daphnin

from The Century Dictionary.

• noun A glucoside found in the bark and flowers of plants of the genus Daphne.

from the GNU version of the Collaborative International Dictionary of English.

• noun rare A dark green bitter resin extracted from the mezereon (Daphne mezereum) and regarded as the essential principle of the plant.
• noun A white, crystalline, bitter substance, regarded as a glucoside, and extracted from Daphne mezereum and Daphne alpina.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun organic chemistry A plant toxin originally isolated from the mezereon.