Ethnobotanical investigations on plants used in folk medicine in the regions of Constantine and Mila (North-East of Algeria)

Ethno-pharmacological relevance Constantine and Mila regions have been investigated in an ethnobotanical study for the first time. A total of 102 medicinal plants have been cited to treat human ailments. Twenty-eight new species of 31 common plants with 151 new therapeutic applications and 12 new cited species including one endemic specie Zygophyllum cornutum Coss were found as compared to other Algerian regions. In addition, to the best of our knowledge, 369 new medicinal uses of 75 known plants, were reported for the first time in the Mediterranean basin. Aim of the study This study is aimed at contributing to safeguard world cultural heritage and document ethnomedicinal uses of plants in Algeria and the Mediterranean basin; data on the national and global uses in the world were obtained to extract new potential species for further phytochemical and clinical investigations. Materials and methods The survey was carried out in two cities in the northeast of Algeria: Constantine and Mila. It was based on semi-structured interviews of 79 local informants. Data were analyzed using quantitative indices, namely, informant consensus factor, fidelity level (FL), use value (UV), and relative frequency citation (RFC), to evaluate the reliability and richness of herbal knowledge in the region. Results The interviewed persons used 102 plant species belonging to 90 genera and distributed among 53 families, represented mainly by Lamiaceae, Apiaceae, and Asteraceae (30%, 13%, and 10%, respectively), which were used to treat 14 ailment categories. The category of most frequent ailments (16%) was digestive disorders (diarrhea, constipation, and stomach bloating). The highest RFC was found for Origanum glandulosum Desf. With regard to the fidelity level, a higher FL was found for Tilia cordata Mill. (100%), followed by Artemisia herba alba Asso. with an FL of 95.74% and Punica granatum L. with an FL of 93.09%) to treat gastrointestinal system diseases, and Aloe sp. L. with an FL of 96.67% for skin diseases. The highest UV was found for Origanum glandulosum Desf. (2.280). Moreover, new medicinal uses were recorded for the first time in Algeria and Mediterranean regions. Conclusion The present study has highlighted the rich herbal knowledge about newfound medicinal plants and their new uses in the Mediterranean region, which could be useful not only in facilitating other studies such as phytochemical and pharmacological investigations and upgrading the sources of biomolecules beneficial to people but also in reopening discussion on pharmacovigilance in herbal medicine as an imperative requirement for local authorities.