Comparison of Phototoxicity Sensitivity by the Neutral Red Uptake Method for BALB/c 3T3, HaCaT, and HDFa Cells In Vitro

ABSTRACT Introduction Phototoxicity is an acute photoinduced reaction. The 3T3 neutral red uptake (NRU) phototoxicity test has high sensitivity for the determination of phototoxic substances. To further optimize the method, this study mainly focused on comparing the phototoxicity sensitivity by using the NRU method for BALB/c 3T3, HaCaT, and HDFa cells in vitro. Methods The NRU method was used to evaluate the phototoxicity of chlorpromazine hydrochloride (CPZ), amiodarone hydrochloride (Amiodar), and L-histidine (L-His) on BALB/c 3T3 cells, HaCaT cells, and HDFa cells. The sensitivity of different cells to ultraviolet (UVA) irradiation in vitro was studied. Results L-His showed no phototoxicity, but the phototoxicity of CPZ and Amiodar showed different sensitivities among the three kinds of cells. The in vitro phototoxicity evaluation of HaCaT cells is closer to that of primary human fibroblasts. Conclusion This study provides a reference for cell line selection to optimize the existing in vitro evaluation method of 3T3 NRU phototoxicity.

Assessment of Skin Photoallergy Risk in Cosmetics Containing Herbal Extract Ingredients

<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.