Phytochemical characterization and biological properties of Arctotis arctotoides (L.f.) O. Hoffm related to the management of Pythium root rot disease

Fungal phytopathogens are the primary causative agents of plant diseases and can significantly limit crop production. As an alternative to synthetic fungicides, often associated with detrimental environmental effects, the use of botanicals is a promising tool for managing fungal infections. This study analysed the phytochemical profiles, as well as the antioxidant and antifungal effect of Arctotis arctotoides (L.F.) Hoffm. The phytochemical profiles were determined using spectrophotometry and Liquid Chromatography-Mass Spectrometry (LC-MS), while two chemical test models were used to assess the antioxidant effect of the plant extract. The antifungal activity was evaluated against Pythium ultimum using the agar well diffusion method. Varying concentrations of total phenolics (131.70 mg gallic acid equivalents per gram (GAE/g) of dry weight (DW) for acetone and 231.56 mg GAE/g DW for methanol extracts) and flavonoids (11.36 mg quercetin equivalents per gram (QE/g) of dry weight (DW) for acetone and 9.86 mg QE/g DW for methanol extracts) were recorded. The LC-MS analysis of the plant extract revealed 14 tentatively identified compounds and 7 unknown bioactive compounds. Two of the compounds, dehydrocostus lactone and methyl pheophorbide A, have been associated with antioxidant effects. Acetone extract (16.67 mm) and methanol extract (18.33 mm) of Arctotis arctotoides exhibited considerable inhibitory effects against P. ultimum. Further antifungal assessment of the identified bioactive compounds remains essential to establish their activity against phytopathogens relevant in the agricultural sector, especially under field conditions.