Ethnopharmacological survey of endemic plants used in ethnomedicinal knowledge of Soqotra Island

Ethnopharmacological relevance: Due to the long biogeographical isolation since ancient times, Soqotra Island (southern Yemen) is rich in medicinal endemic plants. However, information on their traditional therapeutic knowledge is scarce in scientific literature and still not completely documented. Aim of the study: (1) Documentation and search the native traditional therapeutic knowledge focusing on the medicinal plants which are endemic to Soqotra (2) Identification of the important endemic plants treating dis-eases by quantitative analysis of the collected data. Materials and methods: Ethnobotanical data were collected from 105 local informants through open interviews, semi-structured questionnaires and field survey in February 1990 to document the traditional medicinal plants in Soqotra Island. Of them we reported in this study the data of the endemic species, due to their wide biodiversity in the island. The quantitative data were analyzed for use reports (URs) and the informant consensus factor (ICF). The reported diseases were classified according to the International Classification of Primary Care-2 (ICPC-2). New reported medicinal plants in this study were identified compared to literature review. The level of tradi-tional Soqotri knowledge among Islanders was observed during 1990-2003. Results: In the study, 86 medicinal endemic plants with 7654 therapeutic URs were explored for 69 ailments types belongs to 11 (ICPC-2) groups. The highest ICF value (0.99) were calculated for both eye and ear diseases categories, followed by general and unspecified ailments (0.98), digestive and skin (0.97 for each), and musculoskeletal ailments (0.96) among all diseases categories. While the highest URs (2276) were identified for skin diseases, followed by digestive diseases (URs = 2146). All the 86 recorded medicinal plant species were endemic to Soqotra, belonging to 57 genera and 29 families. Euphorbiaceae and Burseraceae were the dominant families, followed by Apocynaceae, Fabaceae and Asteraceae. Shrubs were the dominant growth form (41 spe-cies, 47.67%), followed by herbs (27; 31.4%), and trees (14; 16.28%). Leaves (45 species; 31.25%) were the most frequently used parts, followed by stems (34 species; 23.61%) and barks (species 23; 15.97%). The most cited preparation method was paste for 51 species followed by liquid exudates (48 species) and powder (26 species). Based on the comparative literature review, we recorded 36 new endemic medicinal plants and reported new traditional therapeutic uses for the remaining 50 endemic plants for the first time. On the other hand, all the reported endemic medicinal plants have been enlisted in the IUCN Red List of Threatened Species, of them 21 endemic species enlisted as highest threatened species. Conclusion: According to the quantitative data analyzed, Soqotra Island has a valuable traditional knowledge in several medicinal endemic plants that used by local people in the primary health care until the study time at 1990. This study emphasizes the importance of early time in documenting traditional indigenous knowledge before losing and to protect and conserve the endemic plants against highly endangered. Consequently, these ethnomedicinal data could be used in the future as guide for pharmacological and phytochemical studies to discover new therapeutic drugs.