Update on uses and properties of Citrus flavonolds: New findings in anticancer, cardiovascular, and anti-inflammatory activity
Significantly, much of the activity of Citrus flavonoids
appears to impact blood and microvascular endothelial cells, and it is not surprising that the
two main areas of research on the biological actions of Citrus flavonoids have been inflammation
and cancer. Epidemiological and animal studies point to a possible protective effect of
flavonoids against cardiovascular diseases and some types of cancer. Although flavonoids have
been studied for about 50 years, the cellular mechanisms involved in their biological action are
still not completely known. Many of the pharmacological properties of Citrus flavonoids can be
linked to the abilities of these compounds to inhibit enzymes involved in cell activation.
Attempts to control cancer involve a variety of means, including the use of suppressing,
blocking, and transforming agents. Suppressing agents prevent the formation of new cancers from
procarcinogens, and blocking agents prevent carcinogenic compounds from reaching critical
initiation sites, while transformation agents act to facilitate the metabolism of carcinogenic
components into less toxic materials or prevent their biological actions. Flavonoids can act as
all three types of agent. Many epidemiological studies have shown that regular flavonoid intake
is associated with a reduced risk of cardiovascular diseases. In coronary heart disease, the
protective effects of flavonoids include mainly antithrombotic, anti-ischemic, anti-oxidant, and
vasorelaxant. It is suggested that flavonoids decrease the risk of coronary heart disease by
three major actions: improving coronary vasodilatation, decreasing the ability of platelets in
the blood to clot, and preventing low-density lipoproteins (LDLs) from oxidizing. The anti-
inflammatory properties of the Citrus flavonoids have also been studied. Several key studies have
shown that the anti-inflammatory properties of Citrus flavonoids are due to its inhibition of the
synthesis and biological activities of different pro-inflammatory mediators, mainly the
arachidonic acid derivatives, prostaglandins E-2, F-2, and thromboxane A(2). The anti-oxidant and
anti-inflammatory properties of Citrus flavonoids can play a key role in their activity against
several degenerative diseases and particularly brain diseases. The most abundant Citrus
flavonoids are flavanones, such as hesperidin, naringin, or neohesperidin. However, generally,
the flavones, such as diosmin, apigenin, or luteolin, exhibit higher biological activity, even
though they occur in much lower concentrations. Diosmin and rutin have a demonstrated activity as
a venotonic agent and are present in several pharmaceutical products. Apigenin and their
glucosides have been shown a good anti-inflammatory activity without the side effects of other
anti-inflammatory products. In this paper, we discuss the relation between each structural factor
of Citrus flavonoids and the anticancer, anti-inflammatory, and cardiovascular protection
activity of Citrus flavonoids and their role in degenerative diseases.
