVA Dunn’s method (*) p<0.05
Figure 1: Malassezia restricta growth in presence of the Yeast Ferment Extract in vitro
Such S. aureus suspension obtained were
incubated during 24 hours at 37°C under shaking in absence (untreated control) or presence of positive control (sodium dodecyl sulphate) or Yeast Ferment Extract at different concentrations. Then, OD at 600 nm were measured at the beginning and after 24 hours with a multiplate reader (Tecan, France). The initial OD is subtracted from the final
OD in order to obtain the corrected OD. The results are expressed as percentage of growth compared to the untreated control standardized to 100%. Each condition was carried out in quadruplicate n=4. The statistical analysis was carried out using One Way ANOVA test for positive control SDS versus untreated control, and fermented yeast extract at 0.5%, 1% and 2% versus untreated control.
Corneodesmosin (CDSN) in vitro assay Normal human epidermal keratinocytes (NHEK) are seeded within a standard culture medium MCDB153 containing a low concentration of calcium chloride (0.03 mM) and 2% of fetal calf serum (FCS) in cell culture plates previously coated by a solution of type I collagen. After an incubation of five days at 37°C and at 5%, the culture medium is exchanged to
CO2
fresh standard culture medium (without FCS) in which is added a range of concentrations of the Yeast Ferment Extract. The positive reference is obtained by including calcium chloride at 0.1mM, 0.3mM and 1 mM in the standard medium. After an additional incubation of 3
days at 37°C and CO2 at 5% with the tested
compounds, the culture medium is removed, and the cell viability is measured by the MTT
Statistic: Mean ± SD; n=3 One Way ANOVA Holm-Sidak method (***) p<0.001
100 90 80 70 60 50 40 30 20 10 0
Untreated control
(*)
(*)
(*)
(*) -27% -32% -52%
Positive control
0.50%
1% Yeast Ferment Extract
2%
Statistic: Mean ± SEM; n=4 One Way ANOVA Dunn’s method (*) p<0.05
Figure 2: Staphylococcus aureus growth in presence of the Yeast Ferment Extract in vitro
test. The cellular CDSN is extracted from the keratinocytes and then measured by an ELISA kit, according to the recommendations of the manufacturer. The results have been calculated versus
a range of CDSN, and then they have been expressed in percent versus the control cell culture medium without product (untreated control). The results are presented as a mean ± SD (standard deviation) from one assay made in quadruplicate. The statistical analysis was carried out using Student t test.
Scalp health clinical evaluation The clinical evaluation was conducted as a double-blind, randomized study on the scalps of healthy volunteers. The efficacy of a shampoo containing 1% of the Yeast Ferment Extract was compared to the placebo shampoo and to the scalp situation at the beginning of the study (D0). Two groups of 21 volunteers, aged 18 to 65
years old and comprise of females and males each having scored moderate scalp dryness, were recruited for the study. One group applied a placebo shampoo and the other applied a shampoo with the yeast ferment extract on all hair, each group shampooing three times a week for three weeks. The anti-dryness appearance on 12 areas
on the scalp was quantified by a clinician evaluation, before and after a three-week regimen. Each volunteer’s result was expressed as a mean scoring of the 12 scalp areas. The statistical analysis of the evolution of
the evaluated parameter in function of time has been done with a non-parametric test (Wilcoxon test or Mann-Whitney test).
TABLE 1: SULPHATE-ALTERNATIVE SHAMPOO FORMULATION USED FOR CLINICAL TRIAL Trade name
INCI name
Water demin. Ucare JR400 BioToLifeTM
Dehyton® PK45
Plantapon® ACG 35 Plantacare® 818 UP Eumulgin® EO33 Glydant plus liquid Perfume
Aqua
Polyquaternium-10 Yeast Ferment Extract Cocamidopropyl Betaine Sodium Cocoyl Glutamate Coco-Glucoside
PEG-150 Distearate
DMDM Hydantoin (and) Iodopropynyl Butylcarbamate Parfum
PERSONAL CARE September 2022
% w/w To 100
0.30 1
12.90 15.0 9.50 2.00 0.50 q.s.
Results Support of a healthy scalp microbiota in vitro The positive control Amphotericin B at 6 µg/mL showed a strong inhibitory effect on M. restricta strain; only 2 Log10 were measured after six hours. This count corresponds to the limit of detection and thus validates the experiment. The Yeast Ferment Extract at 0.5% and 1% had no impact on M. restricta growth. However, at 2% the data suggests the ingredient in formulation could support a cleaner scalp. For S. aureus experiment, the positive control SDS at 0.025% showed a strong cytotoxic effect on S. aureus strain after 24 hours. As with the M. restricta data, the Yeast Ferment Extract and the data from S. aureus imply the ingredient in formulation can support a balanced microbiota on the scalp.
Support of environment for Corneodesmosin synthesis in vitro In this in vitro assay on a culture of human keratinocytes, Calcium chloride at 0.1 mM has moderately decreased cell viability by 7%, but it has strongly increased corneodesmosin synthesis by respectively 313% (data not shown).
These results were expected and validated
this in vitro method based on human keratinocytes. In the same in vitro culture of human keratinocytes, fermented yeast extract at 0.001% has not decreased cell viability, but it supports the environment where corneodesmosin can synthesize. This result has established the potential
of the ingredient in formulation to support the body’s natural process of keratinocyte differentiation and thus to support the skin’s natural barrier function.
Decrease in the appearance of scalp dryness After three weeks of use, fermented yeast extract at 1% significantly decreased the perceived dryness of the scalp, scoring compared to baseline by 16% (p<0.05). When compared to the placebo, its efficacy was 20% higher than placebo (p<0.05).
Discussion A healthy scalp is colonized by a perfect balance of microbiota: a flora composed of
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Number of colonies (Log 10 CFU/mL)
Mean growth percentage (%)
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