Total Phenolic Levels, In Vitro Antioxidant Properties, and Fatty Acid Profile of Two Microalgae, Tetraselmis marina Strain IMA043 and Naviculoid Diatom Strain IMA053, Isolated from the North Adriatic Sea

Abstract

This work studied the potential biotechnological applications of a naviculoid diatom (IMA053) and a green microalga (Tetraselmis marina IMA043) isolated from the North Adriatic Sea. Water, methanol, and dichloromethane (DCM) extracts were prepared from microalgae biomass and evaluated for total phenolic content (TPC) and in vitro antioxidant properties. Biomass was profiled for fatty acid methyl esters (FAME) composition. The DCM extracts had the highest levels of total phenolics, with values of 40.58 and 86.14 mg GAE/g dry weight (DW in IMA053 and IMA043, respectively). The DCM extracts had a higher radical scavenging activity (RSA) than the water and methanol ones, especially those from IMA043, with RSAs of 99.65% toward 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) at 10 mg/mL, and of 103.43% against 2,2-diphenyl-1-picrylhydrazyl (DPPH) at 5 mg/mL. The DCM extract of IMA053 displayed relevant copper chelating properties (67.48% at 10 mg/mL), while the highest iron chelating activity was observed in the water extract of the same species (92.05% at 10 mg/mL). Both strains presented a high proportion of saturated (SFA) and monounsaturated (MUFA) fatty acids. The results suggested that these microalgae could be further explored as sources of natural antioxidants for the pharmaceutical and food industry and as feedstock for biofuel production.

Influence of Nutrient Deprivation on the Antioxidant Capacity and Chemical Profile of Two Diatoms from Genus Chaetoceros

“…The same was observed in the species C. costatus and C. socialis from this study, where the phenolic content was significantly lower in all experimental groups exposed to nutrient deficiency (P, N and Si) compared to the control group. Previously, a positive correlation between antioxidant activity and TPC was found in microalgae Tetraselmis marina isolated from the northern Adriatic Sea [16]. Interestingly, in nutrient-deprived culture conditions, both TPC and pigments may contribute significantly to antioxidant capacity [17].…”

Microalgae Produce Antioxidant Molecules with Potential Preventive Effects on Mitochondrial Functions and Skeletal Muscular Oxidative Stress

“…Trentin et al (2022) showed that two microalgae, a naviculoid diatom and a green microalga (Tetraselmis marina), are rich in polyphenolic compounds. Thus, all these microalgae can be considered good candidates to serve as sources of these high-value compounds [35].…”

Bioactivity and Digestibility of Microalgae Tetraselmis sp. and Nannochloropsis sp. as Basis of Their Potential as Novel Functional Foods

“…SBL1 and SBL4 methanolic extracts [ 98 ], and the DPPH and NO radical scavenging activity, metal chelating ability, and FRAP values of N. oculata extracts [ 102 ]. In a recent work, phenolic compounds are recognized as the major factor responsible for the ABTS and DPPH radical scavenging activity and the FRAP values of extracts obtained from T. marina IMA043 strain, although the authors suggest that the remaining activity that cannot be explained by the presence of phenols could be ascribed to other molecules present in the extract [ 85 ]. Similar findings had been reported in previous studies that recognized both phenolic compounds and PUFAs as the contributors on the antioxidant activity exerted by extracts from N. oculata [ 69 ], Tetraselmis sp.…”