10 Afra Khiralla, Rosella Spina, Sakina Yagi et al.
6.2. Diverse Classes of Isolated Natural Products
from Endophytic Fungi
6.2.1. Alkaloids
Alkaloids are naturally occurring chemical compounds containing basic
nitrogen atoms. Alkaloids are quite common secondary metabolites in
endophytes, and some of them showed also anti-microbial activities (Souza et
al., 2004). Chaetoglobosins A, G, V, Vb, and C were characterized from the
culture of an endophytic Chaetomium globosum isolated from Ginkgo biloba.
Some of them revealed cytotoxicity (Li et al., 2014). A great interest that some
of the most potent of these plant-derived antitumor alkaloids have also been
reported as isolates from endophytic fungi. These endophytes have usually
been associated with a host organism that has also been reported to produce
the compound of interest. Camptothecin (CPT) was isolated in 2005 from a
fungal endophyte isolated from the inner bark of Nothapodytes foetida
identified as Entrophosphora infrequens (Puri et al., 2005). Vincristine
(Oncovin®), also known as leurocristine, is a vinca alkaloid originally isolated
from Catharanthus roseus. It has been isolated by different researchers from
the Catharanthus roseus endophyte Fusarium oxysporum (Zhang et al., 2000).
Chaetoglobosin U is a cytochalasin-based alkaloid isolated from Chaetomium
globosum, an endophytic fungus residing within the stem of healthy Imperata
cylindrical (Ding et al., 2006).
6.2.2. Phenols
Phenols and phenolic acids have often been isolated from some endophyte
cultures originating from a variety of the host plants (Yu et al., 2010).
Pestalachloride A and B had a significant anti-fungal activity against three
plant pathogens (Li et al., 2008a). Pestalachloride C and D showed moderate
antibacterial activity (Li et al., 2008b). Furthermore, two isomeric novel
tridepsides cytonic acids A and B were reported as human cytomegalovirus
(an ubiquitous opportunistic pathogen) protease inhibitors from the culture of
the endophytic fungus Cytonaema sp. isolated from Quercus sp (Guo et al.,
2000). Tricin and related flavone glycosides, toxic to mosquito larvae, have
been isolated from endophyte-infected blue grass Poa ampla (Tan and Zou,
2001). Two antimicrobial flavonoids were isolated from the culture extract of
endophytic fungus Nodulisporium sp. from Juniperus cedre on Gomera Island
(Dai et al., 2006).