Phenolic content and antioxidant activity of wild and cultivated Origanum compactum (Benth) leaf extract

Medicinal and aromatic plants, as natural resources, are threatened by over-exploitation. Domestication is considered one of the approaches adopted to preserve these plants. The effectiveness of this approach depends on knowledge of the effect of domestication on the chemical composition and biological activities of the plants. The present work aimed to study the phenolic content and antioxidant capacities of wild and cultivated Origanum compactum, an endemic and overexploited Moroccan plant. It consists of monitoring phenolic compounds and antioxidant activity in aqueous extracts obtained from the leaves of wild and cultivated plants. The plant was cultivated after acclimatisation using a vegetative technique. The polyphenol and flavonoid contents of the aqueous Origanum compactum extracts were monitored during two years of cultivation. Antioxidant activity, assessed by DPPH radical scavenging activity, ABTS radical scavenging assay, and Ferric Reducing Power Assay (FRAP), was also monitored. Results showed that polyphenol content was around 109.70±0.22 and 218.67±10.19 mgGAE/g dw, with the wild type showing the highest content, while cultivated plants showed a high flavonoid content (95.76±0.31 mgQE/g dw). Antioxidant activity revealed that both wild and cultivated plant extracts showed high activity. However, wild plant extracts were the most potent (IC50 = 11.16±0.19 µg/mL with DPPH, IC50 = 7.50±0.89 µg/mL with ABTS, and IC50 = 33.17±0.8 µg/mL with FRAP). In contrast, the antioxidant activity of the cultivated plant extracts, assessed over two years, remained unchanged or decreased significantly compared to the first year of cultivation. Domestication affects the chemical composition and, consequently, the biological activity of Origanum compactum.