| Abstract
| - Widdrol (1) was tested against the necrotrophic plant pathogens Botrytis cinerea and Colletotrichumgloeosporioides. While 1 was found to be inactive against C. gloeosporioides, it showed a selectiveand effective control of B. cinerea, significantly inhibiting the mycelial growth of the fungus atconcentrations of 100 ppm and above. In addition, the biotransformation of 1 by both fungi was studied.Incubation with C. gloeosporioides and B. cinerea afforded four and one biotransformation products(2−6), respectively. Biotransformation with C. gloeosporioides was highly regioselective, yielding forthe most part oxidation products at C-10: 10-oxowiddrol (2), 10β-hydroxywiddrol (3), 10α-hydroxywiddrol (4), and 14α-hydroxywiddrol (5). The structures of all products were determined onthe basis of their spectroscopic data, including coupling constants, two-dimensional NMR analysis(heteronuclear multiple quantum coherence, heteronuclear multiple bond correlation, and nuclearOverhauser enhancement spectroscopy), and nuclear Overhauser effect. The biotransformationproducts were then tested against B. cinerea and found to be inactive. These results shed furtherlight on the structural modifications, which may be necessary to develop selective fungal controlagents against B. cinerea. Keywords: Biotransformation; widdrol; Botrytis cinerea; Colleotrichum gloeosporioides; antifungalactivity
|
