ABSTRACT
Seaweeds, notably cochayuyo (Durvillaea incurvata), are recognized for their rich macro- and micronutrient content, along with their inhibitory effects on the α-glucosidase enzyme. The present study aims to evaluate the effectiveness of this inhibition in actual starchy food products under in vitro gastrointestinal conditions. This study utilized freeze-dried cochayuyo, extracted using hot pressurized liquid extraction with 50% ethanol at 120 °C and 1500 psi. The inhibition mechanism of α-glucosidase was determined, and the polyphenol composition of the extract was analyzed using Ultra-High-Performance Liquid Chromatography. This study further evaluated the extract's impact on starch digestibility, total phenolic content, and antioxidant capacity in pasta (noodles) as representative starchy food under gastrointestinal conditions. The results indicate that the α-glucosidase inhibition mechanism is of mixed type. Phenolic compounds, primarily tetraphloroethol, could contribute to this anti-enzymatic activity. The extract was observed to decrease starch digestibility, indicated by a lower rate constant (0.0158 vs. 0.0261 min-1) and digested starch at an infinite time (77.4 vs. 80.5 g/100 g). A significant increase (~1200 vs. ~390 µmol TROLOX/100 g) in antioxidant activity was also noted during digestion when the extract was used. Thus, this study suggests that the cochayuyo extract can reduce starch digestion and enhance antioxidant capacity under gastrointestinal conditions.
ABSTRACT
Brown marine macroalga Padina gymnospora (Phaeophyceae, Ochrophyta) produces both secondary metabolites (phlorotannins) and precipitate calcium carbonate (CaCO3-aragonite) on its surface as potential defensive strategies against herbivory. Here, we have evaluated the effect of natural concentrations of organic extracts (dichloromethane-DI; ethyl acetate-EA and methanol-ME, and three isolated fractions) and mineralized tissues of P. gymnospora as chemical and physical resistance, respectively, against the sea urchin Lytechinus variegatus through experimental laboratory feeding bioassays. Fatty acids (FA), glycolipids (GLY), phlorotannins (PH) and hydrocarbons (HC) were also characterized and/or quantified in extracts and fractions from P. gymnospora using nuclear magnetic resonance (NMR) and gas chromatography (GC) coupled to mass spectrometry (CG/MS) or GC coupled to flame ionization detector (FID) and chemical analysis. Our results showed that chemicals from the EA extract of P. gymnospora were significantly important in reducing consumption by L. variegatus, but the CaCO3 did not act as a physical protection against consumption by this sea urchin. An enriched fraction containing 76% of the new hydrocarbon 5Z,8Z,11Z,14Z-heneicosatetraene exhibited a significant defensive property, while other chemicals found in minor amounts, such as GLY, PH, saturated and monounsaturated FAs and CaCO3 did not interfere with the susceptibility of P. gymnospora to L. variegatus consumption. We suggest that the unsaturation of the 5Z,8Z,11Z,14Z-heneicosatetraene from P. gymnospora is probably an important structural characteristic responsible for the defensive property verified against the sea urchin.