Humulus lupulus aqueous extract and hydrolate as a potential ingredient for cosmetics: chemical characterization and in vitro antimicrobial, cytotoxicity, antioxidant and anti-inflammatory assessment

Humulus lupulus extracts have in their composition different molecules, such as polyphenols, α-acids, β-acids, and hydrocarbons, which contribute to the plant's medicinal properties. These molecules are associated with antimicrobial, antioxidant and anti-inflammatory activities. This work focuses on the evaluation of H. lupulus biological activities, with the aim of evaluating its potential for inclusion in cosmetic formulations. Two distinct aqueous extracts and two hydrolates obtained via hydrodistillation were evaluated. These include the flower parts (FE, FH) and the mix of aboveground parts (ME, MH). The chemical profiles for both aqueous extracts and hydrolates were identified by high performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC–MS). Antimicrobial, antioxidant, cytotoxicity, and anti-inflammatory activity were tested in vitro using standard methods. Rutin was the major compound found in FE (40.041 μg mg−1 of extract) and ME (2.909 μg mg−1 of extract), while humulenol II was the most abundant compound in hydrolates (FH: 20.83%; MH: 46.80%). Furthermore, FE was able to inhibit the growth of Staphylococcus aureus and Staphylococcus epidermis with MIC values of 50% and 25% (v/v), respectively. FH showed the same effect in Staphylococcus aureus (50% v/v). FH evidenced poor antioxidant potential in DPPH scavenging test and demonstrated significant antioxidant and anti-inflammatory effects by reducing (***p