Ethnobotanical inventory of medicinal plants used by Cashinahua (Huni Kuin) herbalists in Purus Province, Peruvian Amazon

**Background:** The Cashinahua (Huni Kuin) people of the Curanja River in the Peruvian Amazon possess extensive traditional knowledge of medicinal plants, but this knowledge has been poorly documented. The region is remote and biodiverse, with limited access to conventional healthcare, making traditional plant-based medicine essential. This study aimed to inventory medicinal plants used by Cashinahua herbalists and midwives, and to identify species with little or no prior scientific study of their medicinal or phytochemical properties.

**Methods:** Ethnobotanical surveys were conducted over 11 months between November 2010 and June 2015, with an additional short-term visit for voucher collection. Semi-structured interviews were carried out with 10 traditional healers and 10 midwives (age range 36–77 years; 75% aged 60–80). Plant specimens were collected during forest walks, identified taxonomically, and deposited in Peruvian herbaria (UNIA and IVITA). Use reports (UR) were recorded for each species-disease category combination. Informant consensus factor (ICF) was calculated to assess homogeneity of knowledge. A literature review of Web of Science (2018–2022) was performed to identify species unreported or rarely cited for medicinal use or phytochemical analysis. Jaccard’s similarity indices were calculated to compare medicinal plant use with other Amazonian ethnic groups.

**Key Results:** A total of 467 plant taxa were documented, belonging to 99 botanical families. The most represented families were Acanthaceae (35 species), Piperaceae (28), Rubiaceae (27), Araceae and Bignoniaceae (20 each). The most frequently cited species were Pseuderanthemum lanceolatum (38 UR), Leonia glycycarpa and Piper reticulatum (30 UR each). The most common therapeutic categories were: sociocultural uses (398 UR, ICF=0.68), poisonings (311 UR, ICF=0.79), infections/infestations (292 UR, ICF=0.67), and pregnancy/birth disorders (275 UR, ICF=0.80). External application accounted for 85.9% of remedies, with warm/cold baths (32.7%), direct application (22.7%), and rubbing (15.1%) being most frequent. Oral administration was 14.1%. Leaves were the most used plant part (97%). A total of 79 species were identified as having little or no prior medicinal or phytochemical documentation, distributed across 60 genera and 42 families. The highest similarity at species level was with the Brazilian Kaxinawa (Jaccard index 8.89%), and the lowest with the Ese Eja (4.51%).

**Clinical Implications:** This study provides a comprehensive ethnobotanical baseline for the Cashinahua, documenting treatments for neglected tropical diseases such as snakebite envenomation, leishmaniasis, and pregnancy-related disorders. The 79 understudied species represent promising candidates for future pharmacological and phytochemical research. The predominance of external application routes (baths, direct application) suggests potential for transdermal drug delivery systems. The documentation of traditional knowledge supports biocultural conservation, public health in remote areas, and may inform the development of affordable, locally available therapeutic agents. The study also highlights the need to preserve indigenous knowledge, as younger generations show declining interest in traditional medicine.