Use of active extracts of poplar buds against Penicillium italicum and possible modes of action

Volatile organic compounds from endophytic fungi as innovative postharvest control of Fusarium oxysporum in cherry tomato fruits

To assess their potential as biopesticides, the effect on the growth of phytopathogen Fusarium oxysporum of six volatile organic compounds from endophytic fungi was studied in vivo and in vitro; compounds were used both as a mixture and individually. In vivo studies were performed inoculating the pathogen into cherry tomatoes, while the in vitro antifungal effect was studied using agar dilution and gas phase methods. Also, the morphology of the hyphae exposed to these compounds was analyzed. Moreover, the possible mechanism of action of these compounds was determined by studying the respiration and cell membrane permeability. Results show that the compounds have a significant concentration-dependent antifungal effect individually and act in a synergic manner. Additionally, changes in cell membrane permeability, damage to the hyphal morphology, and an inhibitory effect on the respiration were observed. The mixture of the six compounds may be used for postharvest control of F. oxysporum in tomatoes.

Chemical Constituents and Antifungal Activity of Ficus hirta Vahl. Fruits

Phytochemical investigation of Ficus hirta Vahl. (Moraceae) fruits led to isolate two carboline alkaloids (1 and 2), five sesquiterpenoids/norsesquiterpenoids (3-7), three flavonoids (8-10), and one phenylpropane-1,2-diol (11). Their structures were elucidated by the analysis of their 1D and 2D NMR, and HR-ESI-MS data. All of the isolates were isolated from this species for the first time, while compounds 2, 4-6, and 8-11 were firstly reported from the genus Ficus. Antifungal assay revealed that compound 8 (namely pinocembrin-7-O-β-d-glucoside), a major flavonoid compound present in the ethanol extract of F. hirta fruits, showed good antifungal activity against Penicillium italicum, the phytopathogen of citrus blue mold caused the majority rotten of citrus fruits.

The structure-antifungal activity relationship of 5,7-dihydroxyflavonoids against Penicillium italicum

To evaluate the structure-activity relationship of 5,7-dihydroxyflavonoids against P. italicum, we tested the antifungal activity of 23 selected 5,7-dihydroxyflavonoids against spore germination of P. italicum, and the effects of hydroxyl group, hydrogenation, methylation and glycosylation on the antifungal activity are explored. C-4'-OH and C-3-OH are active groups for the 5,7-dihydroxyflavonoids against P. italicum. We find that hydrogenation of the C2/C3 bond decreases the antifungal activity of 5,7-dihydroxyflavonoids. Antifungal activity of 5,7-dihydroxyflavonoids against P. italicum was affected by the conjugation site of glycosylation and the class of sugar moiety. The correlation between antifungal activity and the inhibition of respiration of 5,7-dihydroxyflavonoids was further evaluated. We find no significant relationship among the IC50 of 5,7-dihydroxyflavonoids on spore germination and on respiration. Some 5,7-dihydroxyflavonoids even enhance the respiration of P. italicum. This indicate respiration is not the only target for 5,7-dihydroxyflavonoids against P. italicum.