Bio‐guided isolation of aromatic abietane diterpenoids from Salvia canariensis as biopesticides in the control of phytopathogenic fungi

Abstract

AbstractBackgroundBiofungicides arise as a promising alternative to the indiscriminate use of harmful synthetic fungicides in crop management.ResultsThe present study reports the bio‐guided fractionation of an endemic plant from the Canary Islands, Salvia canariensis against the phytopathogens, Alternaria alternata, Botrytis cinerea, and Fusarium oxysporum. This procedure allowed identifying a series of diterpenoids with an abietane skeleton (1–5), which exhibited remarkable activity against the phytopathogenic fungi assayed. Their structures were established by means of spectroscopic and spectrometric methods, as well as comparison with reported data. Compounds 2 (carnosic acid), 4 (11‐acetoxy carnosic acid) and 5 (11,12‐diacetoxy carnosic acid) showed significant mycelium growth inhibition (%GI > 50 at 0.1 mg/mL concentration) on all the assayed fungi, and with a potency also higher than the positive control, Fosbel‐Plus, a fungicide commonly used in agriculture. A preliminary structure–activity relationship is also discussed.ConclusionsThese findings underline the aromatic abietane diterpenoids as promising eco‐friendly alternatives to conventional fungicides to use in integrated pest management. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.