Improving dandruff shampoo via biobased propanediol

The potential for boosting zinc pyrithione (ZPT) efficacy by using Zemea biobased propanediol in a generic dandruff shampoo formulation was evaluated in this study. A time-dependent, doseresponse relationship was observed between the mortality of Malassezia globosa, a microorganism associated with human dandruff, and Zemea concentration over a range of 0% to 4%. Formulation used in test solution. Ingredient INCI name Weight, % Water Water qs to 100% Zemea Propanediol Propanediol 0 to 4.0 Carbopol Aqua SF-1 Acrylate Copolymer 6.00 Sodium Hydroxide 30% Sodium Hydroxide 0.50 Steol CS230 Sodium Laureth Sulfate 50.00 Cocamidopropyl Betaine Cocamidopropyl Betaine 10.00 Mackamide CMA Cocamide MEA 2.00 Sodium Chloride Sodium Chloride 0.50 Zinc Omadine FPS Zinc Pyrithione 2.50 Na4EDTA, Crystals Tetrasodium EDTA 0.02 Mackstat DM DMDM Hydantoin 0.75 Fragrance Fragrance 0.50 Citric Acid Citric Acid to pH 5.5 w w w. ph ot or ac k. ne t Study design and results Experimental design Formulation The test solutions were manufactured and supplied by Bria Research in Libertyville, IL, US. All formulations contained 1.2% ZPT (2.5 wt.% solution x 48 wt.% ZPT = 1.2% ZPT). Propanediol was added at the 0%, 1%, 2%, 3% and 4% levels. Organism and test methods The organism was prepared and the testing was conducted by Pharmaceutical Laboratories and Consultants Inc. M. globosa (ATCC MYA-4612) was grown on Sabourauds dextrose medium with lecithin and polysorbate 80 as neutralisers for 7 days at 20 ̊C to 25 ̊C. After 7 days, the organism was harvested by scraping and suspending the organism in Butterfields buffer. This suspension was serially diluted and plated to determine initial colony-forming units (CFU). Recovery control of the organism was performed by taking an uninoculated aliquot of the 4% propanediol and serially diluting to 10 and subsequently inoculating each dilution with a 10 suspension of organism, mixing and plating. Exactly 15 grams of each test solution was transferred without dilution into four falcon tubes. Each tube was inoculated with 0.1 mL of M. globosa and the tube was mixed by inversion. After inoculation, a 1 mL aliquot was removed from the tube at the specified time (0, 10 min, 1 hr, and 24 hr), serially diluted, and then transferred to petri plate containing the modified Sabourauds media as described above, with 2% agar. All testing took place at room temperature. Incubation was 20 ̊C to 25 ̊C for 7 calendar days. Each test was performed in triplicate and the mean for the population was reported. Stock solution, recovery test, and dilution All CFU reported as log10 CFU/mL. Initial plating indicated that the stock solution was approximately 2 x 10 CFU/mL. The 4% propanediol was serially diluted to 10 and inoculated with a 10 dilution of initial suspension using 0.1 mL (Table 1). This quality control verification of M. globosa recovery at various dilution levels used in this study verified that the dilution process did not significantly influence viability counts. This was reported by Pharmaceutical Laboratories and Consultants Inc. Results Shown below is the observed timedependent dose-response relationship between M. globosa mortality and propanediol concentrations ranging from 0%-4% (Table 2 and Figure 1). All CFU reported as log10 CFU/mL. All test samples were inoculated with 0.1 mL of a 1:10 dilution of the stock solution. The synergistic effects between propanediol and ZPT showed that with the addition of 4% propanediol/2.5% ZPT, M. globosa mortality rate increased by 90% (Fig. 2). Conclusion Zemea is the world’s first 100% natural glycol replacement approved by Ecocert and certified by the Natural Products Association. With its skin-friendly performance, including no irritation, enhanced moisturisation and excellent aesthetics, Zemea is seeing rapid adoption around the world in skin care, hair care, deodorants, fragrances, and other cosmetic and personal care products. Based on rapidly renewable resources, Zemea can successfully replace or augment petroleumbased glycols or glycerin in many natural and traditional personal care formulations. Formulators may be able to reduce the amount of preservatives used in their formulations with the inclusion of this natural glycol replacement. Zemea propanediol may provide improved efficacy in dandruff shampoos. With the addition of 1% Zemea in combination with 2.5% ZPT, results indicate enhanced mortality of M. globosa over a control with no Zemea. With the addition of 4% Zemea in combination with 2.5% ZPT, mortality rate of M. globosa increased by 90%. Zemea propanediol is not a preservative, nor is it considered an active ingredient. This study demonstrates one of the important benefits that Zemea biobased propanediol provides to dandruff shampoo formulations. Other technical hair care studies have shown additional performance advantages in shampoos, conditioners and styling products: HAIR CARE 78 PERSONAL CARE September 2014 Table 1: Recovery test. Dilution of 4% Zemea. 4% Zemea Recovered cfu/mL