Abstract
The objective of the present study is to determine the antioxidant and anticancer activities of Nostoc linckia extracts cultivated under heavy metal stress conditions (0.44, 0.88, and 1.76 mg/L for zinc and 0.158, 0.316, 0.632 mg/L for copper). Phycobiliprotein, phenolic compounds, flavonoids, and tannins were measured. Active ingredients of extracts were evaluated by GC-mass spectroscopy. The obtained results revealed that higher zinc and copper concentrations showed growth inhibition while 0.22 mg/L (Zn) and 0.079 mg/L (Cu) enhanced growth, reaching its maximum on the 25th day. Increases in catalase, lipids peroxidation, and antioxidants, as well as tannins and flavonoids, have been induced by integration of 0.88 mg/L (Zn) and 0.316 mg/L (Cu). Elevation of Zn concentration induced augmentation of antioxidant activity of crude extract (DPPH or ABTS), with superior activity at 0.44 mg/L zinc concentration (81.22%). The anticancer activity of Nostoc linckia extract (0.44 mg/L Zn) tested against four cancer cell lines: A549, Hela, HCT 116, and MCF-7. The extract at 500 µg/mL appeared the lowest cell viability of tested cell lines. The promising extract (0.44 mg/L Zn) recorded the lowest cell viability of 25.57% in cervical cell line, 29.74% in breast cell line, 33.10% in lung cell line and 34.53% in the colon cell line. The antioxidant active extract showed significant stability against pH with attributed increase in antioxidant activity in the range between 8–12. The extract can be used effectively as a natural antioxidant and anticancer after progressive testing.
Highlights
Cyanobacteria are prokaryote that have a simple cellular structure, and photosynthesislike plants but don’t have plant cell walls as with primitive bacteria
This study aimed to identify the impact of raising levels of copper and/or zinc in the Nostoc linckia culture medium (BG-110) on growth and secondary metabolite production and to assess the antioxidant and anticancer activity of the extracts
Obtained data illustrated that the cyanobacteria cells significantly reached the maximum growth rate on the twenty-fifth day of cultivation; after that, the growth rate declined until the 30th day of planting
Summary
Cyanobacteria are prokaryote that have a simple cellular structure, and photosynthesislike plants but don’t have plant cell walls as with primitive bacteria. Cyanobacteria are considered as valuable sources of natural bioactive compounds, such as phenolic, flavonoids, terpenoids, proteins, lipids, vitamins, polysaccharides with considerable nutritional and medicinal value [1,2,3,4,5]. Nostoc genus is considered an edible source, and the genus belongs to the Nostocaceae family division of Cyanophyta. It forms spherical cells, which link together, forming filaments. Creates numerous compounds with an antimicrobial and antiviral activity, which significantly improved its cultivation [9]. The algal extracts have proven antimicrobial, antiviral, and antitumor activities [25,26]
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