Chemical characterization of Nurexan: composition of a multicomponent natural veterinary medicinal product

Nurexan (veterinary formulation; <i>ad us. vet</i>.) is a natural medication used to mitigate stress responses in domestic animals. Nurexan contains complex plant extracts from <i>Passiflora incarnata, Avena sativa</i>, and <i>Coffea arabica</i>, along with the defined chemical compound <i>Zincum isovalerianicum</i>. The individual ingredients in Nurexan have each been traditionally used to support stress management, sleep regulation, and mood stabilization through calming, anxiolytic, and neuroactive effects. However, the precise chemical composition of Nurexan and the potential synergistic effects of its ingredients have not yet been fully characterized. This study aimed to identify major chemical constituents in the plant extracts and Nurexan and to quantify selected compounds in the product. Ultra-performance liquid chromatography with high-resolution and tandem mass spectrometry (UPLC-HR-MS, LC-MS/MS) was used to analyze <i>Coffea arabica, Passiflora incarnata</i>, and <i>Avena sativa</i> extracts as well as Nurexan tablets (<i>N</i> = 3 batches). A reversed-phase UPLC gradient with electrospray ionization enabled compound screening, and vitexin and isovitexin were quantified using LC-MS/MS. Chromatographic analysis revealed a complex chemical profile in the plant extracts and Nurexan. Caffeine was detected in <i>Coffea arabica</i> and at low levels in Nurexan. Flavonoids including vitexin, isovitexin, orientin, isoorientin, and apigenin, as well as the alkaloid trigonelline, were found in <i>Passiflora incarnata, Avena sativa</i>, and Nurexan. Vitexin was present at 1-2 ng per Nurexan tablet, isovitexin at 4-11 ng. Nurexan exhibits a complex composition, including flavonoids with potential pharmacological relevance for stress and sleep regulation. Further studies are needed to elucidate their functional roles.