Taxon- and Growth Phase-Specific Antioxidant Production by Chlorophyte, Bacillariophyte, and Haptophyte Strains Isolated From Tropical Waters

Abstract

Antioxidants found in microalgae play an essential role in both animals and humans, against various diseases and aging processes by protecting cells from oxidative damage. In this study, 26 indigenous tropical marine microalgae were screened. Out of the 26 screened strains, 10 were selected and were further investigated for their natural antioxidant compounds which include carotenoids, phenolics, and fatty acids collected in their exponential and stationary phases. The antioxidant capacity was also evaluated by a total of four assays, which include ABTS, DPPH, superoxide radical (O2•–) scavenging capacity, and nitric oxide (•NO–) scavenging capacity. This study revealed that the antioxidant capacity of the microalgae varied between divisions, strains, and growth phase and was also related to the content of antioxidant compounds present in the cells. Carotenoids and phenolics were found to be the major contributors to the antioxidant capacity, followed by polyunsaturated fatty acids linoleic acid (LA), eicosapentaenoic acid (EPA), arachidonic acid (ARA), and docosahexaenoic acid (DHA) compared to other fatty acids. The antioxidant capacity of the selected bacillariophytes and haptophytes was found to be positively correlated to phenolic (R2-value = 0.623, 0.714, and 0.786 with ABTS, DPPH, and •NO–) under exponential phase, and to carotenoid fucoxanthin and β-carotene (R2 value = 0.530, 0.581 with ABTS, and 0.710, 0.795 with O2•–) under stationary phase. Meanwhile, antioxidant capacity of chlorophyte strains was positively correlated with lutein, β-carotene and zeaxanthin under the exponential phase (R2 value = 0.615, 0.615, 0.507 with ABTS, and R2 value = 0.794, 0.659, and 0.509 with •NO–). In the stationary phase, chlorophyte strains were positively correlated with violaxanthin (0.755 with •NO–), neoxanthin (0.623 with DPPH, 0.610 with •NO–), and lutein (0.582 with •NO–). This study showed that antioxidant capacity and related antioxidant compound production of tropical microalgae strains are growth phase-dependent. The results can be used to improve the microalgal antioxidant compound production for application in pharmaceutical, nutraceutical, food, and feed industry.

Effect of newly isolated high antioxidant diatom on the reproduction and stress tolerance of the marine copepod, Acartia erythraea under crowding stress

“…The total antioxidant radical‐scavenging capacity was evaluated using the 2,2′‐Azinobis‐(3‐Ethylbenzthiazolin‐6‐Sulfonic Acid) (ABTS) radical cation (ABTS •+ ) assay, as previously described by Re et al (1999). The ABTS •+ radical cation was prepared by mixing 7 mol/m 3 ABTS (Wako Chemical) with 2.45 mol/m 3 potassium persulfate (K 2 S 8 O 4 , Wako Chemical) for 8 hours in the dark at room temperature (21°C).…”

“…Abbreviations: TW P105, Thalassiosira weissflogii TRG10-P105 isolated from Malaysian water (Rahman et al, 2020); Generic TW, Thalassiosira weissflogii (CCMP1052) from Bigelow Culture Collection Centre.…”

“…Recently, several high-antioxidant microalgal strains containing substantial amounts of carotenoids, fatty acids and phenolic compounds have been isolated from the tropical waters of Malaysia (Rahman et al, 2020). Among these, the strain Thalassiosira weissflogii TRG10-P105 has been suggested as the most appropriate algal diet for copepod culture due to its high antioxidant capacity, particularly for tropical species which have specific metabolic pathways against oxidative stress to adapt to highly stressful conditions of high temperature and strong solar radiation, including UV.…”

Lipid Nanoparticles Containing Mixtures of Antioxidants to Improve Skin Care and Cancer Prevention

“…The performed method was conducted as described previously [42]. Briefly, stock methanolic solutions of each NC were prepared, as well as a 0.16 mM DPPH methanolic solution.…”

Antioxidative Responses of Chlorella vulgaris Under Different Growth Phases

“…The concentrations of microalgal bioactive compounds vary widely depending on the original habitat, species, strains, and growth phases, which may influence the differences in the antioxidant responses of certain microalgae (Rahman et al, 2020). The microalgae growth phase is characterized into five phases including lag (initial cell metabolism adaptation to growth), exponential (rapid and maximum growth rate), declining growth rate (due to growth requirements for cell division being limited, causes a decline in cell density), stationary (limiting factor and the growth rate are balanced, resulting in relatively constant cell density) and death phase (cell density rapidly decreases due to depleted nutrient) (Lavens & Sorgeloos, 1996).…”