Assessment of Skin Photoallergy Risk in Cosmetics Containing Herbal Extract Ingredients

Abstract

<b><i>Background/Objective:</i></b> In recent years, herbal extracts are becoming increasingly popular ingredients added in cosmetics; however, the assessment of their potential adverse effects on the skin remains unclear. As <i>Coptis</i>, <i>Phellodendron amurense</i>, curcumin, and shikonin are herbs currently used in cosmetic ingredients, the aim of this study was to assess their skin photoallergy (PA) potential and the concentrations at which they could safely be used. <b><i>Methods:</i></b> In the patch test, <i>Coptis</i>, <i>P. amurense</i>, curcumin, and shikonin with 5, 10, 25, and 50% concentration were applied on 33 healthy Chinese subjects using the T.R.U.E. TEST® patch test system for 48 h. Photopatch testing was performed on 206 Chinese subjects with predisposed photosensitivity history using the Scandinavian photopatch series, and subjects were irradiated by 50% UVA minimum erythema dose. Photopatch testing of herbal extracts was then performed on subjects diagnosed with PA. <b><i>Results:</i></b> Thirty-three subjects (14 with type III skin and 19 with type IV skin) completed contact patch testing of herbal extracts. <i>Coptis</i> induced a contact allergy (CA) reaction on 2 subjects at 25% concentration and on 2 subjects at 10% concentration. <i>P. amurense</i> induced a CA reaction on 1 subject at 10% concentration and on 1 subject at 5% concentration. Shikonin induced a stimulating reaction on 1 subject at 10% concentration. Curcumin induced a stimulating reaction on 1 subject at 10% concentration. Of the 206 Chinese subjects predisposed for photosensitivity, 10.19% had PA, 16.5% showed CA, and 1.45% had both PA + CA. PA-induced substances were promethazine hydrochloride (15%, <i>n</i> = 31), chlorpromazine hydrochloride (10.84%, <i>n</i> = 19), perfume mix (5.82%, <i>n</i> = 12), atranorin (3.39%, <i>n</i> = 7), 6-methyl coumarine (3.39%, <i>n</i> = 7), balsam Peru (1.94%, <i>n</i> = 4), fentichlor (1.94%, <i>n</i> = 4), 3,3′,4′,5-tetrachloro salicylanilide (0.97%, <i>n</i> = 2), hexachlorophene (0.97%, <i>n</i> = 2), chlorhexidine digluconate (0.97%, <i>n</i> = 2), and 4-aminobenzoic acid 2-hydroxy-4-methoxybenzophenone (0.97%, <i>n</i> = 2). <i>Coptis</i> at 25, 10, and 5% concentration and <i>P. amurense</i>, shikonin, and curcumin each at 10 and 5% concentration induced negative photopatch test results in all 10 photosensitive subjects. <b><i>Conclusion:</i></b> We have shown that <i>Coptis</i>, shikonin, or curcumin at 5% concentration in cosmetics could be applied safely without inducing contact allergic and photosensitive reactions on the skin. These findings advance the understanding of herbal extract use in cosmetic ingredients as related to the fields of dermatopharmacology and dermatotoxicology.

Innovative Strategies for Photoallergy Assessment: Breaking Free from Animal Models in Cosmetic Ingredient Development

“…Other potential photoallergens are natural products which are more difficult to evaluate using in vitro methodologies. There are some studies involving volunteers [62], but this kind of study presents ethical concerns, as pointed by the Scientific Committee of Consumer Safety of the European Union [63]. Photopatch tests should be performed only for diagnostic purposes not for the safety evaluation of cosmetic ingredients.…”

Protein Haptenation and Its Role in Allergy

“…A recent study demonstrated involvement of radical intermediates formed from hydroperoxides of citronellol in protein haptenation . Topical nonsteroidal anti-inflammatory drugs (NSAIDs) and organic UV light absorbers in sunscreens are clinically the most relevant photoactivated small molecule allergens, but the list is extended to numerous antibiotics, antifungal agents, agrochemicals, food additives, plant extracts, and fragrances. − …”

Natural Plant-Derived Compounds in Food and Cosmetics: A Paradigm of Shikonin and Its Derivatives

“…In the research, 5, 10, 25, and 50% concentrations were used in the patch test system for 48 h. The test was applied to 33 healthy Chinese subjects, while the photo patch test was administered to 206 subjects, whose skin was characterized by photosensitivity. It was indicated that a 5% concentration of shikonin can be applied in cosmetics products as a safe ingredient not causing photosensitive or contact allergic reactions on the skin [ 74 ]. Another property of shikonin is the ability to stimulate the growth of human keratinocytes and dermal fibroblasts, which was confirmed by MTS assay allowing for cell growth measurements; thus, shikonin can promote wound healing.…”