Mark Muyskens,in his recent contribution (1)to the useful series "Tested Demonstrations",presents an interesting and charming example of fluorescence from a natural product,the wood of narra tree (Pterocarpus indicus).As historical background the author noted that the narra tree was known as Lignum nepbriticum,the mysterious medicinal wood that gave rise to the first reference to fluorescence in Europe in 1565 by Nicolas Monardes from Sevilla (2).In addition,Muyskens reports on his attempts to determine whether the pH-dependent fluorescence of the narra aqueous extract is due to an isoflavone related to formononetin,as was claimed before (3).He concluded finally "formononetin cannot by itself account for the fluorescence".
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