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Impact of Light Intensity on Antioxidant Activity of Tropical Microalgae.

ABSTRACT: Twelve microalgae species isolated in tropical lagoons of New Caledonia were screened as a new source of antioxidants. Microalgae were cultivated at two light intensities to investigate their influence on antioxidant capacity. To assess antioxidant property of microalgae extracts, four assays with different modes of action were used: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-éthylbenzothiazoline-6-sulphonique) (ABTS), oxygen radical absorbance capacity (ORAC), and thiobabituric acid reactive substances (TBARS). This screening was coupled to pigment analysis to link antioxidant activity and carotenoid content. The results showed that none of the microalgae studied can scavenge DPPH and ABTS radicals, but Chaetoceros sp., Nephroselmis sp., and Nitzschia A sp. have the capacity to scavenge peroxyl radical (ORAC) and Tetraselmis sp., Nitzschia A sp., and Nephroselmis sp. can inhibit lipid peroxidation (TBARS). Carotenoid composition is typical of the studied microalgae and highlight the siphonaxanthin, detected in Nephroselmis sp., as a pigment of interest. It was found that xanthophylls were the major contributors to the peroxyl radical scavenging capacity measured with ORAC assay, but there was no link between carotenoids and inhibition of lipid peroxidation measured with TBARS assay. In addition, the results showed that light intensity has a strong influence on antioxidant capacity of microalgae: Overall, antioxidant activities measured with ORAC assay are better in high light intensity whereas antioxidant activities measured with TBARS assay are better in low light intensity. It suggests that different antioxidant compounds production is related to light intensity.

SUBMITTER: Coulombier N

PROVIDER: S-EPMC7073765 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Impact of Light Intensity on Antioxidant Activity of Tropical Microalgae.

Coulombier Noémie N Nicolau Elodie E Le Déan Loïc L Antheaume Cyril C Jauffrais Thierry T Lebouvier Nicolas N

Marine drugs 20200218 2

Twelve microalgae species isolated in tropical lagoons of New Caledonia were screened as a new source of antioxidants. Microalgae were cultivated at two light intensities to investigate their influence on antioxidant capacity. To assess antioxidant property of microalgae extracts, four assays with different modes of action were used: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-éthylbenzothiazoline-6-sulphonique) (ABTS), oxygen radical absorbance capacity (ORAC), and thiobabituric aci ...[more]

PMID: 32085557

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Project description:BackgroundThe minimal physical activity intensity that would confer health benefits among adolescents is unknown. The purpose of this study was to examine the associations of accelerometer-derived light-intensity (split into low and high) physical activity, and moderate- to vigorous-intensity physical activity with cardiometabolic biomarkers in a large population-based sample.MethodsThe study is based on 1,731 adolescents, aged 12-19 years from the 2003/04 and 2005/06 National Health and Nutrition Examination Survey. Low light-intensity activity (100-799 counts/min), high light-intensity activity (800 counts/min to <4 METs) and moderate- to vigorous-intensity activity (? 4 METs, Freedson age-specific equation) were accelerometer-derived. Cardiometabolic biomarkers, including waist circumference, systolic blood pressure, diastolic blood pressure, HDL-cholesterol, and C-reactive protein were measured. Triglycerides, LDL- cholesterol, insulin, glucose, and homeostatic model assessments of ?-cell function (HOMA-%B) and insulin sensitivity (HOMA-%S) were also measured in a fasting sub-sample (n=807).ResultsAdjusted for confounders, each additional hour/day of low light-intensity activity was associated with 0.59 (95% CI: 1.18-0.01) mmHG lower diastolic blood pressure. Each additional hour/day of high light-intensity activity was associated with 1.67 (2.94-0.39) mmHG lower diastolic blood pressure and 0.04 (0.001-0.07) mmol/L higher HDL-cholesterol. Each additional hour/day of moderate- to vigorous-intensity activity was associated with 3.54 (5.73-1.35) mmHG lower systolic blood pressure, 5.49 (1.11-9.77)% lower waist circumference, 25.87 (6.08-49.34)% lower insulin, and 16.18 (4.92-28.53)% higher HOMA-%S.ConclusionsTime spent in low light-intensity physical activity and high light-intensity physical activity had some favorable associations with biomarkers. Consistent with current physical activity recommendations for adolescents, moderate- to vigorous-intensity activity had favorable associations with many cardiometabolic biomarkers. While increasing MVPA should still be a public health priority, further studies are needed to identify dose-response relationships for light-intensity activity thresholds to inform future recommendations and interventions for adolescents.

Project description:Nephroselmis sp. was previously identified as a species of interest for its antioxidant properties owing to its high carotenoid content. In addition, nitrogen availability can impact biomass and specific metabolites' production of microalgae. To optimize parameters of antioxidant production, Nephroselmis sp. was cultivated in batch and continuous culture conditions in stirred closed photobioreactors under different nitrogen conditions (N-repletion, N-limitation, and N-starvation). The aim was to determine the influence of nitrogen availability on the peroxyl radical scavenging activity (oxygen radical absorbance capacity (ORAC) assay) and carotenoid content of Nephroselmis sp. Pigment analysis revealed a specific and unusual photosynthetic system with siphonaxanthin-type light harvesting complexes found in primitive green algae, but also high lutein content and xanthophyll cycle pigments (i.e., violaxanthin, antheraxanthin, and zeaxanthin), as observed in most advanced chlorophytes. The results indicated that N-replete conditions enhance carotenoid biosynthesis, which would correspond to a higher antioxidant capacity measured in Nephroselmis sp. Indeed, peroxyl radical scavenging activity and total carotenoids were higher under N-replete conditions and decreased sharply under N-limitation or starvation conditions. Considering individual carotenoids, siphonaxanthin, neoxanthin, xanthophyll cycle pigments, and lycopene followed the same trend as total carotenoids, while ?-carotene and lutein stayed stable regardless of the nitrogen availability. Carotenoid productivities were also higher under N-replete treatment. The peroxyl radical scavenging activity measured with ORAC assay (63.6 to 154.9 µmol TE g-1 DW) and the lutein content (5.22 to 7.97 mg g-1 DW) were within the upper ranges of values reported previously for other microalgae. Furthermore, contents of siphonaxanthin ere 6 to 20% higher than in previous identified sources (siphonous green algae). These results highlight the potential of Nephroselmis sp. as a source of natural antioxidant and as a pigment of interest.

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Impact of Light Intensity on Antioxidant Activity of Tropical Microalgae.

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Impact of Light Intensity on Antioxidant Activity of Tropical Microalgae.

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