Taking Advantage of the Renewable Forest Bioresource Turpentine to Prepare α,β-Unsaturated Compounds as Highly Efficient Fungicidal Candidates.

In a continuous study on the high-value-added exploration of a renewable forest bioresource turpentine in modern organic agriculture, two series of α-pinene derivatives containing amide and α,β-unsaturated ketone pharmacophores were prepared. Through an in-depth fungicidal activity study, the title compounds presented excellent inhibitory activity against common crop fungi, especially Sclerotinia sclerotiorum, and the notable EC50 values of α,β-unsaturated compounds 3u (funan containing) and 3v (thiophene containing) were 1.657 and 1.749 μg/mL, respectively. Further physiological and biochemical studies on S. sclerotiorum revealed that compounds 3u and 3v reduced the ergosterol content in the cell membrane and increased the permeability of the cell membrane. In combination with their effect on mycelial morphology, the title compounds might have inhibitory effects on the biosynthesis of ergosterol, which is a paramount component of the target cell membrane. Moreover, quantitative structure-activity relationship (QSAR) and SAR studies revealed that the charge distribution of α,β-unsaturated carbonyl ketone derivatives played an important role in the observed fungicidal activity. In summary, this study highlights the design and development of novel high-efficacy turpentine-based antifungal agents.