Phycocyanin - a marine anticancer agent

Phycocyanin - a marine anticancer agent

Phycocyanin, a protein derived from marine organisms, seaweeds, algae and cyanobacteria, has significant anti-cancer properties as well as anti-oxidative properties, anti-inflammatory activity, immune enhancement abilities, and liver and kidney protection effects.


Many studies have now shown that phycocyanin is a very promising anticancer agent, and a natural chemotherapy. Phycocyanin clearly has an anticancer effect, and can block the growth and progression of cancer cells and the formation of tumours (updated by Chris Woollams from a 2021 version of this article).  

The anticancer effects of Phycocyanin 

In a major 2017 review (1), phycocyanin was shown to exert anticancer activity by blocking numerous cancer pathways, the tumour cell cell cycle, angiogenesis, killing cancer cells and inducing tumour cell apoptosis and autophagy. It also has anti-inflammatory and antioxidant properties. This has been shown in a wide variety of cancers including prostate, colorectal, NSCLC, breast cancer, TNBC, ovarian, melanoma, leukaemia and pancreatic tumours.

There are several studies with TNBC. In one study (8), phycocyanin was shown to inhibit proliferation, inhibit metastases, suppress angiogenesis and cause cell death via the MAPK pathway. There was no toxicity to healthy cells.

Some forms of natural phycocyanin made by cultivating spirulina are higher in selenium, research showing a stronger effect with breast cancer tumours. 

The phycocyanin most often studied is the main active ingredient of Arthrospira platensis and has shown antioxidant, antiinflammatory, immunomodulatory and anticancer effects, according to a 2021 German review of all phycocyanin in vivo and in vitro research (7).  Their article refers to phycocyanin as 'a potential anticancer drug', making it an important natural chemotherapy.

While phycocyanin is toxic to cancer cells, it is non-toxic to healthy cells (2). It may also be derived from algae such as chlorella or spirulina and is itself highly nutritious.

Phycocyanin (PC) is a photosynthetic peptide, a piece of protein - a phycobiliprotein - which can capture light energy effectively. In nature, it 'cooperates' with chlorophyll and algae, boosting their oxygen and helping them absorb light energy even at depth. It has not surprisingly been shown to be a radiosensitising agent, with effects via inhibiting the inflammatory Cox-2 pathway (9). 

Phycobiliproteins can be divided into three categories:

   * phycoerythrin (red),

   * phycocyanin (blue), and, 

   * allophycocyanin (bluish green).

Phycocyanin belongs to the deep and intense blue group capturing red and orange light and is safe to consume being already approved by the FDA as a blue food colouring.

While it can be found in limited amounts in spirulina, the safety of spirulina has recently come into question due to possible presence of microcystin, a toxin produced by the bacteria; and spirulina may also contain heavy metals such as lead, mercury, and arsenic. Chlorella is far less affected because of how it is grown and harvested.

Phycocyanin can, itself, be found as a 100% pure extracted supplement.

Phycocyanin has numerous benefits, as shown in research:

  • It has antioxidant and antiinflammatory benefits and has been shown to protect the liver (3,4)
  • It can be activated by light and lasers and used as an agent in photodynamic therapy (5)
  • It can enhance cancer therapies by attaching to the scavenger receptors of Tumour Associated Macrophages (6)
  • It has both in vitro and in vivo research showing effectiveness against breast cancer, lung cancer, colorectal cancer, prostate cancer, melanoma, leukemia, liver cancer and bone marrow cancer amongst others.

Other sea compounds that fight cancer

Phycocyanin is not the only natural sea water anti-cancer compound. Another is Fucoidan. Seaweeds containing fucans, such as fucoxanthin, have been studied since 2002 for their anticancer properties. Fucoidan has recent research showing action with blood and lymph cancers. 

Like Phycocyanin, fucans are also highly nutritious. Seaweeds and algae concentrate minerals like iodine and also contain high levels of polysaccharides, polyphenols, phytosterols and long-chain omega 3.

Marine-derived anticancer drugs

Phycocyanin is not alone as a marine-derived cyanobacterial anti-cancer agent. There are now a number of marine anti-cancer drugs, some including the Phycocyanin peptide. Of particular note is the breast cancer drug Ibrance.

  • Cytarabine (Cytosar-U®) - derived from a Caribbean sponge; approved for the treatment of leukemia
  • Trabectedin (Yondelis®) - derived from a toxic sea squirt; approved for the treatment of soft tissue sarcoma and ovarian cancer.
  • Eribulin mesylate (Halaven®) - derived from the marine sponge, it blocks microtubule formation - used in breast cancer.
  • Brentuximab (Adcetris®) - derived from marine cyanobacteria; approved for Hodgkin’s lymphoma
  • Plitidepsin (Aplidin®) - derived from a sea squirt; approved in 2018 in Australia for the treatment of multiple myeloma, leukemia, and lymphoma .
  • Polatuzumab vedotin (Polivy) - derived from marine bacteria; approved in 2019 for the treatment of B-cell lymphomas, non-Hodgkin lymphomas, and chronic lymphocytic leukemia.
  • Enfortumab vedotin (PADCEV) - a monoclonal antibody derived from marine cyanobacteria; approved in 2019 for the treatment of metastatic urothelial cancer.
  • Belantamab mafodotin (Blenrep) - monoclonal antibody derived from sea moluscs and cyanobacteria; approved in 2020 for the treatment of relapsed and refractory multiple myeloma.
  • Lurbinectedin (Zepzelca) - derived from marine cyanobacteria; approved in 2020 for the treatment of metastatic small cell lung cancer.
  • Ibrance - derived from a marine alkaloid; approved for metastatic breast cancer.

Phycocyanin supplements

Phycocyanin as a stand alone compound is many times more active than spirulina. It is water soluble and non-toxic. Phycocyanin is most commonly a derived peptide (a part of a protein) from the blue wall of spirulina.

C-Phycocyanin (CPC), a pigment-protein complex from the light-harvesting phycobiliprotein family can be derived from several different algae.

It is suitable for vegans.

It is unstable to heat, light and acid.

Typical dose is 2 x 200 mg per day with food.

Go to: The Blushwood Berry - another natural chemo agent?



  1. Review: Phycocyanin: A potential Drug for cancer treatment; Lianggian Jiang et al; J Cancer, 2017 8(17) 3416-3429; 
  2. Ravi M, Tentu S, Baskar G, Rohan Prasad S, Raghavan S, Jayaprakash P. et al. Molecular mechanism of anti-cancer activity of phycocyanin in triple-negative breast cancer cells. BMC cancer. 2015;15:768.
  3. Romay C, Armesto J, Remirez D, Gonzalez R, Ledon N, Garcia I. Antioxidant and anti-inflammatory properties of C-phycocyanin from blue-green algae. Inflammation research: official journal of the European Histamine Research Society [et al] 1998;47:36–41.
  4. Bhat VB, Madyastha KM. C-phycocyanin: a potent peroxyl radical scavenger in vivo and in vitro. Biochemical and biophysical research communications. 2000;275:20–5.
  5. Li B, Chu X, Gao M, Li W. Apoptotic mechanism of MCF-7 breast cells in vivo and in vitro induced by photodynamic therapy with C-phycocyanin. Acta biochimica et biophysica Sinica. 2010;42:80–9.
  6. Wan DH, Zheng BY, Ke MR, Duan JY, Zheng YQ, Yeh CK. et al. C-Phycocyanin as a tumour-associated macrophage-targeted photosensitiser and a vehicle of phthalocyanine for enhanced photodynamic therapy. Chemical communications. 2017;53:4112–5.
  7. Phycocyanin from Arthorospira platensis as potential anti-cancer drug. Review of in vitro and in vivo studies; Steffen Braune et al; Life (Basel) 2021, Jan 27, 11(2):91. 
  8. Molecular mechanism of anti-cancer activity of phycocyanin in triple-negative
    breast cancer cells. Mathangi Ravi et al; BMC Cancer volume 15, Article number: 768 (2015)
  9. C-phycocyanin: a natural product with radiosensitizing property for enhancement of colon cancer radiation therapy efficacy through inhibition of COX-2 expression; Amirhosein Kefayat et al; Scientific Reports volume 9, Article number: 19161 (2019)


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