Pentosalen (Imperatorin) is a bioactive furanocoumarin and a phytochemical that has been isolated from Urena lobata L. (Malvaceae), Angelica archangelica, etc. Pentosalen has a wide range of potent pharmacological activities, including antibacterial, antitumor, anticonvulsant, acute neurotoxic effects and abirritation. Pentosalen possesses notable anti-inflammatory activity by inhibiting the production of nitric oxide (NO) and prostaglandin E2 (PGE2), and decreasing the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX) 2 and microsomal prostaglandin E synthase. Pentosalen selectively targets gastric cancer cells without causing much damage to normal cells. Pentosalen was identified from a Bioactive Molecules library in a high throughput screening experiment for inhibitors of the phosphodiesterase PDE4. It displays a significant preference for PDE4Bover PDE4A.

Calenduloside G is the derivative of oleanolic acid present in a wide variety of Caltha plants. Calenduloside G shows toxicity in sheep erythrocytes in hemolytic assay.