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

João Vasco Valente; Rita Palmeira-de-Oliveira; Liliana Guiomar; Cátia V Vaz; Joana Rolo; Carlos Gaspar; Ana Sofia Oliveira; Débora Caramelo; Luiza Breitenfeld; José Carlos Gonçalves; Fernanda Delgado; José Martinez-de-Oliveira; Ana Palmeira-de-Oliveira

doi:10.1016/j.fitote.2024.105861

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

Fitoterapia. 2024 Feb 12:175:105861. doi: 10.1016/j.fitote.2024.105861. Online ahead of print.

Affiliations

¹ CICS-UBI: Health Sciences Research Center, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal.
² CICS-UBI: Health Sciences Research Center, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal; Faculdade de Ciências da Saúde, University of Beira Interior, Covilhã, Portugal; Labfit-HPRD: Health Products Research and Development Lda, Covilhã, Portugal.
³ CICS-UBI: Health Sciences Research Center, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal; Faculdade de Ciências da Saúde, University of Beira Interior, Covilhã, Portugal.
⁴ Escola Superior Agrária do Instituto Politécnico de Castelo Branco, Portugal; CERNAS: Research Center for Natural Resources, Environment and Society, Agriculture Science Research Group, Castelo Branco, Portugal.
⁵ Escola Superior Agrária do Instituto Politécnico de Castelo Branco, Portugal; CERNAS: Research Center for Natural Resources, Environment and Society, Agriculture Science Research Group, Castelo Branco, Portugal; Centro de Biotecnologia de Plantas da Beira Interior, Castelo Branco, Portugal.
⁶ CICS-UBI: Health Sciences Research Center, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal; Faculdade de Ciências da Saúde, University of Beira Interior, Covilhã, Portugal; Labfit-HPRD: Health Products Research and Development Lda, Covilhã, Portugal. Electronic address: apo@fcsaude.ubi.

PMID: 38354824
DOI: 10.1016/j.fitote.2024.105861

Abstract

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.

Objective: This work focuses on the evaluation of H. lupulus biological activities, with the aim of evaluating its potential for inclusion in cosmetic formulations.

Methods: 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.

Results: 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 < 0.001) intracellular reactive oxygen species (ROS), NO (nitric oxide) levels (***p < 0.001) and cyclooxygenase-2 (COX-2) protein expression (***p < 0.001) in lipopolysaccharide (LPS)-stimulated macrophages. Nevertheless, it is important to note that FH exhibited cytotoxicity at high concentrations in 3T3 fibroblasts and RAW 264.7 macrophages.

Conclusion: The studied H. lupulus aqueous extracts and hydrolates revealed that FH stands out as the most promising bioactive source for cosmetic formulations. However, future research addressing antimicrobial activity is necessary to confirm its potential incorporation into dermatological and cosmetic formulations.

Keywords: Anti-inflammatory; Cosmetics; Plant-based compounds; Wound healing.