A natural alkaloid that acts as a selective and reversible α2-adrenergic receptor antagonist (Ki = 12 nM); also acts as a receptor antagonist at the serotonin 5-HT2B receptor (Ki = 14.3 nM).

A cytotoxic, quinoline alkaloid that inhibits the DNA enzyme topoisomerase I (Top I) by binding the Top1-DNA cleavage complex and inducing DNA-strand breaks; has strong anti-tumor activity and induces DNA damage at concentrations as low as 51 nM in whole cells and 12 nM in isolated nuclei in in…

An analog of folic acid and aminopterin that is used in the treatment of cancer, autoimmune diseases, ectopic pregnancy, and for the induction of medical abortions; induces adenosine release, inhibits the metabolism of folic acid, and blocks key enzymes in the synthesis of purines and pyrimidines…

Inhibits microtubule polymerization (IC₅₀ =3.2 μM) by binding to tubulin, which disrupts spindle formation during mitosis; blocks the growth of MCF-7 human breast carcinoma cells (IC₅₀ = 13 nM); inhibits neutrophil motility and activity (5 μmol/kg in a mouse model of…

A natural 11-membered macrocyclic pyrrolizidine alkaloid used in an animal model of pulmonary hypertension.