Overview of saponin-producing species of Quillajaceae from a global perspective

The search for knowledge about forest species to support their conservation and sustainable use is crucial given the anthropogenic threats faced. The Quillaja genus holds pharmacological and economic relevance but faces risks of extinction. Thus, this study analyzes global scientific studies on the two species of this genus, to identify key scientific advances and conservation gaps concerning Quillaja saponaria and Quillaja lancifolia. A bibliometric review was conducted covering all published research on the topic in the Scopus database until 2022. Only scientific articles focusing on the respective species were considered, resulting in 552 documents involving Q. saponaria and 26 for Q. lancifolia. The country with the highest number of publications on Q. saponaria is the United States, followed by Chile, where the species occurs. With regard to Q. lancifolia, Brazil leads with the highest number of publications, followed by Uruguay. Saponins are the most extensively studied compounds produced by both species, exhibiting various types with different constituents and applications. The bark of Q. saponaria (92%) and the leaves of Q. lancifolia (84%) have been studied the most. The field of health sciences comprises the largest number of publications on both species, which have applications as vaccine adjuvants. However, a gap was identified in the realm of ecological studies, considering the potential of these species for restoring degraded areas. Hence, there is a need to expand silvicultural and conservation research, particularly given the strong demand for saponin production. Additionally, efforts to diversify techniques for sustainable exploitation should be encouraged to ensure the conservation of these species.