*3.2.3. Abietatetraenes*

The abietatetraenes are a group of compounds which possess a fourth double bond which can be located at different positions. Among the 5,6-dehydro derivatives are coleon C and coleon U and related compounds (**Figure 8**). These metabolites are common in plants of the genus *Coleus* (synonym *Plectranthus*) and have described to possess antitumor, antimicrobial, and antiproliferative activity [59, 60] (**Table 1**).
