Valorization of Essential Oils from Cymbopogon citratus, Schinus molle, and Teucrium polium: Chemical Composition and Biological Activities

Abstract

Essential oils from medicinal plants have attracted considerable scientific attention due to their complex phytochemical profiles and wide-ranging bioactivities. This study aimed to characterize the chemical composition, biological activities, and sensory attributes of essential oils extracted from three medicinal plants—Cymbopogon citratus (CCEO), Schinus molle (SMEO), and Teucrium polium (TPEO)—collected from ecologically distinct regions of Algeria. The (GC–MS) and (GC–FID) analyses identified 52, 50, and 72 constituents in CCEO, SMEO, and TPEO, respectively. Citral isomers were predominant in CCEO (α-citral: 43.36%, β-citral: 36.16%), while SMEO was rich in α-phellandrene (12.70%), limonene (11.90%), and germacrene D (10.15%). Notably, TPEO contained a high level of fenchene (16.45%). Antioxidant potential, assessed via five standard assays (β-carotene–linoleic acid, DPPH, ABTS⁺, CUPRAC, and metal chelation), revealed moderate to low activity, with CCEO demonstrating the strongest effect, followed by TPEO and SMEO. All oils exhibited moderate inhibitory activity against key enzymes including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-glucosidase, α-amylase, urease, and tyrosinase, though IC50 values exceeded 200 μg/mL. Anti-inflammatory activity, evaluated through human red blood cell membrane stabilization and egg albumin denaturation assays, was evident in all samples. Antimicrobial activity was determined against two Gram-positive bacteria, two Gram-negative bacteria, and two Candida species, with CCEO showing the lowest minimum inhibitory concentrations (MICs), followed by SMEO and TPEO. Furthermore, the EOs demonstrated moderate to strong interference with bacterial communication, including biofilm formation, quorum sensing, violacein production, and motility (swimming and swarming). Cytotoxicity assessment on healthy human colon cells (CCD18-Co) confirmed the safety of all tested oils at the evaluated concentrations. These findings underscore the promising bioactive potential and safety of Algerian C. citratus, S. molle, and T. polium essential oils, supporting their potential applications in food, pharmaceutical, and cosmetic industries.