Determination of bioactive properties of protein and pigments obtained from Spirulina platensis

Abstract

Microalgae have a great potential for usage in functional foods or ingredients. The amount of the pigments obtained with different solvents from Spirulina platensis and their antioxidant activities, Angiotensin Converting Enzyme (ACE) inhibition of S. platensis and dried phycocyanin powder were investigated. The highest Chlorophyll-a and phycocyanin pigment contents were 9.26 mg chlorophyll-a/g dry spirulina and 78.57 mg phycocyanin/g dry spirulina using sequentially extraction, respectively. It was found that Chlorophyll extracts have higher antioxidant activity (14.62–16.19 mg FeSO4·7H2O/g dry spirulina) than phycocyanin extracts (10.87–12.34 mg FeSO4·7H2O/g dry spirulina). Single extraction was preferred due to increased pigment concentration and antioxidant activity. The percent ACE inhibition values of 10% S. platensis powder and phycocyanin powder suspensions were found as 92.40% and 89.50%, respectively. The necessary protein concentration of S. platensis and phycocyanin powder samples to inhibit 50% of the ACE activity (IC50 values) were 2.93 and 3.96 mg protein/ml, respectively. It was concluded that S. platensis suspension could be more effective than the pure phycocyanin on ACE inhibition. Practical applications Microalgae itself can be considered as functional food or food ingredient because of the bioactive contents such as polyunsaturated fatty acids, sterols, pigments, proteins and enzymes, vitamins, and other bioactive substances. In this study, the quantities and the antioxidant activities of phycocyanin and chlorophyll-a pigments obtained from Spirulina platensis by sequential extraction of methanol and aqueous sodium nitrate solutions were determined. Also, protein contents and ACE inhibition of residual protein rich fraction were determined after the pigment extraction. The results showed that pigment fractions and residual protein content after pigment extraction have antioxidative and antihypertensive health promoting potential.