Speciality Chemicals Magazine NOV / DEC 2021 | Page 26

COSMETICS & PERSONAL CARE

Figure 4 – Shannon diversity index results for formulations SC-DE-20-044-2 & SC-DE-20-067-8 v . untreated control

‣ The emulsifiers Plantaquat * NC ( INCI : Cetearyl Alcohol , Lecithin , Sodium Cetearyl Sulfate , Olus Oil [ EU ]), Plantapon * LC7 ( INCI : Laureth-7 Citrate ) and Dehymuls * PGPH ( INCI : Polyglyceryl-2 Dipolyhydroxystearate ), and the polymers Rheocare * XGN ( INCI : Xanthan Gum ), Hydagen Clean ( INCI : Glucomannan ) and Arlypon * TT ( INCI : PEG / PPG- 120 / 10 Trimethylolpropane Trioleate ( and ) Laureth-2 ) showed the best MIC results . ¹ Based on the results of the three emollients tested neat in human studies ( Cetiol * RLF ( INCI : Capryl Caprylate / Caprate ), Cetiol CC ( INCI : Dicapryl Carbonate ) and Cetiol 4-all ( INCI : Dipropylheptyl Carbonate )), we concluded that these were not expected to perturb the microbiome . The ‘ best of ’ ingredients and concentrations were used to develop two formulation chassis – a serumtype chassis ( SC-DE-20-044-2 ) and an emulsion oil-in-water cream-type ( SC-DE-20-067-8 ) chassis , whose formulations are shown in Figure 3 . These passed stability and microbial challenge testing . Following four weeks of twice-daily use of the two formulations by human

volunteers , analyses of the alpha diversity ( the mean species diversity in sites or habitats at a local scale ) of the skin microbiota , as evidenced by Shannon alpha diversity index data , indicated no significant changes to the microbiome when compared to Day 0 ( Figure 4 ). These results demonstrate that the chassis are truly microbiome-friendly , in vivo as well as in vitro . Interestingly , even the untreated skin showed substantial variations over time , even within one individual . The serum and the cream respectively showed improvements in skin hydration and skin barrier function ( moisture : + 12.6 %/ 12.9 %; transepidermal water loss ( TEWL ): -4.1 %/ -11.3 %) and consumer acceptance ( 7.5 / 7.4 out of 10 ). It was also possible to incorporate a broad range of bioactives without formulation stability being affected , thereby allowing specific modulation of the skin care or microbiome attributes where needed .

Discussion

The skin is colonised by a score of different microorganisms that are almost as unique to an individual as their fingerprints . As such , an individual ’ s healthy skin microbiome should not be disrupted to any great degree . This study shows that by careful selection of ingredients and formulation know-how , truly microbiome-friendly skincare chassis can be developed . Those developed in this study were subjected to full microbiome studies on human volunteers to substantiate effects . The results indicate that these can truly be claimed to be ‘ microbiomefriendly ’ and also fulfil the needs consumers expect from their skin care products , such as moisturisation . These chassis can then be used to incorporate specific bioactives that target defined skin conditions . As very new routes and insights into maintaining a healthy skin microbiome were found , this is a true step forward in formulating microbiome-friendly skin care products . We are still at the beginning of our journey and much is still to be learned but it is a journey well worth embarking on . •

* Plantaquat , Plantapon , Dehymuls , Rheocare , Hydagen , Arlypon & Cetiol are all registered trademarks of BASF

26 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981