Activity Of Phlorotannins Research Articles

Preparation, Characterization and Antioxidant Activities of Kelp Phlorotannin Nanoparticles.

Phlorotannins are a group of major polyphenol secondary metabolites found only in brown algae and are known for their bioactivities and multiple health benefits. However, they can be oxidized due to external factors and their bioavailability is low due to their low water solubility. In this study, the potential of utilizing nanoencapsulation with polyvinylpyrrolidone (PVP) to improve various activities of phlorotannins was explored. Phlorotannins encapsulated by PVP nanoparticles (PPNPS) with different loading ratios were prepared for characterization. Then, the PPNPS were evaluated for in vitro controlled release of phlorotannin, toxicity and antioxidant activities at the ratio of phlorotannin to PVP 1:8. The results indicated that the PPNPS showed a slow and sustained kinetic release of phlorotannin in simulated gastrointestinal fluids, they were non-toxic to HaCaT keratinocytes and they could reduce the generation of endogenous reactive oxygen species (ROS). Therefore, PPNPS have the potential to be a useful platform for the utilization of phlorotannin in both pharmaceutical and cosmetics industries.

Antioxidant activity of phlorotannins from brown algae

Abstract: The antioxidant activity of the phlorotannins extracted from five marine algae species (Saccharina latissima, Alaria esculenta, Laminaria digitata, Fucus vesiculosus and Ascophyllum nodosum) was studied. Three phlorotannin groups, including soluble, membrane-bound, and extracted membrane-bound phlorotannins obtained by two solvent extraction methods were investigated for their DPPH radical scavenging activity. F. vesiculosus and A. nodosum showed the highest phlorotannin yield (14.83 mg-extract/g-algae and 12.80 mg-extract/g-algae, respectively) among the five algae species. Their soluble phlorophannin (SP), membrane-bound phlorotannin (MP) and extracted membrane-bound phlorotannin (eMP) extracts all showed equal or greater DPPH radical scavenging activity than the commercial antioxidants of butylated hydroxytoluene and ascorbic acid. The antioxidant potential that combines phlorotannin yield and antioxidant activity of the MP extracts of F. vesiculosus and A. nodosum (5890 mL/g and 5278 mL/g algae, respectively) were higher than those of SP and eMP, suggesting that the MPs of F. vesiculosus and A. nodosum had great potential to be used as antioxidants. Different extraction methods also showed significantly different effects on the antioxidant activity of the phlorotannin extracts. Keywords: brown algae, phlorotannin, antioxidant activity, antioxidant, bioseparation, polyphenol, solvent extraction methods DOI: 10.25165/j.ijabe.20171006.2854 Citation: Liu X, Yuan W Q, Sharma-Shivappa R, van Zanten J. Antioxidant activity of phlorotannins from brown algae. Int J Agric & Biol Eng, 2017; 10(6): 184–191.

α‐Glucosidase‐ and α‐amylase‐inhibitory activities of phlorotannins from Eisenia bicyclis

In an effort to develop alternative therapeutic agents, strong inhibitory activity against α-glucosidase and α-amylase was detected in Eisenia bicyclis methanolic extract. In this study, two phlorotannins were isolated from E. bicyclis and characterised by chromatography and nuclear magnetic resonance. The active substances were identified as fucofuroeckol A (FF) and dioxinodehydroeckol (DD). To the authors' knowledge, this is the first report of the identification of these substances in E. bicyclis. However, to date, no antidiabetic activity of FF and DD has been reported. Both phlorotannins demonstrated significant inhibitory activity against α-glucosidase and α-amylase. FF showed potent antidiabetic activity, with IC(50) values of 131.34 nmol L(-1) against α-glucosidase and 42.91 µmol L(-1) against α-amylase. The corresponding IC(50) values of DD were 93.33 nmol L(-1) and 472.7 µmol L(-1) . Furthermore, kinetic analysis revealed that FF and DD exhibited non-competitive inhibitory activity against α-glucosidase. These results suggest that FF and DD may be candidates for the development of an antidiabetic pharmaceutical agent or food additive.