Molecular docking and two-dimensional quantitative structure-activity relationship studies of synthetic flavonoids on horseradish peroxidase compounds (I, II, and III).

For the first time, the enzymatic inhibition activity of 13 synthetic flavonoids was assessed by quantitative structure-activity relationship (QSAR) modeling and molecular docking with the three states of the enzyme horseradish peroxidase (HRP). The results show that apigenin, quercetin, kaempferol, fisetin, tricetin, and luteolin exerted a high competitive inhibition on HRP (Ki between 0.14 and 1.74 mM) compared with other flavonoids. The QSAR model of enzymatic activity (R2 = 0.95, RMSE = 5.48) showed that Ghose-Crippen octanol-water partition coefficient (Alog P) and lowest unoccupied molecular orbital's energy (εlumo ) correlated with 0.65 and 0.17, respectively, with Ki values. According to the docking results using Molegro Virtual Docker program, all the flavonoids have shown great binding affinity towards peroxidase. Apigenin has the largest MolDock score in the three states of HRP noting an increased affinity of these flavonoids between compound I and compound II by 2.26%. However, these affinities strongly decrease between compound II and compound III by 28.43% especially for luteolin whose MolDock score decreased by 74.7%. With the results of docking, the affinities of the flavonoids tested and translated by their Ki values are much more presentative of the inhibition of the first reaction states of HRP because their inhibitory effect is important.

Variability of composition and effects of essential oils from Rhanterium adpressum Coss. & Durieu against mycotoxinogenic Fusarium strains.

The antifungal potency of the essential oils of Rhanterium adpressum was evaluated against four mycotoxigenic strains of the genus Fusarium. The essential oils were obtained, separately, by hydro-distillation of the aerial parts of R. adpressum (leaves and flowers). The parts were collected during the period of bloom (3 months) for 3 years. The GC-MS analysis revealed thirty-six compounds for the essential oils, divided into four classes of chemical compounds, with variable percentages according to the month of extraction. The monoterpene hydrocarbons form the main class in these oils. On the other hand, the highest percentages of the oxygenated compounds are observed in the samples collected during the month of May. The direct contact method was used to evaluate the antifungal activity of the essential oils. The activity can be attributed to their relatively high composition of oxygenated monoterpenes. Flowers extract showed strong inhibitory activity, with very interesting concentrations of IC50 and MIC for both tests on solid and liquid medium. The effect of these oils on the production of type B trichothecenes (TCTBs) was evaluated, showing a significant inhibitory effect on TCTBs production, for both extracts (leaves and flowers). The rates of inhibition were 66-97 and 76-100% of FX, 3-ADON and 15-ADON, respectively. The inhibition of fungal biomass and the production of TCTBs depended on the used concentration of the essential oils. These results suggest that the essential oils from R. adpressum are able to control the growth of the tested strains and their subsequent production of TCTB mycotoxins.