In Vitro Protocols for Measuring the Antioxidant Capacity of Algal Extracts

Abstract

In the last decade a large amount of research has been directed at targeting algal resources for biologically active molecules. High-throughput in vitro antioxidant assays are routinely used to screen for biologically active compounds present in algal extracts when the requirement is to identify samples for progression to more detailed biological scrutiny. Whilst a myriad of antioxidant assays have been developed, this present chapter aims to give step-by-step practical guidance on how to carry out some of the most popular and biologically relevant assays at the bench.

Microbial Population Changes in Decaying Ascophyllum nodosum Result in Macroalgal-Polysaccharide-Degrading Bacteria with Potential Applicability in Enzyme-Assisted Extraction Technologies

“…Results obtained from the EAE of the total phenolic compounds from F. vesiculosus , performed with or without commercial enzymes conducted at 50 °C, and with or without the enzymatic bacterial supernatants (EBS) conducted at 28 °C, are shown in Figure 3. The total phenolic content (TPC) of F. vesiculosus obtained by exhaustive solid-liquid extraction had previously been reported as 68.6 ± 8.3 mg PE.g −1 DWB [36]. This content was thus considered as a reference value for TPC, corresponding to a yield of extraction of 100%.…”

“…Phloroglucinol was used as the external standard and a calibration curve was performed by serial dilution of a 2 mg mL −1 stock solution (10, 20, 50, 80, 120, 160 μg mL −1 ). Total phenolic content (TPC) was expressed as milligram of phloroglucinol equivalents (PE) per gram of dry weight extract (mg PE g −1 DWE) or per gram of dry weight biomass (mg PE g −1 DWB) [36]. TPC quantification was performed in triplicate for each crude extract.…”

Impact of Light Intensity on Antioxidant Activity of Tropical Microalgae

“…In presence of radical scavenger, purple DPPH radical is reduced to a pale yellow compound and the discoloration of the radical is measured at 515 nm [39]. DPPH radical scavenging capacity of microalgae extracts was evaluated with the slightly modified method of Kenny et al [81]. Trolox, ascorbic acid, α-tocopherol, β-carotene, and astaxanthin were used as reference compounds.…”

Atypical antipsychotic clozapine binds fibrinogen and affects fibrin formation

“…The ORAC assay [25] was performed in duplicate by measuring the reduction of intrinsic fluorescence of 100 nM fibrinogen, alone or in the presence of 3.4 and 6.8 µM clozapine. The reduction of protein fluorescence was achieved by incubating the samples with 52.5 mM AAPH (2,2'-azobis(2-amidinopropane) dihydrochloride), a free (dominantly peroxyl) radical inducer.…”

“…In the HORAC assay, the reduction of fluorescence of 100 nM fibrinogen, alone or in the presence of 6.8 and 13.6 µM clozapine, was achieved by incubating samples with the substances [25] inducing hydroxyl radical production (31 mM H 2 O 2 and 260 µM CoF 2 x 4H 2 O/ 460 µM picolinic acid). Immediately after the addition of all components, mixtures were placed in FluoroMax®-4 spectrofluorimeter (Horiba Scientific, Japan).…”