People want their hair to be beautiful and lustrous as it plays a key role in enhancing one’s overall appearance. Healthy-looking hair is mainly influenced by the scalp health itself.
Scalp health holds a lot of significance in terms of hair care as it determines the volume, the strength and shine of the hair. A healthy scalp and hair can be characterised as a scalp with a normal physiological sebum secretion, with no signs of inflammation and with a physiological level of present microorganisms as Malassezia species, part of the skin/scalp microflora. When these conditions are not fulfilled, the scalp problems linked to the excess production of sebum or bacterial over-proliferation accompanied by hyperkeratosis can appear. The most common scalp disorder is dandruff. This affection concerns more than 50% of the population.1 The current available data support a direct causal link between Malassezia and dandruff.1,2,3 Associated inflammatory problems generate sensations of discomfort and itching, leaving hair shafts weakened and dull. The analysis of stratum corneum of dandruff sufferers shows an increased level of inflammatory biomarkers, interleukin-1?, IL-1 receptor antagonist (IL-RA) and IL-8. A disturbance of the barrier integrity has been also revealed.4 The histamine level in the subjects with dandruff is more than twice as high compared to the subjects without dandruff.5 Antifungal treatments are generally extremely effective in reducing dandruff but have a low impact on regulating sebum production. Itching persists while hair remains dull and lacklustre in appearance. Synthetic molecules are most effective when it comes to deep-cleansing the scalp, but naturally-provided effectiveness has real market value. A successful treatment of scalp disorders should not only provide a cleansing effect of the scalp but also should offer an efficacy on the regulation of sebum secretion and a reduction of discomfort sensation such as itching. Additionally, the treatment should provide an improvement of the hair’s cosmetic properties, in a perceivable and visible way.
Enhancing scalp health and hair beauty
The development of Sanicapyl, a natural complex targeting two major scalp disorders – dandruff conditions and scalp oiliness – while enhancing hair beauty with perceivable and visible results, is of real added value for the hair care segment, ensuring that both scalp comfort and the overall appearance of healthy-looking hair are improved. Sanicapyl, INCI name: Sodium Lauroyl Lactylate (and) Butylene Glycol (and) Piper Nigrum (Pepper) Fruit Extract (and) Inga Alba Bark Extract, is a natural complex made of the extract of Piper nigrum berries (black pepper) titrated in piperine, Inga alba bark extract and sodium lauroyl lactylate of botanical origin. Black pepper and long pepper have been used in Ayurvedic medicine for the treatment of various diseases and in Sanicapyl (now referred to as “the natural complex”) the extract is responsible for anti-inflammatory and soothing properties of the active ingredient.6,7 The antioxidant and anti-inflammatory activities of piperine have been recently confirmed.8,9 Inga alba is a tree growing in the French Guyana rain forest. The bark of Inga alba is used in the local traditional medicine. The Inga alba bark extract is rich in polyphenols and catechic tannins. Sodium lauroyl lactylate is a salt derived from the lauric acid ester of lactyl lactate. Lactylates are appreciated in personal care for their ability to penetrate the upper layers of stratum corneum and provide moisturisation. Moreover to its cosmetic properties, Sodium lauroyl lactylate shows also very good antimicrobial properties against some Gram-positive and Gram-negative bacteria, and yeast. The combination of these three components results in an active ingredient with good balanced proportions of anti-inflammatory, moisturising, skin barrier protecting, cleansing and purifying properties. Each of the above mentioned activities has been demonstrated by an appropriated in vitro test and the scalp purifying and hair beautifying activities have been confirmed by an in vivo test.
Efficacy studies – methods and results
Anti-microbial activity (in vitro test)
The antimicrobial activity of the natural complex has been evaluated against the bacterial strains (Malassezia globosa and Malassezia furfur), present on hair scalp and responsible for dandruff, inflammation and irritation. The Minimum Inhibitory Concentrations (MICs) of the sample were determined using the agar dilution method after the incubation for 48 hours at 30°C. MIC corresponds to the lowest test substance concentration that completely inhibits the growth of the tested microorganism.
Result and conclusion
The natural complex exhibited a strong antimicrobial activity against the tested strains. The MIC against Malassezia globosa was 0.063% and against Malassezia furfur was 1%.
Anti-inflammatory activity (in vitro test)
The anti-inflammatory activity of the natural complex was evaluated on human keratinocytes in the model of UVB induced inflammation. Aspirin, an inhibitor of cyclooxygenase activity was used as positive control.
Result and conclusion
The natural complex, in the same way as Aspirin, has not influenced the effect of UVB on cell viability, but it has significantly decreased the levels of released LDH and PGE2 in a dose dependent way (Fig. 1).
Moisturising activity (in vitro test on human horny layer)
The moisturising activity of the natural complex was evaluated after incorporation at 2% in hydrogel comparatively to placebo hydrogel, by measurements of dielectric conductivity of human stratum corneum. Dry stratum corneum is a dielectric medium of weak electric conduction. The hydration of stratum corneum makes it more sensitive to the electric field, because of the bipolarity of water molecules. Determination of the conductance of high frequency electric current enables to evaluate the hydration state of stratum corneum.
Result and conclusion
The increase of dielectric conductivity after the treatment with hydrogels containing either 2% glycerin (positive control) or 2% the natural complex was significantly superior to placebo hydrogel (Fig. 2), with a long-lasting effect. Long-lasting moisturising efficacy on scalp can lead to regulation of desquamation and preservation of the skin barrier.
Improvement of the scalp and hair properties (clinical test)
The aim of the clinical test was to evaluate, in vivo, the improvement of scalp conditions (dandruff, sebum) of a shampoo with 1% the natural complex versus a shampoo with 1% zinc pyrithione, after 4 weeks of treatment and 2 weeks of remanence period. The study has been performed on two groups of volunteers, with the dandruff degree ?2 at the end of wash-out period. Semi-quantitative evaluation of dandruff and scalp oiliness was done by trained panelists and at the end of the study volunteers answered the questionnaire linked to the shampoo efficiency as well as to the evaluation of cosmetic properties.
The schema of protocol is in the Figure 3.
Results and conclusion
• Reduction of dandruff Significant reduction of dandruff was observed after 28 days of treatment (D28) comparatively to before treatment (D0) for the natural complex at 1%. This dandruff diminution was maintained also after the 14 days of remanence period (D42). The anti-dandruff activity of the natural complex was comparable to the activity of zinc pyrithione at 1% (Fig. 4).
• Reduction of sebum Significant diminution of sebum secretion was observed for the shampoo containing 1% the natural complex, after the remanence period (D42). The treatment with shampoo with 1% of the natural complex has a superior effect on the sebum secretion than zinc pyrithione at 1% (Fig. 5).
• Subjective questionnaire The positive appreciation of evaluated cosmetic properties for formulation with the natural complex was superior comparatively to the zinc pyrithione formulation (Fig. 6).
The results of the subjective evaluation confirmed the natural complex’s ability to significantly improve the scalp conditions (reduction of dandruff state, sebum production and sensation of itching) as well as a visible action on hair beautifying (hair radiance and softness).
Scalp disorders such as dandruff and oily skin are very often of chronic nature and require long lasting treatment. The proposed treatment should not only reduce microbial proliferation and sebum production but should, at the same time, also provide cosmetic benefits for hair and scalp. The results obtained in an in vitro test on two most representative strains of Malassezia have clearly demonstrated a good antifungal activity for Sanicapyl™. The dandruff and the hyperactivity of sebaceous glands are linked with an increase of inflammation that is perceived in vivo by an appearance of itching sensations. The obtained in vitro data demonstrated a dose dependent diminution of the released marker PGE2 in presence of the natural complex. The diminution of the release of PGE2 constitutes a good presumption for an in vivo benefit for the scalp health. The long lasting moisturising effect on the scalp can lead to regulation of desquamation and preservation of the skin barrier. The efficacy of shampoo with 1% Sanicapyl was evaluated after 28 days of treatment and 14 days of remanence period, in a normal use conditions, comparatively to shampoo with 1% zinc pyrithione. The evaluated parameters were the reduction of dandruff, and of sebum secretion. After 28 days of treatment with shampoo containing 1% the natural complex, the dandruff state was improved by 23%. This improvement was observed also after the remanence period and the diminution of dandruff was 31% comparatively to before treatment situation. This improvement was comparable to the anti-dandruff efficacy of the benchmark, zinc pyrithione, incorporated at 1% in the same shampoo formulation. The good efficacy of the natural complex was also observed for sebum secretion. The sebum secretion was reduced by 14% after 28 days of treatment. The anti-sebum effect was more pronounced after the remanence period (diminution by 54%). The objectively measured effect of the natural complex was confirmed by the volunteers’ perception. The monitored anti-dandruff and anti-itching activities of the natural complex improved its condition compared to before treatment. The subjective questionnaire has confirmed the positive effect of the natural complex on hair cosmetic properties. Positive appreciation by volunteers for formulation with the natural complex was superior comparatively to the zinc pyrithione formulation especially for the parameters such as hair manageability, hair softness and hair radiance.
The authors acknowledge Lydie Martin-Teixeira, Emmanuel Charrois, Nathalie Andres and Cecile Delluc for their skilled technical contribution.
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