In Mexico, native orchids are appreciated for their ornamental value and traditional uses and in many indigenous communities they comprise part of a biocultural heritage. The orchid Prosthechea karwinskii (Mart.) J.M.H. Shaw, Orchidaceae, is particularly relevant in this context, although some of its traditional uses have been attributed to a very similar species, P. citrina. A recent study of P. karwinskii reported unknown medicinal and other traditional uses by the Mixtec community in Mexico. Unfortunately, increasing acculturation of indigenous communities has resulted in a loss of the community's traditional knowledge, thus, we herein documented the worldview and practices associated with the medicinal use of P. karwinskii as well as the socioeconomic aspects that characterize the holders of this knowledge. People with this knowledge are mainly indigenous women with little or no schooling, who learned the medicinal practices from family tradition. They use pseudobulbs, leaves, or flowers of the plant to treat coughs (infusions), wounds and burns (poultices), diabetes (tea or chewed), to prevent miscarriages and to assist in childbirth (infusions). These results show a promising future for ethnopharmacological research on P. karwinskii

The orchid Prosthechea karwinskii is a medicinal orchid in Oaxaca, Mexico, used to treat diabetes, cough, wounds, and burns, prevent miscarriage and assist in labor. Each part of the plant (leaves, pseudobulbs, or flowers) is used by healers for certain treatment conditions, indicating that each part has different biocompounds with specific pharmacological activity. To characterize the biocompounds in extracts from leaves, pseudobulbs, and flowers of P. karwinskii and evaluate their ROS inhibition capacity to associate it with medicinal uses. The compounds present in extracts from leaves, pseudobulbs, and flowers of P. karwinskii were identified by UPLC-ESI-qTOF-MS/MS. The chemical differentiation of each extract was tested by principal component analysis (PCA) using compound intensity values. For each extract, total phenol and flavonoid contents were quantified. Their antioxidant capacity was evaluated ex vivo by inhibition of ROS with DCFH-DA and in vitro with DPPH radical. Based on the PCA, it was observed that some compounds were completely separated from others according to the correlation that they presented. The compounds common to all three plant parts were quinic, malic, succinic, azelaic, and pinellic acids. Among the compounds identified, two were exclusive to leaves, four to pseudobulbs, and ten to flowers. Some of the identified compounds have well-known antioxidant activity. The leaves had the highest content of total phenols and flavonoids, and the highest in vitro and ex vivo antioxidant capacity. A strong correlation was observed between phenol and flavonoid contents, and antioxidant capacity ex vivo and in vitro. It was found that the bioactive compounds and antioxidant capacity of each part of the plant were associated with its traditional medicinal use. A pharmacological potential was also found in P. karwinskii for further biological studies because of the type of compounds it contained.