25 Nov Antioxidant properties
The generation of reactive oxygen species in all organisms is associated with the damage of biologically relevant molecules such as DNA, proteins, carbohydrates and lipids.
These highly reactive species include the hydroxyl radical, the superoxide anion radical, hydrogen peroxide and singlet molecular oxygen as well as hypochlorite, the nitric oxide radical and peroxynitrite.
A variety of biological processes and diseases e.g., inflammation, photobiological effects, antimicrobial defence, radiation damage, carcinogenesis, neurodegenerative diseases, atherosclerosis and aging involve reactive oxygen species.
Our organism processes various defence mechanisms against the highly reactive oxygen species including the action of endogenous or exogenous antioxidant molecules.
Exogenous antioxidants of dietary origin include vitamin C, vitamin E, carotenoids and polyphenols.
The antioxidant properties of Spirulina are mainly related to the strong antioxidant and free radical scavenging activities of phycocyanin, although other antioxidant constituents contribute to the total antioxidant potential of the microalga.
In this respect, it has been shown:
(a) The potent peroxyl radical scavenging activity of phycocyanin. In this respect, the covalently linked chromophore phycocyanobilin is involved in this antioxidant activity,
(b) The scavenging of peroxynitrite by phycocyanin. Peroxynitrite is an inorganic toxin of biological importance, which can be generated in vivo from nitric oxide and superoxide,
(c) The strong selective inhibition of cyclooxygenase-2 (COX-2) by phycocyanin, with a very low COX-2/COX-1 ratio (0.04).
The capacity of phycocyanin to inhibit COX-2 is much higher than those of the non-steroid anti-inflammatory drugs celecoxib and rofecoxib, the well-known selective COX-2 inhibitors; thus, anti-inflammatory properties of phycocyanin reported in the literature may be due, in part, to its selective COX-2 inhibitory property, although its ability to scavenge free radicals may also be involved,
(d) The scavenging of hydroxyl and alcoxyl radicals by phycocyanin (phycocyanobilin moiety is the main part of phycocyanin involved in scavenging hydroxyl radicals), and
(e) The scavenging of stable free radicals by a variety of Spirulina extracts (**21, **28, **29).
Cell-free and cell-based assays were also used to examine the antioxidant and anti-inflammatory properties of Spirulina preparations.
The results showed inactivation of free superoxide radicals as well as an anti-inflammatory effect which is related to the reduction of metabolic activity of neutrophils (**38).
Animal experiments have shown that Spirulina is able to protect the organism from drug-induced oxidative damages (nephrotoxicity and cardiotoxicity), from metal-induced oxidative damages (lead, cadmium, mercury) and from hepatotoxin-induced oxidative damage (hepatotoxicity from carbon tetrachloride) as well as from neuronal oxidative damages.
In the last case it has been proposed that phycocyanin may be useful for the treatment of neurodegenerative disorders such as Alzheimer’s, Parkinson’s and Huntington’s diseases (**28, **30).
(**) Literature on the subject
