THE PROBLEM OF MISIDENTIFICATION BETWEEN A WILD EDIBLE PLANT AND A POISONOUS ONE: THE CASE OF BORAGE

At present, in many European countries people is looking for wild edible plants to experience new tastes and flavors, by following the new trend of being green and environmentally friendly (1). Borago officinalis L. (borage) is an annual herb originating in the Mediterranean region but naturalized and widely cultivated throughout most of Europe, traditionally used for culinary and medicinal purposes. Its leaves are mixed in salads and used as a vegetable in different European countries, such as Germany, Spain, Greece, and Italy (2), especially in Liguria as a stuff of traditional ravioli and pansoti (3). However, young borage leaves can be easily confused by inexpert pickers with those of other plants, including poisonous ones, such as Mandragora autumnalis (mandrake), common in Southern Italy and Sicily, or Digitalis purpurea (foxglove), in Northern Italy. Patients who turn to Italian Poison Control Centers or Hospital Emergency Rooms after accidental ingestion of these plants, show anticholinergic symptoms due to unintentional ingestion of the leaves of mandrake (most commonly) or foxglove (less frequently). In the period 1995-2007, 50 cases of intoxication by accidental ingestion of mandrake and 6 cases after ingestion of foxglove have been reported in Italy (1). In the present work we show the pharmacognostic characterization of young leaves from B. officinalis (Boraginaceae), M. autumnalis (Solanaceae), and D. purpurea (Scrophulariaceae). Micromorphological, phytochemical and molecular identification techniques were used. Fresh leaf samples were analyzed by optical and scanning electron microscopy, highlighting main anatomical and histological features, such as stomata and trichome types and distribution (Fig 1, A-C). DNA barcoding sequences (using a region of the plastidial RbcL as DNA marker), analyzed using a bioinformatics tool (MEGA v. 7.0), allowed to determine the intra- and inter-genetic variability (K2P distance) among the three taxa. No genetic variation was detected within species, while consistent genetic distances were observed among species: borage vs foxglove K2P = 7.46%, foxglove vs. mandrake K2P = 7.46% and borage vs mandrake K2P = 7.46%. GC-MS analysis of fresh leaves pentane/hexane extract (5:1, v/v) revealed a typical chemical fingerprint of each plant analyzed and a particularly interesting difference between poisonous and nonpoisonous plants. In fact, M. autumnalis and D. purpurea leaf extract contain vitamin E, while in B. officinalis this metabolite is absent. Therefore, the authors conclude that, in this case, the presence of this metabolite is discriminant among poisonous and edible plants and could be used as a phytochemical marker, while among the poisonous ones becomes useful analyze the discriminant wax alkanes to differentiate them. This study provides a multi-disciplinary approach to the problem of misidentification between wild edible plants and poisonous species. The reported protocols provide fast and reliable determination of species causing poisoning, allowing a quick management of poisoned patients.