72 Khaled A. Selim, Mohamed M. S. Nagia and Dina E. El. Ghwas
Figure 8. Chemical structures (60-84) show the diversity of terpenoidal metabolites
isolated from endophytic fungi.
An endophytic fungus identified as Aspergillus sp. YXf3 isolated from
Ginkgo biloba produced a C18 norditerpenoid, aspergiloid I (81). Its structure
is characterized by having a novel carbon scaffold containing a rare 6/5/6
tricyclic ring system holding α, β- unsaturated spirolactone unit in ring B. It
was the first report of a new subclass of norditerpenoid named aspergilane.
The biosynthetic pathway of compound (81) is proposed to start by the
attachment of dimethylallyl pyrophosphate unit (DMAPP) with three
isopentenyl pyrophosphate (IPP) units to form geranyl geranyl pyrophosphate
then an intermediate pimarane (Guo et al., 2014). Chemical examination of the
extracts of an endophytic fungus belongs to Ulocladium sp. isolated from the
lichen Everniastrum sp. from china resulted in the isolation of three novel
mixed terpenoids, tricycloalternarenes F–H (82-84) with another ten
previously reported terpenoidal compounds (Wang et al., 2013). Figure (8)