Variation in Phenolic Profile, β‐Carotene and Flavonoid Contents, Biological Activities of Two Tagetes Species from Pakistani Flora

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.