Development and validation of a simple high performance liquid chromatography - evaporative light scattering detector method for direct quantification of native cyclodextrins in a cyclization medium.

A simple HPLC-ELSD method was developed for the separation and quantification of native cyclodextrins. The technique was validated in the presence of two interfering matrices composed of byproducts from the cyclization medium. A fast separation of the compounds was achieved (in <20min) using a NUCLEODUR(®) C18 Pyramid column (150mm×4.6mm; particle size 5µm) at 30°C. The analytes were eluted using a linear gradient of acetonitrile and water containing 1% (v/v) of acetic acid at a flow rate of 0.3mL/min. Validation results showed that the method was accurate (93-110%) and selective. The precision was ≤5.7% for a hydrolyzed starch blank matrix spiked with cyclodextrins, and ≤6.2% for a blank matrix composed of a mixture of dextrin and glucose spiked with cyclodextrins. The limit of quantification was 0.05g/L for alpha- and 0.06g/L for beta- and gamma-cyclodextrins. The new HPLC-ELSD method could accurately quantify the three cyclodextrins directly in a cyclization medium, without pretreatment of the samples.

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.

Insecticidal activity of synthetic amides on Spodoptera frugiperda.

The phytochemistry of the genus Piper (Piperaceae) has been widely studied due to the biological properties of amides from these plants. In this work, we have synthesized and evaluated the toxic effect of 11 amides against the fall armyworm Spodoptera frugiperda larvae. The naturally occurring piperine was also evaluated. The most active amide was N-[3-(3',4'-methylenedioxyphenyl)-2-(E)-propenoyl]piperidine with a LD50 of 1.07 microg mg(-1) larvae. This amide was also evaluated by ingestion.