Barbasco is a common name for several plant species known for their distinct properties. These plants have historical and cultural significance, particularly in tropical and subtropical areas. Their unique characteristics have led to diverse applications, influencing both traditional practices and modern industries.
What is Barbasco
Barbasco refers to a group of plant species found in tropical and subtropical regions. The most notable genera include Lonchocarpus, Derris, and Dioscorea. These plants exhibit varying growth habits, from woody shrubs and climbers to vines, and are native to areas like South America, Southeast Asia, and Central America.
Examples include Lonchocarpus urucu and Lonchocarpus nicou from northern South America, and Derris elliptica (tuba plant) from Southeast Asia. In Mexico and Central America, wild yams such as Dioscorea mexicana and Dioscorea composita are also called barbasco. These plants typically thrive in moist tropical climates.
Traditional and Modern Uses
Historically, indigenous communities used barbasco plants, their roots, as a piscicide for fishing. This method involved crushing the plant and introducing it into water, stunning fish for easier collection. This practice was documented among groups like the Shuar and Nukak peoples in the Americas.
Beyond traditional fishing, barbasco has modern applications in agriculture and the pharmaceutical industry. In agriculture, extracts from barbasco species, containing compounds like rotenone, are used as natural insecticides for pest control on various crops. However, agricultural uses of rotenone have been voluntarily canceled in some regions.
In the pharmaceutical sector, certain Dioscorea species (wild yams) are a significant source of diosgenin. Diosgenin serves as a precursor for the commercial synthesis of various steroidal hormones and pharmaceutical compounds, including corticosteroids, pregnenolone, and progesterone, vital in developing medications like oral contraceptives.
How Barbasco Works and Its Active Compounds
The effects of barbasco plants are attributed to their active compounds: rotenone and diosgenin. Rotenone, found in the roots of Lonchocarpus and Derris species, functions as an insecticide and piscicide. It disrupts cellular respiration in affected organisms by inhibiting mitochondrial complex I, a key component of the electron transport chain, leading to a loss of usable energy for cellular function. This explains its high toxicity to gilled organisms like fish and aquatic insects, as it is readily absorbed through their gills.
Diosgenin, a steroidal sapogenin, is found in various Dioscorea species (wild yams). It is a precursor for steroid drug synthesis. Diosgenin can be chemically converted into progesterone, cortisone, and other steroid hormones. These synthesized steroids are used in a wide range of pharmaceutical products, including contraceptives and corticosteroids.
Safety and Environmental Considerations
The use of rotenone-containing barbasco varieties raises safety and environmental concerns. Rotenone is highly toxic to aquatic life, including fish and aquatic invertebrates, as it interferes with their cellular respiration. While less toxic to terrestrial animals, large ingestions can be harmful, though human fatalities from rotenone poisoning are rare. Exposure can cause symptoms from mild irritation to vomiting, and high doses may lead to respiratory and neurological effects.
Environmentally, rotenone degrades rapidly when exposed to light and warm temperatures. However, it can persist longer in colder conditions or when bound to organic matter in soil. While it generally does not accumulate long-term in water or soil and is unlikely to contaminate groundwater, its immediate impact on non-target aquatic organisms is a concern. Fisheries managers sometimes time rotenone treatments to minimize impact on non-target aquatic populations. Affected populations of aquatic invertebrates typically recover within one to two years.