Progress in the Chemistry of Cytochalasans
81
also have been reported [235]. In 2014, Cimmino and coworkers found that cytochalasans inhibited the germination of GR24-treated broomrape seeds. The growth of
broomrape radicles was potently inhibited by compounds belonging to the cytochalasan class. Broomrape radicles treated with epi-sphaeropsidone developed a layer
of papillae while radicles treated with cytochalasans turned necrotic. These findings enabled potential new natural herbicides to be identified for the management of
parasitic weeds [236]. The herbicidal activity of cytochalasans against selected plant
species suggests their possible use as biocontrol agents for weed management.
The production of secondary metabolites enables an organism to compete with
other organisms in its natural environment. In this case, the production of a toxins
such as the cytochalasans might play a major role in deterring predators or competitors. It is believed that endophytes living inside plant tissues obtain nutrition and
protection from the host. In return, they may enhance the fitness of the host plant by
producing certain functional metabolites [237]. Thus, the secretion of antimicrobial
cytochalasans might foster the close association of the fungus and the host plant by
protecting the plant from herbivores or plant pathogens, thus maintaining the delicate equilibrium between the antagonism of a host and a fungus. A similar ecological
function might be inferred for cytochalasin F (111), isolated from an endophyte of
Teucrium scorodonia that was shown to possess the algicidal activity and to inhibit
photosynthesis.
3.7 Future Prospects
Cytochalasans have a wide range of distinctive biological activities. The most welldocumented one is their influence on cellular processes based on interference with the
microfilament network formation. Therefore, they have become useful compounds
for the investigation and understanding of microfilament-involved cellular processes
like cell division, multinucleation, and migration. As a result of their effects on
such cellular processes, many cytochalasans also exhibit a range of cytotoxic properties and evidence of antineoplastic effects, as well as antimicrobial, antiparasitic,
antiviral, and anti-inflammatory activities. Therefore, selected cytochalasans potentially could be developed into drugs. Among these compounds, cancer-related activity
is the most promising. Many cytochalasans exhibit cancer cell inhibitory activity,
when used either alone or when combined with established cancer chemotherapeutic drugs, as indicated by numerous laboratory studies conducted over the last
two decades. Thus, more focus should be put on the antineoplastic investigations
of cytochalasans in the future, not only limited to compounds that have already
been well studied such as cytochalasin B (110) and D (2), but also less well-known
compounds such as amichalasines A (109) and B (110).
In addition, research on cellular targets and the exact mechanisms of action by
cytochalasans are areas that need to be strengthened in the future. Previous studies
have shown that some cytochalasans inhibit cholesterol synthesis, interfere with
glucose transport by binding to high-affinity sites on glucose-transporter proteins,
81
also have been reported [235]. In 2014, Cimmino and coworkers found that cytochalasans inhibited the germination of GR24-treated broomrape seeds. The growth of
broomrape radicles was potently inhibited by compounds belonging to the cytochalasan class. Broomrape radicles treated with epi-sphaeropsidone developed a layer
of papillae while radicles treated with cytochalasans turned necrotic. These findings enabled potential new natural herbicides to be identified for the management of
parasitic weeds [236]. The herbicidal activity of cytochalasans against selected plant
species suggests their possible use as biocontrol agents for weed management.
The production of secondary metabolites enables an organism to compete with
other organisms in its natural environment. In this case, the production of a toxins
such as the cytochalasans might play a major role in deterring predators or competitors. It is believed that endophytes living inside plant tissues obtain nutrition and
protection from the host. In return, they may enhance the fitness of the host plant by
producing certain functional metabolites [237]. Thus, the secretion of antimicrobial
cytochalasans might foster the close association of the fungus and the host plant by
protecting the plant from herbivores or plant pathogens, thus maintaining the delicate equilibrium between the antagonism of a host and a fungus. A similar ecological
function might be inferred for cytochalasin F (111), isolated from an endophyte of
Teucrium scorodonia that was shown to possess the algicidal activity and to inhibit
photosynthesis.
3.7 Future Prospects
Cytochalasans have a wide range of distinctive biological activities. The most welldocumented one is their influence on cellular processes based on interference with the
microfilament network formation. Therefore, they have become useful compounds
for the investigation and understanding of microfilament-involved cellular processes
like cell division, multinucleation, and migration. As a result of their effects on
such cellular processes, many cytochalasans also exhibit a range of cytotoxic properties and evidence of antineoplastic effects, as well as antimicrobial, antiparasitic,
antiviral, and anti-inflammatory activities. Therefore, selected cytochalasans potentially could be developed into drugs. Among these compounds, cancer-related activity
is the most promising. Many cytochalasans exhibit cancer cell inhibitory activity,
when used either alone or when combined with established cancer chemotherapeutic drugs, as indicated by numerous laboratory studies conducted over the last
two decades. Thus, more focus should be put on the antineoplastic investigations
of cytochalasans in the future, not only limited to compounds that have already
been well studied such as cytochalasin B (110) and D (2), but also less well-known
compounds such as amichalasines A (109) and B (110).
In addition, research on cellular targets and the exact mechanisms of action by
cytochalasans are areas that need to be strengthened in the future. Previous studies
have shown that some cytochalasans inhibit cholesterol synthesis, interfere with
glucose transport by binding to high-affinity sites on glucose-transporter proteins,