8.7 Applications
183
The other anticancer approach ulvans is thought to use is the prevention of cancer
cell proliferation. This has been investigated by measuring the reduction in the level
of DNA replication activity in the cancer cells. This is quantified by the reduction
in the level of proliferating cell nuclear antigen (Hussein et al. 2015). The level of
DNA replication activity reduced to noticeable levels in rat hepatocytes when treated
with ulvan from Ulva lactuca. Anticancer activity of ulvans has also been measured
as a function or tumor mass and cytotoxicity where a reduction in tumor mass and
a high cytotoxicity are indicative of reduced cell proliferation and hence anticancer
activity.
Although a number of studies have presented anticancer properties of ulvans,
there are also studies which show no cytotoxicity of ulvan against cancer cells. An
example of such is studies on Ulvan intestinalis which show no cytotoxicity against
sarcoma tumor cells at a relatively high concentration of 50–800 µg per ml. However,
this study also further showed that ulvans from different species could take different
pathways to achieving anticancer activities. While no cytotoxicity was measured
in vitro, there was 61–7% (Jiao et al. 2009) reduction in the tumor cell mass in vivo
when applied to mice in vivo at a dose of 100–400 mg/kg.
The anticancer activity is very low compared to conventional chemotherapy
agents. With such a low level of effectiveness, ulvan can at best serve in adjunct roles
in cancer treatment. As a polymeric material with pH-dependent rheological properties, ulvan can serve roles in anticancer therapy delivery system as pH-responsive
polysaccharide systems (Yang et al. 2017) and nanoparticle delivery systems (Li
et al. 2018a, b). No conclusive data yet exists to relate the chemical structure such
as degree of sulfation or molecular weight to the anticancer activity of ulvan.
8.7.4 Anticoagulant Activity
Undesired blood clots could lead to severe health risks and could result from conditions such as operated blood vessels. Anticoagulants have different mechanisms of
action with the general goal being to interfere with the pathways leading to blood
clotting. Anticoagulant activity of ulvan is affected by degree of sulfation at a particular molecular weight range. Most studies are in agreement that a higher degree
of sulfation leads to increased anticoagulant activity of ulvans. However, the effect
of molecular weight varies. For ulvans extracted from Enteromorpha prolifera, for
example, beyond a given molecular weight of 200 kDa, further increase in degree
of sulfation did not yield any anticoagulant property (Li et al. 2018a, b). Increasing
the degree of sulfation resulted in increased anticoagulant activity for ulvans of E.
prolifera with molecular weight less than 200 kDa. However, when the molecular
weight is increased beyond this value, the ulvan no longer had any anticoagulant
effect.
Anticoagulant effect of ulvans is much less than those of currently commercially available anticoagulants such as heparin (Qi et al. 2013). It also varies from
species and source since the degree of sulfation and molecular weight is also species
183
The other anticancer approach ulvans is thought to use is the prevention of cancer
cell proliferation. This has been investigated by measuring the reduction in the level
of DNA replication activity in the cancer cells. This is quantified by the reduction
in the level of proliferating cell nuclear antigen (Hussein et al. 2015). The level of
DNA replication activity reduced to noticeable levels in rat hepatocytes when treated
with ulvan from Ulva lactuca. Anticancer activity of ulvans has also been measured
as a function or tumor mass and cytotoxicity where a reduction in tumor mass and
a high cytotoxicity are indicative of reduced cell proliferation and hence anticancer
activity.
Although a number of studies have presented anticancer properties of ulvans,
there are also studies which show no cytotoxicity of ulvan against cancer cells. An
example of such is studies on Ulvan intestinalis which show no cytotoxicity against
sarcoma tumor cells at a relatively high concentration of 50–800 µg per ml. However,
this study also further showed that ulvans from different species could take different
pathways to achieving anticancer activities. While no cytotoxicity was measured
in vitro, there was 61–7% (Jiao et al. 2009) reduction in the tumor cell mass in vivo
when applied to mice in vivo at a dose of 100–400 mg/kg.
The anticancer activity is very low compared to conventional chemotherapy
agents. With such a low level of effectiveness, ulvan can at best serve in adjunct roles
in cancer treatment. As a polymeric material with pH-dependent rheological properties, ulvan can serve roles in anticancer therapy delivery system as pH-responsive
polysaccharide systems (Yang et al. 2017) and nanoparticle delivery systems (Li
et al. 2018a, b). No conclusive data yet exists to relate the chemical structure such
as degree of sulfation or molecular weight to the anticancer activity of ulvan.
8.7.4 Anticoagulant Activity
Undesired blood clots could lead to severe health risks and could result from conditions such as operated blood vessels. Anticoagulants have different mechanisms of
action with the general goal being to interfere with the pathways leading to blood
clotting. Anticoagulant activity of ulvan is affected by degree of sulfation at a particular molecular weight range. Most studies are in agreement that a higher degree
of sulfation leads to increased anticoagulant activity of ulvans. However, the effect
of molecular weight varies. For ulvans extracted from Enteromorpha prolifera, for
example, beyond a given molecular weight of 200 kDa, further increase in degree
of sulfation did not yield any anticoagulant property (Li et al. 2018a, b). Increasing
the degree of sulfation resulted in increased anticoagulant activity for ulvans of E.
prolifera with molecular weight less than 200 kDa. However, when the molecular
weight is increased beyond this value, the ulvan no longer had any anticoagulant
effect.
Anticoagulant effect of ulvans is much less than those of currently commercially available anticoagulants such as heparin (Qi et al. 2013). It also varies from
species and source since the degree of sulfation and molecular weight is also species