The objective of present study was to evaluate the variation in phenolic profile, β-carotene, flavonoid contents, antioxidant and antimicrobial properties of Tagetes erecta and Tagetes patula (T. erecta and T. patula) through different in vitro assays. Antioxidant activity was determined through 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and inhibition of linoleic acid peroxidation assays and antibacterial and antifungal activities studied using the disc diffusion and resazurin microtiter-plate assays against bacterial and fungal strains. Moreover, total phenolics (TP), total carotenoids (TC) and total flavonoids (TF) were also determined. Highest (TP 35.8 mg GAE/g) and TF (16.9 mg CE/g) contents were found in MeOH extract of T. patula. T. erecta extract showed higher TC contents (6.45 mg/g) than T. patula extract (6.32 mg/g). T. erecta exhibited the highest DPPH radical-scavenging activity (IC50 ) (5.73 μg/mL) and inhibition of linoleic acid peroxidation (80.1%). RP-HPLC revealed the presence of caffeic acid, sinapic acid and ferulic acid in Tagetes extracts, m-coumaric acid in T. erecta whereas chlorogenic acid in T. patula extract only. Both extracts possessed promising antimicrobial activity compared to the ciprofloxacin and flumequine (+ve controls) against Bacillus subtilis and Alternaria alternate. Both extract were rich source of polyphenols exhibiting excellent biological activities.
Keywords: Tagetes erecta; Caffeic acid; DPPH Radical scavenging; Flavonoids; Phenolic acids.
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