In vivo evaluation of antibacterial activity and wound healing power of a gel based on phenolic compounds extracted from by-products of the wine industry Vanessa Silva 1-4 *, Cecília Peirone 5-7 , Rupesh Kumar Singh 8 , Virgílio Falco 8 , Isabel Pires 5,9 , Carla Miranda 1,4,5 , Luís Maltez 5,9 , José Eduardo Pereira 5,9 , Gilberto Igrejas 2-4 , Patrícia Poeta 1,4 1 Microbiology and An/bio/c Resistance Team (MicroART), Department of Veterinary Sciences, University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal; 2 Department of Gene/cs and Biotechnology, University of Trás-os-Montes and Alto Douro, 5000-801 Vila Real, Portugal; 3 Func/onal Genomics and Proteomics Unit, University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal; 4 Associated Laboratory for Green Chemistry (LAQV-REQUIMTE), University NOVA of Lisboa, Lisboa, 2829-516 Caparica, Portugal; 5 Department of Veterinary Sciences, University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal; 6 Hospital Center of Trás-os-Montes and Alto Douro E.P.E., 5000-185 Vila Real, Portugal; 7 Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), UTAD, 5000-801 Vila Real, Portugal; 8 Chemistry Research Centre (CQ-VR), University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal; 9 Veterinary and Animal Research Centre, University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal. *vanessasilva@utad.pt Agro-industrial by-products have been described as poten5al sources of phenolic compounds, which exhibit several proper5es, such as, an5microbial, an5oxidant, an5-inflammatory and wound healing. Therefore, we aimed to evaluate the the effect of topical applica5on of a phenolic compounds-base gel on the treatment of skin infected with MRSA and its wound healing capacity in an animal model. The extrac5on of phenolic compounds from grape’s peel, stem and seed was performed using ethanol/water (80:20) mixture. Carbopol gel (0.8%) was neutralized with triethanolamine and enriched with the extracts. Ten Wistar rats were inoculated by an intradermic injec5on of MRSA suspension, producing an abscess lesion. APer 3 days, the skin epidermis was removed to open the wound (Figure 1). Group 1 (control) received an applica5on of Carbopol gel and Group 2 received an applica5on of Carbopol gel enriched with phenolic extracts (10%). APer the treatment period, skin was collected to quan5fy colony forming units (CFU) of bacteria and to examine the following histological structures and processes: epidermal regenera5on, granula5on 5ssue thickness, fibroblast prolifera5on, angiogenesis and the presence of inflammatory cells. Although phenolic compounds extracted from winery by-products seem to have a promising antibacterial activity in vitro, the same seems to not true in vivo. References Vázquez-Olivo, G.; Cabanillas-Bojórquez, L.A.; Elizalde-Romero, C.A.; Heredia, J.B. Phenolics from Agro-industrial By-Products BT - Plant Phenolics in Sustainable Agriculture: Volume 1. In; Lone, R., Shuab, R., Kamili, A.N., Eds.; Springer Singapore: Singapore, 2020; pp. 331–346 ISBN 978-981-15-4890-1. Dev, S.K.; Choudhury, P.K.; Srivastava, R.; Sharma, M. An/microbial, an/-inflammatory and wound healing ac/vity of polyherbal formula/on. Biomed. Pharmacother. 2019, 111, 555–567. Acknowledgements This work was supported by the Associate Laboratory for Green Chemistry - LAQV which is financed by na/onal funds from FCT /MCTES (UIDB/50006/2020). Vanessa Silva is grateful to FCT (Fundação para a Ciência e a Tecnologia) for financial support through PhD grant SFRH/BD/137947/2018. Introduc)on ________________________________ Material and Methods ________________________________ Group 1 and 2 presented a similar number of CFU/mL (difference not sta5s5cally significant) (Figure 2) which is not in line with that obtained from previous in vitro studies in which phenolic extracts present an5bacterial ac5vity. Regarding the histological evalua5on, the presence of histological structures was also similar except for the presence of inflammatory cells. ________________________________ Results Conclusions _______________________________________________________________________ 0,00E+00 5,00E+01 1,00E+02 1,50E+02 2,00E+02 2,50E+02 Group 1 Group 2 CFU/mL Figure 1. Abscess lesion (A); application of Carbopol gel enriched with phenolic extracts (B). A B Figure 2. CFU/mL present in the skin of control group (Group 1) and treated group (Group 2). REPÚBLICA PORTUGUESA