Nematicidal Activity of 3-Acyltetramic Acid Analogues Against Pine Wood Nematode, Bursaphelenchus xylophilus

Among 98 3-acyltetramic acid analogues, compounds , , and , showed >90% nematicidal activity against the pine wood nematode at a 10 μg/mL concentration. The nematicidal activities of compounds , , and were a little lower at 88.0%, 85.8%, and 57.2% at a 10 μg/mL concentration, respectively. The nematicidal activity of emamection benzoate, widely used in Korea for the prevention of pine wilt disease, was 32.3% at a 10 μg/mL concentration. Other 3-acyltetramic acid analogues showed less than 30% nematicidal activity. A structure-activity relationship study indicated that the chain length of the C-acyl substituent was very important for high nematicidal activity. All active compounds had C H or C H acyl substituents, in two closely related groups with the common physicochemical properties of a polar surface area 57.6A², PSA (polar surface area) 7.8-8.6% and ClogP (calculated partition coefficient) 5.1-5.9 and a polar surface area 75-84A², PSA 11.1-11.6% and ClogP 4.7-5.1, respectively. Our study indicates that active 3-acyltetramic acid analogues could have potential as lead compounds for developing novel pine wood nematode control agents.