*3.3.1. Cythane diterpenes*

*3.2.1.1.3. Ferruginol*

118 Terpenes and Terpenoids

**Figure 7.** Synthesis of compounds 2–10 [42].

*3.2.1.1.4. Callitrisic acid*

group have been isolated [55].

anti-inflammatory activity [56].

*3.2.2. Abietatriene 20-7 lactones*

Ferruginol (abieta-8, 11, 13-triene-12-ol) is the simplest phenolic abietane diterpenoid (3). This abietane occurs in plants belonging to the Podocarpaceae and Lamiaceae families [22].

Biological activity: This diterpene has attracted much attention since it has exhibited important bioactivities, such as antimicrobial [46], miticidal [47], cardioactive [48], and antioxidative [49]. Moreover, it accelerates the gastric ulcer healing process, and such effects have been related with the ability of ferruginol to increase the gastric prostaglandin content in vitro [50–52].

Callitrisic acid is a diterpenoid acid contained in the resins of several *Callitris* species (Cupressaceae). It was simultaneously reported as a new natural product [53, 54]. This acid also occurs in plants of the genus *Juniperus* and *Calceolaria*, and it has also been found in the genus *Illicium*. Recently, a series of related acids to callitrisic acid having a C-19 carboxylic

Biological activity: All these acids demonstrated important antiviral activity and significant

The abietatriene lactones are a group of compounds which possess an oxygen-containing ring which predominantly is in the form of lactones (i.e., abietatrien-20,7-olides). This group *Cyathus* is a genus of fungi in the Nidulariaceae, a family collectively known as the bird's nest fungi. Such compounds are named so, as they resemble tiny bird's nests filled with "eggs," structures large enough to have been mistaken in the past for seeds. The first cyathin A3 and allocyathin B3 were reported from fungus *C. helenae* in 1972, and since then a number of other diterpenes being isolated and documented from different species belong to genus *Cyathus* [61]. In particular, the species belonging to the genus *Cyathus* is recognized as prolific producer of bioactive cyathane diterpenoids with inimitable tricyclic ring skeleton [62]. Cyathane diterpenoids also represent a group of natural products with versatility both in structure and bioactivity [63, 64]. Cyathane diterpenes are important bioactive metabolites extracted from the genus *Cyathus*, *Hericium*, and *Sarcodon.* Genus *Cyathus* is beneficial in producing healthy food and possesses the potential of nitric oxide (NO) inhibition and antibacterial activities [64].
