Evaluation of the phototoxic potential of plants used in oriental medicine

Aim of the study: Phototoxicity can be either harmful or beneficial. Yet the phototoxicity of oriental medicinal plants is an understudied area. The purpose of this study is to fill in this gap. Materials and methods: The phototoxic potential of oriental medicinal plants was examined in vitro using photohemolysis and the Candida albicans test. Seventeen medicinal plants [Acorus gramineus (ACC), Panax ginseng C.A. (PAG), Platycodon grandiflorum (PLG), Aractylodes japonica (ATJ), Xanthium strumarium (XAS), Dioscorea batatas (DIB), Anemarrhena asphodeloides (ANA), Polygonatum sibiricum Red (PSR), Cocculus trilobus (COT), Ficus carica (FIC), Chelidonium majus var. asiaticum (CMA), Pulsatilla koreana (PUK), Agrimonia pilosa (AGP), Zanthoxylum schinifolium (ZAS), Angelica gigas (ANG), Ledebouriella seseloides (LES), and Cnidium officinale (CNO)] were selected because they showed strong fluorescence in one of our previous studies of 62 plants. We further evaluated in vivo phototoxicity in mice. 0.75 mL/kg of seed oil for Xanthium strumarium (XAS, (sic)), or 1.25 mL/kg of extracted solutions of Atractylodes japonica (ATJ, (sic)), Chelidonium majus var. asiaticum (CMA, (sic)), Zanthoxylum schinifolium (ZAS, (sic)), and Ledeboutiella seseloides (LES, (sic)) were given once, and evaluated for sunburn edema, formation of sunburn cell, decrease of epidermal Langerhans cells and local suppression of contact hypersensitivity by UVA irradiation. Results: Sixteen out of the 17 plants tested except COT showed significant photohemolysis, and 5 of those exhibited phototoxic killing of Candida albicans. The phototoxicity of oriental medicines using those 5 plants was then studied in mice. The 5 plants increased sunburn edema and formation of sunburn cell, and suppressed immune responses locally by decreasing epidermal Langerhans cells and contact hypersensitivity by UVA irradiation. Conclusions: More than a quarter of oriental medicinal plants can be phototoxic, and strong fluorescence measured by absorption and fluorescence spectra can be an easier way to screen for phototoxicity. On the other hand, the phototoxicity of the plants may also be used therapeutically. Further studies regarding the phototoxicity of active components extracted from both live and dried oriental medicinal plants are necessary. (C) 2009 Elsevier Ireland Ltd. All rights reserved.