The natural diterpenoid kamebanin

Kamebanin, alternatively called rel-(-)-(1R,4R,8S,9R,10S,13S,16R)-2,8,16-trihydroxy-5,5,9-trimethyl-14-methylenetetracyclo[11.2.1.0(1,10).0(4,9)]hexadecan-15-one, C(20)H(30)O(4), is a natural diterpenoid which has cytotoxic and antibacterial activity. The molecule is composed of three six-membered rings, which all adopt chair conformations, and one five-membered ring, which adopts an envelope conformation. The conjugated alpha-methylenecyclopentanone ring is the active part in the molecule due to the ring strain. All three hydroxy groups serve as hydrogen-bond donors and acceptors, forming a continuous two-dimensional network.