Phycocyanin: From natural pigment to multifunctional bioactive substance

 Phycocyanin, a blue-green pigment protein derived from algae such as Spirulina, belongs to the phycobiliprotein family and is responsible for capturing and transmitting light energy in photosynthesis. This natural substance has attracted attention because of its distinctive blue colour and diverse biological activities, and is widely used in various fields such as food, medicine and cosmetics.

Basic Properties and Chemical Composition 

Algae blue protein appears as dark blue granules or powder, belongs to protein-binding pigments, and has the same properties as proteins. Its isoelectric point is 3.4, soluble in water but insoluble in alcohol and oil. This pigment is sensitive to heat, light and acid, and remains stable in weakly acidic and neutral environments (pH 4.5-8), precipitates under acidic conditions (pH 4.2), and decolourises in strong alkaline environments.

In terms of chemical structure, phycocyanin consists of de-coordinated proteins covalently bound to phycobilins, and the basic structural units are the α-subunit and β-subunit with molecular masses between 17-22 kDa. As an important member of the phycobiliprotein family, it is found in algae together with phycocyanin, phycocyanin and alloxyphycocyanin, of which phycobiliprotein and phycocyanin account for 4% and 2.4% of the dry mass, respectively.

Main effects and biological activities 

Antioxidant and anti-inflammatory effects: Alginin has significant antioxidant capacity, which can effectively scavenge free radicals and mitigate cellular damage caused by oxidative stress. Its anti-inflammatory mechanism includes blocking inflammatory signalling pathways such as NF-κB and reducing the release of inflammatory factors such as prostaglandin E2 (PGE-α) and tumour necrosis factor-α (TNF-α). Clinical data show that the inflammation-relieving effect on arthritis patients is similar to that of conventional anti-inflammatory drugs, but with fewer side effects.

Immunomodulation and haematopoiesis: In vitro experiments have confirmed that phycocyanin is able to stimulate erythropoietic colony production, acting similarly to erythropoietin (EPO). This property makes it potentially valuable in promoting blood cell regeneration. At the same time, it can also enhance the body's immunity by regulating the function of the immune system.

Anti-tumour potential: Several studies have shown that phycocyanin has a significant inhibitory effect on the growth of a variety of tumour cells, such as A375 and U251, and its mechanism may include inducing apoptosis, inhibiting angiogenesis, and interfering with DNA synthesis in cancer cells. It is worth noting that it usually has no significant inhibitory effect on non-tumour cells, showing better selectivity.

Neuroprotection: In recent years, it has been found that phycocyanin is able to pass the blood-brain barrier, which may have a potential protective effect on neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease, etc., and the research in this field is being carried out in depth.

Applications and Usage 

Food Industry: As a natural edible blue pigment, algal blue protein is widely used as a food colouring agent because of its non-toxicity, good water-solubility, bright and lovely colour. In Europe, America, Japan and other countries, it is often used in candy, beverage, dairy products and other food colouring, through and other natural pigments with can be deployed a variety of colours.

Medicine and health care: Since 1986, Japan developed phycocyanin as a rehabilitation aid for cancer patients and leukaemia patients, its application in the medical field has been expanding. Currently it is mainly used for:

Cancer adjuvant therapy 

haematopoietic function promotion 

immune regulation 

gastric ulcer adjuvant therapy (through its anti-inflammatory and antioxidant effect to reduce gastric mucosal damage) 

cosmetic field: alginin is added to some high-level skin care products, mainly using its antioxidant, moisturising and anti-inflammatory properties, for the improvement of the face of fine lines, dryness, and redness of the skin and so on have a certain effect. However, due to individual differences, the exact effect varies from person to person.

Scientific reagents: Due to its blue colour and fluorescent properties, phycocyanin is used as a special reagent for biological, chemical and cytological experiments.