COSSMA 2023 article: Tagra WS SA50™ water-soluble salicylic acid cut dandruff particles 51.1% and dandruff area 54.9% in a 28-day scalp serum trial.
Dr Shaher Duchi, Chief Scientist, and Dr Danny Goldstein, Vice President R&D, Tagra Biotechnologies Ltd. COSSMA 6/2023, pp. 26–29.
Water Soluble Salicylic Acid: an innovative way to design unique salicylic acid formulations. Tagra's 'WS SA50' appears as a white powder and is said to open new possibilities for hair care products, working effectively against dandruff. Dr Shaher Duchi and Dr Danny Goldstein introduce the new invention.
Salicylic acid (SA) is an organic beta-hydroxy acid (BHA) first extracted in 1829 by Pierre-Joseph Leroux. SA is a colorless, crystalline, and bitter-tasting solid that is naturally present in several plants. Due to its well-known keratolytic and anti-inflammatory properties, SA is commonly used in many skincare, scalp care, and hair care products for soothing sensitive skin, reducing redness, and treating acne and other skin disorders. SA is also used as a preservative in concentrations of up to 0.5% to protect formulas against the growth of micro-organisms [1]. Recently, it was announced to be also considered safe for "other uses" at a concentration up to 2.0% for various skincare cosmetic products and at a concentration up to 3.0% for certain hair products [2,3].
However, SA presents several formulation issues: it is a crystalline powder which has poor water solubility (0.2g/100ml at 20°C) and therefore tends to recrystallise in water-based formulations. Currently, topical SA is widely used by dissolving it in other solvents (mainly alcohols and glycols) to increase its solubility in the formulation to be more effective. Yet, using alcohol as solubiliser for SA can result in some adverse effects such as skin dryness and irritation and lead to noticeable problems in the formula, such as crystallisation and discoloration, which detract from the product's consumer appeal.
To improve SA's effectiveness and overcome the aforementioned formulation challenges, Tagra Biotechnologies developed 'WS SA50', an innovative water-soluble powder form of SA with a concentration of 50% SA. The 'WS SA50' has a water solubility level of 5g/100ml compared to 0.2g/100ml for free SA. Tagra's technology leads to a significant increase in SA's aqueous solubility without the addition of solubilizers and prevents recrystallisation, thereby making the SA more effective.
Powder Characterisation
The 'WS SA50' appears as a white powder with an average SA content of 46.5% ± 0.2%. The quantification of SA was performed using the reverse-phase HPLC method with a JASCO HPLC system equipped with variable ultraviolet detectors. Particle morphology and size were analysed by scanning electron microscopy (SEM) as shown in figure 1.
Figure 1: SEM observation of 'WS SA50' powder showing particles with spherical morphology in the range of 2-30 microns.
Solubility Test
The water solubility property of WS SA50 powder was measured in distilled water (DW) by dissolving it at 2%, 4%, and 6%, which is equivalent to 1%, 2% and 3% of free SA, respectively. WS SA50 increases the solubility of SA up to 15 times when compared to free SA and does not require using alcohol as solubilizer. Likewise, there is no unwanted recrystallisation effect.
In Vitro Efficacy Test: Antibacterial Properties Against P. Acnes
The Tagra team tested the effectiveness of WS SA50 on P. Acnes growth through disk diffusion assay, and the results show that a water solution containing 4% WS SA50 is more potent than a traditional hydroalcoholic solution containing 2% free SA and an Ampicillin 4µg/ml solution, as shown in figure 2.
Figure 2: Antibacterial properties of WS SA50 against P. Acne tested in-vitro by Disc Diffusion Assay.
Similarly, when comparing the Minimum Inhibitory Concentration (MIC) for both the 4% WS SA50 and 2% SA solutions, it is shown that the water solution containing 4% WS SA50 is 30-50% more effective than the hydroalcoholic solution with 2% free SA (both solutions at same %), as shown in figure 3.
Figure 3: Comparison of the Minimum Inhibitory Concentration against P. Acnes between a water solution with 4% WS SA50 and a hydroethanolic solution with 2% free SA. Ampicillin was used as a positive control (10 μg/ml) diluted in 25% DDW.
In Vivo Anti-Dandruff Trial
As part of our efforts, the team completed a clinical evaluation of a scalp serum, anti-dandruff treatment formulation containing 4% WS SA50. The test group consisted of 30 volunteers (male and female), aged from 18 to 56 years (mean 26.4 ± 9.7). The volunteers suffered from an overly oily scalp (sebum levels > 120 µg/cm²) and visible dandruff flakes (score 1-3 in Van Abbe's scoring scale), after being submitted to 15 days of wash-out phase without specific hair treatment (only use of normal shampoo). The volunteers were instructed to apply the test product for 28 days following a protocol of daily treatments (6-7 mL per application) directly on the scalp. Before the start of the treatment (D0) and after 4 weeks of its application (D28), the volunteers came for scalp measurements to assess hair dandruff (number and total area).
Volunteer dandruff was quantified in the specific Region of Interest (ROI) for each volunteer using a Nikon D5600 installed with the HeadScan Bench Light Face and FrameScan NG-48 software for 2D image analysis. Additionally, two independent technicians conducted a visual expert evaluation, using Van Abbe's scoring scale (0-3) for dandruff. High resolution macroscopic pictures were obtained using the Nikon D5600 camera installed in the HeadScan Bench Light Face. Data recorded from each volunteer at each of the timepoints (D0 through D28) were normalised versus baseline values (D0) and statistically analysed between timepoints.
The topical application of the 4% WS SA50 Serum significantly reduced the number of dandruff particles by 51.1% after 28 days of topical application, when compared to D0. Consistently, the treatment with 4% WS SA50 Serum significantly reduced the total area of dandruff by 54.9% at D28 (figure 4).
Figure 4: Effect of 4% WS SA50 Serum on hair dandruff parameters. Graphical representation of the number and total area of dandruff particles, evaluated through image analysis, before (D0) and after 28 days (D28) of treatment with 4% WS SA50 Serum.
The clinical expert evaluation (CEE), the more subjective of the assessments, also indicated a significant reduction of visible dandruff, with a clinical score of 1.76 at baseline (D0) to 0.92 at D28 (figures 5 and 6).
Figure 5: Effect of 4% WS SA50 Serum on hair scalp dandruff, before treatment (D0) and after 4 weeks (D28) of topical application treatment.
Figure 6: Effect of 4% WS SA50 Serum on hair dandruff after Clinical Expert Evaluation. Graphical representation of the dandruff levels subjectively evaluated using Van Abbe's scoring scale (0-3), before (D0) and after 28 days (D28) of treatment.
Parameter | Result at D28 vs. D0 |
|---|---|
Number of dandruff particles | -51.1% |
Total area of dandruff | -54.9% |
Clinical expert score (Van Abbe, 0-3) | 1.76 → 0.92 |
Regarding cutaneous compatibility and acceptability, participants showed no Serious Undesirable Effects (SUE) throughout the period of treatment or the following 7 days.
Conclusion
WS SA50 opens new dimensions for formulators and product development teams that are aiming to design new salicylic acid-based formulations and new product concepts. Such a technology contributes to better skin and increased product acceptance by consumers, as it results in healthy, non-irritated skin.
References
www.mayoclinic.org/drugs-supplements/salicylic-acid-topical-route/description/drg-20066030
www.ec.europa.eu/health/ph_risk/committees/sccp/documents/out170_en.pdf
www.cirs-group.com/en/cosmetics/sccs-issued-a-preliminary-opinion-on-salicylic-acid
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