Vitória Beatriz Silva, Adauto A Silva Júnior, Dalmarcia de Souza C Mourão, Paulo Ricardo de S Fernandes, Rosilene da Costa P de Carvalho, Ana G Amaral, Marcos Paz S Câmara, Eugênio E Oliveira, Raimundo W de Sousa Aguiar, Ildon R do Nascimento, Marcos V Giongo, Marcos G da Silva, Eduardo Valarezo, Luis O Viteri, Gil R Dos Santos
Adenium obesum (Forssk.) Roem. & Schult (desert rose) is one of the most popular ornamental species cultivated in residential gardens and as a potted plant for balconies and verandas in Brazil. However, Neocosmospora keratoplastica has recently been identified as one of the causal agents of rot disease in this species. Therefore, this study evaluated the antifungal potential of Ocimum tenuiflorum L. essential oil (EO) as a preventive and curative treatment against this pathogen, while assessing its phytotoxicity and selectivity toward beneficial fungi. The EO was obtained by hydrodistillation and chemically characterized. In vitro mycelial growth inhibition assays, in vivo evaluations on A. obesum seedlings, and selectivity tests against Trichoderma asperellum were performed. In addition, in silico molecular docking analyses were conducted to investigate the interaction of the major EO constituents with fungal target proteins. Eugenol (47.04%) and 1,8-cineole (29.47%) were identified as the predominant compounds in the EO. Mycelial growth inhibition reached a maximum of 59% at 100 μL mL-1, but strong phytotoxicity was evident; while a concentration of 50 μL mL-1 yielded an 18% inhibition rate representing an approximately three-fold greater effect than that of thiophanate methyl (7.68%) at the recommended dose, with a slight phytotoxicity. The lowest Area Under the Disease Progress Curve (AUDPC) was recorded when the EO was applied preventively, and intermediate concentrations were selective toward T. asperellum. Molecular docking analyses indicated that eugenol and 1,8-cineole exhibited greater affinity for CYP51A than for α/β-tubulin, whereas dehydroaromadendrane and α-copaene showed the strongest interactions with these target proteins. Overall, O. tenuiflorum EO exhibits promising potential as a preventive treatment against N. keratoplastica in desert rose, while preserving beneficial fungi at moderate concentrations.