Abstract
The so-called active ingredients in skin care product formulations are purported to deliver the intended functions of the product. Active ingredients, such as the antioxidants can efficiently protect the skin if the activities are retained after incorporating into the base matrices in the product formulation. Here, we investigated the antioxidant activities of 24 extracts/compounds that are being used in skin care formulations and their ability to retain the activities (efficacy) after being mixed with the base matrices. The antioxidant activities were evaluated using 2, 2’-azino-bis (3- ethylbenzothiazoline-6-sulphonic acid (ABTS) and diphenyl-picryl hydrazine (DPPH) assays. To test the efficacy of the samples in formulation, the samples were mixed with base cream 1%, 2% and 4% (w:w) and allowed to settle overnight. Results were expressed as either percentage inhibition (%) or IC50 (μg/mL). Out of the 24 samples, ten exhibited significantly high antioxidant activities with resveratrol> pomegranate> green tea> mango> amla> bearberry> ellagic acid> tetrahydrocurcuminoid> Rhodiola rosea> kakadu plum in the ABTS assay. In the DPPH assay, green tea> pomegranate> tetrahydrocurcuminoid> mango> amla> resveratrol> bearberry> Rhodiola rosea>kakudu plum>ellagic acid. Four out of the ten samples (amla, green tea, mango and pomegranate extracts) had IC50 value lower than Trolox standard and were included in the efficacy test. Trolox standard and amla extract seemed to retain their antioxidant activities in the formulations, while green tea and pomegranate extracts had a decrease in activities. Only mango extract had a synergistic effect with the cream base with higher antioxidant activity observed compared with the extract alone. This study demonstrates the potential interaction between active and vehicle compounds, which may hinder or enhance the activities of the active ingredients in the final product. The outcome of the research has an impact in the cosmetic product formulation particularly in the quality control, chemistry and efficacy of the finished products.
Highlights
The human skin is continuously exposed to various environmental insults that are damaging to the skin, leading to skin aging
We evaluated the antioxidant activities of 24 extracts/ compounds used in skin care formulations and their ability to retain their efficacy in product formulation
Screening Significantly high antioxidant activities were observed with the following extracts/ compounds; amla extract, bearberry extract, ellagic acid, green tea with 90% EGCG, kakadu plum extract, mango extract, pomegranate extract, resveratrol, Rhodiola rosea extract, tetrahydrocurcuminoid and oleuropein 40%), whereas low to intermediate antioxidant activities were observed for: Centella asiatica whole extract, Centella asiatica with 2% asiaticoside and Moringa oleifera leaf extract’ and low to no activity for fucoidan, nobiletin, galangal extract, kojic acid dipalmitate, niacinamide, pullulan, sea buckthorn oil, aloe extract, L-carnosine and willow bark extract (Table 1)
Summary
The human skin is continuously exposed to various environmental insults (cigarette smoke, pollutants, infrared radiation, ultraviolet radiation etc) that are damaging to the skin, leading to skin aging. Cosmetic products with claimed benefits are commonly termed as “cosmeceuticals”, a word coined by merging the word cosme-(tic) and (pharma)-ceutical, to describe “active” and science based cosmetic.[4,5] The actives in the product formulation are expected to deliver their functions especially after mixing with other ingredients in the product formulation. Some of the commonly used actives are antioxidants.[6,7,8,9] The use of antioxidants in product formulation is due to understanding the role of oxidative stress in the aging of the skin.[10,11,12,13,14] In this study, we evaluated the antioxidant activities of 24 extracts/ compounds used in skin care formulations and their ability to retain their efficacy in product formulation
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