ANTIFUNGAL ACTIVITY ON BOTRYTIS CINEREA OF FLAVONOIDS AND DITERPENOIDS ISOLATED FROM THE SURFACE OF PSEUDOGNAPHALIUM SPP.
The activity of the extracts obtained from the resinous exudates of the plants Pseudognaphalium cheiranthifolium, P. heterotrichium, P. robustum and P. vira vira on mycelial growth of the phytopathogenic fungus Botrytis cinerea was analyzed. Ten flavones, two flavanones and three diterpenoids isolated from these extracts were also tested for antifungal activity against B. cinerea. The extracts reduced mycelial growth and the inhibitory activity of the pure compounds was higher. Flavones with two hydroxyl groups on ring- A showed higher antifungal activity. Flavanones were inactive. The diterpenoid, 3b -hydroxy-kaurenoic acid was the most active compound of this set against mycelial growth of B. cinerea. This compound also retarded the germination of conidia of the fungus