Combined theoretical and experimental study of nordihydroguaiaretic acid – from traditional medicine to modern spectroscopic research

Combined theoretical and experimental analysis is utilized in this work to spectroscopically examine nordihydroguaiaretic acid’s (NDGA) biomechanistic structure-function relationships that are related to its efficacy in preventing and treating various diseases or in generating toxicological effects. Although the medicinal and antiviral properties of this chemical extract from the Larrea tridentata plant have been studied in vitro and in vivo, an accurate distinction between its morphological changes had not yet been optically identified and reported. Obvious trends in vibrational signatures of NDGA’s confirmations were successfully elucidated here. Our findings showed that the absence of the Raman feature at 780 ± 5 cm^-1 is indicative of a fully oxidized NDGA form, which, together with the orthoquinone, is likely to create the compound’s bio-toxicity through accumulation. Other characteristic signatures of these toxic forms are the 1582 ± 1 cm^-1 and 1698 ± 1 cm^-1 Raman lines, and the 1680 ± 17 cm^-1 IR vibrational line. If the development of new drugs and their effective implementation is further envisioned, potentially even for COVID-19 pandemic, this study provides some needed comprehension in optically assessing important morphological changes that occur for this plant-derived compound due to its oxidation and creation of metabolites.