Which herb from Rhamnaceae has bark as the part used and is a laxative/purgative with anthraquinones?

• A. Rhamnus frangula
• B. Quercus rubra
• C. Pulsatilla vulgaris
• D. Prunus africana

Answer: (A)

The key idea is recognizing stimulant laxatives from buckthorn bark in the Rhamnaceae family. Buckthorn bark contains anthraquinone glycosides that are activated in the colon to irritate the mucosa, increasing peristalsis and fluid secretion, producing a laxative/purgative effect. Among herbs in this family, the bark is the part used for this action, so the species with bark used as a laxative due to anthraquinones fits best. That makes Rhamnus frangula the correct choice. The other options belong to different families or use different plant parts or actions (oak bark is more astringent; Pulsatilla vulgaris is a different genus with other toxic/laxative profiles; Prunus africana is used for urinary issues), so they do not match the described combination.