Examining Safety of Biocolourants from Fungal and Plant Sources-Examples from Cortinarius and Tapinella, Salix and Tanacetum spp. and Dyed Woollen Fabrics.

Biocolourants have been investigated as alternatives to synthetic dyes. However, natural origin per se is not a label of harmlessness and research is needed to obtain safe dyes. We studied the cytotoxicity of the extracts from fungal (Cortinarius semisanguineus, Tapinella atrotomentosa) and plant (Tanacetum vulgare, Salix phylicifolia) sources and the woollen fabrics dyed with the extracts. Cytotoxicity in vitro using hepa-1 mouse hepatoma cells for 24 h and 72 h exposure was observed as the highest tolerated dose. All biocolourants produced intensive colour on fabrics with fastness properties from moderate to good. The Salix and Cortinarius samples did not show any cytotoxic effects, whereas the Tanacetum and Tapinella samples had slightly higher test values but were not interpreted as being significantly toxic. Higher than zero values of the undyed fabrics showed the importance of examining their toxicity as well. It was found that the cytotoxicity of the samples dyed with the biocolourants did not differ significantly from the undyed wool fabric. The concentrations of dyes used in the assays were very low, imitating the dose of the user. In addition to colouring properties, natural dyes may have pharmaceutical and antibacterial properties which would enhance the interest in using them in products for added value.

Metabolic and molecular analyses of white mutant Vaccinium berries show down-regulation of MYBPA1-type R2R3 MYB regulatory factor.

MAIN CONCLUSION: MYBPA1-type R2R3 MYB transcription factor shows down-regulation in white mutant berries of Vaccinium uliginosum deficient in anthocyanins but not proanthocyanidins suggesting a role in the regulation of anthocyanin biosynthesis. Berries of the genus Vaccinium are among the best natural sources of flavonoids. In this study, the expression of structural and regulatory flavonoid biosynthetic genes and the accumulation of flavonoids in white mutant and blue-colored wild-type bog bilberry (V. uliginosum) fruits were measured at different stages of berry development. In contrast to high contents of anthocyanins in ripe blue-colored berries, only traces were detected by HPLC-ESI-MS in ripe white mutant berries. However, similar profile and high levels of flavonol glycosides and proanthocyanidins were quantified in both ripe white and ripe wild-type berries. Analysis with qRT-PCR showed strong down-regulation of structural genes chalcone synthase (VuCHS), dihydroflavonol 4-reductase (VuDFR) and anthocyanidin synthase (VuANS) as well as MYBPA1-type transcription factor VuMYBPA1 in white berries during ripening compared to wild-type berries. The profiles of transcript accumulation of chalcone isomerase (VuCHI), anthocyanidin reductase (VuANR), leucoanthocyanidin reductase (VuLAR) and flavonoid 3'5' hydroxylase (VuF3'5'H) were more similar between the white and the wild-type berries during fruit development, while expression of UDP-glucose: flavonoid 3-O-glucosyltransferase (VuUFGT) showed similar trend but fourfold lower level in white mutant. VuMYBPA1, the R2R3 MYB family member, is a homologue of VmMYB2 of V. myrtillus and VcMYBPA1 of V. corymbosum and belongs to MYBPA1-type MYB family which members are shown in some species to be related with proanthocyanidin biosynthesis in fruits. Our results combined with earlier data of the role of VmMYB2 in white mutant berries of V. myrtillus suggest that the regulation of anthocyanin biosynthesis in Vaccinium species could differ from other species studied.