Enhanced Antioxidant and Antimicrobial Activity through mixture design predictive modelling of an Essential Oil Blend from Syzygium aromaticum, Zingiber officinale, and Cananga odorata of Comoros Islands

Medicinal and aromatic plants from the Comoros Islands are a potential source of unexploited bioactive compounds. This study investigates the chemical composition and biological properties of essential oils (EOs) from three emblematic Comorian plants: Syzygium aromaticum (L.) Merr. & L.M.Perry (clove), Cananga odorata (Lam.) Hook. f. & Thomson (ylang-ylang), and Zingiber officinale Roscoe (ginger). EOs were characterized using gas chromatography coupled with mass spectrometry (GC-MS). Antioxidant activities were evaluated using the DPPH and molybdenum-reducing power methods, while antimicrobial properties were determined by the microdilution method against various pathogenic strains. A mixture design was applied to optimize EO combinations, identifying significant synergies in their biological activities. GC-MS analysis revealed that the major compounds in S. aromaticum EO were cinnamal (53.23%), eucalyptol (16.37%), and camphene (9.74%), Z. officinale EO was characterized by α-zingiberene (19.33%), eucalyptol (16.37%), β-citral (12.93%), and β-cymene (7.16%), while C. odorata EO contained primarily o-cresol (14.09%), germacrene D (11.16%), and β-linalool (10.47%). Mixture design optimization revealed that the combination of S. aromaticum and Z. officinale EOs significantly enhanced antioxidant activity (DPPH assay). Additionally, Escherichia coli , Candida albicans, and Pseudomonas aeruginosa exhibited the highest susceptibility to a binary mixture of S. aromaticum and C. odorata EOs. Moreover, S. aromaticum EO alone demonstrated the highest total antioxidant activity in the phosphomolybdenum assay. Furthermore, molecular docking analysis of the three main compounds in the EOs revealed strong interactions with the binding sites of various selected proteins, confirming their potential antioxidant and antibacterial properties. This research contributes to the valorization of Comorian natural resources and opens new perspectives for their exploitation in pharmaceutical and environmental sectors.