Chemical composition of the essential oils of Tagetes patula L. during different phenological stages

The present study aims to investigate the detailed essential oil profiling of Tagetes patula L. at different stages of plant growth i.e. pre-flowering stage, full flowering and seed settings stages. The essential oils were obtained through hydro-distillation and analyzed by GC and GC/MS for the identification of their chemical constituents. The essential oil yield (%) from fresh aerial parts of T. patula were 0.06%, 0.06% and 0.08% (v/w) at pre flowering, full flowering and seed setting stages, respectively. A total of 38 components were identified, representing 89.65%, 91.94% and 90.84% in pre flowering, full flowering and seed setting stages, respectively. Chromatographic analysis (GC and GC/MS) has shown that all the oils of T. patula were dominated by monoterpene hydrocarbons (39.81-45.08%) followed by oxygenated monoterpenes (27.57-31.66%), sesquiterpene hydrocarbons (7.72-10.52%), oxygenated sesquiterpenes (6.63-7.57%) while diterpenes (1.39-1.68%) and oxygenated diterpenes (0.93-1.55%) were found in the lesser amounts. The major constituents in the oils were z-()-ocimene (12.76-20.29%), -terpinolene (11.01-14.79%), piperitenone (6.46-11.96%), limonene (6.62-7.57%) and propanedinitrile dicyclohexyl (5.17-5.85%). Maximum content of z-()-ocimene (20.29%) was found at full flowering stage, while -terpinolene (14.79%) and piperitenone (11.96%) at pre-flowering stage. The study concluded that however the oils were qualitatively similar but differed quantitatively during different growth stages.