Influence of Growth Stage on the Chemical Composition, Antimicrobial, and Antioxidant Potential of Cymbopogon martinii (Roxb.) Wats. Essential Oil

Priyankaraj SonigraMukesh Meena^*

• Mohanlal Sukhadia University Faculty of Science, Udaipur, India

Cymbopogon martinii (Roxb.) Wats. essential oil (CMEO) exhibits bioactivities influenced by the plant growth stage. This study assessed the chemical composition, antimicrobial, and antioxidant potential of CMEO at vegetative, reproductive, and post-reproductive stages. Oils were extracted by hydro-distillation and analyzed using GC-MS, identifying 59 compounds in total, with the reproductive stage showing the highest compound diversity and notably yielding the greatest amount of oil. Antibacterial activity (disc diffusion method) and antifungal activity (direct contact assay) were strongest during the reproductive stage, particularly against Staphylococcus aureus and Alternaria alstroemeriae, a post-harvest fungal pathogen.Antioxidant potential, evaluated using DPPH, ABTS, and β-carotene bleaching assays, was highest in the post-reproductive stage, as indicated by lower IC50 values. These findings demonstrate that the growth stage significantly influences CMEO's composition and bioactivity, highlighting the importance of harvest timing for optimizing therapeutic or industrial applications.Cymbopogon martinii (Roxb.) Wats. essential oil (CMEO) exhibits significant variation in composition and bioactivity across different growth stages. This study evaluated the chemical composition, antimicrobial, and antioxidant potential of CMEO extracted at the vegetative, reproductive, and post-reproductive stages using hydro-distillation followed by GC-MS analysis. A total of 59 compounds were identified, with the reproductive stage showing the highest diversity (49 compounds, 97.86%) and oil yield. Major compounds varied across stages: carveol (20.87%), trans-p-mentha-1(7),8-dien-2-ol (12.9%), and D-limonene (6.2%) dominated the vegetative phase; cis-piperitol (15.27%), cis-p-mentha-1(7),8-dien-2-ol (15.52%), and carvone (3.31%) were abundant in the reproductive phase; while the postreproductive phase was rich in trans-p-mentha-1(7),8-dien-2-ol (19.58%) and carveol (11.32%). Antibacterial and antifungal activities, assessed via disc diffusion and direct contact assays, were highest during the reproductive stage-particularly against Staphylococcus aureus and Alternaria alstroemeriae. Antioxidant potential, measured using DPPH, ABTS, and β-carotene bleaching assays, peaked during the post-reproductive phase with the lowest IC₅₀ values. Correlation analysis revealed negative associations between key bioactive compounds (e.g., carvone, D-limonene, α-methylcinnamaldehyde, and (S)-perillyl alcohol) and microbial/oxidative inhibition thresholds, confirming their contribution to CMEO bioactivity. These findings underscore the critical role of harvest timing in maximizing the therapeutic and industrial potential of CMEO.