Evaluation of the acute toxicity, phototoxicity and embryotoxicity of a residual aqueous fraction from extract of the Antarctic moss Sanionia uncinata

Andréia Da Silva Fernandes,Elisa Raquel Anastácio Ferraz,Lara Barroso Brito,Gisele Augusto Rodrigues Oliveira,Heitor Evangelista,Israel Felzenszwalb,José Luiz Mazzei

doi:10.1186/s40360-019-0353-3

Abstract

BackgroundUltraviolet (UV) radiation is the main exogenous inductor of skin damage and so photoprotection is important to control skin disorders. The Antarctic moss Sanionia uncinata is an important source of antioxidants and the photoprotective activity of its organic extracts has been investigated. This study aimed to evaluate the potential photoprotection, cytotoxicity and embryotoxicity of residual aqueous fraction (AF) from the moss S. uncinata.MethodsUV-visible spectrum and SPF (sun protection factor) were determined by spectrophotometry. Embryotoxicity potential was evaluated by Fish embryo-larval toxicity test using zebrafish (Danio rerio) as organism model. Cell death assays by water-soluble tetrazolium salt (WST-1) and lactate dehydrogenase (LDH) were investigated using HaCaT keratinocyte cell line cultured in monolayers and three dimensions (3D). Phototoxicity and association with UV-filters were performed by 3T3 neutral red uptake test.ResultsThe AF showed sharp absorption bands in the UV region and less pronounced in the visible region. The SPF was low (2.5 ± 0.3), but the SPF values of benzophenone-3 and octyl-methoxycinnamate increased ~ 3 and 4 times more, respectively, in association with AF. The AF did not induce significant lethal and sublethal effects on zebrafish early-life stages. In monolayers, the HaCaT cell viability, evaluated by WST-1, was above 70% by ≤0.4 mg AF/mL after 48 and 72-h exposure, whereas ≤1 mg AF/mL after 24-h exposure. The LDH assay showed that the cell viability was above 70% by ≤0.4 mg AF/mL even after 72-h exposure, but ≤1 mg/mL after 24 and 48-h exposure. In 3D cell culture, an increased cell resistance to toxicity was observed, because cell viability of HaCaT cell by WST-1 and LDH was above ~ 90% when using ≤1 and 4 mg AF/mL, respectively. The AF demonstrated values of photo irritation factor < 2 and of photo effect < 0.1, even though in association with UV-filters.ConclusionsThe residual AF absorbs UV-vis spectrum, increased SPF values of BP-3 and OMC and does not induce embryotoxicity to zebrafish early life-stage. The cell death assays allowed establishing non-toxic doses of AF and phototoxicity was not detected. AF of S. uncinata presents a good potential for skin photoprotection against UV-radiation.

Highlights

Ultraviolet (UV) radiation is the main exogenous inductor of skin damage and so photoprotection is important to control skin disorders
Except for MBC and OCT that have an expected natural additive increasing on absorption intensity, the association of aqueous fraction (AF) with BP-3 and OMC led to a significant higher increase (P < 0.05, t-Student) of sun protection factor (SPF) values: 12.3 ± 0.9 for BP-3 increased to 18.0 ± 1.2, equivalent to ~ 3-fold increasing; 17.6 ± 0.8 for OMC increased to 24.5 ± 0.7 equivalent to ~ 4-fold increasing
The significant synergic effect between the AF and these UV-filters can be seen in the Fig. 2, in which are represented the calculated E x I x AU curves of AF + BP-3 and AF + OMC mixtures determined from observed absorption and by predicting if only additive absorption would be presented

Summary

Introduction

Ultraviolet (UV) radiation is the main exogenous inductor of skin damage and so photoprotection is important to control skin disorders. The Antarctic moss Sanionia uncinata is an important source of antioxidants and the photoprotective activity of its organic extracts has been investigated. This study aimed to evaluate the potential photoprotection, cytotoxicity and embryotoxicity of residual aqueous fraction (AF) from the moss S. uncinata. The human incidences of skin cancer and photoaging, that result from the excessive solar ultraviolet radiation (UVR) exposure, are increasing around the world [1]. Acute and chronic skin exposures to UVR result in deleterious effects on human skin such as erythema, photo-ageing and initiation of carcinogenic processes [3]. Sunscreens are intended to protect the surface of the skin by reflecting (inorganic UV filters) or absorbing (organic UV filters) radiation [4]. Some UV-filters can diffuse into deep layers of the skin and the systemic absorption can result in efficiency loss and local and systemic toxicity [7]

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