Ethnobotanical, Phytochemical Study and Evaluation of the Antibacterial Activity of Calendula arvensis L. Against Fire Blight (Erwinia amylovora)

Abstract

Calendula arvensis L. ''field marigold, " is a medicinal plant commonly used in phytotherapy for its anti-inflammatory, anti-cancer, and anti-oxidant properties. The present study is part of the valorization approach of medicinal natural resources through an ethnobotanical, phytochemical, and biological study of Calendula arvensis L. from the Meknes region, Morocco, using the flowers and leaves of the plants. An ethnobotanical survey was conducted among herbalists and villagers, and we detected and studied the species of the Calendula genus present in this region, as well as the influence of altitude on their density. Phytochemical screening was performed to identify the main chemical classes present in the extracts. Moreover, the effect of Calendula arvensis L. extracts on the causal agent of fire blight, "Erwinia amylovora.” The results showed that the most common species was C. arvensis, which grew in abundance between 499 and 689 m. Phytochemical screening showed that field marigold is rich in secondary compounds, particularly polyphenols, which differ according to the extract type and plant part; the flowers are richer in carotenoids, terpenes, and condensed tannins, while the leaves are rich in saponosides. GC-MS analysis showed that 2,4-di-tert-butylphenol was the dominant compound in the ethanolic (74.92%) and methanolic (19.60%) extracts. The extracts had low in vitro antibacterial activity (<8 mm) against Erwinia amylovora, the causal agent of fire blight. Future studies should focus on bioassay-guided fractionation and purification to concentrate the active constituents and potentially enhance their antibacterial efficacy.