From Chemical Composition to Biological Activity: Phytochemical, Antioxidant, and Antimicrobial Comparison of Matricaria chamomilla and Tripleurospermum inodorum

Matricaria chamomilla and Tripleurospermum inodorum (syn. Matricaria inodora) are two closely related species in the Asteraceae family that are often mistaken for one another due to their similar appearance. However, they differ significantly in their chemical composition and biological activities. This study offers comparative characterisation through microscopy, phytochemical profiling, and biological assays. Microscopic observations revealed distinct morphological differences in the structure of the receptacle and the size of the pollen grains between the two species. Total phenol and flavonoid contents were quantified using spectrophotometry, while essential oils were extracted through hydrodistillation and analysed by gas chromatography–mass spectrometry (GC-MS). M. chamomilla was found to have a higher phenol content (20.48 mg GAE/g DW), whereas T. inodorum showed a greater flavonoid concentration (15.93 mg RE/g DW). The essential oils from each species displayed different chemical composition: M. chamomilla was dominated by bisabolol oxides and chamazulene, while T. inodorum primarily contained β-farnesene and cis-lachnophyllum ester. The antioxidant activity of both species was evaluated using the DPPH assay and found to be moderate compared to standard antioxidants, such as ascorbic acid (IC50 < 5 µg/mL). The IC50 values for M. chamomilla ranged from 17.7 to 21.5 µg/mL, while for T. inodorum, they ranged from 8.4 to 10.2 µg/mL. In antimicrobial tests, the essential oil of T. inodorum inhibited both Staphylococcus aureus and Candida albicans, while M. chamomilla was only active against C. albicans. These findings highlight important morphological and chemical markers that differentiate the two species and affirm T. inodorum as a promising source of bioactive compounds.