Glossary of Abbreviations iNOS: inducible nitric oxide synthase COX-2: cyclooxygenase 2 CAT: catalase SOD: superoxide dismutase GSH-px: glutathione peroxidase Bcl-2: -cell lymphoma 2 (anti-apoptotic protein of the Bcl-2 family) GLUT-4: glucose transporter type Fas: cell surface death receptor XIAP: X-linked inhibitor of apoptosis protein FLIP: FLICE (caspase 8)-inhibitory protein AKT: serine/threonine-specific protein kinase, also known as PKB (protein kinase B) Bid: BH3 interacting domain death agonist (pro-apoptotic protein of the Bcl-2 family) Bim: BH3 only protein (pro-apoptotic member of the Bcl-2 family) Bak: Bcl-2 homologous antagonist/killer (pro-apoptotic protein of the Bcl-2 family) Bax: Bcl-2-associated X protein (pro-apoptotic member of the Bcl-2 family) p53: tumor suppressor protein (p) 53 NF-B: nuclear factor kappa B, a transcription factor involved in stress responses and regulation of cell proliferation and apoptosis Bcl-xl: -cell lymphoma-extra large (anti-apoptotic protein of the Bcl-2 family) PI3K: phosphatidylinositol 3-kinase RAF-1: rapidly accelerated fibrosarcoma, a serine/threonine-specific kinase ERK: extracellular signal-regulated kinase EGFR: epidermal growth factor receptor, a proliferation-stimulating protein Con formato: Español (Chile) Con formato: Inglés (Estados Unidos) Con formato: Inglés (Reino Unido) According to Liu (2004), phytochemicals are categorized into six major groups: phenolic compounds, alkaloids, nitrogen-containing compounds, organosulfur compounds, phytosterols and carotenoids. According to Liu (2004), phytochemicals are bioactive non-nutritive compounds present in fruit, vegetables and other plant foods that have been related to reductions in the risks of major NCDs. They have been widely studied in the last two decades through in vitro assays, in vivo models and clinical trials, which have shed light into the structure-function relation responsible for their healthpromoting effects. In plants, phytochemicals accomplish defence and reproductive functions (Huang, Xiao, Burton-Freeman, & Edirisinghe, 2016). They are categorized into six major groups: phenolic compounds, alkaloids, nitrogen-containing compounds, organosulfur compounds, phytosterols and carotenoids. Phenolic compounds are the most studied phytochemicals since they are ubiquitous and abundant in all plant-based diets (Tsao, 2010). They are chemically defined as compounds having one or more aromatic rings with one or more hydroxyl groups (Liu, 2004). One high-value group of polyphenolic compounds-or polyphenols-only found in brown seaweeds are phlorotannins. These have attracted considerable interest because of their superior antioxidant capacity (Shibata, Ishimaru, Kawaguchi, Yoshikawa, & Hama, 2008; Wang et al., 2012) and valuable biological activities, such as anti-inflammatory, antihyperglycaemic and anti-tumour (Catarino, Silva, & Cardoso, 2017). Although phlorotannins have been widely studied through in vitro assays, in vivo models and some clinical trials, which have shed light into a possibl...

BackgroundIn plant-derived animal feedstuffs, nearly 80 % of the total phosphorus content is stored as phytate. However, phytate is poorly digested by monogastric animals such as poultry, swine and fish, as they lack the hydrolytic enzyme phytase; hence it is regarded as a nutritionally inactive compound from a phosphate bioavailability point of view. In addition, it also chelates important dietary minerals and essential amino acids. Therefore, dietary supplementation with bioavailable phosphate and exogenous phytases are required to achieve optimal animal growth. In order to simplify the obtaining and application processes, we developed a phytase expressing cell-wall deficient Chlamydomonas reinhardtii strain.ResultsIn this work, we developed a transgenic microalgae expressing a fungal phytase to be used as a food supplement for monogastric animals. A codon optimized Aspergillus niger PhyA E228K phytase (mE228K) with improved performance at pH 3.5 was transformed into the plastid genome of Chlamydomonas reinhardtii in order to achieve optimal expression. We engineered a plastid-specific construction harboring the mE228K gene, which allowed us to obtain high expression level lines with measurable in vitro phytase activity. Both wild-type and cell-wall deficient strains were selected, as the latter is a suitable model for animal digestion. The enzymatic activity of the mE228K expressing lines were approximately 5 phytase units per gram of dry biomass at pH 3.5 and 37 °C, similar to physiological conditions and economically competitive for use in commercial activities.ConclusionsA reference basis for the future biotechnological application of microalgae is provided in this work. A cell-wall deficient transgenic microalgae with phytase activity at gastrointestinal pH and temperature and suitable for pellet formation was developed. Moreover, the associated microalgae biomass costs of this strain would be between US$5 and US$60 per ton of feedstuff, similar to the US$2 per ton of feedstuffs of commercially available phytases. Our data provide evidence of phytate-hydrolyzing microalgae biomass for use as a food additive without the need for protein purification.

The increment of non-communicable chronic diseases is a constant concern worldwide, with type-2 diabetes mellitus being one of the most common illnesses. A mechanism to avoid diabetes-related hyperglycemia is to reduce food digestion/absorption by using anti-enzymatic (functional) ingredients. This research explored the potential of six common Chilean seaweeds to obtain anti-hyperglycemic polyphenol extracts, based on their capacity to inhibit key enzymes related with starch digestion. Ethanol/water hot pressurized liquid extraction (HPLE), which is an environmentally friendly method, was studied and compared to conventional extraction with acetone. Total polyphenols (TP), antioxidant activity, cytotoxicity and inhibition capacity on α-glucosidase and α-amylase were analyzed. Results showed that the Durvillaea antarctica (cochayuyo) acetone extract had the highest TP content (6.7 ± 0.7 mg gallic acid equivalents (GAE)/g dry seaweed), while its HPLE ethanol/water extract showed the highest antioxidant activity (680.1 ± 11.6 μmol E Trolox/g dry seaweed). No extract affected cell viability significantly. Only cochayuyo produced extracts having relevant anti-enzymatic capacity on both studied enzymes, showing a much stronger inhibition to α-glucosidase (even almost 100% at 1000 µg/mL) than to α-amylase. In conclusion, from the Chilean seaweeds considered in this study, cochayuyo is the most suitable for developing functional ingredients to moderate postprandial glycemic response (starchy foods), since it showed a clear enzymatic inhibition capacity and selectivity.

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Brown seaweed phlorotannins have shown the potential to promote several health benefits. Durvillaea incurvata and Lessonia spicata—species that are widely distributed in central and southern Chile—were investigated to obtain phlorotannin extracts with antioxidant and antihyperglycemic potential. The use of an environmentally friendly and food-grade glycerol-based pressurized hot liquid extraction (PHLE) process (15% v/v glycerol water) was assessed for the first time to obtain phlorotannins. Multiple effects were analyzed, including the effect of the species, harvesting area (Las Cruces and Niebla), and anatomical part (holdfast, stipe, and frond) on the extracts’ polyphenol content (TPC), antioxidant capacity (AC), and carbohydrate-hydrolyzing enzyme—α-glucosidase and α-amylase—inhibitory activity. Contaminants, such as mannitol, heavy metals (As, Cd, Pb, Hg, and Sn), and 5-hydroxymethylfurfural (HMF), were also determined. The anatomical part used demonstrated a significant impact on the extracts’ TPC and AC, with holdfasts showing the highest values (TPC: 95 ± 24 mg phloroglucinol equivalents/g dry extract; DPPH: 400 ± 140 μmol Trolox equivalents/g dry extract; ORAC: 560 ± 130 μmol TE/g dry extract). Accordingly, holdfast extracts presented the most potent α-glucosidase inhibition, with D. incurvata from Niebla showing an activity equivalent to fifteen times that of acarbose. Only one frond and stipe extract showed significant α-glucosidase inhibitory capacity. No α-amylase inhibition was found in any extract. Although no HMF was detected, potentially hazardous cadmium levels (over the French limit) and substantial mannitol concentrations—reaching up to 50% of the extract dry weight—were found in most seaweed samples and extracts. Therefore, further purification steps are suggested if food or pharmaceutical applications are intended for the seaweed PHLE extracts obtained in this study.