Phytochemical screening of twelve species of phytoplankton isolated from Arabian Sea coast

Objective: To analyze the phytochemicals in twelve species of marine phytoplankton. Methods: Total phenolic content of methanol extract was estimated by the Folin-Ciocalteu method. Total flavonoid content of the methanol extarct was determined by aluminium chloride method. Chlorophylls, β-carotene and astaxanthin were estimated by acetone extraction method. Vitamin C was determined by dinitrophenyl-hydrazine method. Phycobiliproteins such as allophycocyanin, phycocyanin and phycoerythrin in the aqueous extracts were determined. Results: Total phenolics varied from 5.41 mg gallic acid equivalents/g dry weight (DW) in Phormidium corium (P. corium) to 17.37 mg gallic acid equivalents/g DW in Oscillatoria fremyii (O. fremyii). Total flavonoids ranged between 0.74 mg quercetin equivalent/g DW in P. corium and 9.87 mg quercetin equivalent/g DW in Nannochloropsis oceanica. Chlorophyll-a pigment was high in Chaetoceros calcitrans (C. calcitrans) (15.51 mg/g DW) and low in P. corium (1.08 mg/g DW). Chlorophyll-c ranged between 0.07 mg/g DW in Nannochloropsis oceanica and 4.62 mg/g DW in C. calcitrans. High contents of β-carotene and astaxanthin were found in C. calcitrans and low in P. corium which ranged from 0.33 to 10.03 mg/g DW and 0.18 to 3.85 mg/g DW, respectively. Vitamin C content varied from 0.50 mg/g DW in C. calcitrans to 1.51 mg/g DW in Phormidium tenue. O. fremyii showed highest total phycobiliproteins of 317.05 mg/g DW. High contents of allophycocyanin and phycocyanin were found in O. fremyii, whereas high contents of phycoerythrin were found in Oscillatoria sancta. All the three phycobiliproteins were low in Chroococcus turgidus. Conclusions: Marine phytoplankton are one of the natural sources providing novel biologically active compounds with potential for pharmaceutical applications