Late Boneset (Eupatorium serotinum) is a perennial herb native to North America, primarily found across the eastern and central United States. As a member of the Asteraceae family, it belongs to a genus historically recognized in folk medicine for various applications. It is often called Late Thoroughwort due to its late-season flowering habit. Modern investigation focuses on the specific compounds responsible for its proposed effects and the safety profile of the entire genus.
Late Boneset: Identification and Traditional Preparation
Late Boneset is an herbaceous perennial that commonly reaches heights between three and six feet. It is physically distinguished by its lanceolate leaves, which have coarsely serrated edges and feature petioles (small leaf stalks) up to an inch long, allowing them to nod downward. This is a key difference from its close relative, Common Boneset (Eupatorium perfoliatum), whose leaves clasp and fuse around the stem.
The plant produces dense, flat-topped clusters of small white flowers, blooming late in the summer or early fall. The leaves are primarily arranged oppositely along the lower stem, transitioning to an alternate pattern near the flower clusters. Historically, the entire aerial part of the plant—the leaves and flowers—was the material used in traditional preparations.
Traditional use of the Boneset genus included making teas from the dried leaves and flowers, often consumed to induce sweating (diaphoretic action) to help reduce fever. The common name is thought to have originated from a historical practice of using poultices made from the leaves on broken limbs, suggesting a use for bone-related aches or injuries. The preparation method of infusion or decoction remains the primary way the herb was processed for internal use.
How Active Compounds Influence Biological Systems
Late Boneset is rich in various phytochemicals that underlie its traditional applications, particularly compounds like sesquiterpenoids, flavonoids, and triterpenes. Eupatorium serotinum contains specialized compounds such as Olean-2-en-3-yl acetate and Pterocarpan. Olean-2-en-3-yl acetate is a pentacyclic triterpene that has demonstrated potential anti-diabetic and anti-cancer effects in laboratory settings by increasing apoptosis (programmed cell death).
The biological activities of the Eupatorium genus are largely attributed to its concentration of sesquiterpene lactones, which act as anti-inflammatory agents. These compounds inhibit the production of pro-inflammatory signaling molecules, such as Tumor Necrosis Factor-alpha (TNF-α) and Interleukin-6 (IL-6). By lowering these mediators in immune cells, the herb is proposed to offer immune support and inflammation reduction.
The anti-inflammatory mechanism of sesquiterpene lactones often involves alkylation, a chemical reaction that interferes with the function of certain proteins involved in the inflammatory cascade. Pterocarpan, an isoflavone identified in Late Boneset, also has demonstrated antimicrobial and anti-inflammatory properties.
Crucial Safety Guidelines and Contraindications
A major safety consideration for Late Boneset and other members of the Eupatorium genus is the potential presence of hepatotoxic pyrrolizidine alkaloids (PAs). While it is not definitively established that E. serotinum contains these chemicals, many related species do, and the risk of liver damage from ingesting PAs is significant. These compounds are metabolized in the liver into toxic substances that can cause veno-occlusive disease, a serious condition where small veins in the liver become blocked.
Due to this potential risk, Boneset is classified as “Possibly Unsafe” when taken orally, especially in large amounts or for prolonged periods. The Food and Drug Administration (FDA) has classified Boneset as an “Herb of Undefined Safety.” Individuals with pre-existing liver disease should strictly avoid consuming any part of the plant, as the PAs could exacerbate the condition.
The herb should also be avoided by pregnant or breastfeeding individuals because the potential liver-damaging chemicals could harm a developing fetus or be passed through breast milk. Furthermore, Boneset belongs to the Asteraceae family, which includes ragweed, and may trigger allergic reactions in people sensitive to related plants like daisies or chrysanthemums. Because of the risk of interactions, anyone taking medications that are broken down by the liver, such as certain Cytochrome P450 3A4 inducers, should consult a healthcare professional before considering use.