Early History of Solution Fluorescence: The Lignum nephriticum of Nicolás Monardes

Abstract

The history of molecular fluorescence is closely associated with the emission from plant extracts.N. Monardes, in his Historia Medicinal (Seville, 1565), was the firstto describe the blue opalescence of the water infusion of the wood of a Mexican tree used to treatkidney ailments. The strange optical properties of the wood, known as Lignum nephriticum(kidney wood), were later investigated by Kircher, Grimaldi, Boyle, Newton and many other scientists andnaturalists in the ensuing centuries. However, when G.G. Stokes published in 1852 the first correct relationshipbetween light absorption and fluorescence, his observations were based on the emission of quinine sulphatesolution, because in Europe the wood of Lignum nephriticum was no longeravailable and its botanic origin was unknown. An inspection of the works of sixteenth century Spanish missionariesand scholars who compiled information on the Aztec culture, such as Fr. Bernardino de Sahagun and FranciscoHernandez, indicates that pre-Hispanic Indian doctors had already noticed the blue color (fluorescence)of the infusion of coatli, a wood used to treat urinary diseases.Coatli wood was obtained from Eyserhardtia, a tree of the familyof Leguminosae, and is the most likely source of the exotic Lignum nephriticum. The wood of Eysenhardtia polystachyacontains large quantities of Coatline B, a rare C-glucosyl-α-hydroxydihydrochalcone. This compound gives rise to a fluorescentreaction product, in slightly alkaline water at room temperature, which is responsible for the blue emissionof Lignum nephriticum infusion.

“y pediles, me diesen personas habiles, y esperimentadas con quien pudiese platicar:... señalaronme, hasta diez, o doze principales ancianos: y dixeronme, que con aquellos, podiacomunicar”[1mm] (I requested able and experimented persons to whom I could enquire: they presented meup to ten or twelve old learned men: I was told that I could communicate with all of them.)[1mm] Fr.Bernardino de Sahagún. Historia General de las Cosas de Nueva España (ca. 1575–1577).