sesterterpenes

ses·ter·ter·penes

(ses'tĕr'ter-pēnz),
Compounds formed from five isoprene units; often have a tricyclic structure; formed from geranylfarnesylpyrophosphate (for example, cochliobolin B).
[L. sestertius, two and one-half, fr. semis, half, + tertius, third, + terpene]