High quality Green (Brazilian) propolis extracts characterized for active biomolecules exert epigenetic effects able to have a positive influence on cell oxidative stress

High quality Green (Brazilian) propolis extracts characterized for active biomolecules exert epigenetic effects able to have a positive influence on cell oxidative stress 1Daglia Maria, 1Valeria Curti, 1,2Vincenzo Zaccaria, 3Fabio Galeotti, 2Laura Crimaldi, 3Francesca Maccari, 2Alfredo Fachini, 3Nicola Volpi 1Department of Drug Sciences. University of Pavia, Via Taramelli 12. Pavia, Italy. 2B Natural R&D Unit, Via Gran Sasso 33. Corbetta (Milano), Italy 3Department of Life Sciences. University of Modena and Reggio Emilia, Via Campi 213/D, Modena, Italy. Study Objective(s). Recently, EFSA (European Food Safety Authority) provided negative responses on the substantiation of health claims related to propolis based on two main points: I) propolis is very heterogeneous and its main active components (bio)flavonoids are not well characterized and II) due to the absence of structural characterization of propolis and related products, no structure/composition and effect/activity relationship may be established. Thus, the aim of this study is to show that a high quality Green Brazilian propolis extract GreenArt® (prepared according to proprietress and patented technology) exerts epigenetic effects, being able to modulate the expression levels of miRNAs connected with oxidative stress. Method. High quality propolis extracts prepared from green propolis were manufactured by B Natural according to patented technology. Total polyphenols, phenolic acids and bioflavonoids, were characterized and quantified by HPLC-UV-ESI-MS (and tandem mass). The epigenetic effect of green propolis preparations was studied by evaluating the levels of two miRNA, miR-27a-3p able to modulate the expression of genes involved in oxidative stress responses. Moreover, its validated target, mRNA coding for nuclear factor (erythroid-derived 2)-like 2 (NFE2L2, involved in oxidative stress) was studied. Results. The high quality Green Brazilian propolis extracts GreenArt® have been characterized for the presence and amount of phenolic acids (artepillin C, caffeic acid and derivatives, dicaffeic, ferulic, cinnamic and coumaric acids), bioflavonoids (quercetin and derivatives, kaempferol, apigenin, pinobanksin, isorhamnetin) and glycosylated forms. As regards miRNA expression levels, miR-27a-3p expression levels increased in cells treated with growing concentrations of green propolis preparation tested at sub-toxic concentrations in comparison with untreated cell cultures. The study of the validated mRNA target expression levels revealed that mRNA coding for NFE2L2 decreased in agreement with the increase of the corresponding miR-27a-3p. Conclusions. The high quality Green Brazilian propolis extract GreenArt® with a well specific and characterized profile of active biomolecules is able to exert epigenetic effects at low concentrations, and to have a positive influence on the expression levels of mRNA coding for NFE2L2, a transcription factor marker of absence of cell oxidative stress. In conclusion, with this investigation, we showed that it is possible to characterize green propolis and its main active components, to have a specific fingerprint related to the products of different origin and preparations, using HPLC-UV-ESI-MS analytical technique. Furthermore, GreenArt® resulted to be able to reduce oxidative stress through epigenetic mechanism of action. Funding. Structural characterization of green propolis extracts was funded by B Natural. Studies of miRNA expressions were financed within the project “Studio della composizione delle proprietà nutraceutiche dei prodotti dell’alveare” approved by Regione Lombardia - Direzione Generale Istruzione, Formazione e Lavoro (DD.n. 9089, published on 03/Oct/2014)