Biochemical Characterization of Japanese Spirulina sp. Microalgal Powder: Pigment, β-Carotene, and Phenolic Profiling with Antioxidant Assessment
Trung Vo *
Department of Biochemistry, Faculty of Pharmacy, Nguyen Tat Thanh University, Ho Chi Minh City, VietNam.
Phuc Thi Hong Nguyen
Department of Biochemistry, Faculty of Pharmacy, Nguyen Tat Thanh University, Ho Chi Minh City, VietNam.
*Author to whom correspondence should be addressed.
Abstract
Background: Spirulina microalgae are filamentous, multicellular, blue–green cyanobacteria that serve as popular nutritional sources in medicine, the food industry and aquaculture. Spirulina has a high content of macro- and micronutrients, antioxidants and pigments such as carotene, chlorophyll and phycocyanin.
Aims: This study aimed to determine the pigment, β-carotene, phenolic, and antioxidant profile of Japanese Spirulina microalgal powder as a basis for evaluating its relevance to future functional food and nutraceutical development.
Materials and Methods: The characteristics of the powder were assessed by visual inspection and optical microscopy. Pigment (carotenoid and chlorophyll) contents were determined by UV-Vis spectrophotometry. β-carotene was quantified by reversed-phase HPLC using an isocratic elution programme with a mobile phase of dichloromethane:acetonitrile:methanol (40:45:15, v/v/v). Total phenolic content and antioxidant activity were assessed using the Folin-Ciocalteu and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays, respectively.
Results: The microalgal powder was a uniform, homogeneous substance with a slightly fishy odour, appropriate for analysis. Total carotenoid and chlorophyll contents reached 3.306 mg/g DW and 6.471 mg/g DW, respectively. The retention time of β-carotene was approximately 11.827 minutes, and the linear regression equation showed statistical significance (R² = 0.9995); the β-carotene content of the microalgal powder was 2.677 mg/g DW. Total phenolic content was 0.444 mg GAE/g DW, and DPPH radical scavenging activity was 25%, equivalent to 2.487 µg/mL of vitamin C.
Conclusions: The Japanese Spirulina sp. microalgal powder possessed a stable, well-characterised biochemical composition — carotenoids, chlorophylls, β-carotene and phenolics — together with measurable in vitro antioxidant activity. These findings support its potential as a biochemically characterised ingredient for further investigation in functional food and nutraceutical research.
Keywords: Spirulina sp., β-carotene, carotenoids, chlorophyll, total phenolic content, DPPH assay, antioxidant activity, HPLC, UV–Vis spectrophotometry, microalgal powder