Microalga Nannochloropsis gaditana as a Sustainable Source of Bioactive Peptides: A Proteomic and In Silico Approach

Abstract

The impact of the world's growing population on food systems and the role of dietary patterns in the management of non-communicable diseases underscore the need to explore sustainable and dietary protein sources. Although microalgae have stood out as alternative sources of proteins and bioactive peptides, some species such as Nannochloropsis gaditana remain unexplored. This study aimed to characterize N. gaditana's proteome and evaluate its potential as a source of bioactive peptides by using an in silico approach. A total of 1955 proteins were identified and classified into functional groups of cellular components, molecular functions, and biological processes. In silico gastrointestinal digestion of identified proteins demonstrated that 202 hydrophobic and low-molecular-size peptides with potential bioactivity were released. Among them, 27 exhibited theorical antioxidant, antihypertensive, antidiabetic, anti-inflammatory, and/or antimicrobial activities. Seven of twenty-seven peptides showed ≥20% intestinal absorption, suggesting potential systemic effects, while the rest could act at local level. Molecular docking demonstrated strong affinities with key enzymes such as MPO, ACE, and DPPIV. Resistance to the digestion, capacity to be absorbed, and multifunctionality were demonstrated for peptide FIPGL. This study highlights N. gaditana's potential as a sustainable source of novel potential bioactive peptides with promising local and systemic biological effects.

Keywords: Nannochloropsis sp.; functional analysis; in silico digestion; microalgae; proteomics.

Figure 1

Graphical representation of the workflow followed in the present study.

Figure 2

Proteomic functional distribution of identified proteins from Nannochloropsis gaditana biomass using gene ontology (GO). (A) Proteomic percentage distribution at GO level 1 classification. (B) Cellular component GO level 2 distribution. (C) Biological process GO level 2 distribution. (D) Molecular function GO level 2 distribution.

Figure 3

Peptide profile of the peptides released after in silico gastrointestinal digestion from Nannochloropsis gaditana biomass and predicted as bioactive using the Peptide Ranker software tool. (A) Size distribution expressed as number of amino acids; (B) amino acid distribution.

Figure 4

Molecular docking of the potential bioactive peptide FIPGL from Nannochloropsis gaditana digest with the human myeloperoxidase (MPO) and the angiotensin converting enzyme (ACE). (A) 3D molecular docking representation of FIPGL with MPO; Red: alpha-helices; Blue: beta-strands; Green: loops connecting alpha-helices and beta-strands; Grey: protein backbone or coil regions that do not form distinct secondary structural elements (B) interaction type between FIPGL and MPO. Bright green dotted lines: conventional hydrogen bonds; Pink dotted lines: alkyl and Pi-alkyl bonds (C) 3D molecular docking representation of FIPGL with ACE; Red: alpha-helices; Blue: beta-strands; Green: loops connecting alpha-helices and beta-strands; Grey: protein backbone or coil regions that do not form distinct secondary structural elements (D) interaction type between FIPGL and ACE. Bright green dots lines: conventional hydrogen bonds; Light green dotted lines: Pi-donor hydrogen bonds; Pink dotted lines: alkyl and Pi-alkyl bonds.