Photoprotective effects of glucomannan isolated from Candida utilis Ema Ruszova, a, * Stanislav Pavek, a Veronika Hajkova, a Sarka Jandova, a Vladimir Velebny, a Ivana Papezikova b and Lukas Kubala b a CPN spol. s.r.o, 561 02 Dolni Dobrouc 401, Czech Republic b Institute of Biophysics Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno, Czech Republic Received 15 August 2007; received in revised form 8 November 2007; accepted 11 November 2007 Available online 19 November 2007 Abstract—Glucomannans belong to yeast and fungal cell wall polysaccharides with known immunostimulatory and radioprotective effects. However, glucomannan protective effects against pathological consequences of skin exposure to short wavelength solar light, ultraviolet (UV) radiation, are unclear. Herein, a highly branched glucomannan (GM) isolated from the cell wall of Candida utilis,a member of the a-(1!6)-D-mannan group, was tested for its photoprotective effects in an in vitro model of UVB-irradiated human keratinocytes and an in vivo model of UV-induced erythema formation in human volunteers. GM suppressed the UVB-induced decrease of keratinocyte viability, which was connected with the suppression of UVB-induced keratinocyte apoptosis. GM reduced UVB-mediated caspase activation together with suppression of DNA fragment release into the cytoplasm. Furthermore, GM suppressed UVB-induced gene expression of pro-inflammatory markers including nuclear factor kappa B, inducible nitric oxide synthase, interleukins 8 and 1, together with suppression of prostaglandin E2 and interleukin 1a protein release. In vivo, GM decreased UV-induced skin erythema formation, which was correlated with a decrease of phosholipase A 2 activity within the stratum corneum. It could be concluded that GM isolated from C. utilis possesses significant photoprotective effects on human keratinocytes in vitro as well as in vivo. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Glucomannan; Candida utilis; HaCaT keratinocytes; UV-protection; Polysaccharide; Apoptosis 1. Introduction It is well recognized that skin exposure to solar radiation has detrimental consequences, both acute and chronic. In particular, the short wavelength part of solar light, ultraviolet (UV) radiation, contributes significantly to undesirable effects, which could lead to the development of cutaneous malignancies. 1–3 The impact of cutaneous malignancies is significant since melanoma and non- melanoma skin cancer are the most abundant carcino- mas in western countries. 1,4 Therefore, development and improvement of skin protection strategies against solar radiation is a critical issue. Different mechanisms are suggested to contribute to the adverse effects of UV radiation on the skin. One of the most significant mechanisms is UV-induced suppres- sion of immune functions connected with massive cuta- neous cell death. Decrease of cutaneous cell viability is related to UV-induced cell damage due to the formation of free radicals that destruct cellular structures including lipids, nucleic acids, and proteins. 1,2 Physiological func- tions associated with UV-induced impairment of skin are directly associated with the inflammatory response provoked by the damaged keratinocytes, which leads to the release of a wide range of inflammatory mediators. Cytokines released during this early phase of UV-induced skin reaction are considered to be impor- 0008-6215/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.carres.2007.11.010 Abbreviations: aMSH, alpha melanocyte stimulating hormone; CR3, complement receptor 3; GM, glucomannan; iNOS, inducible nitric oxide synthase; IL-1a, interleukin 1 alpha; MR, mannose receptor; NO, nitric oxide; NFjB, nuclear factor jB; PAMPs, pathogen- associated molecular patterns; PLA 2 , phospholipase A 2 ; PGE 2 , pros- taglandin E 2 ; TLR, toll-like receptor; UVB, ultraviolet light B * Corresponding author. Tel.: +420 465 519548; fax: +420 465 543 793; e-mail: ruszova@contipro.cz Available online at www.sciencedirect.com Carbohydrate Research 343 (2008) 501–511