Dehydration process influences the phenolic profile, antioxidant and antimicrobial properties of Galium aparine L.

Galium aparine L. is a very disseminated plant in temperate zones, commonly known as clivers or bedstraw, belonging to the Rubiaceae family and it is traditionally used for its medicinal applications. In this study, G. aparine hydromethanolic extracts and infusions were prepared from air-dried and freeze-dried samples in order to assess their phenolic profile, antioxidant, antimicrobial, and cytotoxic properties. All the studied extracts revealed a similar phenolic profile, but the hydromethanolic extract obtained from the freeze-dried sample presented the highest concentration of phenolic compounds, followed by the respective infusion and the airdried sample hydromethanolic extract. The major compound detected in the extracts was 5-O-caffeoylquinic acid (from 145 to 163 mg/g extract). Regarding the bioactivity, in general, the extracts presenting higher phenolic concentrations also revealed enhanced bioactive properties. The EC50 values obtained in the antioxidant activity assays ranged from 13.5 to 884 μg/mL, with the freeze-dried sample hydromethanolic extract presenting the highest activity (13.5–555 μg/mL). Similar conclusions could be made in terms of antimicrobial properties, with this extract showing the lowest MIC (1.85–15 mg/mL), MBC (3.75–7.5 mg/mL), and MFC (3.75–20 mg/mL) values. None of the extracts revealed cytotoxicity. The results obtained in this study suggested that G. aparine extracts can be a good source of phenolic compounds with antioxidant and antimicrobial properties.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013); to FCT for L. Barros research contract; to FCT for the grant attributed to C. Pereira (SFRH/BPD/122650/2016) through the Programa Operacional Capital Humano (POCH) supported by the European Social Fund and National Funds of MCTES (Ministério da Ciência, Tecnologia, e Ensino Superior); and to FEDER-Interreg España-Portugal programme for financial support through the project 0377_Iberphenol_6_E. The authors are also grateful to the Serbian Ministry of Education, Science and Technological Development, grant number 173032 for financial support.