Spirulina platensis, a blue-green alga of Cyanophyta family, was isolated from Wady El-Natron district, El-Behara Governorate, 30.58333°N 30.33333°E. The dried biomass was de-termined to have a nutritional value of 61.0% protein, 23.5% carbohydrates, and 6.21% lipids. HPLC analysis revealed presence of eight essential amino acids (23.7 g·100 g−1) and nine non-essential amino acids (28.7 g·100 g−1). The major essential amino acid is methionine (4.8 g·100 g−1). However, glutamic acid is a significant non-essential amino acid in dried powder (7.8 g/100 g). Additionally, three major sugars totaling 3.108 g·100 g−1 of dried S. platensis are identified. Along with minerals and a few polyphenolic compounds, various forms of vitamin B (B-1, 2,3,6,9, and 12) were detected. C-phycocyanin was extracted from wet biomass using organic acid extraction and cold maceration methods, followed by purification with various concentrations of ammonium sulfate. The two procedures were compared to determine the most efficient one for maximum C-PC recovery, and then the extract was screened as an antioxidant using DPPH & ABTS beside to anticancer agents against the human breast (MCF-7), human colon (HCT-116), and human liver (HepG 2) carcinoma cell lines by 5.1%, 14.3%, and 31.2% inhibition, respectively, with cold maceration being the most efficient and effective process.