Chemical Composition, Antioxidant and Antimicrobial Potential of the Essential Oils from Aerial Parts of Tagetes patula L. at Different Phenological Stages

Abstract

The current study aims at determining the variability in composition, antibacterial and antioxidant properties of the essential oils extracted from aerial parts of Tagetes patula at different phenological stages of plant growth i.e., the vegetative, full blooming and seed setting stages. The maximum average yield of hydrodistilled essential oils was obtained as 0.083 ± 0.003% (seed setting), 0.068±0.007% (full flowering) and 0.059±0.005% (pre flowering). (Z)-β-ocimene was found to be most abundant compound of essential oil of T. patula, and α-terpinolene, piperitenone, limonene and propanedinitrile, dicyclohexyl were found as major compounds in oil extracted at different phenological stages of plant. Contribution of (Z)-β-Ocimene was highest in full flowering stage (18.27±3.14%) as compared to other two stages where its amount ranged from 12.03-17.17 %. α-Terpinolene the second major component was found highest in the pre-flowering stage (13.86±1.15%) compared to other stages. Significant variation was observed in the percent content of piperitenone during all three phenological stages The antioxidant (DPPH radical scavenging) assay showed that T. patula oils have maximum activity at the pre-flowering stage. Antibacterial activities of the essential oils were observed at the pre-flowering stage against different bacteria; i.e., Bacillus sp., Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus and exhibited promising values of MIC (0.125 % v/v -0.5 % v/v) and MBC (0.25 v/v to 1% v/v) against bacterial cultures.