Phytochemical and morphometric authentication of medicinal plants marketed as Ostokhudus in Iran

The ancient Persian term "Ostokhudus" refers to a medicinal plant traditionally used to address various health concerns, including insomnia, irritability, and indigestion problems. However, it has been applied to different plant species with similar morphological characteristics in their dried forms. In this study, we aim to investigate the authenticity of certain species labeled as Ostokhudus collected from Iranian herbal markets and industries. A total of nine herbal samples (HS1-HS9) and seven commercial herbal products (HP1-HP7) labeled as Ostokhudus were investigated using morphological, micromorphological, and phytochemical approaches (GC-FID and GC-MS analyses). HS1-HS4, HP6, and HP7 samples were characterized based on an appendage on their five- to eight-toothed, and 13-nerved calyx, the presence of branched (dendroid) trichomes on their leaf and calyx surface. Moreover, the high percentages of linalool and linalyl acetate as the major chemical components of HS1, HS2, HS3, and HP1-HP7 samples were more consistent with those of Lavandula species. Various leaf forms and trichome types were observed in HS5, HS6, and HS7 samples; however, the 15-nerved calyces, along with the presence of nepetalactone isomers in the chemical profile, differentiated them among other studied samples, which were similar to those of the genus Nepeta. The elliptic-oblong leaf shape of the HS8 sample and its distinct morphological features led to its accurate identification as Stachys lavandulifolia Vahl. HS9 sample having linear-lanceolate cauline leaves with purplish spiked inflorescence was characterized as Ziziphora tenuior L. This study highlights the limitations of traditional morphometric approaches for the precise identification of certain species. In such cases, using multidisciplinary approaches including morphological, micromorphological, and phytochemical techniques can offer a reliable and efficacious method for the accurate identification of species.