Response Surface Methodology-Based Optimization of Ultrasound-Assisted Extraction from Comarum palustre L.: Chemical Composition and Antioxidant Properties

Recently, plant raw materials, which are a source of valuable secondary metabolites such as polyphenols and terpenoids with antioxidant properties, have been gaining increasing importance in cosmetology as key active ingredients in plant extracts. One such species is Comarum palustre L. (C. palustre), traditionally valued mainly for its anti-inflammatory and regenerative properties, and more recently also for its antioxidant activity. The aim of the study was to evaluate the impact and optimize the technological parameters of the C. palustre extraction process using response surface methodology (RSM). The factors analyzed included extraction time (2–10 min) and the volumetric concentrations of aqueous solvent solutions—ethanol (Et), isopropanol (Ipa), and acetone (Ac)—ranging from 20 to 100% v/v. The process was optimized taking into account antioxidant activity (determined based on the ability to neutralize free radicals using the DPPH method and reduce Fe3+ ions using the FRAP method), chelating activity (assessed based on the ability to bind Fe2+ ions using the ferrozine method), total polyphenol content (TPC, determined by the Folin–Ciocalteu method), and the extraction yield of neophytadiene (NFD) and phytol—active compounds with proven antioxidant properties, analyzed by GC-MS. The use of optimal technological parameters, including a 5-min extraction time and a 50% (v/v) concentration of aqueous solvent solutions (acetone, ethanol, and isopropanol), made it possible to obtain an extract from C. palustre herb characterized by the following properties: antioxidant activity > 120 mg Tx/L (DPPH), Fe3+ ion reduction capacity > 25 mmol Fe2+/L (FRAP), chelating activity > 330 mg Fe2+/L (ferrozine method), and total polyphenol content exceeding 6 g GAE/L (Folin–Ciocalteu method). Maximum extraction yields for phytol (phytol > 40 mg/kg) and neophytadiene (NFD > 20 mg/kg) were obtained in GC-MS analyses using Et, Ipa, and Ac at concentrations exceeding 60 and 100% v/v, respectively. The results obtained confirm the validity of using the C. palustre herb extraction optimization process to obtain extracts with maximum content of polyphenols and terpenoids, such as neophytadiene and phytol, which have significant antioxidant potential. The optimization of the extraction process of this raw material, which has not been subjected to such procedures so far and, as a result, has had limited application in cosmetic preparations, may significantly contribute to increasing interest and wider use of C. palustre in the cosmetics industry.