Flow Injection Analysis Coupled with Carbon Electrodes as the Tool for Analysis of Naphthoquinones with Respect to Their Content and Functions in Biological Samples

Naphthoquinones are one of the groups of secondary metabolites widespread innature, where they mostly appear as chromatic pigments. They embody broad-range ofbiological actions from phytotoxic to fungicidal. An anticancer effect of naphthoquinonesstimulates an interest in determination and characterization of single derivatives of 1,2- and1,4-quinones in biological samples. The main aim of this work was to suggest a techniquesuitable to determine lawsone, juglone and/or plumbagin in biological samples and to studyof their influence on BY-2 tobacco cells. The BY-2 tobacco cells were cultivated in thepresence of the naphthoquinones of interest (500 μg.l-1) for 24 h and then the morphologicalchanges were observed. We found out that naphthoquinones triggered the programmed celldeath at BY-2 cells, which can be confirmed by the apoptotic bodies in nucleus. After thatwe suggested and optimized different electrochemical techniques such differential pulsevoltammetry (DPV) coupled with hanging mercury drop (HMDE) and carbon pasteelectrode, micro flow device coupled with carbon screen printed electrodes and flowinjection analysis coupled with Coulochem III detector to determine them. The detectionlimits of naphthoquinones of interest were expressed as 3S/N and varied from units tohundreds of ng per millilitres according to methods used. Moreover, we utilized DPVcoupled with HMDE and micro flow device to determine content of juglone in leavesPersian walnut (Juglans regia). We determined that the leaves contained juglone tenths of gper 100 g of fresh weight. The results obtained show the convincing possibilities of using ofthese methods in analysis of plant secondary metabolites.