Crude to leads: a triple-pronged direct NMR approach in coordination with docking simulation.

The screening of compounds that bind to the target of interest (specific proteins) plays a vital role in drug discovery. Usually, the identification of biologically active compounds is done from a library of structurally known compounds. However, we successfully illustrate here, that NMR techniques including saturation transfer difference (STD), transfer nuclear Overhauser spectroscopy (TrNOESY) and STD-TOCSY (total correlation spectroscopy) in combination with separation methods not only enable the rapid and comprehensive screening of active components, but also their unequivocal structural characterization. Furthermore, a time saving for the recognition of leads is also possible with this application. To probe the binding studies, a hydroethanolic fraction of crude extract (1 mg) from natural product (Rauia resinous) was used for the initial assessment with BSA protein. The docking simulation was performed with BSA in the region of Thr190, Arg198, Arg217, Trp213, Arg256, Ala290 and Tyr451 to further refine the active compound towards the leads. Docking results mimic binding as identified by STD, Tr-NOESY and STD-TOCSY. Isovetexine-2-rhamnosoide (2) was found to be most active through group epitope mapping results as well as the docking simulation with relative free energy of -7.2770. This experiment provided excellent results through the direct NMR screening method. Using Bovine Serum Albumin as a reference, we illustrate that this approach offers an excellent way for the first hand detection of the active constituents/inhibitors from natural remedies used in folk medicinal treatments.

Synthesis of a combinatorial library of amides and its evaluation against the fall armyworm, Spodoptera frugiperda.

The fall armyworm Spodoptera frugiperda is a polyphagous pest that causes important damage in different regions of America and mainly affects corn crops in both tropical and subtropical areas. Currently, control relies on both transgenic plants and/or chemical pesticides. In this work we describe the preparation of an indexed combinatorial library of amides and its toxic effect by contact against S. frugiperda . (E)-1-(1-Piperidinyl)-3-[4-(trifluoromethoxy)phenyl]-2-propen-1-one was the most active compound with an LD(50) = 0.793 µg mg(-1) of larva. This amide was also evaluated by ingestion and at the lowest concentration (1 mg kg(-1)) achieved 83.3% mortality.