In silico assessment of Rhanterium adpressum sesquiterpenes inhibitory effect on 3 and 15-O-trichothecene acetyltransferases

Essential oils (EO) from leaves and flowers of Rhanterium adpressum have shown to inhibit the mycelial growth and type B trichothecenes production. The four strains of Fusarium culmorum and Fusarium graminearum were inhibited with 0.25 μL.mL-1 of each oil. The inhibitory activity of 11 sesquiterpenes identified in these oils was here examined in silico against two key enzymes in the biosynthesis pathway  of trichotecenes namely: 15-O-trichothecene acetyltransferase and 3-O-trichothecene acetyltransferase. In sesquiterpene composition, T-Muurolol and α-Eudesmol have the highest percentages ranging from 1.4 to 2.75 %. Three-dimensional structures of these two enzymes were modeled using SWISS-MODEL with GMQE = 0.93 and QMEAN = -0.45 for 3-O-trichothecene acetyltransferase and GMQE = 0.93, QMEAN = -0.58 for 15-O-trichothecene acetyltransferase. By the results of docking, T-Muurolol and α-Eudesmol showed high affinity compared to 15-Decalonectrin and Deoxynivalenol. These molecules are all sesquiterpenes with no major conformational difference with an RMSD of 3.7 A and 3.5 A between 15-decalonectrin and α-Eudesmol, T-Muurolol respectively. The results of docking prove the inhibitory effect of R. adpressum EO sesquiterpenes on the enzymes of mycotoxins biosynthesis pathway of F. culmorum and F. graminearum.